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  • Is Python appropriate for algorithms focused on scientific computing?

    - by gmatt
    My interests in programming lie mainly in algorithms, and lately I have seen many reputable researchers write a lot of their code in python. How easy and convenient is python for scientific computing? Does it have a library of algorithms that compares to matlab's? Is Python a scripting language or does it compile? Is it a great language for prototyping an algorithm? How long would it take me to learn enough of it to be productive provided I know C well and OO programming somewhat? Is it OO based? Sorry for the condensed format of questions, but I'm very curious and was hoping a more experienced programmer could help me out.

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  • LINQ to Twitter Maintenance Feedback

    - by Joe Mayo
    Originally posted on: http://geekswithblogs.net/WinAZ/archive/2013/06/16/linq-to-twitter-maintenance-feedback.aspxIt’s always fun to receive positive feedback on your work. If you receive a sufficient amount of positive feedback, you know you’re doing something right. Sometimes, people provide negative feedback too. There are a couple ways to handle it: come back fighting or engage for clarification. The way you handle the negative feedback depends on what your goals are. Feedback Approaches If you know the feedback is incorrect and you need to promote your idea or product, you might want to come back fighting. The feedback might just be comments by a troll or competitor wanting to spread FUD. However, this could be the totally wrong approach if you misjudge the source and intentions of the feedback. In a lot of cases, feedback is a golden opportunity. Sometimes, a problem exists that you either don’t know about or don’t realize the true impact of the problem. If you decide to come back fighting, you might loose the opportunity to learn something new. However, if you engage the person providing the feedback, looking for clarification, you might learn something very important. Negative feedback and it’s clarification can lead to the collection of useful and actionable data. In my case, something that prompted this blog post, I noticed someone who tweeted a negative comment about LINQ to Twitter. Normally, any less than stellar comments are usually from folks that need help – so I help if I can. This was different. I was like “Don’t use LINQ to Twitter”. This is an open source project, the comment didn’t come from a competing project, and  sounded more like an expression of frustration. So I engaged. Not only did the person respond, but I got some decent quality feedback. What’s also interesting is a couple other side conversations sprouted on the subject, which gave me more useful data. LINQ to Twitter Thread Actions Essentially, this particular issue centered around maintenance. There are actually several sub-issues at play here: dependencies, error handling, debugging, and visibility. I’ll describe each one and my interpretation. Dependencies Dependencies are where a library has references to other libraries. This means that when you build your application, you need DLLs for the entire dependency graph for your application. There are several potential problems with this that include more libraries for configuration management, potential versioning mismatches, and lack of cross-platform support. In the early days of LINQ to Twitter, I allowed developers to contribute and add dependencies, but it became very problematic (for reasons stated). It was like a ball and chain that kept me from moving forward. So, I refactored and pulled other open-source into my project to eliminate external dependencies. This lets me fix the code in my project without relying on someone else to upgrade or fix their DLL. The motivation for this was from early negative feedback that translated as important data and acted on it. Today, LINQ to Twitter has zero dependencies. Note: Rejecting good code from community members who worked hard to make your project better is a painful experience in itself. I have to point out that any contribution was not in vain because they had a positive influence on my subsequent refactoring that resulted in a better developer experience. Error Handling Error handling has been a problem in the past. I have this combination of supporting both synchronous and asynchronous (APM) processing that can be complex at times. Within the last 6 months, I did a fair amount of refactoring to detect errors and process them properly. I also refactored TwitterQueryException so it includes important data from Twitter. During this refactoring, I’ve made breaking changes that I felt would improve the development experience (small things like renaming a callback property to Exception, rather than Error). I think the async error handling is much better than it was a year ago. For all the work I’ve done, there is more to do. I think that a combination of more error handling support, e.g. improving semantics, and education through documentation and samples will improve the error handling story. Because of what I’ve done so far, it isn’t bad, but I see opportunities for improvement. Debugging Debugging can be painful. Here’s why: you have multiple layers of technology to navigate and figure out where the real problem is – Twitter API, Security, HTTP, LINQ to Twitter, and application. You can probably add your own nuances to that list, but the point is that debugging in this environment can be complex. I think that my plans for error handling will contribute to making the debugging process easier. However, there’s more I can do in the way of documentation and guidance. Some of the questions to be answered revolve around when something goes wrong, how does the developer figure out that there is a problem, what the problem is, and what to do about it. One example that has gone a long way to helping LINQ to Twitter developers is the 401 FAQ. A 401 Unauthorized is the error that the Twitter API returns when a use isn’t able to authenticate and is one of the most difficult problems faced by LINQ to Twitter developers. What I did was read guidance from Twitter and collect techniques from my own development and actions helping other developers to compile an extensive list of reasons for the 401 and ways to fix the problem. At one time, over half of the questions I answered in the forums were to help solve 401 issues. After publishing the 401 FAQ, I rarely get a 401 question and it’s because the person didn’t know about the FAQ. If the person is too lazy to read the FAQ, that’s not my issue, but the results in support issues have been dramatic. I think debugging can benefit from the education and documentation approach, but I’m always open to suggestions on whatever else I can do. Visibility Visibility is a nuance of the error handling/debugging discussion but is deeply rooted in comfort and control. The questions to ask in this area are what is happening as my code runs and how testable is the code. In support of these areas, LINQ to Twitter does have logging and TwitterContext properties that help see what’s happening on requests. The logging functionality allows any developer to connect a TextWriter to the Log property of TwitterContext to see what’s happening. Further, TwitterContext has a Headers property to see the headers Twitter returns and a RawResults property to show the Json string Twitter returns. From a testing perspective, I’ve been able to write hundreds of unit tests, over 600 when this post is published, and growing. If you write your own library, you have full control over all of these aspects. The tradeoff here is that while you have access to the LINQ to Twitter source code and modify it for all the visibility, LINQ to Twitter *will* change (which is good) and you will have to figure out how to merge that with your changes (which is hard). The fact is that this is a limitation of any 3rd party library, not just LINQ to Twitter. So, it’s a design decision where the tradeoff is between control and productivity. That said, there are things I can do with LINQ to Twitter to make the visibility story more compelling. I think there are opportunities to improve diagnostics. This would be a ton of work because it would need to provide multi-level logging that can be tuned for production and support any logging provider you want to attach. I’ve considered approaches such as how the new Semantic Logging application block connects to Windows Error Reporting as a potential target. Whatever I do would need to be extensible without creating native external dependencies. e.g. how many 3rd party libraries force a dependency on a logging framework that you don’t use. So, this won’t be an easy feat, but I believe it can be part of the roadmap. I think that a lot of developers are unaware of existing visibility features, so the first step would be to provide more documentation and guidance. My thought are that this would lead to more feedback that will help improve this area. Summary Recent feedback highlights some of items that are important to LINQ to Twitter developers, such as dependencies, error handling, debugging, and visibility. I know that there are maintenance issues that have been problems for LINQ to Twitter developers in the past. I’ve done a lot of work in this area, such as improving error handling, adding visibility features, and providing extensive API documentation. That said, there is more to be done to make LINQ to Twitter the best Twitter API experience available for .NET developers and I welcome anyone’s thoughts on what I’ve written here or new improvements. @JoeMayo

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  • Whats the deal with python?

    - by gmatt
    My interests in programming lie mainly in algorithms, and lately I have seen many reputable researchers write a lot of their code in python. How easy and convenient is python for scientific computing? Does it have a library of algorithms that compares to matlab's? Is Python a scripting language or does it compile? Is it a great language for prototyping an algorithm? How long would it take me to learn enough of it to be productive provided I know C well and OO programming somewhat? Is it OO based? Sorry for the condensed format of questions, but I'm very curious and was hoping a more experienced programmer could help me out.

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  • efficient video format/codec for sparse & binary blob tracking

    - by user391339
    I am working on a blob tracking project and have many high-definition videos that I would like to reduce in size for storage and downstream tracking/shape-analysis. I want to use a lossless method that takes advantage of the black and white nature of the video as well as the fact that not much is moving between individual frames. The videos are quite sparse, with 5 to 10 b&w blobs per frame occupying <30% of the space in total, with each blob moving <5-10% of the field of view between frames and not changing shape too much between 2-3 frames. I will work in Python, Matlab, or LabView for this project, and could use a batch utility if available. It may be worthwhile to export the files as compressed image stacks if a proper video format can't be found. What are the pros and cons of this? A video codec uses correlations between neighboring frames, so it should be more efficient, but not if the wrong one is chosen or if it is improperly configured.

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  • Cleanest way to store lists of filter coefficients in a C header

    - by Nick T
    I have many (~100 or so) filter coefficients calculated with the aid of some Matlab and Excel that I want to dump into a C header file for general use, but I'm not sure what the best way to do this would be. I was starting out as so: #define BUTTER 1 #define BESSEL 2 #define CHEBY 3 #if FILT_TYPE == BUTTER #if FILT_ROLLOFF == 0.010 #define B0 256 #define B1 512 #define B2 256 #define A1 467 #define A2 -214 #elif FILT_ROLLOFF == 0.015 #define B0 256 #define B1 512 // and so on... However, if I do that and shove them all into a header, I need to set the conditionals (FILT_TYPE, FILT_ROLLOFF) in my source before including it, which seems kinda nasty. What's more, if I have 2+ different filters that want different roll-offs/filter types it won't work. I could #undef my 5 coefficients (A1-2, B0-2) in that coefficients file, but it still seems wrong to have to insert an #include buried in code.

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  • Can I control the mouse cursor from within R?

    - by Bernd Meyer
    Is it possible, to control the mouse pointer from the R console? I have something like this in mind: move_mouse(x_pos=100,y_pos=200) # move the mouse pointer to position (100,200) mouse_left_button_down # simulate a press of the left button move_mouse(x_pos=120,y_pos=250) # move mouse to select something mose_release_left_button # release the pressed button In MATLAB, something like this is possible with the following code import java.awt.Robot; mouse = Robot; mouse.mouseMove(0, 0); mouse.mouseMove(100, 200); Is something similar possible for the keybord? E.g. simulate keybord events?

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  • A 3-D grid of regularly spaced points

    - by Jack
    I want to create a list containing the 3-D coords of a grid of regularly spaced points, each as a 3-element tuple. I'm looking for advice on the most efficient way to do this. In C++ for instance, I simply loop over three nested loops, one for each coordinate. In Matlab, I would probably use the meshgrid function (which would do it in one command). I've read about meshgrid and mgrid in Python, and I've also read that using numpy's broadcasting rules is more efficient. It seems to me that using the zip function in combination with the numpy broadcast rules might be the most efficient way, but zip doesn't seem to be overloaded in numpy.

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  • OWB 11gR2 - Find and Search Metadata in Designer

    - by David Allan
    Here are some tools and techniques for finding objects, specifically in the design repository. There are ways of navigating and collating objects that are useful for day to day development and build-time usage - this includes features out of the box and utilities constructed on top. There are a variety of techniques to navigate and find objects in the repository, the first 3 are out of the box, the 4th is an expert utility. Navigating by the tree, grouping by project and module - ok if you are aware of the exact module/folder that objects reside in. The structure panel is a useful way of finding parts of an object, especially when large rather than using the canvas. In large scale projects it helps to have accelerators (either find or collections below). Advanced find to search by name - 11gR2 included a find capability specifically for large scale projects. There were improvements in both the tree search and the object editors (including highlighting in mapping for example). So you can now do regular expression based search and quickly navigate to objects within a repository. Collections - logically organize your objects into virtual folders by shortcutting the actual objects. This is useful for a range of things since all the OWB services operate on collections too (export/import, validation, deployment). See the post here for new collection functionality in 11gR2. Reports for searching by type, updated on, updated by etc. Useful for activities such as periodic incremental actions (deploy all mappings changed in the past week). The report style view is useful since I can quickly see who changed what and when. You can see all the audit details for objects within each objects property inspector, but its useful to just get all objects changed today or example, all objects changed since my last build etc. This utility combines both UI extensions via experts and the public views on the repository. In the figure to the right you see the contextual option 'Object Search' which invokes the utility, you can see I have quite a number of modules within my project. Figure out all the potential objects which have been changed is not simple. The utility is an expert which provides this kind of search capability. The utility provides a report of the objects in the design repository which satisfy some filter criteria. The type of criteria includes; objects updated in the last n days optionally filter the objects updated by user filter the user by project and by type (table/mappings etc.) The search dialog appears with these options, you can multi-select the object types, so for example you can select TABLE and MAPPING. Its also possible to search across projects if need be. If you have multiple users using the repository you can define the OWB user name in the 'Updated by' property to restrict the report to just that user also. Finally there is a search name that will be used for some of the options such as building a collection - this name is used for the collection to be built. In the example I have done, I've just searched my project for all process flows and mappings that users have updated in the last 7 days. The results of the query are returned in a table containing the object names, types, full path and audit details. The columns are sort-able, you can sort the results by name, type, path etc. One of the cool things here, is that you can then perform operations on these objects - such as edit them, export single selection or entire results to MDL, create a collection from the results (now you have a saved set of references in the repository, you could do deploy/export etc.), create a deployment script from the results...or even add in your own ideas! You see from this that you can do bulk operations on sets of objects based on search results. So for example selecting the 'Build Collection' option creates a collection with all of the objects from my search, you can subsequently deploy/generate/maintain this collection of objects. Under the hood of the expert if just basic OMB commands from the product and the use of the public views on the design repository. You can see how easy it is to build up macro-like capabilities that will help you do day-to-day as well as build like tasks on sets of objects.

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  • SQL SERVER – MSQL_XP – Wait Type – Day 20 of 28

    - by pinaldave
    In this blog post, I am going to discuss something from my field experience. While consultation, I have seen various wait typed, but one of my customers who has been using SQL Server for all his operations had an interesting issue with a particular wait type. Our customer had more than 100+ SQL Server instances running and the whole server had MSSQL_XP wait type as the most number of wait types. While running sp_who2 and other diagnosis queries, I could not immediately figure out what the issue was because the query with that kind of wait type was nowhere to be found. After a day of research, I was relieved that the solution was very easy to figure out. Let us continue discussing this wait type. From Book On-Line: ?MSQL_XP occurs when a task is waiting for an extended stored procedure to end. SQL Server uses this wait state to detect potential MARS application deadlocks. The wait stops when the extended stored procedure call ends. MSQL_XP Explanation: This wait type is created because of the extended stored procedure. Extended Stored Procedures are executed within SQL Server; however, SQL Server has no control over them. Unless you know what the code for the extended stored procedure is and what it is doing, it is impossible to understand why this wait type is coming up. Reducing MSQL_XP wait: As discussed, it is hard to understand the Extended Stored Procedure if the code for it is not available. In the scenario described at the beginning of this post, our client was using third-party backup tool. The third-party backup tool was using Extended Stored Procedure. After we learned that this wait type was coming from the extended stored procedure of the backup tool they were using, we contacted the tech team of its vendor. The vendor admitted that the code was not optimal at some places, and within that day they had provided the patch. Once the updated version was installed, the issue on this wait type disappeared. As viewed in the wait statistics of all the 100+ SQL Server, there was no more MSSQL_XP wait type found. In simpler terms, you must first identify which Extended Stored Procedure is creating the wait type of MSSQL_XP and see if you can get in touch with the creator of the SP so you can help them optimize the code. If you have encountered this MSSQL_XP wait type, I encourage all of you to write how you managed it. Please do not mention the name of the vendor in your comment as I will not approve it. The focus of this blog post is to understand the wait types; not talk about others. Read all the post in the Wait Types and Queue series. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussion of Wait Stats in this blog is generic and varies from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • Oracle Fusion Procurement Designed for User Productivity

    - by Applications User Experience
    Sean Rice, Manager, Applications User Experience Oracle Fusion Procurement Design Goals In Oracle Fusion Procurement, we set out to create a streamlined user experience based on the way users do their jobs. Oracle has spent hundreds of hours with customers to get to the heart of what users need to do their jobs. By designing a procurement application around user needs, Oracle has crafted a user experience that puts the tools that people need at their fingertips. In Oracle Fusion Procurement, the user experience is designed to provide the user with information that will drive navigation rather than requiring the user to find information. One of our design goals for Oracle Fusion Procurement was to reduce the number of screens and clicks that a user must go through to complete frequently performed tasks. The requisition process in Oracle Fusion Procurement (Figure 1) illustrates how we have streamlined workflows. Oracle Fusion Self-Service Procurement brings together billing metrics, descriptions of the order, justification for the order, a breakdown of the components of the order, and the amount—all in one place. Previous generations of procurement software required the user to navigate to several different pages to gather all of this information. With Oracle Fusion, everything is presented on one page. The result is that users can complete their tasks in less time. The focus is on completing the work, not finding the work. Figure 1. Creating a requisition in Oracle Fusion Self-Service Procurement is a consumer-like shopping experience. Will Oracle Fusion Procurement Increase Productivity? To answer this question, Oracle sought to model how two experts working head to head—one in an existing enterprise application and another in Oracle Fusion Procurement—would perform the same task. We compared Oracle Fusion designs to corresponding existing applications using the keystroke-level modeling (KLM) method. This method is based on years of research at universities such as Carnegie Mellon and research labs like Xerox Palo Alto Research Center. The KLM method breaks tasks into a sequence of operations and uses standardized models to evaluate all of the physical and cognitive actions that a person must take to complete a task: what a user would have to click, how long each click would take (not only the physical action of the click or typing of a letter, but also how long someone would have to think about the page when taking the action), and user interface changes that result from the click. By applying standard time estimates for all of the operators in the task, an estimate of the overall task time is calculated. Task times from the model enable researchers to predict end-user productivity. For the study, we focused on modeling procurement business process task flows that were considered business or mission critical: high-frequency tasks and high-value tasks. The designs evaluated encompassed tasks that are currently performed by employees, professional buyers, suppliers, and sourcing professionals in advanced procurement applications. For each of these flows, we created detailed task scenarios that provided the context for each task, conducted task walk-throughs in both the Oracle Fusion design and the existing application, analyzed and documented the steps and actions required to complete each task, and applied standard time estimates to the operators in each task to estimate overall task completion times. The Results The KLM method predicted that the Oracle Fusion Procurement designs would result in productivity gains in each task, ranging from 13 percent to 38 percent, with an overall productivity gain of 22.5 percent. These performance gains can be attributed to a reduction in the number of clicks and screens needed to complete the tasks. For example, creating a requisition in Oracle Fusion Procurement takes a user through only two screens, while ordering the same item in a previous version requires six screens to complete the task. Modeling user productivity has resulted not only in advances in Oracle Fusion applications, but also in advances in other areas. We leveraged lessons learned from the KLM studies to establish products like Oracle E-Business Suite (EBS). New user experience features in EBS 12.1.3, such as navigational improvements to the main menu, a Google-type search using auto-suggest, embedded analytics, and an in-context list of values tool help to reduce clicks and improve efficiency. For more information about KLM, refer to the Measuring User Productivity blog.

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  • Personal Technology – Excel Tip: Comparing Excel Files

    - by Pinal Dave
    This guest post is by Vinod Kumar. Vinod Kumar has worked with SQL Server extensively since joining the industry over a decade ago. Working on various versionsfrom SQL Server 7.0, Oracle 7.3 and other database technologies – he now works with the Microsoft Technology Center (MTC) as a Technology Architect. Let us read the blog post in Vinod’s own voice. I have been writing about Excel Tips over my blog and thought it would be great to share one interesting tips here as a guest blog here. Assume a situation where you want to compare multiple excel files. Here is a typical scenario I have encountered as a common activity. Assume you are sending an Excel file with tons of data, formulae and multiple sheets. Now you are requesting your colleague to validate the file and if required change content for correctness. After receiving the file from your colleague, now you want to know what changes were made by this person to your document. Now here is a cool new addition to Excel 2013 that can help you achieve this task. To get to this option, click the INQUIRE Tab. Incase you don’t have the INQUIRE Tab, check Options using INQUIRE blog. In that post, we discuss all the other options of INQUIRE tab. Once you are on the INQUIRE Tab, select “Compare Files” button as shown in the figure above. This brings a dialog as below. If you are on Windows 8 or Windows 7 OS, search for an application called “Spreadsheet Compare 2013”. Ultimately both the options lead us to the same application. If you are using the stand alone app, once the App initializes, click the “Compare files” options from the toolbar. Make sure to give two different Excel files as shown in the figure above. After selecting the Excel Sheets, you can see the Compare tool has a number of other options to play from. We will talk about some of them later in this post. Just below our toolbar is a colorful side-by-side comparison of both our excel sheets. We can also see the various Tab’s from each file. There is a meaning for each of our color coding which will be discussed next. As you saw above, the color coding has a meaning. For example the bottom pane lists each of the color coding and most importantly each of the changes as compared side-by-side. The detailed information shown below can be exported using the “Export Results” options from the toolbar as a separate Excel Workbook or can be copied to clipboard to be used later. The final piece of the puzzle is to show a graphical view of these differences results based on each category. We cannot drill down per se, but this is a great way to know that the maximum changes seem to be based on “Cell Formats” and then few “Calculated Values” have changed. The INQUIRE option and Spreadsheet Compare 2013 tool is part of Excel 2013. So as you explore using the new version of Excel, there are many such hidden features that are worth exploring. Do let us know if you enjoyed learning a new feature today and I hope you will play around with this feature in your day-today challenges when working with Excel files. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology Tagged: Excel, Personal Technology

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  • Running Multiple WebLogic and OSB Domains

    - by jeff.x.davies
    I have any number of OSB domain created on my machine at any point in time. For example, I have different domains for different version of Oracle Service Bus and Oracle SOA Suite. I also have different domains for different purposes. I have a demo domain and another domain for the projects in my blog. Starting with OSB 11g and the Apache Derby server, there is a small "gotcha" if you want to create multiple domains on a devevelopment machine. When you create a new domain for OSB 11g it will use the same database info for all databases and this will cause an error when starting the admin server of the second domain (the first domain doesn't have to be running for this error to occur). Here is an example of the error message in the server console: ####<Mar 8, 2011 2:58:48 PM PST> <Critical> <JTA> <jeff-laptop> <AdminServer> <[ACTIVE] ExecuteThread: '0' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1299625128464> <BEA-110482> <A logging last resource failed during initialization. The server cannot boot unless all configured logging last resources (LLRs) initialize. Failing reason: weblogic.transaction.loggingresource.LoggingResourceException: java.sql.SQLException: JDBC LLR, table verify failed for table 'WL_LLR_ADMINSERVER', row 'JDBC LLR Domain//Server' record had unexpected value 'osb11gR1PS3//AdminServer' expected 'OSBCIM//AdminServer'*** ONLY the original domain and server that creates an LLR table may access it *** The solution is to create a database instance for each of your domains and this is very simple to do. After you create a domain using the Configuration Wizard, locate the wlsbjmsrpDataSource-jdbc.xml file that is found under the DOMAIN_HOME/config/jdbc directory. Near the top of the file you will see the following entry: <url>jdbc:derby://localhost:1527/osbexamples;create=true;ServerName=localhost;databaseName=osbexamples</url> You need to modify this entry with a different and unique database name. The easiest way to do this is to substiture the name of your domain. For example: <url>jdbc:derby://localhost:1527/mydomain;create=true;ServerName=localhost;databaseName=mydomain</url> will create a database named mydomain . Now, when you restart the admin server for the domain, it will create the new database for you. Do this for each domain you create on your development machine and you'll have no troubles. The process is much simpler if you are creating a domain using the Configuration Wizard. Simply name the database when you get to the Configure JDBC Component Schema step of the Configuration Wizard, select the OSB JMS Reporting Provider and set the name in the DBMS/Service field to whatever name you like, as shown in Figure 1 below. Figure 1 – Configuring the JDBC Component Schema That is all there is to it. Now you can create as many domains on your leptop or development machine as you like and not have to worry about them conflicting with each other.

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  • Spritesheet per pixel collision XNA

    - by Jixi
    So basically i'm using this: public bool IntersectPixels(Rectangle rectangleA, Color[] dataA,Rectangle rectangleB, Color[] dataB) { int top = Math.Max(rectangleA.Top, rectangleB.Top); int bottom = Math.Min(rectangleA.Bottom, rectangleB.Bottom); int left = Math.Max(rectangleA.Left, rectangleB.Left); int right = Math.Min(rectangleA.Right, rectangleB.Right); for (int y = top; y < bottom; y++) { for (int x = left; x < right; x++) { Color colorA = dataA[(x - rectangleA.Left) + (y - rectangleA.Top) * rectangleA.Width]; Color colorB = dataB[(x - rectangleB.Left) + (y - rectangleB.Top) * rectangleB.Width]; if (colorA.A != 0 && colorB.A != 0) { return true; } } } return false; } In order to detect collision, but i'm unable to figure out how to use it with animated sprites. This is my animation update method: public void AnimUpdate(GameTime gameTime) { if (!animPaused) { animTimer += (float)gameTime.ElapsedGameTime.TotalMilliseconds; if (animTimer > animInterval) { currentFrame++; animTimer = 0f; } if (currentFrame > endFrame || endFrame <= currentFrame || currentFrame < startFrame) { currentFrame = startFrame; } objRect = new Rectangle(currentFrame * TextureWidth, frameRow * TextureHeight, TextureWidth, TextureHeight); origin = new Vector2(objRect.Width / 2, objRect.Height / 2); } } Which works with multiple rows and columns. and how i call the intersect: public bool IntersectPixels(Obj me, Vector2 pos, Obj o) { Rectangle collisionRect = new Rectangle(me.objRect.X, me.objRect.Y, me.objRect.Width, me.objRect.Height); collisionRect.X += (int)pos.X; collisionRect.Y += (int)pos.Y; if (IntersectPixels(collisionRect, me.TextureData, o.objRect, o.TextureData)) { return true; } return false; } Now my guess is that i have to update the textureData everytime the frame changes, no? If so then i already tried it and miserably failed doing so :P Any hints, advices? If you need to see any more of my code just let me know and i'll update the question. Updated almost functional collisionRect: collisionRect = new Rectangle((int)me.Position.X, (int)me.Position.Y, me.Texture.Width / (int)((me.frameCount - 1) * me.TextureWidth), me.Texture.Height); What it does now is "move" the block up 50%, shouldn't be too hard to figure out. Update: Alright, so here's a functional collision rectangle(besides the height issue) collisionRect = new Rectangle((int)me.Position.X, (int)me.Position.Y, me.TextureWidth / (int)me.frameCount - 1, me.TextureHeight); Now the problem is that using breakpoints i found out that it's still not getting the correct color values of the animated sprite. So it detects properly but the color values are always: R:0 G:0 B:0 A:0 ??? disregard that, it's not true afterall =P For some reason now the collision area height is only 1 pixel..

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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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  • Oracle Fusion Supply Chain Management (SCM) Designs May Improve End User Productivity

    - by Applications User Experience
    By Applications User Experience on March 10, 2011 Michele Molnar, Senior Usability Engineer, Applications User Experience The Challenge: The SCM User Experience team, in close collaboration with product management and strategy, completely redesigned the user experience for Oracle Fusion applications. One of the goals of this redesign was to increase end user productivity by applying design patterns and guidelines and incorporating findings from extensive usability research. But a question remained: How do we know that the Oracle Fusion designs will actually increase end user productivity? The Test: To answer this question, the SCM Usability Engineers compared Oracle Fusion designs to their corresponding existing Oracle applications using the workflow time analysis method. The workflow time analysis method breaks tasks into a sequence of operators. By applying standard time estimates for all of the operators in the task, an estimate of the overall task time can be calculated. The workflow time analysis method has been recently adopted by the Applications User Experience group for use in predicting end user productivity. Using this method, a design can be tested and refined as needed to improve productivity even before the design is coded. For the study, we selected some of our recent designs for Oracle Fusion Product Information Management (PIM). The designs encompassed tasks performed by Product Managers to create, manage, and define products for their organization. (See Figure 1 for an example.) In applying this method, the SCM Usability Engineers collaborated with Product Management to compare the new Oracle Fusion Applications designs against Oracle’s existing applications. Together, we performed the following activities: Identified the five most frequently performed tasks Created detailed task scenarios that provided the context for each task Conducted task walkthroughs Analyzed and documented the steps and flow required to complete each task Applied standard time estimates to the operators in each task to estimate the overall task completion time Figure 1. The interactions on each Oracle Fusion Product Information Management screen were documented, as indicated by the red highlighting. The task scenario and script provided the context for each task.  The Results: The workflow time analysis method predicted that the Oracle Fusion Applications designs would result in productivity gains in each task, ranging from 8% to 62%, with an overall productivity gain of 43%. All other factors being equal, the new designs should enable these tasks to be completed in about half the time it takes with existing Oracle Applications. Further analysis revealed that these performance gains would be achieved by reducing the number of clicks and screens needed to complete the tasks. Conclusions: Using the workflow time analysis method, we can expect the Oracle Fusion Applications redesign to succeed in improving end user productivity. The workflow time analysis method appears to be an effective and efficient tool for testing, refining, and retesting designs to optimize productivity. The workflow time analysis method does not replace usability testing with end users, but it can be used as an early predictor of design productivity even before designs are coded. We are planning to conduct usability tests later in the development cycle to compare actual end user data with the workflow time analysis results. Such results can potentially be used to validate the productivity improvement predictions. Used together, the workflow time analysis method and usability testing will enable us to continue creating, evaluating, and delivering Oracle Fusion designs that exceed the expectations of our end users, both in the quality of the user experience and in productivity. (For more information about studying productivity, refer to the Measuring User Productivity blog.)

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  • How do you formulate the Domain Model in Domain Driven Design properly (Bounded Contexts, Domains)?

    - by lko
    Say you have a few applications which deal with a few different Core Domains. The examples are made up and it's hard to put a real example with meaningful data together (concisely). In Domain Driven Design (DDD) when you start looking at Bounded Contexts and Domains/Sub Domains, it says that a Bounded Context is a "phase" in a lifecycle. An example of Context here would be within an ecommerce system. Although you could model this as a single system, it would also warrant splitting into separate Contexts. Each of these areas within the application have their own Ubiquitous Language, their own Model, and a way to talk to other Bounded Contexts to obtain the information they need. The Core, Sub, and Generic Domains are the area of expertise and can be numerous in complex applications. Say there is a long process dealing with an Entity for example a Book in a core domain. Now looking at the Bounded Contexts there can be a number of phases in the books life-cycle. Say outline, creation, correction, publish, sale phases. Now imagine a second core domain, perhaps a store domain. The publisher has its own branch of stores to sell books. The store can have a number of Bounded Contexts (life-cycle phases) for example a "Stock" or "Inventory" context. In the first domain there is probably a Book database table with basically just an ID to track the different book Entities in the different life-cycles. Now suppose you have 10+ supporting domains e.g. Users, Catalogs, Inventory, .. (hard to think of relevant examples). For example a DomainModel for the Book Outline phase, the Creation phase, Correction phase, Publish phase, Sale phase. Then for the Store core domain it probably has a number of life-cycle phases. public class BookId : Entity { public long Id { get; set; } } In the creation phase (Bounded Context) the book could be a simple class. public class Book : BookId { public string Title { get; set; } public List<string> Chapters { get; set; } //... } Whereas in the publish phase (Bounded Context) it would have all the text, release date etc. public class Book : BookId { public DateTime ReleaseDate { get; set; } //... } The immediate benefit I can see in separating by "life-cycle phase" is that it's a great way to separate business logic so there aren't mammoth all-encompassing Entities nor Domain Services. A problem I have is figuring out how to concretely define the rules to the physical layout of the Domain Model. A. Does the Domain Model get "modeled" so there are as many bounded contexts (separate projects etc.) as there are life-cycle phases across the core domains in a complex application? Edit: Answer to A. Yes, according to the answer by Alexey Zimarev there should be an entire "Domain" for each bounded context. B. Is the Domain Model typically arranged by Bounded Contexts (or Domains, or both)? Edit: Answer to B. Each Bounded Context should have its own complete "Domain" (Service/Entities/VO's/Repositories) C. Does it mean there can easily be 10's of "segregated" Domain Models and multiple projects can use it (the Entities/Value Objects)? Edit: Answer to C. There is a complete "Domain" for each Bounded Context and the Domain Model (Entity/VO layer/project) isn't "used" by the other Bounded Contexts directly, only via chosen paths (i.e. via Domain Events). The part that I am trying to figure out is how the Domain Model is actually implemented once you start to figure out your Bounded Contexts and Core/Sub Domains, particularly in complex applications. The goal is to establish the definitions which can help to separate Entities between the Bounded Contexts and Domains.

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  • Walkthrough: Scheduling jobs using Quartz.net &ndash; Part 1: What is Quartz.Net?

    - by Tarun Arora
    Quartz.NET is a full-featured, open source enterprise job scheduling system written in .NET platform that can be used from smallest apps to large scale enterprise systems. What is the problem that we trying to address? I want to schedule the execution of a task but only when something happens. Let’s call that something a trigger, so... if the trigger is met => execute the task. Sounds simple, why not use windows task scheduler for this? Well, windows task scheduler is great for tasks where the trigger can be easily defined. With windows task scheduler will you be able to schedule a task to run on every working day according to the UK calendar (exclude all weekends & bank holidays) without either writing the logic for day check in the task or a wrapper script calling into the task. The task should just contain the execution logic and should not have anything to do with the schedule for execution; Quartz.net allows you to achieve this and lots more. A quartz.net trigger gives you the flexibility for task invocation based on the following triggers, 1. at a certain time of day (to the millisecond) 2. on certain days of the week 3. on certain days of the month 4. on certain days of the year 5. not on certain days listed within a registered Calendar (such as business holidays) 6. repeated a specific number of times 7. repeated until a specific time/date 8. repeated indefinitely 9. repeated with a delay interval Did 8 – repeat indefinitely just ring a bell? I’ll be covering that in the future post. Using Quartz.net as a windows service You can have Quartz.net run as a standalone instance within its own .NET virtual machine instance via .NET Remoting. Let’s take a look at typical application architecture. In the figure below, I have the application tier set up on Machine 1, database set up on Machine 2 and Quartz.net set up on Machine 3 which is normally the architecture for most (if not all) enterprise applications. Figure 1 -  Typical Application architecture while using Quartz.net as a windows service What other options do I have if I don’t want to use Quartz.net? Quartz.net is just one of the many job scheduling services. Have a look at this comprehensive list of free and paid enterprise job scheduling software along with their feature comparison. http://en.wikipedia.org/wiki/List_of_job_scheduler_software This was first in the series of posts on enterprise scheduling using Quartz.net, in the next post I’ll be covering how to Install Quartz.net as a windows service. Thank you for taking the time out and reading this blog post. If you enjoyed the post, remember to subscribe to http://feeds.feedburner.com/TarunArora. Stay tuned!

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  • RemoveHandler Issues with Custom Events

    - by Jeff Certain
    This is a case of things being more complicated that I thought they should be. Since it took a while to figure this one out, I thought it was worth explaining and putting all of the pieces to the answer in one spot. Let me set the stage. Architecturally, I have the notion of generic producers and consumers. These put items onto, and remove items from, a queue. This provides a generic, thread-safe mechanism to load balance the creation and processing of work items in our application. Part of the IProducer(Of T) interface is: 1: Public Interface IProducer(Of T) 2: Event ItemProduced(ByVal sender As IProducer(Of T), ByVal item As T) 3: Event ProductionComplete(ByVal sender As IProducer(Of T)) 4: End Interface Nothing sinister there, is there? In order to simplify our developers’ lives, I wrapped the queue with some functionality to manage the produces and consumers. Since the developer can specify the number of producers and consumers that are spun up, the queue code manages adding event handlers as the producers and consumers are instantiated. Now, we’ve been having some memory leaks and, in order to eliminate the possibility that this was caused by weak references to event handles, I wanted to remove them. This is where it got dicey. My first attempt looked like this: 1: For Each producer As P In Producers 2: RemoveHandler producer.ItemProduced, AddressOf ItemProducedHandler 3: RemoveHandler producer.ProductionComplete, AddressOf ProductionCompleteHandler 4: producer.Dispose() 5: Next What you can’t see in my posted code are the warnings this caused. The 'AddressOf' expression has no effect in this context because the method argument to 'AddressOf' requires a relaxed conversion to the delegate type of the event. Assign the 'AddressOf' expression to a variable, and use the variable to add or remove the method as the handler.  Now, what on earth does that mean? Well, a quick Bing search uncovered a whole bunch of talk about delegates. The first solution I found just changed all parameters in the event handler to Object. Sorry, but no. I used generics precisely because I wanted type safety, not because I wanted to use Object. More searching. Eventually, I found this forum post, where Jeff Shan revealed a missing piece of the puzzle. The other revelation came from Lian_ZA in this post. However, these two only hinted at the solution. Trying some of what they suggested led to finally getting an invalid cast exception that revealed the existence of ItemProducedEventHandler. Hold on a minute! I didn’t create that delegate. There’s nothing even close to that name in my code… except the ItemProduced event in the interface. Could it be? Naaaaah. Hmmm…. Well, as it turns out, there is a delegate created by the compiler for each event. By explicitly creating a delegate that refers to the method in question, implicitly cast to the generated delegate type, I was able to remove the handlers: 1: For Each producer As P In Producers 2: Dim _itemProducedHandler As IProducer(Of T).ItemProducedEventHandler = AddressOf ItemProducedHandler 3: RemoveHandler producer.ItemProduced, _itemProducedHandler 4:  5: Dim _productionCompleteHandler As IProducer(Of T).ProductionCompleteEventHandler = AddressOf ProductionCompleteHandler 6: RemoveHandler producer.ProductionComplete, _productionCompleteHandler 7: producer.Dispose() 8: Next That’s “all” it took to finally be able to remove the event handlers and maintain type-safe code. Hopefully, this will save you the same challenges I had in trying to figure out how to fix this issue!

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  • Creating a Corporate Data Hub

    - by BuckWoody
    The Windows Azure Marketplace has a rich assortment of data and software offerings for you to use – a type of Software as a Service (SaaS) for IT workers, not necessarily for end-users. Among those offerings is the “Data Hub” – a  codename for a project that ironically actually does what the codename says. In many of our organizations, we have multiple data quality issues. Finding data is one problem, but finding it just once is often a bigger problem. Lots of departments and even individuals have stored the same data more than once, and in some cases, made changes to one of the copies. It’s difficult to know which location or version of the data is authoritative. Then there’s the problem of accessing the data. It’s fairly straightforward to publish a database, share or other location internally to store the data. But then you have to figure out who owns it, how it is controlled, and pass out the various connection strings to those who want to use it. And then you need to figure out how to let folks access the internal data externally – bringing up all kinds of security issues. Finally, in many cases our user community wants us to combine data from the internally sources with external data, bringing up the security, strings, and exploration features up all over again. Enter the Data Hub. This is an online offering, where you assign an administrator and data stewards. You import the data into the service, and it’s available to you - and only you and your organization if you wish. The basic steps for this service are to set up the portal for your company, assign administrators and permissions, and then you assign data areas and import data into them. From there you make them discoverable, and then you have multiple options that you or your users can access that data. You’re then able, if you wish, to combine that data with other data in one location. So how does all that work? What about security? Is it really that easy? And can you really move the data definition off to the Subject Matter Experts (SME’s) that know the particular data stack better than the IT team does? Well, nothing good is easy – but using the Data Hub is actually pretty simple. I’ll give you a link in a moment where you can sign up and try this yourself. Once you sign up, you assign an administrator. From there you’ll create data areas, and then use a simple interface to bring the data in. All of this is done in a portal interface – nothing to install, configure, update or manage. After the data is entered in, and you’ve assigned meta-data to describe it, your users have multiple options to access it. They can simply use the portal – which actually has powerful visualizations you can use on any platform, even mobile phones or tablets.     Your users can also hit the data with Excel – which gives them ultimate flexibility for display, all while using an authoritative, single reference for the data. Since the service is online, they can do this wherever they are – given the proper authentication and permissions. You can also hit the service with simple API calls, like this one from C#: http://msdn.microsoft.com/en-us/library/hh921924  You can make HTTP calls instead of code, and the data can even be exposed as an OData Feed. As you can see, there are a lot of options. You can check out the offering here: http://www.microsoft.com/en-us/sqlazurelabs/labs/data-hub.aspx and you can read the documentation here: http://msdn.microsoft.com/en-us/library/hh921938

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  • Creating a Corporate Data Hub

    - by BuckWoody
    The Windows Azure Marketplace has a rich assortment of data and software offerings for you to use – a type of Software as a Service (SaaS) for IT workers, not necessarily for end-users. Among those offerings is the “Data Hub” – a  codename for a project that ironically actually does what the codename says. In many of our organizations, we have multiple data quality issues. Finding data is one problem, but finding it just once is often a bigger problem. Lots of departments and even individuals have stored the same data more than once, and in some cases, made changes to one of the copies. It’s difficult to know which location or version of the data is authoritative. Then there’s the problem of accessing the data. It’s fairly straightforward to publish a database, share or other location internally to store the data. But then you have to figure out who owns it, how it is controlled, and pass out the various connection strings to those who want to use it. And then you need to figure out how to let folks access the internal data externally – bringing up all kinds of security issues. Finally, in many cases our user community wants us to combine data from the internally sources with external data, bringing up the security, strings, and exploration features up all over again. Enter the Data Hub. This is an online offering, where you assign an administrator and data stewards. You import the data into the service, and it’s available to you - and only you and your organization if you wish. The basic steps for this service are to set up the portal for your company, assign administrators and permissions, and then you assign data areas and import data into them. From there you make them discoverable, and then you have multiple options that you or your users can access that data. You’re then able, if you wish, to combine that data with other data in one location. So how does all that work? What about security? Is it really that easy? And can you really move the data definition off to the Subject Matter Experts (SME’s) that know the particular data stack better than the IT team does? Well, nothing good is easy – but using the Data Hub is actually pretty simple. I’ll give you a link in a moment where you can sign up and try this yourself. Once you sign up, you assign an administrator. From there you’ll create data areas, and then use a simple interface to bring the data in. All of this is done in a portal interface – nothing to install, configure, update or manage. After the data is entered in, and you’ve assigned meta-data to describe it, your users have multiple options to access it. They can simply use the portal – which actually has powerful visualizations you can use on any platform, even mobile phones or tablets.     Your users can also hit the data with Excel – which gives them ultimate flexibility for display, all while using an authoritative, single reference for the data. Since the service is online, they can do this wherever they are – given the proper authentication and permissions. You can also hit the service with simple API calls, like this one from C#: http://msdn.microsoft.com/en-us/library/hh921924  You can make HTTP calls instead of code, and the data can even be exposed as an OData Feed. As you can see, there are a lot of options. You can check out the offering here: http://www.microsoft.com/en-us/sqlazurelabs/labs/data-hub.aspx and you can read the documentation here: http://msdn.microsoft.com/en-us/library/hh921938

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  • Application Logging needs work

    Application Logging Application logging is the act of logging events that occur within an application much like how a court report documents what happens in court case. Application logs can be useful for several reasons, but the most common use for logs is to recreate steps to find the root cause of applications errors. Other uses can include the detection of Fraud, verification of user activity, or provide audits on user/data interactions. “Logs can contain different kinds of data. The selection of the data used is normally affected by the motivation leading to the logging. “ (OWASP, 2009) OWASP also stats that logging include applicable debugging information like the event date time, responsible process, and a description of the event. “There are many reasons why a logging system is a necessary part of delivering a distributed application. One of the most important is the ability to track exactly how many users are using the application during different time periods.” (Hatton, 2000) Hatton also states that application logging helps system designers determine whether parts of an application aren't being used as designed. He implies that low usage can be used to identify if users like or do not like aspects of a system based on user usage of the application. This enables application designers to extract why users don't like aspects of an application so that changes can be made to increase its usefulness and effectiveness. “Logging memory usage can also assist you in tuning up the internals of your application. If you're experiencing a randomly occurring problem, being able to match activities performed with the memory status at the time may enable you to discover the cause of the problem. It also gives you a good indication of the health of the distributed server machine at the time any activity is performed. “ (Hatton, 2000) Commonly Logged Application Events (Defined by OWASP) Access of Data Creation of Data Modification of Data in any form Administrative Functions  Configuration Changes Debugging Information(Application Events)  Authorization Attempts  Data Deletion Network Communication  Authentication Events  Errors/Exceptions Application Error Logging The functionality associated with application error logging is actually the combination of proper error handling and applications logging.  If we look back at Figure 4 and Figure 5, these code examples allow developers to handle various types of errors that occur within the life cycle of an application’s execution. Application logging can be applied within the Catch section of the TryCatch statement allowing for the errors to be logged when they occur. By placing the logging within the Catch section specific error details can be accessed that help identify the source of the error, the path to the error, what caused the error and definition of the error that occurred. This can then be logged and reviewed at a later date in order recreate the error that was received based data found in the application log. By allowing applications to log errors developers IT staff can use them to recreate errors that are encountered by end-users or other dependent systems.

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  • MVC Communication Pattern

    - by Kedu
    This is kind of a follow up question to this http://stackoverflow.com/questions/23743285/model-view-controller-and-callbacks, but I wanted to post it separately, because its kind of a different topic. I'm working on a multiplayer cardgame for the Android platform. I split the project into MVC which fits the needs pretty good, but I'm currently stuck because I can't figure out a good way to communicate between the different parts. I have everything setup and working with the controller being a big state machine, which is called over and over from the gameloop, and calls getter methods from the GUI and the android/network part to get the input. The input itself in the GUI and network is set by inputlisteners that set a local variable which I read in the getter method. So far so good, this is working. But my problem is, the controller has to check every input separately,so if I want to add an input I have to check in which states its valid and call the getter method from all these states. This is not good, and lets the code look pretty ugly, makes additions uncomfortable and adds redundance. So what I've got from the question I mentioned above is that some kind of command or event pattern will fit my needs. What I want to do is to create a shared and threadsafe queue in the controller and instead of calling all these getter methods, I just check the queue for new input and proceed it. On the other side, the GUI and network don't have all these getters, but instead create an event or command and send it to the controller through, for example, observer/observable. Now my problem: I can't figure out a way, for these commands/events to fit a common interface (which the queue can store) and still transport different kind of data (button clicks, cards that are played, the player id the command comes from, synchronization data etc.). If I design the communication as command pattern, I have to stick all the information that is needed to execute the command into it when its created, that's impossible because the GUI or network has no knowledge of all the things the controller needs to execute stuff that needs to be done when for example a card is played. I thought about getting this stuff into the command when executing it. But over all the different commands I have, I would need all the information the controller has, and thus give the command a reference to the controller which would make everything in it public, which is real bad design I guess. So, I could try some kind of event pattern. I have to transport data in the event. So, like the command, I would have an interface, which all events have in common, and can be stored in the shared queue. I could create a big enum with all the different events that a are possible, save one of these enums in the actual event, and build a big switch case for the events, to proceed different stuff for different events. The problem here: I have different data for all the events. But I need a common interface, to store the events in a queue. How do I get the specific data, if I can only access the event through the interface? Even if that wouldn't be a problem, I'm creating another big switch case, which looks ugly, and when i want to add a new event, I have to create the event itself, the case, the enum, and the method that's called with the data. I could of course check the event with the enum and cast it to its type, so I can call event type specific methods that give me the data I need, but that looks like bad design too.

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  • Why is the framerate (fps) capped at 60?

    - by dennmat
    ISSUE I recently moved a project from my laptop to my desktop(machine info below). On my laptop the exact same code displays the fps(and ms/f) correctly. On my desktop it does not. What I mean by this is on the laptop it will display 300 fps(for example) where on my desktop it will show only up to 60. If I add 100 objects to the game on the laptop I'll see my frame rate drop accordingly; the same test on the desktop results in no change and the frames stay at 60. It takes a lot(~300) entities before I'll see a frame drop on the desktop, then it will descend. It seems as though its "theoretical" frames would be 400 or 500 but will never actually get to that and only do 60 until there's too much to handle at 60. This 60 frame cap is coming from no where. I'm not doing any frame limiting myself. It seems like something external is limiting my loop iterations on the desktop, but for the last couple days I've been scratching my head trying to figure out how to debug this. SETUPS Desktop: Visual Studio Express 2012 Windows 7 Ultimate 64-bit Laptop: Visual Studio Express 2010 Windows 7 Ultimate 64-bit The libraries(allegro, box2d) are the same versions on both setups. CODE Main Loop: while(!abort) { frameTime = al_get_time(); if (frameTime - lastTime >= 1.0) { lastFps = fps/(frameTime - lastTime); lastTime = frameTime; avgMspf = cumMspf/fps; cumMspf = 0.0; fps = 0; } /** DRAWING/UPDATE CODE **/ fps++; cumMspf += al_get_time() - frameTime; } Note: There is no blocking code in the loop at any point. Where I'm at My understanding of al_get_time() is that it can return different resolutions depending on the system. However the resolution is never worse than seconds, and the double is represented as [seconds].[finer-resolution] and seeing as I'm only checking for a whole second al_get_time() shouldn't be responsible. My project settings and compiler options are the same. And I promise its the same code on both machines. My googling really didn't help me much, and although technically it's not that big of a deal. I'd really like to figure this out or perhaps have it explained, whichever comes first. Even just an idea of how to go about figuring out possible causes, because I'm out of ideas. Any help at all is greatly appreciated. EDIT: Thanks All. For any others that find this to disable vSync(windows only) in opengl: First get "wglext.h". It's all over the web. Then you can use a tool like GLee or just write your own quick extensions manager like: bool WGLExtensionSupported(const char *extension_name) { PFNWGLGETEXTENSIONSSTRINGEXTPROC _wglGetExtensionsStringEXT = NULL; _wglGetExtensionsStringEXT = (PFNWGLGETEXTENSIONSSTRINGEXTPROC) wglGetProcAddress("wglGetExtensionsStringEXT"); if (strstr(_wglGetExtensionsStringEXT(), extension_name) == NULL) { return false; } return true; } and then create and setup your function pointers: PFNWGLSWAPINTERVALEXTPROC wglSwapIntervalEXT = NULL; PFNWGLGETSWAPINTERVALEXTPROC wglGetSwapIntervalEXT = NULL; if (WGLExtensionSupported("WGL_EXT_swap_control")) { // Extension is supported, init pointers. wglSwapIntervalEXT = (PFNWGLSWAPINTERVALEXTPROC) wglGetProcAddress("wglSwapIntervalEXT"); // this is another function from WGL_EXT_swap_control extension wglGetSwapIntervalEXT = (PFNWGLGETSWAPINTERVALEXTPROC) wglGetProcAddress("wglGetSwapIntervalEXT"); } Then just call wglSwapIntervalEXT(0) to disable vSync and 1 to enable vSync. I found the reason this is windows only is that openGl actually doesn't deal with anything other than rendering it leaves the rest up to the OS and Hardware. Thanks everyone saved me a lot of time!

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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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  • Getting 2D Platformer entity collision Response Correct (side-to-side + jumping/landing on heads)

    - by jbrennan
    I've been working on a 2D (tile based) 2D platformer for iOS and I've got basic entity collision detection working, but there's just something not right about it and I can't quite figure out how to solve it. There are 2 forms of collision between player entities as I can tell, either the two players (human controlled) are hitting each other side-to-side (i. e. pushing against one another), or one player has jumped on the head of the other player (naturally, if I wanted to expand this to player vs enemy, the effects would be different, but the types of collisions would be identical, just the reaction should be a little different). In my code I believe I've got the side-to-side code working: If two entities press against one another, then they are both moved back on either side of the intersection rectangle so that they are just pushing on each other. I also have the "landed on the other player's head" part working. The real problem is, if the two players are currently pushing up against each other, and one player jumps, then at one point as they're jumping, the height-difference threshold that counts as a "land on head" is passed and then it registers as a jump. As a life-long player of 2D Mario Bros style games, this feels incorrect to me, but I can't quite figure out how to solve it. My code: (it's really Objective-C but I've put it in pseudo C-style code just to be simpler for non ObjC readers) void checkCollisions() { // For each entity in the scene, compare it with all other entities (but not with one it's already compared against) for (int i = 0; i < _allGameObjects.count(); i++) { // GameObject is an Entity GEGameObject *firstGameObject = _allGameObjects.objectAtIndex(i); // Don't check against yourself or any previous entity for (int j = i+1; j < _allGameObjects.count(); j++) { GEGameObject *secondGameObject = _allGameObjects.objectAtIndex(j); // Get the collision bounds for both entities, then see if they intersect // CGRect is a C-struct with an origin Point (x, y) and a Size (w, h) CGRect firstRect = firstGameObject.collisionBounds(); CGRect secondRect = secondGameObject.collisionBounds(); // Collision of any sort if (CGRectIntersectsRect(firstRect, secondRect)) { //////////////////////////////// // // // Check for jumping first (???) // // //////////////////////////////// if (firstRect.origin.y > (secondRect.origin.y + (secondRect.size.height * 0.7))) { // the top entity could be pretty far down/in to the bottom entity.... firstGameObject.didLandOnEntity(secondGameObject); } else if (secondRect.origin.y > (firstRect.origin.y + (firstRect.size.height * 0.7))) { // second entity was actually on top.... secondGameObject.didLandOnEntity.(firstGameObject); } else if (firstRect.origin.x > secondRect.origin.x && firstRect.origin.x < (secondRect.origin.x + secondRect.size.width)) { // Hit from the RIGHT CGRect intersection = CGRectIntersection(firstRect, secondRect); // The NUDGE just offsets either object back to the left or right // After the nudging, they are exactly pressing against each other with no intersection firstGameObject.nudgeToRightOfIntersection(intersection); secondGameObject.nudgeToLeftOfIntersection(intersection); } else if ((firstRect.origin.x + firstRect.size.width) > secondRect.origin.x) { // hit from the LEFT CGRect intersection = CGRectIntersection(firstRect, secondRect); secondGameObject.nudgeToRightOfIntersection(intersection); firstGameObject.nudgeToLeftOfIntersection(intersection); } } } } } I think my collision detection code is pretty close, but obviously I'm doing something a little wrong. I really think it's to do with the way my jumps are checked (I wanted to make sure that a jump could happen from an angle (instead of if the falling player had been at a right angle to the player below). Can someone please help me here? I haven't been able to find many resources on how to do this properly (and thinking like a game developer is new for me). Thanks in advance!

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