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• Developer Profile: Marcelo Quinta

  - by Tori Wieldt

  As the Java developer community lead for Oracle, the best part of my job is going to conferences and meeting Java developers. I’ve had the pleasure to meet men and women who are smart, fun and passionate about Java—they make the Java community happen. The current issue of Java Magazine provides profiles of other young Java developers around the world. Subscribe to read them! Marcelo Quinta Age: 24Occupation: Professor, Federal University of GoiasLocation: Goias, Brazil Twitter: @mrquinta Marcelo (white polo shirt, center) and class OTN: When did you realize that you were good at programming? When I was in graduate school, I developed a Java system that displayed worked out the logics of getting the maximum coverage using the fewest resources (for example, the minimum number of soldiers [and positions] needed for a battlefield. It may seems not difficult, but it's a hard problem to solve, mathematically. Here I was, a freshman, who came up with an app  "solving" it. Some Master's students use my software today. It was then I began to believe in what I could do.OTN: What most inspires you about programming?I'm really inspired by the challenges and tension that comes from solving a complicated problems. Lately, I've been doing a new system focused on education and digital inclusion and was very gratifying to see it working and the results. I felt useful for the community. OTN: What are some things you would like to accomplish using Java?Java is a very strong platform and that gives us power to develop applications for different devices and purposes, from home automation with little microcontrollers to systems in big servers. I would like to build more systems that integrate the people life or different business contexts, from PCs to cell phones and tablets, ubiquitously. I think IT has reached a level where the current challenge is to make systems that leverage existing technologies that are present in daily life. Java gives us a very interesting set of options to put it into practice, especially in systems that require more strength.OTN: What technical insights into Java technology have been most important to you?I have really enjoyed the way that Java has evolved with Oracle, with new features added, many of them which were suggested by the community. Java 7 came with substantial improvements in the language syntax and it seems that Java 8 takes it even further. I also made some applications in JavaFX and liked the new version. The Java GUI is on a higher level than is offered out there. I saw some JavaFX prototypes running in modern tablets and I got excited. OTN: What would you like to be doing 10 years from now?I want my work to make a difference for individuals or an institution. It would be interesting to be improving one of the systems that I am making today. Recently I've been mixing my hobbies and work, playing with Arduino and home automation. The JHome project, winner of the Duke's Choice Award in 2011, is very interesting to me.OTN: Do you listen to music when you write code? If so, what kind?Absolutely! I usually listen to electronic music (Prodigy, Fatboy Slim and Paul Oakenfold), rock (Metallica, Strokes, The Black Keys) and a bit of local alternative music. I live in Goiânia, "The Brazilian Seattle" and I profit from it very well. OTN: What do you do when you're not programming?I like to play guitar and to fish. Last year I sold my economy car and bought a old jeep. Some people called me crazy, but since then I've been having a great time and having adventures on the backroads of Brazil. Once I broke my glasses in a funny game involving my car's suspension and the airbags. OTN: Does your girlfriend think you are crazy?Crazy is someone who doesn't have courage to do strange things! My girlfriend likes my style. =D Subscribe to the free Java Magazine to read profiles of other young Java developers. Visit the Java channel on YouTube to see a video of Marcelo in action.

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• Where to start with game development?

  - by steven_desu

  I asked this earlier in this thread at stackoverflow.com. One of the early comments redirected me here to gamedev.stackexchange.com, so I'm reposting here. Searching for related questions I found a number of very specific questions, but I'm afraid the specifics have proved fruitless for me and after 4 hours on Google I'm no closer than I started, so I felt reaching out to a community might be in order. First, my goal: I've never made a game before, although I've muddled over the possibility several times. I decided to finally sit down and start learning how to code games, use game engines, etc. All so that one day (hopefully soon) I'll be able to make functional (albeit simple) games. I can start adding complexity later, for now I'd be glad to have a keyboard-controlled camera moving in a 3D world with no interaction beyond that. My background: I've worked in SEVERAL programming languages ranging from PHP to C++ to Java to ASM. I'm not afraid of any challenges that come with learning the new syntax or limitations inherent in a new language. All of my past programming experience, however, has been strictly non-graphical and usually with little or extremely simple interaction during execution. I've created extensive and brilliant algorithms for solving logical and mathematical problems as well as graphing problems. However in every case input was either defined in a file, passed form an HTML form, or typed into the console. Real-time interaction with the user is something with which I have no experience. My question: Where should I start in trying to make games? Better yet- where should I start in trying to create a keyboard-navigable 3D environment? In searching online I've found several resources linking to game engines, graphics engines, and physics engines. Here's a brief summary of my experiences with a few engines I tried: Unreal SDK: The tutorial videos assume that you already have in-depth knowledge of 3D modeling, graphics engines, animations, etc. The "Getting Started" page offers no formal explanation of game development but jumps into how Unreal can streamline processes it assumes you're already familiar with. After downloading the SDK and launching it to see if the tools were as intuitive as they claimed, I was greeted with about 60 buttons and a blank void for my 3D modeling. Clicking on "add volume" (to attempt to add a basic cube) I was met with a menu of 30 options. Panicking, I closed the editor. Crystal Space: The website seemed rather informative, explaining that Crystal Space was just for graphics and the companion software, CEL, provided entity logic for making games. A demo game was provided, which was built using "CELStart", their simple tool for people with no knowledge of game programming. I launched the game to see what I might look forward to creating. It froze several times, the menus were buggy, there were thousands of graphical glitches, enemies didn't respond to damage, and when I closed the game it locked up. Gave up on that engine. IrrLicht: The tutorial assumes I have Visual Studio 6.0 (I have Visual Studio 2010). Following their instructions I was unable to properly import the library into Visual Studio and unable to call any of the functions that they kept using. Manually copying header files, class files, and DLLs into my project's folder - the project failed to properly compile. Clearly I'm not off to a good start and I'm going in circles. Can someone point me in the right direction? Should I start by downloading a program like Blender and learning 3D modeling, or should I be learning how to use a graphics engine? Should I look for an all-inclusive game engine, or is it better to try and code my own game logic? If anyone has actually made their own games, I would prefer to hear how they got their start. Also- taking classes at my school is not an option. Nothing is offered.

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• Where to start with game development?

  - by steven_desu

  Searching for related questions I found a number of very specific questions, but I'm afraid the specifics have proved fruitless for me and after 4 hours on Google I'm no closer than I started, so I felt reaching out to a community might be in order. First, my goal: I've never made a game before, although I've muddled over the possibility several times. I decided to finally sit down and start learning how to code games, use game engines, etc. All so that one day (hopefully soon) I'll be able to make functional (albeit simple) games. I can start adding complexity later, for now I'd be glad to have a keyboard-controlled camera moving in a 3D world with no interaction beyond that. My background: I've worked in SEVERAL programming languages ranging from PHP to C++ to Java to ASM. I'm not afraid of any challenges that come with learning the new syntax or limitations inherent in a new language. All of my past programming experience, however, has been strictly non-graphical and usually with little or extremely simple interaction during execution. I've created extensive and brilliant algorithms for solving logical and mathematical problems. However in every case input was either defined in a file, passed form an HTML form, or typed into the console. Real-time interaction with the user is something with which I have no experience. My question: Where should I start in trying to make games? Better yet- where should I start in trying to create a keyboard-navigable 3D environment? In searching online I've found several resources linking to game engines, graphics engines, and physics engines. Here's a brief summary of my experiences with a few engines I tried: Unreal SDK: The tutorial videos assume that you already have in-depth knowledge of 3D modeling, graphics engines, animations, etc. The "Getting Started" page offers no formal explanation of game development but jumps into how Unreal can streamline processes it assumes you're already familiar with. After downloading the SDK and launching it to see if the tools were as intuitive as they claimed, I was greeted with about 60 buttons and a blank void for my 3D modeling. Clicking on "add volume" (to attempt to add a basic cube) I was met with a menu of 30 options. Panicking, I closed the editor. Crystal Space: The website seemed rather informative, explaining that Crystal Space was just for graphics and the companion software, CEL, provided entity logic for making games. A demo game was provided, which was built using "CELStart", their simple tool for people with no knowledge of game programming. I launched the game to see what I might look forward to creating. It froze several times, the menus were buggy, there were thousands of graphical glitches, enemies didn't respond to damage, and when I closed the game it locked up. Gave up on that engine. IrrLicht: The tutorial assumes I have Visual Studio 6.0 (I have Visual Studio 2010). Following their instructions I was unable to properly import the library into Visual Studio and unable to call any of the functions that they kept using. Manually copying header files, class files, and DLLs into my project's folder - the project failed to properly compile. Clearly I'm not off to a good start and I'm going in circles. Can someone point me in the right direction? Should I start by downloading a program like Blender and learning 3D modeling, or should I be learning how to use a graphics engine? Should I look for an all-inclusive game engine, or is it better to try and code my own game logic? If anyone has actually made their own games, I would prefer to hear how they got their start. Also- taking classes at my school is not an option. Nothing is offered.

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• Tuning Red Gate: #1 of Many

  - by Grant Fritchey

  Everyone runs into performance issues at some point. Same thing goes for Red Gate software. Some of our internal systems were running into some serious bottlenecks. It just so happens that we have this nice little SQL Server monitoring tool. What if I were to, oh, I don't know, use the monitoring tool to identify the bottlenecks, figure out the causes and then apply a fix (where possible) and then start the whole thing all over again? Just a crazy thought. OK, I was asked to. This is my first time looking through these servers, so here's how I'd go about using SQL Monitor to get a quick health check, sort of like checking the vitals on a patient. First time opening up our internal SQL Monitor instance and I was greeted with this: Oh my. Maybe I need to get our internal guys to read my blog. Anyway, I know that there are two servers where most of the load is. I'll drill down on the first. I'm selecting the server, not the instance, by clicking on the server name. That opens up the Global Overview page for the server. The information here much more applicable to the "oh my gosh, I have a problem now" type of monitoring. But, looking at this, I am seeing something immediately. There are four(4) drives on the system. The C:\ has an average read time of 16.9ms, more than double the others. Is that a problem? Not sure, but it's something I'll look at. It's write time is higher too. I'll keep drilling down, first, to the unclosed alerts on the server. Now things get interesting. SQL Monitor has a number of different types of alerts, some related to error states, others to service status, and then some related to performance. Guess what I'm seeing a bunch of right here: Long running queries and long job durations. If you check the dates, they're all recent, within the last 24 hours. If they had just been old, uncleared alerts, I wouldn't be that concerned. But with all these, all performance related, and all in the last 24 hours, yeah, I'm concerned. At this point, I could just start responding to the Alerts. If I click on one of the the Long-running query alerts, I'll get all kinds of cool data that can help me determine why the query ran long. But, I'm not in a reactive mode here yet. I'm still gathering data, trying to understand how the server works. I have the information that we're generating a lot of performance alerts, let's sock that away for the moment. Instead, I'm going to back up and look at the Global Overview for the SQL Instance. It shows all the databases on the server and their status. Then it shows a number of basic metrics about the SQL Server instance, again for that "what's happening now" view or things. Then, down at the bottom, there is the Top 10 expensive queries list: This is great stuff. And no, not because I can see the top queries for the last 5 minutes, but because I can adjust that out 3 days. Now I can see where some serious pain is occurring over the last few days. Databases have been blocked out to protect the guilty. That's it for the moment. I have enough knowledge of what's going on in the system that I can start to try to figure out why the system is running slowly. But, I want to look a little more at some historical data, to understand better how this server is behaving. More next time.

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• C# 5 Async, Part 2: Asynchrony Today

  - by Reed

  The .NET Framework has always supported asynchronous operations.  However, different mechanisms for supporting exist throughout the framework.  While there are at least three separate asynchronous patterns used through the framework, only the latest is directly usable with the new Visual Studio Async CTP.  Before delving into details on the new features, I will talk about existing asynchronous code, and demonstrate how to adapt it for use with the new pattern. The first asynchronous pattern used in the .NET framework was the Asynchronous Programming Model (APM).  This pattern was based around callbacks.  A method is used to start the operation.  It typically is named as BeginSomeOperation.  This method is passed a callback defined as an AsyncCallback, and returns an object that implements IAsyncResult.  Later, the IAsyncResult is used in a call to a method named EndSomeOperation, which blocks until completion and returns the value normally directly returned from the synchronous version of the operation.  Often, the EndSomeOperation call would be called from the callback function passed, which allows you to write code that never blocks. While this pattern works perfectly to prevent blocking, it can make quite confusing code, and be difficult to implement.  For example, the sample code provided for FileStream’s BeginRead/EndRead methods is not simple to understand.  In addition, implementing your own asynchronous methods requires creating an entire class just to implement the IAsyncResult. Given the complexity of the APM, other options have been introduced in later versions of the framework.  The next major pattern introduced was the Event-based Asynchronous Pattern (EAP).  This provides a simpler pattern for asynchronous operations.  It works by providing a method typically named SomeOperationAsync, which signals its completion via an event typically named SomeOperationCompleted. The EAP provides a simpler model for asynchronous programming.  It is much easier to understand and use, and far simpler to implement.  Instead of requiring a custom class and callbacks, the standard event mechanism in C# is used directly.  For example, the WebClient class uses this extensively.  A method is used, such as DownloadDataAsync, and the results are returned via the DownloadDataCompleted event. While the EAP is far simpler to understand and use than the APM, it is still not ideal.  By separating your code into method calls and event handlers, the logic of your program gets more complex.  It also typically loses the ability to block until the result is received, which is often useful.  Blocking often requires writing the code to block by hand, which is error prone and adds complexity. As a result, .NET 4 introduced a third major pattern for asynchronous programming.  The Task<T> class introduced a new, simpler concept for asynchrony.  Task and Task<T> effectively represent an operation that will complete at some point in the future.  This is a perfect model for thinking about asynchronous code, and is the preferred model for all new code going forward.  Task and Task<T> provide all of the advantages of both the APM and the EAP models – you have the ability to block on results (via Task.Wait() or Task<T>.Result), and you can stay completely asynchronous via the use of Task Continuations.  In addition, the Task class provides a new model for task composition and error and cancelation handling.  This is a far superior option to the previous asynchronous patterns. The Visual Studio Async CTP extends the Task based asynchronous model, allowing it to be used in a much simpler manner.  However, it requires the use of Task and Task<T> for all operations.

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• Is inconsistent formatting a sign of a sloppy programmer?

  - by dreza

  I understand that everyone has their own style of programming and that you should be able to read other people's styles and accept it for what it is. However, would one be considered a sloppy programmer if one's style of coding was inconsistent across whatever standard they were working against? Some example of inconsistencies might be: Sometimes naming private variables with _ and sometimes not Sometimes having varying indentations within code blocks Not aligning braces up i.e. same column if using start using new line style Spacing not always consistent around operators i.e. p=p+1, p+=1 vs other times p =p+1 or p = p + 1 etc Is this even something that as a programmer I should be concerned with addressing? Or is it such a minor nit picking thing that at the end of the day I should just not worry about it and worry about what the end user sees and whether the code works rather than how it looks while working? Is it sloppy programming or just over obsessive nit picking? EDIT: After some excellent comments I realized I may have left out some information in my question. This question came about after reviewing another colleagues code check-in and noticing some of these things and then realizing that I've seen these kind of in-consistencies in previous check-ins. It then got me thinking about my code and whether I do the same things and noticed that I typically don't etc I'm not suggesting his technique is either bad or good in this question or whether his way of doing things is right or wrong. EDIT: To answer some queries to some more good feed back. The specific instance this review occurred in was using Visual Studio 2010 and programming in c# so I don't think the editor would cause any issues. In fact it should only help I would hope. Sorry if I left that piece of info out and it effects any current answers. I was trying to be a bit more generic in understanding if this would be considered sloppy etc. And to add an even more specific example of a code piece I saw during reading of the check-in: foreach(var block in Blocks) { // .. some other code in here foreach(var movement in movements) { movement.Moved.Zero(); } // the un-formatted brace } Such a minor thing I know, but many small things add up(???), and I did have to double glance at the code at the time to see where everything lined up I guess. Please note this code was formatted appropriately before this check-in. EDIT: After reading some great answers and varying thoughts, the summary I've taken from this was. It's not necessarily a sign of a sloppy programmer however as programmers we have a duty (to ourselves and other programmers) to make the code as readable as possible to assist in further ongoing development. However it can hint at inadequacies which is something that is only possible to review on a case by case (person by person) basis. There are many reasons why this might occur. They should be taken in context and worked through with the person/people involved if reasonable. We have a duty to try and help all programmers become better programmers! In the good old days when development was done using good old notepad (or other simple text editing tool) this occurred much more frequently. However we have the assistance of modern IDE's now so although we shouldn't necessarily become OTT about this, it should still probably be addressed to some degree. We as programmers vary in our standards, styles and approaches to solutions. However it seems that in general we all take PRIDE in our work and as a trait it is something that can stand programmers apart. Making something to the best of our abilities both internal (code) and external (end user result) goes along way to giving us that big fat pat on the back that we may not go looking for but swells our heart with pride. And finally to quote CrazyEddie from his post below. Don't sweat the small stuff

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• Things I've noticed with DVCS

  - by Wes McClure

  Things I encourage: Frequent local commits This way you don't have to be bothered by changes others are making to the central repository while working on a handful of related tasks.  It's a good idea to try to work on one task at a time and commit all changes at partitioned stopping points.  A local commit doesn't have to build, just FYI, so a stopping point doesn't mean a build point nor a point that you can push centrally.  There should be several of these in any given day.  2 hours is a good indicator that you might not be leveraging the power of frequent local commits.  Once you have verified a set of changes works, save them away, otherwise run the risk of introducing bugs into it when working on the next task.  The notion of a task By task I mean a related set of changes that can be completed in a few hours or less.  In the same token don’t make your tasks so small that critically related changes aren’t grouped together.  Use your intuition and the rest of these principles and I think you will find what is comfortable for you. Partial commits Sometimes one task explodes or unknowingly encompasses other tasks, at this point, try to get to a stopping point on part of the work you are doing and commit it so you can get that out of the way to focus on the remainder.  This will often entail committing part of the work and continuing on the rest. Outstanding changes as a guide If you don't commit often it might mean you are not leveraging your version control history to help guide your work.  It's a great way to see what has changed and might be causing problems.  The longer you wait, the more that has changed and the harder it is to test/debug what your changes are doing! This is a reason why I am so picky about my VCS tools on the client side and why I talk a lot about the quality of a diff tool and the ability to integrate that with a simple view of everything that has changed.  This is why I love using TortoiseHg and SmartGit: they show changed files, a diff (or two way diff with SmartGit) of the current selected file and a commit message all in one window that I keep maximized on one monitor at all times. Throw away / stash commits There is extreme value in being able to throw away a commit (or stash it) that is getting out of hand.  If you do not commit often you will have to isolate the work you want to commit from the work you want to throw away, which is wasted productivity and highly prone to errors.  I find myself doing this about once a week, especially when doing exploratory re-factoring.  It's much easier if I can just revert all outstanding changes. Sync with the central repository daily The rest of us depend on your changes.  Don't let them sit on your computer longer than they have to.  Waiting increases the chances of merge conflict which just decreases productivity.  It also prohibits us from doing deploys when people say they are done but have not merged centrally.  This should be done daily!  Find a way to partition the work you are doing so that you can sync at least once daily. Things I discourage: Lots of partial commits right at the end of a series of changes If you notice lots of partial commits at the end of a set of changes, it's likely because you weren't frequently committing, nor were you watching for the size of the task expanding beyond a single commit.  Chances are this cost you productivity if you use your outstanding changes as a guide, since you would have an ever growing list of changes. Committing single files Committing single files means you waited too long and no longer understand all the changes involved.  It may mean there were overlapping changes in single files that cannot be isolated.  In either case, go back to the suggestions above to avoid this.  Committing frequently does not mean committing frequently right at the end of a day's work. It should be spaced out over the course of several tasks, not all at the end in a 5 minute window.

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• Types of semantic bugs, logic errors [closed]

  - by C-Otto

  I am a PhD student and currently focus on automatically finding instances of new types of bugs in (Java) programs that cannot be found by existing tools like FindBugs. The existing tool currently is used to prove/disprove termination of (Java) programs. I have some ideas (see below), but I could need more input from you (experienced programmers, potential users of my tool). What kind of bugs do you wish to find? What types of bugs exist and might be suitable for my analysis? One strength of the approach I use is detailled information about the heap. So in contrast to FindBugs, I can work with knowledge of the form "variable x and variable y are disjoint on the heap" or "variable z is not cyclic". It is also possible to see if a method might have side effects (and if so, which variables may/may not be affected by it). Example 1: Vacuous call: Graph graphOne = createGraph(); Graph graphTwo = createGraph(); Node source = graphTwo.getRootNode(); for (Node n : graphOne.getNodes()) { if (areConnected(source, n)) { graphTwo.addNode(n); } } Imagine createGraph() creates a fresh graph, so that graphOne and graphTwo are disjoint on the heap. Then, because source is taken from graphTwo instead of graphOne, the call to areConnected always returns false. In this situation I could find out that the call areConnected is useless (because it does not have any side effect and the return value always is false) which helps finding the real bug (taking source from the wrong graph). For this the information that x and y are disjoint (because graphOne and graphTwo are disjoint) is crucial. This bug is related to calling x.equals(y) where x and y are objects of different classes. In this scenario, most implementations of equals() always return false, which most likely is not the intended result. FindBugs already finds this bug (hardcoded to equals(), semantics of implementation is not checked). Example 2: Useless code: someCode(); while (something()) { yetMoreSomething(); } moreCode(); In the case that the loop (so the code in something() and yetMoreSomething()) does not modify anything visible outside the loop, it does not make sense to run this code - the program has the same behaviour as someCode(); moreCode() (i.e., without the loop). To find this out, one needs detailled information about the side effects of the (possibly useless) code. If I can prove that the code does not have any side effect that can be observed afterwards (in the example: in moreCode() or later), then the code indeed is useless. Of course, here Input/Output of any form must be seen as a side effect, so that a System.out.println(...) is not considered useless. Example 3: Ignored return value: Instead of x = foo(); and making use of x, the method is called without storing the result: foo();. If the method does not have any side effect, its invocation is useless and can be dropped. Most likely, the bug here is that the returned value should have been used. Here, too, detailled information about side effects are needed. Can you think of similar types of bugs that might be detected (only) with detailled information about the heap, side effects, semantics of called methods, ...? Did you encounter bugs related to the ones shown below in "real life"? By the way, the tool is AProVE and Java related publications can be found on my homepage. Thanks a lot, Carsten

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• Disneyland Inside Out on iPhone and Android

  - by Ryan Cain

  It's hard to believe October was the last time I was over here on my blog.  Ironically after getter the developer phone from Microsoft I have been knee deep in iPhone programming and for the past few weeks Android programming again.  This time I've spent all my non-working hours programming a fun project for my "other" website, Disneyland Inside Out.  Disneyland Inside Out, a vacation planning site for Disneyland in California, has been around in various forms since June 1996.  It has always been a place for me to explore new technologies and learn about some of the new trends on the web.  I recently migrated the site over to DotNetNuke and have been building out custom modules for DNN.  I've also been hacking things together w/ the URLRewrite module in IIS 7.5 to provide strong SEO optimized URLs.  I can't say all that has really stuck within the DNN model of doing things, but it has worked pretty well. As part of my learning process, I spent most of the Fall bringing Disneyland Inside Out to the iPhone.  I will post more details on my development experiences later.  But this project gave me a really great opportunity to get a good feel for Objective-C development.  After 3 months I actually feel somewhat competent in the language and iPhone SDK, instead of just floundering around getting things to work.  The project also gave me a chance to play with some new frameworks on the iPhone and really dig into the Facebook SDK.  I also dug into some of the Gowalla REST api's as well.  We've been live with the app in iTunes for just about 10 days now, and have been sitting in the top 200 of free travel apps for the past few days.  You can get more info and the direct iTunes download link on our site: Disneyland Inside Out for iPhone Since launching the iPhone version I have gotten back into Android development, porting the Disneyland Inside Out app over to Android.  As I said in my first review of iPhone vs. Android, coming from a managed code background, Android is much easier to get going with.  I just about 3 weeks total I will have about 85 - 90% of the functionality up and running in the Android app, that took probably 1.5 - 2x's that time for iPhone.  That isn't a totally fair comparison as I am much more comfortable w/ Xcode and Objective-C today and can get some of the basic stuff done much faster than I could in the fall.  Though I'd say some of the hardest code to debug is still the null pointer issues on objects that were dealloc'd too early in Objective-C.  This isn't too bad with the NSZoombies enabled for synchronous code, but when you have a lot of async, which my app does, it can be hairy at times to track exactly what was causing the issue.   I will post more details later, as I am trying to wrap up a beta of the Android app today.  But in the meantime, if you have an iPhone, iPod Touch or iPad head on over to the site and take a look at my app.

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• Communication between state machines with hidden transitions

  - by slartibartfast

  The question emerged for me in embedded programming but I think it can be applied to quite a number of general networking situations e.g. when a communication partner fails. Assume we have an application logic (a program) running on a computer and a gadget connected to that computer via e.g. a serial interface like RS232. The gadget has a red/green/blue LED and a button which disables the LED. The LEDs color can be driven by software commands over the serial interface and the state (red/green/blue/off) is read back and causes a reaction in the application logic. Asynchronous behaviour of the application logic with regard to the LED color down to a certain delay (depending on the execution cycle of the application) is tolerated. What we essentially have is a resource (the LED) which can not be reserved and handled atomically by software because the (organic) user can at any time press the button to interfere/break the software attempt to switch the LED color. Stripping this example from its physical outfit I dare to say that we have two communicating state machines A (application logic) and G (gadget) where G executes state changes unbeknownst to A (and also the other way round, but this is not significant in our example) and only A can be modified at a reasonable price. A needs to see the reaction and state of G in one piece of information which may be (slightly) outdated but not inconsistent with respect to the short time window when this information was generated on the side of G. What I am looking for is a concise method to handle such a situation in embedded software (i.e. no layer/framework like CORBA etc. available). A programming technique which is able to map the complete behaviour of both participants on classical interfaces of a classical programming language (C in this case). To complicate matters (or rather, to generalize), a simple high frequency communication cycle of A to G and back (IOW: A is rapidly polling G) is out of focus because of technical restrictions (delay of serial com, A not always active, etc.). What I currently see as a general solution is: the application logic A as one thread of execution an adapter object (proxy) PG (presenting G inside the computer), together with the serial driver as another thread a communication object between the two (A and PG) which is transactionally safe to exchange The two execution contexts (threads) on the computer may be multi-core or just interrupt driven or tasks in an RTOS. The com object contains the following data: suspected state (written by A): effectively a member of the power set of states in G (in our case: red, green, blue, off, red_or_green, red_or_blue, red_or_off...etc.) command data (written by A): test_if_off, switch_to_red, switch_to_green, switch_to_blue operation status (written by PG): operation_pending, success, wrong_state, link_broken new state (written by PG): red, green, blue, off The idea of the com object is that A writes whichever (set of) state it thinks G is in, together with a command. (Example: suspected state="red_or_green", command: "switch_to_blue") Notice that the commands issued by A will not work if the user has switched off the LED and A needs to know this. PG will pick up such a com object and try to send the command to G, receive its answer (or a timeout) and set the operation status and new state accordingly. A will take back the oject once it is no longer at operation_pending and can react to the outcome. The com object could be separated of course (into two objects, one for each direction) but I think it is convenient in nearly all instances to have the command close to the result. I would like to have major flaws pointed out or hear an entirely different view on such a situation.

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• Move on and look elsewhere, or confront the boss?

  - by Meister

  Background: I have my Associates in Applied Science (Comp/Info Tech) with a strong focus in programming, and I'm taking University classes to get my Bachelors. I was recently hired at a local company to be a Software Engineer I on a team of about 8, and I've been told they're looking to hire more. This is my first job, and I was offered what I feel to be an extremely generous starting salary ($30/hr essentially + benefits and yearly bonus). What got me hired was my passion for programming and a strong set of personal projects. Problem: I had no prior experience when I interviewed, so I didn't know exactly what to ask them about the company when I was hired. I've spotted a number of warning signs and annoyances since then, such as: Four developers when I started, with everyone talking about "Ben" or "Ryan" leaving. One engineer hired thirty days before me, one hired two weeks after me. Most of the department has been hiring a large number of people since I started. Extremely limited internet access. I understand the idea from an IT point of view, but not only is Facebook blocked, but so it Youtube, Twitter, and Pandora. I've also figured out that they block all access to non-DNS websites (http://xxx.xxx.xxx.xxx/) and strangely enough Miranda-IM. Low cubicles. Which is fine because I like my immediate coworkers, but they put the developers with the customer service, customer training, and QA department in a huge open room. Noise, noise, noise, and people stop to chitchat all day long. Headphones only go so far. Several emails have been sent out by my boss since I started telling us programmers to not talk about non-work-related-things like Video Games at our cubicles, despite us only spending maybe five minutes every few hours doing so. Further digging tells me that this is because someone keeps complaining that the programmers are "slacking off". People are looking over my shoulder all day. I was in the Freenode webchat to get help with a programming issue, and within minutes I had an email from my boss (to all the developers) telling us that we should NOT be connected to any outside chat servers at work. Version control system from 2005 that we must access with IE and keep the Java 1.4 JRE installed to be able to use. I accidentally updated to Java 6 one day and spent the next two days fighting with my PC to undo this "problem". No source control, no comments on anything, no standards, no code review, no unit testing, no common sense. I literally found a problem in how they handle string resource translations that stems from the simple fact that they don't trim excess white spaces, leading to developers doing: getResource("Date: ") instead of: getResource("Date") + ": ", and I was told to just add the excess white spaces back to the database instead of dealing with the issue directly. Some of these things I'd like to try to understand, but I like having IRC open to talk in a few different rooms during the day and keep in touch with friends/family over IM. They don't break my concentration (not NEARLY as much as the lady from QA stopping by to talk about her son), but because people are looking over my shoulder all day as they walk by they complain when they see something that's not "programmer-looking work". I've been told by my boss and QA that I do good, fast work. I should be judged on my work output and quality, not what I have up on my screen for the five seconds you're walking by So, my question is, even though I'm just barely at my 90 days: How do you decide to move on from a job and looking elsewhere, or when you should start working with your boss to resolve these issues? Is it even possible to get the boss to work with me in many of these things? This is the only place I heard back from even though I sent out several resume's a day for several months, and this place does pay well for putting up with their many flaws, but I'm just starting to get so miserable working here already. Should I just put up with it?

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• Ubuntu 12.04 LXC nat prerouting not working

  - by petermolnar

  I have a running Debian Wheezy setup I copied exactly to an Ubuntu 12.04 ( elementary OS, used as desktop as well ) While the Debian setup runs flawlessly, the Ubuntu version dies on the prerouting to containers ( or so it seems ) In short: lxc works containers work and run connecting to container from host OK ( including mixed ports & services ) connecting to outside world from container is fine What does not work is connecting from another box to the host on a port that should be NATed to a container. The setups: /etc/rc.local CMD_BRCTL=/sbin/brctl CMD_IFCONFIG=/sbin/ifconfig CMD_IPTABLES=/sbin/iptables CMD_ROUTE=/sbin/route NETWORK_BRIDGE_DEVICE_NAT=lxc-bridge HOST_NETDEVICE=eth0 PRIVATE_GW_NAT=192.168.42.1 PRIVATE_NETMASK=255.255.255.0 PUBLIC_IP=192.168.13.100 ${CMD_BRCTL} addbr ${NETWORK_BRIDGE_DEVICE_NAT} ${CMD_BRCTL} setfd ${NETWORK_BRIDGE_DEVICE_NAT} 0 ${CMD_IFCONFIG} ${NETWORK_BRIDGE_DEVICE_NAT} ${PRIVATE_GW_NAT} netmask ${PRIVATE_NETMASK} promisc up Therefore lxc network is 192.168.42.0/24 and the host eth0 ip is 192.168.13.100; setup via network manager as static address. iptables: *mangle :PREROUTING ACCEPT [0:0] :INPUT ACCEPT [0:0] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [0:0] :POSTROUTING ACCEPT [0:0] COMMIT *filter :FORWARD ACCEPT [0:0] :INPUT DROP [0:0] :OUTPUT ACCEPT [0:0] # Accept traffic from internal interfaces -A INPUT -i lo -j ACCEPT # accept traffic from lxc network -A INPUT -d 192.168.42.1 -s 192.168.42.0/24 -j ACCEPT # Accept internal traffic Make sure NEW incoming tcp connections are SYN # packets; otherwise we need to drop them: -A INPUT -p tcp ! --syn -m state --state NEW -j DROP # Packets with incoming fragments drop them. This attack result into Linux server panic such data loss. -A INPUT -f -j DROP # Incoming malformed XMAS packets drop them: -A INPUT -p tcp --tcp-flags ALL ALL -j DROP # Incoming malformed NULL packets: -A INPUT -p tcp --tcp-flags ALL NONE -j DROP # Accept traffic with the ACK flag set -A INPUT -p tcp -m tcp --tcp-flags ACK ACK -j ACCEPT # Allow incoming data that is part of a connection we established -A INPUT -m state --state ESTABLISHED -j ACCEPT # Allow data that is related to existing connections -A INPUT -m state --state RELATED -j ACCEPT # Accept responses to DNS queries -A INPUT -p udp -m udp --dport 1024:65535 --sport 53 -j ACCEPT # Accept responses to our pings -A INPUT -p icmp -m icmp --icmp-type echo-reply -j ACCEPT # Accept notifications of unreachable hosts -A INPUT -p icmp -m icmp --icmp-type destination-unreachable -j ACCEPT # Accept notifications to reduce sending speed -A INPUT -p icmp -m icmp --icmp-type source-quench -j ACCEPT # Accept notifications of lost packets -A INPUT -p icmp -m icmp --icmp-type time-exceeded -j ACCEPT # Accept notifications of protocol problems -A INPUT -p icmp -m icmp --icmp-type parameter-problem -j ACCEPT # Respond to pings, but limit -A INPUT -m icmp -p icmp --icmp-type echo-request -m state --state NEW -m limit --limit 6/s -j ACCEPT # Allow connections to SSH server -A INPUT -p tcp -m tcp --dport 22 -m state --state NEW -m limit --limit 12/s -j ACCEPT COMMIT *nat :OUTPUT ACCEPT [0:0] :PREROUTING ACCEPT [0:0] :POSTROUTING ACCEPT [0:0] -A PREROUTING -d 192.168.13.100 -p tcp -m tcp --dport 2221 -m state --state NEW -m limit --limit 12/s -j DNAT --to-destination 192.168.42.11:22 -A PREROUTING -d 192.168.13.100 -p tcp -m tcp --dport 80 -m state --state NEW -m limit --limit 512/s -j DNAT --to-destination 192.168.42.11:80 -A PREROUTING -d 192.168.13.100 -p tcp -m tcp --dport 443 -m state --state NEW -m limit --limit 512/s -j DNAT --to-destination 192.168.42.11:443 -A POSTROUTING -d 192.168.42.0/24 -o eth0 -j SNAT --to-source 192.168.13.100 -A POSTROUTING -o eth0 -j MASQUERADE COMMIT sysctl: net.ipv4.conf.all.forwarding = 1 net.ipv4.conf.all.mc_forwarding = 0 net.ipv4.conf.default.forwarding = 1 net.ipv4.conf.default.mc_forwarding = 0 net.ipv4.ip_forward = 1 I've set up full iptables log on the container; none of the packets addressed to 192.168.13.100, port 80 is reaching the container. I've even tried different kernels ( server kernel, raring lts kernel, etc ), modprobe everything iptables & nat related, nothing. Any ideas?

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• [EF + ORACLE] Updating and Deleting Entities

  - by JTorrecilla

  Prologue In previous chapters we have seen how to insert data through EF, with and without sequences. In this one, we are going to see how to Update and delete Data from the DB. Updating data The update of the Entity Data (properties) is a very common and easy action. Before of change any of the properties of the Entity, we can check the EntityState property, and we can see that is EntityState.Unchanged.   For making an update it is needed to get the Entity which will be modified. In the following example, I use the GetEmployeeByNumber to get a valid Entity: 1: EMPLEADOS emp=GetEmployeeByNumber(2); 2: emp.Name="a"; 3: emp.Phone="2"; 4: emp.Mail="aa"; After modifying the desired properties of the Entity, we are going to check again Entitystate property, which now has the EntityState.Modified value. To persist the changes to the DB is necessary to invoke the SaveChanges function of our context. 1: context.SaveChanges(); After modifying the desired properties of the Entity, we are going to check again Entitystate property, which now has the EntityState.Modified value. To persist the changes to the DB is necessary to invoke the SaveChanges function of our context. If we check again the EntityState property we will see that the value will be EntityState.Unchanged.   Deleting Data Another easy action is to delete an Entity.   The first step to delete an Entity from the DB is to select the entity: 1: CLIENTS selectedClient = GetClientByNumber(15); 2: context.CLIENTES.DeleteObject(clienteSeleccionado); Before invoking the DeleteObject function, we will check EntityStet which value must be EntityState.Unchanged. After deleting the object, the state will be changed to EntitySate.Deleted. To commit the action we have to invoke the SaveChanges function. Aftar that, the EntityState property will be EntityState.Detached. Cascade Entity Framework lets cascade updates and deletes, although I never see cascade updates. What is a cascade delete? A cascade delete is an action that allows to delete all the related object to the object we desire to delete. This option could be established in the DB manager, or it could be in the EF model designer. For example: With a given relation (1-N) between clients and requests. The common situation must be to let delete those clients whose have no requests. If we select the relation between both entities, and press the second mouse button, we can see the properties panel of the relation. The props are: This grid shows the relations indicating the Master table(Clients) and the end point (Cabecera or Requests) The property “End 1 OnDelete” indicates the action to do when a Entity from the Master will be deleted. There are two options: - None: No action will be done, it is said, if a Entity has details entities it could not be deleted. - Cascade: It will delete all related entities to the master Entity. If we enable the cascade delete in a relation, and we invoke the DeleteObject function of the set, we could observe that all the related object indicates a Entitystate.Deleted state. Like an update, insert or common delete, until we commit the changes with SaveChanges function, the data would not be commited. Si habilitamos el borrado en cascada de una relación, e invocamos a la función DeleteObject del conjunto, podremos observar que todas las entidades de Detalle (de la relación indicada) presentan el valor EntityState.Deleted en la propiedad EntityState. Del mismo modo que en el borrado, inserción o actualización, hasta que no se invoque al método SaveChanges, los cambios no van a ser confirmados en la Base de Datos. Finally In this chapter we have seen how to update a Entity, how to delete an Entity and how to implement Cascade Deleting through EF. In next chapters we will see how to query the DB data.

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• Is this over-abstraction? (And is there a name for it?)

  - by mwhite

  I work on a large Django application that uses CouchDB as a database and couchdbkit for mapping CouchDB documents to objects in Python, similar to Django's default ORM. It has dozens of model classes and a hundred or two CouchDB views. The application allows users to register a "domain", which gives them a unique URL containing the domain name that gives them access to a project whose data has no overlap with the data of other domains. Each document that is part of a domain has its domain property set to that domain's name. As far as relationships between the documents go, all domains are effectively mutually exclusive subsets of the data, except for a few edge cases (some users can be members of more than one domain, and there are some administrative reports that include all domains, etc.). The code is full of explicit references to the domain name, and I'm wondering if it would be worth the added complexity to abstract this out. I'd also like to know if there's a name for the sort of bound property approach I'm taking here. Basically, I have something like this in mind: Before in models.py class User(Document): domain = StringProperty() class Group(Document): domain = StringProperty() name = StringProperty() user_ids = StringListProperty() # method that returns related document set def users(self): return [User.get(id) for id in self.user_ids] # method that queries a couch view optimized for a specific lookup @classmethod def by_name(cls, domain, name): # the view method is provided by couchdbkit and handles # wrapping json CouchDB results as Python objects, and # can take various parameters modifying behavior return cls.view('groups/by_name', key=[domain, name]) # method that creates a related document def get_new_user(self): user = User(domain=self.domain) user.save() self.user_ids.append(user._id) return user in views.py: from models import User, Group # there are tons of views like this, (request, domain, ...) def create_new_user_in_group(request, domain, group_name): group = Group.by_name(domain, group_name)[0] user = User(domain=domain) user.save() group.user_ids.append(user._id) group.save() in group/by_name/map.js: function (doc) { if (doc.doc_type == "Group") { emit([doc.domain, doc.name], null); } } After models.py class DomainDocument(Document): domain = StringProperty() @classmethod def domain_view(cls, *args, **kwargs): kwargs['key'] = [cls.domain.default] + kwargs['key'] return super(DomainDocument, cls).view(*args, **kwargs) @classmethod def get(cls, *args, **kwargs, validate_domain=True): ret = super(DomainDocument, cls).get(*args, **kwargs) if validate_domain and ret.domain != cls.domain.default: raise Exception() return ret def models(self): # a mapping of all models in the application. accessing one returns the equivalent of class BoundUser(User): domain = StringProperty(default=self.domain) class User(DomainDocument): pass class Group(DomainDocument): name = StringProperty() user_ids = StringListProperty() def users(self): return [self.models.User.get(id) for id in self.user_ids] @classmethod def by_name(cls, name): return cls.domain_view('groups/by_name', key=[name]) def get_new_user(self): user = self.models.User() user.save() views.py @domain_view # decorator that sets request.models to the same sort of object that is returned by DomainDocument.models and removes the domain argument from the URL router def create_new_user_in_group(request, group_name): group = request.models.Group.by_name(group_name) user = request.models.User() user.save() group.user_ids.append(user._id) group.save() (Might be better to leave the abstraction leaky here in order to avoid having to deal with a couchapp-style //! include of a wrapper for emit that prepends doc.domain to the key or some other similar solution.) function (doc) { if (doc.doc_type == "Group") { emit([doc.name], null); } } Pros and Cons So what are the pros and cons of this? Pros: DRYer prevents you from creating related documents but forgetting to set the domain. prevents you from accidentally writing a django view - couch view execution path that leads to a security breach doesn't prevent you from accessing underlying self.domain and normal Document.view() method potentially gets rid of the need for a lot of sanity checks verifying whether two documents whose domains we expect to be equal are. Cons: adds some complexity hides what's really happening requires no model modules to have classes with the same name, or you would need to add sub-attributes to self.models for modules. However, requiring project-wide unique class names for models should actually be fine because they correspond to the doc_type property couchdbkit uses to decide which class to instantiate them as, which should be unique. removes explicit dependency documentation (from group.models import Group)

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• Software and/(x)or Hardware Projects for Pre-School Kids

  - by haylem

  I offered to participate at my kid's pre-school for various activities (yes, I'm crazy like that), and one of them is to help them discover extra-curricular (big word for a pre-school, but by lack of a better one... :)) hobbies, which may or may not relate to a professional activity. At first I thought that it wouldn't be really easy to have pre-schoolers relate to programming or the internal workings of a computer system in general (and I'm more used to teaching middle-school to university-level students), but then I thought there must be a way. So I'm trying to figure out ways to introduce very young kids (3yo) to computer systems in a fun and preferably educational way. Of course, I don't expect them to start smashing the stack for fun and profit right away (or at least not voluntarily, though I could use the occasion for some toddler tests...), but I'm confident there must be ways to get them interested in both: using the systems, becoming curious about understanding what they do, interacting with the systems to modify them. I guess this setting is not really relevant after all, it's pretty much the same as if you were aiming to achieve the same for your own kids at home. Ideas Considering we're talking 3yo pre-schoolers here, and that at this age some kids are already quite confident using a mouse (some even a keyboard, if not for typing, at least to press some buttons they've come to associate with actions) while others have not yet had any interaction with computers of any kind, it needs to be: rather basic, demonstrated and played with in less then 5 or 10 minutes, doable in in groups or alone, scalable and extendable in complexity to accommodate their varying abilities. The obvious options are: basic smallish games to play with, interactive systems like LOGO, Kojo, Squeak and clones (possibly even simpler than that), or thngs like Lego Systems. I guess it can be a thing to reflect on both at the software and the hardware levels: it could be done with a desktop or laptop machine, a tablet, a smartphone (or a crap-phone, for that matter, as long as you can modify it), or even get down to building something from scratch (Raspberry Pi and Arduino being popular options at the moment). I can probably be in the form of games, funny visualizations (which are pretty much games) w/ Prototype, virtual worlds to explore. I also thought on the moment (and I hope this won't offend anyone) that some approaches to teaching pets could work (reward systems, haptic feedback and such things could quickly point a kid in the right direction to understanding how things work, in a similar fashion - I'm not suggesting to shock the kids!). Hmm, Is There an Actual Question in There? What type of systems do you think might be a good fit, both in terms of hardware and software? Do you have seen such systems, or have anything in mind to work on? Are you aware of some research in this domain, with tangible results? Any input is welcome. It's not that I don't see options: there are tons, but I have a harder time pinpointing a more concrete and definite type of project/activity, so I figure some have valuable ideas or existing ones. Note: I am not advocating that every kid should learn to program, be interested in computer systems, or that all of them in a class would even care enough to follow such an introduction with more than a blank stare. I don't buy into the "everybody would benefit from learning to program" thing. Wouldn't hurt, but not necessary in any way. But if I can walk out of there with a few of them having smiled using the thing (or heck, cried because others took them away from them), that'd be good enough. Related Questions I've seen and that seem to complement what I'm looking for, but not exactly for the same age groups or with the same goals: Teaching Programming to Kids Recommendations for teaching kids math concepts & skills for programming?

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• What do you need to know to be a world-class master software developer? [closed]

  - by glitch

  I wanted to bring up this question to you folks and see what you think, hopefully advise me on the matter: let's say you had 30 years of learning and practicing software development in front of you, how would you dedicate your time so that you'd get the biggest bang for your buck. What would you both learn and work on to be a world-class software developer that would make a large impact on the industry and leave behind a legacy? I think that most great developers end up being both broad generalists and specialists in one-two areas of interest. I'm thinking Bill Joy, John Carmack, Linus Torvalds, K&R and so on. I'm thinking that perhaps one approach would be to break things down by categories and establish a base minimum of "software development" greatness. I'm thinking: Operating Systems: completely internalize the core concepts of OS, perhaps gain a lot of familiarity with an OSS one such as Linux. Anything from memory management to device drivers has to be complete second nature. Programming Languages: this is one of those topics that imho has to be fully grokked even if it might take many years. I don't think there's quite anything like going through the process of developing your own compiler, understanding language design trade-offs and so on. Programming Language Pragmatics is one of my favorite books actually, I think you want to have that internalized back to back, and that's just the start. You could go significantly deeper, but I think it's time well spent, because it's such a crucial building block. As a subset of that, you want to really understand the different programming paradigms out there. Imperative, declarative, logic, functional and so on. Anything from assembly to LISP should be at the very least comfortable to write in. Contexts: I believe one should have experience working in different contexts to truly be able to appreciate the trade-offs that are being made every day. Embedded, web development, mobile development, UX development, distributed, cloud computing and so on. Hardware: I'm somewhat conflicted about this one. I think you want some understanding of computer architecture at a low level, but I feel like the concepts that will truly matter will be slightly higher level, such as CPU caching / memory hierarchy, ILP, and so on. Networking: we live in a completely network-dependent era. Having a good understanding of the OSI model, knowing how the Web works, how HTTP works and so on is pretty much a pre-requisite these days. Distributed systems: once again, everything's distributed these days, it's getting progressively harder to ignore this reality. Slightly related, perhaps add solid understanding of how browsers work to that, since the world seems to be moving so much to interfacing with everything through a browser. Tools: Have a really broad toolset that you're familiar with, one that continuously expands throughout the years. Communication: I think being a great writer, effective communicator and a phenomenal team player is pretty much a prerequisite for a lot of a software developer's greatness. It can't be overstated. Software engineering: understanding the process of building software, team dynamics, the requirements of the business-side, all the pitfalls. You want to deeply understand where what you're writing fits from the market perspective. The better you understand all of this, the more of your work will actually see the daylight. This is really just a starting list, I'm confident that there's a ton of other material that you need to master. As I mentioned, you most likely end up specializing in a bunch of these areas as you go along, but I was trying to come up with a baseline. Any thoughts, suggestions and words of wisdom from the grizzled veterans out there who would like to share their thoughts and experiences with this? I'd really love to know what you think!

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• Concurrent Affairs

  - by Tony Davis

  I once wrote an editorial, multi-core mania, on the conundrum of ever-increasing numbers of processor cores, but without the concurrent programming techniques to get anywhere near exploiting their performance potential. I came to the.controversial.conclusion that, while the problem loomed for all procedural languages, it was not a big issue for the vast majority of programmers. Two years later, I still think most programmers don't concern themselves overly with this issue, but I do think that's a bigger problem than I originally implied. Firstly, is the performance boost from writing code that can fully exploit all available cores worth the cost of the additional programming complexity? Right now, with quad-core processors that, at best, can make our programs four times faster, the answer is still no for many applications. But what happens in a few years, as the number of cores grows to 100 or even 1000? At this point, it becomes very hard to ignore the potential gains from exploiting concurrency. Possibly, I was optimistic to assume that, by the time we have 100-core processors, and most applications really needed to exploit them, some technology would be around to allow us to do so with relative ease. The ideal solution would be one that allows programmers to forget about the problem, in much the same way that garbage collection removed the need to worry too much about memory allocation. From all I can find on the topic, though, there is only a remote likelihood that we'll ever have a compiler that takes a program written in a single-threaded style and "auto-magically" converts it into an efficient, correct, multi-threaded program. At the same time, it seems clear that what is currently the most common solution, multi-threaded programming with shared memory, is unsustainable. As soon as a piece of state can be changed by a different thread of execution, the potential number of execution paths through your program grows exponentially with the number of threads. If you have two threads, each executing n instructions, then there are 2^n possible "interleavings" of those instructions. Of course, many of those interleavings will have identical behavior, but several won't. Not only does this make understanding how a program works an order of magnitude harder, but it will also result in irreproducible, non-deterministic, bugs. And of course, the problem will be many times worse when you have a hundred or a thousand threads. So what is the answer? All of the possible alternatives require a change in the way we write programs and, currently, seem to be plagued by performance issues. Software transactional memory (STM) applies the ideas of database transactions, and optimistic concurrency control, to memory. However, working out how to break down your program into sufficiently small transactions, so as to avoid contention issues, isn't easy. Another approach is concurrency with actors, where instead of having threads share memory, each thread runs in complete isolation, and communicates with others by passing messages. It simplifies concurrent programs but still has performance issues, if the threads need to operate on the same large piece of data. There are doubtless other possible solutions that I haven't mentioned, and I would love to know to what extent you, as a developer, are considering the problem of multi-core concurrency, what solution you currently favor, and why. Cheers, Tony.

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• Best way to load application settings

  - by enzom83

  A simple way to keep the settings of a Java application is represented by a text file with ".properties" extension containing the identifier of each setting associated with a specific value (this value may be a number, string, date, etc..). C# uses a similar approach, but the text file must be named "App.config". In both cases, in source code you must initialize a specific class for reading settings: this class has a method that returns the value (as string) associated with the specified setting identifier. // Java example Properties config = new Properties(); config.load(...); String valueStr = config.getProperty("listening-port"); // ... // C# example NameValueCollection setting = ConfigurationManager.AppSettings; string valueStr = setting["listening-port"]; // ... In both cases we should parse strings loaded from the configuration file and assign the ??converted values to the related typed objects (parsing errors could occur during this phase). After the parsing step, we must check that the setting values ??belong to a specific domain of validity: for example, the maximum size of a queue should be a positive value, some values ??may be related (example: min < max), and so on. Suppose that the application should load the settings as soon as it starts: in other words, the first operation performed by the application is to load the settings. Any invalid values for the settings ??must be replaced automatically with default values??: if this happens to a group of related settings, those settings are all set with default values. The easiest way to perform these operations is to create a method that first parses all the settings, then checks the loaded values ??and finally sets any default values??. However maintenance is difficult if you use this approach: as the number of settings increases while developing the application, it becomes increasingly difficult to update the code. In order to solve this problem, I had thought of using the Template Method pattern, as follows. public abstract class Setting { protected abstract bool TryParseValues(); protected abstract bool CheckValues(); public abstract void SetDefaultValues(); /// <summary> /// Template Method /// </summary> public bool TrySetValuesOrDefault() { if (!TryParseValues() || !CheckValues()) { // parsing error or domain error SetDefaultValues(); return false; } return true; } } public class RangeSetting : Setting { private string minStr, maxStr; private byte min, max; public RangeSetting(string minStr, maxStr) { this.minStr = minStr; this.maxStr = maxStr; } protected override bool TryParseValues() { return (byte.TryParse(minStr, out min) && byte.TryParse(maxStr, out max)); } protected override bool CheckValues() { return (0 < min && min < max); } public override void SetDefaultValues() { min = 5; max = 10; } } The problem is that in this way we need to create a new class for each setting, even for a single value. Are there other solutions to this kind of problem? In summary: Easy maintenance: for example, the addition of one or more parameters. Extensibility: a first version of the application could read a single configuration file, but later versions may give the possibility of a multi-user setup (admin sets up a basic configuration, users can set only certain settings, etc..). Object oriented design.

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• E-Business Suite Technology Sessions at OpenWorld 2012

  - by Max Arderius

  Oracle OpenWorld 2012 is almost here! We're looking forward to updating you on our products, strategy, and roadmaps. This year, the E-Business Suite Applications Technology Group (ATG) will participate in 25 speaker sessions, two Meet the Experts round-table discussions, five demoground booths and seven Special Interest Group meetings as guest speakers. We hope to see you at our sessions.  Please join us to hear the latest news and connect with senior ATG development staff. Here's a downloadable listing of all Applications Technology Group-related sessions with times and locations: FOCUS ON Oracle E-Business Suite - Applications Tools and Technology (PDF) General Sessions GEN8474 - Oracle E-Business Suite - Strategy, Update, and RoadmapCliff Godwin, SVP, Oracle Monday, Oct 1, 12:15 PM - 1:15 PM - Moscone West 2002/2004 In this session, hear Oracle E-Business Suite General Manager Cliff Godwin deliver an update on the Oracle E-Business Suite product line. This session covers the value delivered by the current release of Oracle E-Business Suite, the momentum, and how Oracle E-Business Suite applications integrate into Oracle’s overall applications strategy. You’ll come away with an understanding of the value Oracle E-Business Suite applications deliver now and will deliver in the future. GEN9173 - Optimize and Extend Oracle Applications - The Path to Oracle Fusion ApplicationsNadia Bendjedou, Oracle; Corre Curtice, Bhavish Madurai (CSC) Tuesday, Oct 2, 10:15 AM - 11:15 AM - Moscone West 3002/3004 One of the main objectives of this session is to help organizations build their IT roadmap for the next five years and be aligned with the Oracle Applications strategy in general and the Oracle Fusion Applications strategy in particular. Come hear about some of the common sense, practical steps you can take to optimize the performance of your Oracle Applications today and prepare your path to Oracle Fusion Applications for when your organization is ready to embrace them. Each step you take in adopting Oracle Fusion technology gets you partway to Oracle Fusion Applications. Conference Sessions CON9024 - Oracle E-Business Suite Technology: Latest Features and Roadmap Lisa Parekh, Oracle Monday, Oct 1, 10:45 AM - 11:45 AM - Moscone West 2016 This Oracle development session provides a comprehensive overview of Oracle’s product strategy for Oracle E-Business Suite technology, the capabilities and associated business benefits of recent releases, and a review of capabilities on the product roadmap. This is the cornerstone session for the Oracle E-Business Suite technology stack. Come hear about the latest new usability enhancements of the user interface; systems administration and configuration management tools; security-related updates; and tools and options for extending, customizing, and integrating Oracle E-Business Suite with other applications. CON9021 - Oracle E-Business Suite Future Directions: Deployment and System AdministrationMax Arderius, Oracle Monday, Oct 1, 3:15 PM - 4:15 PM - Moscone West 2016  What’s coming in the next major version of Oracle E-Business Suite 12? This Oracle Development session covers the latest technology stack, including the use of Oracle WebLogic Server (Oracle Fusion Middleware 11g) and Oracle Database 11g Release 2 (11.2). Topics include an architectural overview of the latest updates, installation and upgrade options, new configuration options, and new tools for hot cloning and automated “lights-out” cloning. Come learn how online patching (based on the Oracle Database 11g Release 2 Edition-Based Redefinition feature) will reduce your database patching downtimes to however long it takes to bounce your database server. CON9017 - Desktop Integration in Oracle E-Business Suite 12.1 Padmaprabodh Ambale, Gustavo Jimenez, Oracle Monday, Oct 1, 4:45 PM - 5:45 PM - Moscone West 2016 This presentation covers the latest functional enhancements in Oracle Web Applications Desktop Integrator and Oracle Report Manager, enhanced Microsoft Office support, and greater support for building custom desktop integration solutions. The session also presents tips and tricks for upgrading from Oracle Applications Desktop Integrator to Oracle Web Applications Desktop Integrator and Oracle Report Manager. CON9023 - Oracle E-Business Suite Technology Certification Primer and Roadmap Steven Chan, Oracle Tuesday, Oct 2, 10:15 AM - 11:15 AM - Moscone West 2016  Is your Oracle E-Business Suite technology stack up to date? Are you taking advantage of all the latest options and capabilities? This Oracle development session summarizes the latest certifications and roadmap for the Oracle E-Business Suite technology stack, including elements such as database releases and options, Java, Oracle Forms, Oracle Containers for J2EE, desktop operating systems, browsers, JRE releases, development and Web authoring tools, user authentication and management, business intelligence, Oracle Application Management Packs, security options, clouds, Oracle VM, and virtualization. The session also covers the most commonly asked questions about tech stack component support dates and upgrade implications. CON9028 - Minimizing Oracle E-Business Suite Maintenance DowntimesSantiago Bastidas, Elke Phelps, Oracle Tuesday, Oct 2, 11:45 AM - 12:45 PM - Moscone West 2016 This Oracle development session features a survey of the best techniques sysadmins can use to minimize patching downtimes. It starts with an architectural-level review of Oracle E-Business Suite fundamentals and then moves to a practical view of the various tools and approaches for downtimes. Topics include patching shortcuts, merging patches, distributing worker processes across multiple servers, running ADPatch in noninteractive mode, staged APPL_TOPs, shared file systems, deferring systemwide database tasks, avoiding resource bottlenecks, and more. An added bonus: hear about the upcoming Oracle E-Business Suite 12 online patching capabilities based on the groundbreaking Oracle Database 11g Release 2 Edition-Based Redefinition feature. CON9116 - Extending the Use of Oracle E-Business Suite with the Oracle Endeca PlatformOsama Elkady, Muhannad Obeidat, Oracle Tuesday, Oct 2, 11:45 AM - 12:45 PM - Moscone West 2018 The Oracle Endeca platform includes a leading unstructured data correlation and analytics engine, together with a best-in class catalog search and guided navigation solution, to improve the productivity of all types of users in your enterprise. This development session focuses on the details behind the Oracle Endeca platform’s integration into Oracle E-Business Suite. It demonstrates how easily you can extend the use of the Oracle Endeca platform into other areas of Oracle E-Business Suite and how you can bring in your own data and build new Oracle Endeca applications for Oracle E-Business Suite. CON9005 - Oracle E-Business Suite Integration Best PracticesVeshaal Singh, Oracle, Jeffrey Hand, Zebra Technologies Tuesday, Oct 2, 1:15 PM - 2:15 PM - Moscone West 2018 Oracle is investing across applications and technologies to make the application integration experience easier for customers. Today Oracle has certified Oracle E-Business Suite on Oracle Fusion Middleware 11g and provides a comprehensive set of integration technologies. Learn about Oracle’s integration offering across data- and process-centric integrations. These technologies can be used to address various application integration challenges and styles. In this session, you will get an understanding of how, when, and where you can leverage Oracle’s integration technologies to connect end-to-end business processes across your enterprise, including your Oracle Applications portfolio.  CON9026 - Latest Oracle E-Business Suite 12.1 User Interface and Usability EnhancementsPadmaprabodh Ambale, Oracle Tuesday, Oct 2, 1:15 PM - 2:15 PM - Moscone West 2016 This Oracle development session details the latest UI enhancements to Oracle Application Framework in Oracle E-Business Suite 12.1. Developers will get a detailed look at new features to enhance usability, offer more capabilities for personalization and extensions, and support the development and use of dashboards and Web services. Topics include new rich UI capabilities such as new home page features, Navigator and Favorites pull-down menus, REST interface, embedded widgets for analytics content, Oracle Application Development Framework (Oracle ADF) task flows, third-party widgets, a look-ahead list of values, inline attachments, pop-ups, personalization and extensibility enhancements, business layer extensions, Oracle ADF integration, and mobile devices. CON8805 - Planning Your Oracle E-Business Suite Upgrade from 11i to Release 12.1 and BeyondAnne Carlson, Oracle Tuesday, Oct 2, 5:00 PM - 6:00 PM - Moscone West 3002/3004 Attend this session to hear the latest Oracle E-Business Suite 12.1 upgrade planning tips from Oracle’s support, consulting, development, and IT organizations. You’ll get specific cross-product advice on how to understand the factors that affect your project’s duration, decide on your project’s scope, develop a robust testing strategy, leverage Oracle Support resources, and more. In a nutshell, this session tells you things you need to know before embarking upon your Release 12.1 upgrade project. CON9053 - Advanced Management of Oracle E-Business Suite with Oracle Enterprise ManagerAngelo Rosado, Oracle Tuesday, Oct 2, 5:00 PM - 6:00 PM - Moscone West 2016 The task of managing and monitoring Oracle E-Business Suite environments can be very challenging. Oracle Enterprise Manager is the only product on the market that is designed to monitor and manage all the different technologies that constitute Oracle E-Business Suite applications, including end user, midtier, configuration, host, and database management—to name just a few. Customers that have implemented Oracle Enterprise Manager have experienced dramatic improvements in system visibility and diagnostic capability as well as administrator productivity. The purpose of this session is to highlight the key features and benefits of Oracle Enterprise Manager and Oracle Application Management Suite for Oracle E-Business Suite. CON8809 - Oracle E-Business Suite 12.1 Upgrade Best Practices: Technical InsightIsam Alyousfi, Udayan Parvate, Oracle Wednesday, Oct 3, 10:15 AM - 11:15 AM - Moscone West 3011 This session is ideal for organizations thinking about upgrading to Oracle E-Business Suite 12.1. It covers the fundamentals of upgrading to Release 12.1, including the technology stack components and supported upgrade paths. Hear from Oracle Development about the set of best practices for patching in general and executing the Release 12.1 technical upgrade, with special considerations for minimizing your downtime. Also get to know about relatively recent upgrade resources. CON9032 - Upgrading Your Customizations of Oracle E-Business Suite 12.1Sara Woodhull, Oracle Wednesday, Oct 3, 10:15 AM - 11:15 AM - Moscone West 2016 Have you personalized Oracle Forms or Oracle Application Framework screens in Oracle E-Business Suite? Have you used mod_plsql in Release 11i? Have you extended or customized your Release 11i environment with other tools? The technical options for upgrading these customizations as part of your Oracle E-Business Suite Release 12.1 upgrade can be bewildering. Come to this Oracle development session to learn about selecting the best upgrade approach for your existing customizations. The session will help you understand customization scenarios and use cases, tools, and technologies to ensure that your Oracle E-Business Suite Release 12.1 environment fits your users’ needs closely and that any future customizations will be easy to upgrade. CON9259 - Oracle E-Business Suite Internationalization and Multilingual FeaturesMaher Al-Nubani, Oracle Wednesday, Oct 3, 10:15 AM - 11:15 AM - Moscone West 2018 Oracle E-Business Suite supports more countries, languages, and regions than ever. Come to this Oracle development session to get an overview of internationalization features and capabilities and see new Release 12 features such as calendar support for Hijra and Thai, new group separators, lightweight multilingual support (MLS) setup, new character sets such as AL32UTF, newly supported languages, Mac certifications, Oracle iSetup support for moving MLS setups, new file export options for Unicode, new MLS number spelling options, and more. CON7188 - Mobile Apps for Oracle E-Business Suite with Oracle ADF Mobile and Oracle SOA SuiteSrikant Subramaniam, Joe Huang, Veshaal Singh, Oracle Wednesday, Oct 3, 10:15 AM - 11:15 AM - Moscone West 3001 Follow your mobile customers, employees, and partners with Oracle Fusion Middleware. See how native iPhone and iPad applications can easily be built for Oracle E-Business Suite with the new Oracle ADF Mobile and Oracle SOA Suite. Using Oracle ADF Mobile, developers can quickly develop native applications for Apple iOS and other mobile platforms. The Oracle SOA Suite/Oracle ADF Mobile combination can execute business transactions on Oracle E-Business Suite. This session includes a demo in which a mobile user approves a business transaction in Oracle E-Business Suite and a demo of the tools used to build a native on-device solution. These concepts for mobile applications also apply to other Oracle applications.CON9029 - Oracle E-Business Suite Directions: Slashing Downtimes with Online PatchingKevin Hudson, Oracle Wednesday, Oct 3, 11:45 AM - 12:45 PM - Moscone West 2016 Oracle E-Business Suite will soon include online patching (based on the Oracle Database 11g Release 2 Edition-Based Redefinition feature), which will reduce your database patching downtimes to however long it takes to bounce your database server. This Oracle development session details how online patching works, with special attention to what’s happening at a database object level when database patches are applied to an Oracle E-Business Suite environment that’s still running. Come learn about the operational and system management implications for minimizing maintenance downtimes when applying database patches with this new technology and the related impact on customizations you might have built on top of Oracle E-Business Suite. CON8806 - Upgrading to Oracle E-Business Suite 12.1: Technical and Functional PanelAndrew Katz, Komori America Corporation; Sandra Vucinic, VLAD Group, Inc. ;Srini Chavali, Cummins Inc.; Amrita Mehrok, Nadia Bendjedou, Anne Carlson Oracle Wednesday, Oct 3, 1:15 PM - 2:15 PM - Moscone West 2018 In this panel discussion, Oracle experts, customers, and partners share their experiences in upgrading to the latest release of Oracle E-Business Suite, Release 12.1. The panelists cover aspects of a typical Release 12 upgrade, technical (upgrading the technical infrastructure) as well as functional (upgrading to the new financial infrastructure). Hear directly from the experts who either develop the product or support, implement, or upgrade it, and find out how to apply their lessons learned to your organization. CON9027 - Personalize and Extend Oracle E-Business Suite Applications with Rich MashupsGustavo Jimenez, Padmaprabodh Ambale, Oracle Wednesday, Oct 3, 1:15 PM - 2:15 PM - Moscone West 2016 This session covers the use of several Oracle Fusion Middleware technologies to personalize and extend your existing Oracle E-Business Suite applications. The Oracle Fusion Middleware technologies covered include Oracle Application Development Framework (Oracle ADF), Oracle WebCenter, Oracle Endeca applications, and Oracle Business Intelligence Enterprise Edition with Oracle E-Business Suite Oracle Application Framework applications. CON9036 - Advanced Oracle E-Business Suite Architectures: Maximum Availability, Security, and MoreElke Phelps, Oracle Wednesday, Oct 3, 3:30 PM - 4:30 PM - Moscone West 2016 This session includes architecture diagrams and configuration instructions for building a maximum availability architecture (MAA) that will help you design a disaster recovery solution that fits the needs of your business. Database and application high-availability features it describes include Oracle Data Guard, Oracle Real Application Clusters (Oracle RAC), Oracle Active Data Guard, load-balancing Web and forms services, parallel concurrent processing, and the use of Oracle Exalogic and Oracle Exadata to provide a highly available environment. The session also covers the latest updates to systems management tools, AutoConfig, cloud computing, virtualization, and Oracle WebLogic Server and provides sneak previews of upcoming functionality. CON9047 - Efficiently Scaling Oracle E-Business Suite on Oracle Exadata and Oracle ExalogicIsam Alyousfi, Nishit Rao, Oracle Wednesday, Oct 3, 5:00 PM - 6:00 PM - Moscone West 2016 Oracle Exadata and Oracle Exalogic are designed from the ground up with optimizations in software and hardware to deliver superfast performance for mission-critical applications such as Oracle E-Business Suite. Oracle E-Business Suite applications run three to eight times as fast on the Oracle Exadata/Oracle Exalogic platform in standard benchmark tests. Besides performance, customers benefit from simplified support, enhanced manageability, and the ability to consolidate multiple Oracle E-Business Suite instances. Attend this session to understand best practices for Oracle E-Business Suite deployment on Oracle Exalogic and Oracle Exadata through customer case studies. Learn how adopting the Exa* platform increases efficiency, simplifies scaling, and boosts performance for peak loads. CON8716 - Web Services and SOA Integration Options for Oracle E-Business SuiteRekha Ayothi, Veshaal Singh, Oracle Thursday, Oct 4, 11:15 AM - 12:15 PM - Moscone West 2016 This Oracle development session provides a deep dive into a subset of the Web services and SOA-related integration options available to Oracle E-Business Suite systems integrators. It offers a technical look at Oracle E-Business Suite Integrated SOA Gateway, Oracle SOA Suite, Oracle Application Adapters for Data Integration for Oracle E-Business Suite, and other Web services options for integrating Oracle E-Business Suite with other applications. Systems integrators and developers will get an overview of the latest integration capabilities and technologies available out of the box with Oracle E-Business Suite and possibly a sneak preview of upcoming functionality and features. CON9030 - Recommendations for Oracle E-Business Suite Performance TuningIsam Alyousfi, Samer Barakat, Oracle Thursday, Oct 4, 11:15 AM - 12:15 PM - Moscone West 2018 Need to squeeze more performance out of your existing servers? This packed Oracle development session summarizes practical tips and lessons learned from performance-tuning and benchmarking the world’s largest Oracle E-Business Suite environments. Apps sysadmins will learn concrete tips and techniques for identifying and resolving performance bottlenecks on all layers, with special attention to application- and database-tier servers. Learn about tuning Oracle Forms, Oracle Concurrent Manager, Apache, and Oracle Discoverer. Track down memory leaks and other issues at the Java and JVM layers. The session also covers Oracle E-Business Suite product-level tuning, including Oracle Workflow, Oracle Order Management, Oracle Payroll, and other modules. CON3429 - Using Oracle ADF with Oracle E-Business Suite: The Full Integration ViewSiva Puthurkattil, Lake County; Juan Camilo Ruiz, Sara Woodhull, Oracle Thursday, Oct 4, 11:15 AM - 12:15 PM - Moscone West 3003 Oracle E-Business Suite delivers functionality for handling the core business of your organization. However, user requirements and new technologies are driving an emerging need to implement new types of user interfaces for these applications. This session provides an overview of how to use Oracle Application Development Framework (Oracle ADF) to deliver cutting-edge Web 2.0 and mobile rich user interfaces that front existing Oracle E-Business Suite processes, and it also explores all the existing types of integration between the two worlds. CON9020 - Integrating Oracle E-Business Suite with Oracle Identity Management SolutionsSunil Ghosh, Elke Phelps, Oracle Thursday, Oct 4, 12:45 PM - 1:45 PM - Moscone West 2016 Need to integrate Oracle E-Business Suite with Microsoft Windows Kerberos, Active Directory, CA Netegrity SiteMinder, or other third-party authentication systems? Want to understand your options when Oracle Premier Support for Oracle Single Sign-On ends in December 2011? This Oracle Development session covers the latest certified integrations with Oracle Access Manager 11g and Oracle Internet Directory 11g, which can be used individually or as bridges for integrating with third-party authentication solutions. The session presents an architectural overview of how Oracle Access Manager, its WebGate and AccessGate components, and Oracle Internet Directory work together, with implications for Oracle Discoverer, Oracle Portal, and other Oracle Fusion identity management products. CON9019 - Troubleshooting, Diagnosing, and Optimizing Oracle E-Business Suite TechnologyGustavo Jimenez, Oracle Thursday, Oct 4, 2:15 PM - 3:15 PM - Moscone West 2016 This session covers how you can proactively diagnose Oracle E-Business Suite applications, including extensions built with Oracle Fusion Middleware technologies such as Oracle Application Development Framework (Oracle ADF) and Oracle WebCenter to catch potential issues in the middle tier before they become more serious. Topics include debugging, logging infrastructure, warning signs, performance tuning, information required when logging service requests, general JVM optimization, and an overall picture of all the moving parts that make it possible for Oracle E-Business Suite to isolate and fix problems. Also learn how Oracle Diagnostics Framework will help prevent downtime caused by failures. CON9031 - The Top 10 Things You Can Do to Secure Your Oracle E-Business Suite InstanceEric Bing, Erik Graversen, Oracle Thursday, Oct 4, 2:15 PM - 3:15 PM - Moscone West 2018 Learn the top 10 things you can do to secure your applications and your sensitive data. This Oracle development session for system administrators and security professionals explores some of the most important and overlooked things you can do to secure your Oracle E-Business Suite instance. It also covers data masking and other mechanisms for protecting sensitive data. Special Interest Groups (SIG) Some of our most senior staff have been invited to participate on the following SIG meetings as guest speakers: SIG10525 - OAUG - Archive & Purge SIGBrian Bent - Pre-Sales Engineer, TierData, Inc. Sunday, Sep 30, 10:30 AM - 12:00 PM - Moscone West 3011 The Archive and Purge SIG is an organization in which users can share their experiences and solicit functional and technical advice on archiving and purging data in Oracle E-Business Suite. This session provides an opportunity for users to network and share best practices, tips, and tricks. Guest: Oracle E-Business Suite Database Performance, Archive & Purging - Q&A SessionIsam Alyousfi, Senior Director, Applications Performance, Oracle SIG10547 - OAUG - Oracle E-Business (EBS) Applications Technology SIGSrini Chavali - IT Director, Cummins Inc Sunday, Sep 30, 10:30 AM - 12:00 PM - Moscone West 3018 The general purpose of the EBS Applications Technology SIG is to inform and educate its members about current and future components of the tech stack as they relate to Oracle E-Business Suite. Attend this meeting for networking and education and to share best practices. Guest: Oracle E-Business Suite Technology Certification Roadmap - Presentation and Q&ASteven Chan, Sr. Director, Applications Technology Group, Oracle SIG10559 - OAUG - User Management SIGSusan Behn - VP of Oracle Delivery, Infosemantics, Inc. Sunday, Sep 30, 10:30 AM - 12:00 PM - Moscone West 3024 The E-Business Suite User Management SIG focuses on the components of user management that enable Oracle E-Business Suite users to define administrative functions and manage users’ access to functions and data based on roles within an organization—rather than the user’s individual identity—which is referred to as role-based access control (RBAC). This meeting includes an introduction to Oracle User Management that covers the Oracle User Management building blocks and presents an example of creating a security policy.Guest: Security and User Management - Q&A SessionEric Bing, Sr. Director, EBS Security, OracleSara Woodhull, Principal Product Manager, Applications Technology Group, Oracle SIG10515 - OAUG – Upgrade SIGBarbara Matthews - Consultant, On Call DBASandra Vucinic, VLAD Group, Inc. Sunday, Sep 30, 12:00 PM - 2:00 PM - Moscone West 3009 This Upgrade SIG session starts with a business meeting and then features a Q&A panel discussion on Oracle E-Business Suite upgrade topics. The session• Reviews Upgrade SIG goals and objectives• Provides answers, during the Q&A session, to questions related to Oracle E-Business Suite upgrades• Shares “real world” experiences, tips, and techniques for Oracle E-Business Suite upgrades to Release 12.1. Guest: Oracle E-Business Suite Upgrade - Q&A SessionAnne Carlson - Sr. Director, Oracle E-Business Suite Product Strategy, OracleUdayan Parvate - Director, EBS Release Engineering, OracleSuzana Ferrari, Sr. Principal Consultant, OracleIsam Alyousfi, Sr. Director, Applications Performance, Oracle SIG10552 - OAUG - Oracle E-Business Suite SIGDonna Rosentrater - Manager, Global Sourcing & Procurement Systems, TJX Sunday, Sep 30, 12:15 PM - 1:45 PM - Moscone West 3020 The E-Business Suite SIG, affiliated with OAUG, supports Oracle E-Business Suite users through networking, education, and sharing of best practices. This SIG meeting will feature a general discussion of Oracle E-Business Suite product strategies in Release 12 and migration to Oracle Fusion Applications. Guest: Oracle E-Business Suite - Q&A SessionJeanne Lowell, Vice President, EBS Product Strategy, OracleNadia Bendjedou, Sr. Director, Product Strategy, Oracle SIG10556 - OAUG - SysAdmin SIGRandy Giefer - Sr Systems and Security Architect, Solution Beacon, LLC Sunday, Sep 30, 12:15 PM - 1:45 PM - Moscone West 3022 The SysAdmin SIG provides a forum in which OAUG members and participants can share updates, tips, and successful practices relating to system administration in an Oracle applications environment. The SysAdmin SIG strives to enable system administrators to become more effective and efficient in their jobs by providing them with access to people and information that can increase their system administration knowledge and experience. Attend this meeting to network, share best practices, and benefit from educational content. Guest: Oracle E-Business Suite 12.2 Online Patching- Presentation and Q&AKevin Hudson, Sr. Director, Applications Technology Group, Oracle SIG10553 - OAUG - Database SIGMichael Brown - Senior DBA, COLIBRI LTD LC Sunday, Sep 30, 2:00 PM - 3:15 PM - Moscone West 3020 The OAUG Database SIG provides an opportunity for applications database administrators to learn from and share their experiences with supporting the various Oracle applications environments. This session will include a brief business meeting followed by a short presentation. It will end with an open discussion among the attendees about items of interest to those present. Guest: Oracle E-Business Suite Database Performance - Presentation and Q&AIsam Alyousfi, Sr. Director, Applications Performance, Oracle Meet the Experts We're planning two round-table discussions where you can review your questions with senior E-Business Suite ATG staff: MTE9648 - Meet the Experts for Oracle E-Business Suite: Planning Your Upgrade Jeanne Lowell - VP, EBS Product Strategy, Oracle John Abraham - Sr. Principal Product Manager, Oracle Nadia Bendjedou - Sr. Director - Product Strategy, Oracle Anne Carlson - Sr. Director, Applications Technology Group, Oracle Udayan Parvate - Director, EBS Release Engineering, Oracle Isam Alyousfi, Sr. Director, Applications Performance, Oracle Monday, Oct 1, 3:15 PM - 4:15 PM - Moscone West 2001A Don’t miss this Oracle Applications Meet the Experts session with experts who specialize in Oracle E-Business Suite upgrade best practices. This is the place where attendees can have informal and semistructured but open one-on-one discussions with Strategy and Development regarding Oracle Applications strategy and your specific business and IT strategy. The experts will be available to discuss the value of the latest releases and share insights into the best path for your enterprise, so come ready with your questions. Space is limited, so make sure you register. MTE9649 - Meet the Oracle E-Business Suite Tools and Technology Experts Lisa Parekh - Vice President, Technology Integration, Oracle Steven Chan - Sr. Director, Oracle Elke Phelps - Sr. Principal Product Manager, Applications Technology Group, Oracle Max Arderius - Manager, Applications Technology Group, Oracle Tuesday, Oct 2, 1:15 PM - 2:15 PM - Moscone West 2001A Don’t miss this Oracle Applications Meet the Experts session with experts who specialize in Oracle E-Business Suite technology. This is the place where attendees can have informal and semistructured but open one-on-one discussions with Strategy and Development regarding Oracle Applications strategy and your specific business and IT strategy. The experts will be available to discuss the value of the latest releases and share insights into the best path for your enterprise, so come ready with your questions. Space is limited, so make sure you register. Demos We have five booths in the exhibition demogrounds this year, where you can try ATG technologies firsthand and get your questions answered. Please stop by and meet our staff at the following locations: Advanced Architecture and Technology Stack for Oracle E-Business Suite (W-067) New User Productivity Capabilities in Oracle E-Business Suite (W-065) End-to-End Management of Oracle E-Business Suite (W-063) Oracle E-Business Suite 12.1 Technical Upgrade Best Practices (W-066) SOA-Based Integration for Oracle E-Business Suite (W-064)

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• Scaling-out Your Services by Message Bus based WCF Transport Extension &ndash; Part 1 &ndash; Background

  - by Shaun

  Cloud computing gives us more flexibility on the computing resource, we can provision and deploy an application or service with multiple instances over multiple machines. With the increment of the service instances, how to balance the incoming message and workload would become a new challenge. Currently there are two approaches we can use to pass the incoming messages to the service instances, I would like call them dispatcher mode and pulling mode.   Dispatcher Mode The dispatcher mode introduces a role which takes the responsible to find the best service instance to process the request. The image below describes the sharp of this mode. There are four clients communicate with the service through the underlying transportation. For example, if we are using HTTP the clients might be connecting to the same service URL. On the server side there’s a dispatcher listening on this URL and try to retrieve all messages. When a message came in, the dispatcher will find a proper service instance to process it. There are three mechanism to find the instance: Round-robin: Dispatcher will always send the message to the next instance. For example, if the dispatcher sent the message to instance 2, then the next message will be sent to instance 3, regardless if instance 3 is busy or not at that moment. Random: Dispatcher will find a service instance randomly, and same as the round-robin mode it regardless if the instance is busy or not. Sticky: Dispatcher will send all related messages to the same service instance. This approach always being used if the service methods are state-ful or session-ful. But as you can see, all of these approaches are not really load balanced. The clients will send messages at any time, and each message might take different process duration on the server side. This means in some cases, some of the service instances are very busy while others are almost idle. For example, if we were using round-robin mode, it could be happened that most of the simple task messages were passed to instance 1 while the complex ones were sent to instance 3, even though instance 1 should be idle. This brings some problem in our architecture. The first one is that, the response to the clients might be longer than it should be. As it’s shown in the figure above, message 6 and 9 can be processed by instance 1 or instance 2, but in reality they were dispatched to the busy instance 3 since the dispatcher and round-robin mode. Secondly, if there are many requests came from the clients in a very short period, service instances might be filled by tons of pending tasks and some instances might be crashed. Third, if we are using some cloud platform to host our service instances, for example the Windows Azure, the computing resource is billed by service deployment period instead of the actual CPU usage. This means if any service instance is idle it is wasting our money! Last one, the dispatcher would be the bottleneck of our system since all incoming messages must be routed by the dispatcher. If we are using HTTP or TCP as the transport, the dispatcher would be a network load balance. If we wants more capacity, we have to scale-up, or buy a hardware load balance which is very expensive, as well as scaling-out the service instances. Pulling Mode Pulling mode doesn’t need a dispatcher to route the messages. All service instances are listening to the same transport and try to retrieve the next proper message to process if they are idle. Since there is no dispatcher in pulling mode, it requires some features on the transportation. The transportation must support multiple client connection and server listening. HTTP and TCP doesn’t allow multiple clients are listening on the same address and port, so it cannot be used in pulling mode directly. All messages in the transportation must be FIFO, which means the old message must be received before the new one. Message selection would be a plus on the transportation. This means both service and client can specify some selection criteria and just receive some specified kinds of messages. This feature is not mandatory but would be very useful when implementing the request reply and duplex WCF channel modes. Otherwise we must have a memory dictionary to store the reply messages. I will explain more about this in the following articles. Message bus, or the message queue would be best candidate as the transportation when using the pulling mode. First, it allows multiple application to listen on the same queue, and it’s FIFO. Some of the message bus also support the message selection, such as TIBCO EMS, RabbitMQ. Some others provide in memory dictionary which can store the reply messages, for example the Redis. The principle of pulling mode is to let the service instances self-managed. This means each instance will try to retrieve the next pending incoming message if they finished the current task. This gives us more benefit and can solve the problems we met with in the dispatcher mode. The incoming message will be received to the best instance to process, which means this will be very balanced. And it will not happen that some instances are busy while other are idle, since the idle one will retrieve more tasks to make them busy. Since all instances are try their best to be busy we can use less instances than dispatcher mode, which more cost effective. Since there’s no dispatcher in the system, there is no bottleneck. When we introduced more service instances, in dispatcher mode we have to change something to let the dispatcher know the new instances. But in pulling mode since all service instance are self-managed, there no extra change at all. If there are many incoming messages, since the message bus can queue them in the transportation, service instances would not be crashed. All above are the benefits using the pulling mode, but it will introduce some problem as well. The process tracking and debugging become more difficult. Since the service instances are self-managed, we cannot know which instance will process the message. So we need more information to support debug and track. Real-time response may not be supported. All service instances will process the next message after the current one has done, if we have some real-time request this may not be a good solution. Compare with the Pros and Cons above, the pulling mode would a better solution for the distributed system architecture. Because what we need more is the scalability, cost-effect and the self-management.   WCF and WCF Transport Extensibility Windows Communication Foundation (WCF) is a framework for building service-oriented applications. In the .NET world WCF is the best way to implement the service. In this series I’m going to demonstrate how to implement the pulling mode on top of a message bus by extending the WCF. I don’t want to deep into every related field in WCF but will highlight its transport extensibility. When we implemented an RPC foundation there are many aspects we need to deal with, for example the message encoding, encryption, authentication and message sending and receiving. In WCF, each aspect is represented by a channel. A message will be passed through all necessary channels and finally send to the underlying transportation. And on the other side the message will be received from the transport and though the same channels until the business logic. This mode is called “Channel Stack” in WCF, and the last channel in the channel stack must always be a transport channel, which takes the responsible for sending and receiving the messages. As we are going to implement the WCF over message bus and implement the pulling mode scaling-out solution, we need to create our own transport channel so that the client and service can exchange messages over our bus. Before we deep into the transport channel, let’s have a look on the message exchange patterns that WCF defines. Message exchange pattern (MEP) defines how client and service exchange the messages over the transportation. WCF defines 3 basic MEPs which are datagram, Request-Reply and Duplex. Datagram: Also known as one-way, or fire-forgot mode. The message sent from the client to the service, and no need any reply from the service. The client doesn’t care about the message result at all. Request-Reply: Very common used pattern. The client send the request message to the service and wait until the reply message comes from the service. Duplex: The client sent message to the service, when the service processing the message it can callback to the client. When callback the service would be like a client while the client would be like a service. In WCF, each MEP represent some channels associated. MEP Channels Datagram IInputChannel, IOutputChannel Request-Reply IRequestChannel, IReplyChannel Duplex IDuplexChannel And the channels are created by ChannelListener on the server side, and ChannelFactory on the client side. The ChannelListener and ChannelFactory are created by the TransportBindingElement. The TransportBindingElement is created by the Binding, which can be defined as a new binding or from a custom binding. For more information about the transport channel mode, please refer to the MSDN document. The figure below shows the transport channel objects when using the request-reply MEP. And this is the datagram MEP. And this is the duplex MEP. After investigated the WCF transport architecture, channel mode and MEP, we finally identified what we should do to extend our message bus based transport layer. They are: Binding: (Optional) Defines the channel elements in the channel stack and added our transport binding element at the bottom of the stack. But we can use the build-in CustomBinding as well. TransportBindingElement: Defines which MEP is supported in our transport and create the related ChannelListener and ChannelFactory. This also defines the scheme of the endpoint if using this transport. ChannelListener: Create the server side channel based on the MEP it’s. We can have one ChannelListener to create channels for all supported MEPs, or we can have ChannelListener for each MEP. In this series I will use the second approach. ChannelFactory: Create the client side channel based on the MEP it’s. We can have one ChannelFactory to create channels for all supported MEPs, or we can have ChannelFactory for each MEP. In this series I will use the second approach. Channels: Based on the MEPs we want to support, we need to implement the channels accordingly. For example, if we want our transport support Request-Reply mode we should implement IRequestChannel and IReplyChannel. In this series I will implement all 3 MEPs listed above one by one. Scaffold: In order to make our transport extension works we also need to implement some scaffold stuff. For example we need some classes to send and receive message though out message bus. We also need some codes to read and write the WCF message, etc.. These are not necessary but would be very useful in our example.   Message Bus There is only one thing remained before we can begin to implement our scaling-out support WCF transport, which is the message bus. As I mentioned above, the message bus must have some features to fulfill all the WCF MEPs. In my company we will be using TIBCO EMS, which is an enterprise message bus product. And I have said before we can use any message bus production if it’s satisfied with our requests. Here I would like to introduce an interface to separate the message bus from the WCF. This allows us to implement the bus operations by any kinds bus we are going to use. The interface would be like this. 1: public interface IBus : IDisposable 2: { 3: string SendRequest(string message, bool fromClient, string from, string to = null); 4:  5: void SendReply(string message, bool fromClient, string replyTo); 6:  7: BusMessage Receive(bool fromClient, string replyTo); 8: } There are only three methods for the bus interface. Let me explain one by one. The SendRequest method takes the responsible for sending the request message into the bus. The parameters description are: message: The WCF message content. fromClient: Indicates if this message was came from the client. from: The channel ID that this message was sent from. The channel ID will be generated when any kinds of channel was created, which will be explained in the following articles. to: The channel ID that this message should be received. In Request-Reply and Duplex MEP this is necessary since the reply message must be received by the channel which sent the related request message. The SendReply method takes the responsible for sending the reply message. It’s very similar as the previous one but no “from” parameter. This is because it’s no need to reply a reply message again in any MEPs. The Receive method takes the responsible for waiting for a incoming message, includes the request message and specified reply message. It returned a BusMessage object, which contains some information about the channel information. The code of the BusMessage class is 1: public class BusMessage 2: { 3: public string MessageID { get; private set; } 4: public string From { get; private set; } 5: public string ReplyTo { get; private set; } 6: public string Content { get; private set; } 7:  8: public BusMessage(string messageId, string fromChannelId, string replyToChannelId, string content) 9: { 10: MessageID = messageId; 11: From = fromChannelId; 12: ReplyTo = replyToChannelId; 13: Content = content; 14: } 15: } Now let’s implement a message bus based on the IBus interface. Since I don’t want you to buy and install the TIBCO EMS or any other message bus products, I will implement an in process memory bus. This bus is only for test and sample purpose. It can only be used if the service and client are in the same process. Very straightforward. 1: public class InProcMessageBus : IBus 2: { 3: private readonly ConcurrentDictionary<Guid, InProcMessageEntity> _queue; 4: private readonly object _lock; 5:  6: public InProcMessageBus() 7: { 8: _queue = new ConcurrentDictionary<Guid, InProcMessageEntity>(); 9: _lock = new object(); 10: } 11:  12: public string SendRequest(string message, bool fromClient, string from, string to = null) 13: { 14: var entity = new InProcMessageEntity(message, fromClient, from, to); 15: _queue.TryAdd(entity.ID, entity); 16: return entity.ID.ToString(); 17: } 18:  19: public void SendReply(string message, bool fromClient, string replyTo) 20: { 21: var entity = new InProcMessageEntity(message, fromClient, null, replyTo); 22: _queue.TryAdd(entity.ID, entity); 23: } 24:  25: public BusMessage Receive(bool fromClient, string replyTo) 26: { 27: InProcMessageEntity e = null; 28: while (true) 29: { 30: lock (_lock) 31: { 32: var entity = _queue 33: .Where(kvp => kvp.Value.FromClient == fromClient && (kvp.Value.To == replyTo || string.IsNullOrWhiteSpace(kvp.Value.To))) 34: .FirstOrDefault(); 35: if (entity.Key != Guid.Empty && entity.Value != null) 36: { 37: _queue.TryRemove(entity.Key, out e); 38: } 39: } 40: if (e == null) 41: { 42: Thread.Sleep(100); 43: } 44: else 45: { 46: return new BusMessage(e.ID.ToString(), e.From, e.To, e.Content); 47: } 48: } 49: } 50:  51: public void Dispose() 52: { 53: } 54: } The InProcMessageBus stores the messages in the objects of InProcMessageEntity, which can take some extra information beside the WCF message itself. 1: public class InProcMessageEntity 2: { 3: public Guid ID { get; set; } 4: public string Content { get; set; } 5: public bool FromClient { get; set; } 6: public string From { get; set; } 7: public string To { get; set; } 8:  9: public InProcMessageEntity() 10: : this(string.Empty, false, string.Empty, string.Empty) 11: { 12: } 13:  14: public InProcMessageEntity(string content, bool fromClient, string from, string to) 15: { 16: ID = Guid.NewGuid(); 17: Content = content; 18: FromClient = fromClient; 19: From = from; 20: To = to; 21: } 22: }   Summary OK, now I have all necessary stuff ready. The next step would be implementing our WCF message bus transport extension. In this post I described two scaling-out approaches on the service side especially if we are using the cloud platform: dispatcher mode and pulling mode. And I compared the Pros and Cons of them. Then I introduced the WCF channel stack, channel mode and the transport extension part, and identified what we should do to create our own WCF transport extension, to let our WCF services using pulling mode based on a message bus. And finally I provided some classes that need to be used in the future posts that working against an in process memory message bus, for the demonstration purpose only. In the next post I will begin to implement the transport extension step by step.   Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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• Android: trouble updating to Android SDK Tools, revision 7.

  - by Arhimed

  Currently I have Android SDK 2.1 (+ tools revision 4). I'd like to upgrade to Android SDK 2.2. When I try to do it I'm informed I need to upgrade Android SDK Tools to revision 7 first. So I agree, the process starts and then I get an error: -= warning! =- A folder failed to be renamed or moved. On Windows this typically means that a program Is using that Folder (for example Windows Explorer or your anti-virus software.) Please momentarily deactivate your anti-virus software. Please also close any running programs that may be accessing the directory 'D:\Install\Programming\android-sdk-working-dir\android-sdk_r04-windows\android-sdk-windows\too!s'. When ready, press YES to try again. Downloading Android SDK Tools, revision 7 Installing Android SDK Tools, revision 7 Failed to rename directory D:\Install\Programming\android-sdk-working-dir\android-sdk_r04-windows\android-sdk-windows\tools to D:\Install\Programming\android-sdk-working-dir\android-sdk_r04-windows\android-sdk-windows\temp\ToolPackage.old01. I am aware of http/https and antivirus issues. So I disactivated my AV. I also closed any application that might hold a handle to the folder. Eclipse is also closed (I start the manager via command line). However I still get the same error. Looks like the only app that can hold a handle to the folder is the manager itself, because its starting directory is the one the error complains about ('\tools'). I am on Win XP Pro + SP3. Does anyone have an idea?

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• Complete list of tools and technologies that make up a solid ASP.NET MVC 2 development environment f

  - by Dr Dork

  This question is related to another wiki I found on SO, but I'd like to develop a more comprehensive example of an automated ASP MVC 2 development environment that can be used to develop and deploy a wide range of small-scale websites by beginners. As far as characteristics of the dev environment go, I'd like to focus on beginner-friendly over powerful since the other wiki focuses more on advanced, powerful setups. This information is targeted for beginners (that already know C# and understand web dev concepts) that have selected... ASP.NET MVC 2 as their dev framework Visual Studio 2010 Pro (or 2008 Pro SP1) as their IDE Windows 7 as their OS and are looking for a quick and easy-to-setup environment that covers managing, building, testing, tracking, and deploying their website with as much automation as possible. A system that can be used for becoming familiar with the whole process, as well as a launching point for exploring other, more custom and powerful systems. Since we've already selected the Compiler, Framework, and OS, I'd like to develop ideas for... Code editor (unless you feel VS will suffice for all areas of code) Database and related tools Unit testing (VS?) Continuous integration build system (VS?) Project Planning Issue tracking Deployment (VS?) Source management (VS?) ASP, C#, VS, and related blogs that beginners can follow Any other categories I'm probably missing Since we're already using Visual Studio, I'd like to focus on the out-of-the-box solutions and features built into Visual Studio, unless you feel there are better solutions that work well with VS and are easier to use than the features built directly into VS. Thanks so much in advance for your wisdom!

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• Newbie, deciding Python or Erlang

  - by Joe

  Hi Guys, I'm a Administrator (unix, Linux and some windows apps such as Exchange) by experience and have never worked on any programming language besides C# and scripting on Bash and lately on powershell. I'm starting out as a service provider and using multiple network/server monitoring tools based on open source (nagios, opennms etc) in order to monitor them. At this moment, being inspired by a design that I came up with, to do more than what is available with the open source at this time, I would like to start programming and test some of these ideas. The requirement is that a server software that captures a stream of data and store them in a database(CouchDB or MongoDB preferably) and the client side (agent installed on a server) would be sending this stream of data on a schedule of every 10 minutes or so. For these two core ideas, I have been reading about Python and Erlang besides ruby. I do plan to use either Amazon or Rackspace where the server platform would run. This gives me the scalability needed when we have more customers with many servers. For that reason alone, I thought Erlang was a better fit(I could be totally wrong, new to this game) and I understand that Erlang has limited support in some ways compared to Ruby or Python. But also I'm totally new to the programming realm of things and any advise would be appreciated grately. Jo

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• Status of VB6/ Best Desktop Application Language with Native Compilation

  - by Sandeep Jindal

  I was looking for a Desktop Application Programming Language with one of the biggest constraint: - “I need to output as native executable”. I explored multiple options: Java is not a very good option for desktop programming, but still you can use it. But Java to Exe is a problem. Only GCJ and Excelsior-Jet provides this. .Net platform does not support native compilation. Only very few expensive tools are available which can do the job. Python is not an option for native compilation. Right? VB6 is the option I am left with. From the above list, if I am correct, VB6 is the only and probably the best option I have. But VB6 itself has issues like: It is no more under development since There are questions on support of VB6 IDE with Vista Thus my questions are: From the list of programming language options, do you want to add any more? If VB6 is good/best option, looking at its development status, would you suggest using VB6 in this era?

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• Python PyQt Timer Firmata

  - by George Cullins

  Hello. I am pretty new to python and working with firmata I am trying to play around with an arduino . Here is what I want to happen: Set arduino up with an LED as a digital out Set potentiometer to analog 0 Set PyQt timer up to update potentiometer position in application Set a threshold in PyQt to turn LED on (Analog in has 1024bit resolution, so say 800 as the threshold) I am using this firmata library : Link Here is the code that I am having trouble with: import sys from PyQt4 import QtCore, QtGui from firmata import * # Arduino setup self.a = Arduino('COM3') self.a.pin_mode(13, firmata.OUTPUT) # Create timer self.appTimer = QtCore.QTimer(self) self.appTimer.start(100) self.appTimer.event(self.updateAppTimer()) def updateAppTimer(self): self.analogPosition = self.a.analog_read(self, 0) self.ui.lblPositionValue.setNum() I am getting the error message: Traceback (most recent call last): File "D:\Programming\Eclipse\IO Demo\src\control.py", line 138, in myapp = MainWindow() File "D:\Programming\Eclipse\IO Demo\src\control.py", line 56, in init self.appTimer.event(self.updateAppTimer()) File "D:\Programming\Eclipse\IO Demo\src\control.py", line 60, in updateAppTimer self.analogPosition = self.a.analog_read(self, 0) TypeError: analog_read() takes exactly 2 arguments (3 given) If I take 'self' out I get the same error message but that only 1 argument is given What is python doing implicitly that I am not aware of? Blockquote

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