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• How can I tweak this A* search pathfinding algorithm to handle different terrain movement values?

  - by user422318

  I'm creating a 2D map-based action game with similar interaction design as Diablo II. In other words, the player clicks around a map to move their player. I just finished player movement and am moving on to pathfinding. In the game, enemies should charge the player's character. There are also five different terrain types that give different movement bonuses. I want the AI to take advantage of these terrain bonuses as they try to reach the player. I was told to check out the A* search algorithm (http://en.wikipedia.org/wiki/A*_search_algorithm). I'm doing this game in HTML5 and JavaScript, and found a version in JavaScript: http://www.briangrinstead.com/blog/astar-search-algorithm-in-javascript I'm trying to figure out how to tweak it though. Below are my ideas about what I need to change. What else do I need to worry about? When I create a graph, I will need to initialize the 2D array I pass in passed on with a traversal of a map that corresponds to the different terrain types. in graph.js: "GraphNodeType" definition needs to be modified to handle the 5 terrain types. There will be no walls. in astar.js: The g and h scoring will need to be modified. How should I do this? in astar.js: isWall() should probably be removed. My game doesn't have walls. in astar.js: I'm not sure what this is. I think it indicates a node that isn't valid to be processed. When would this happen, though? At a high level, how do I change this algorithm from "oh, is there a wall there?" to "will this terrain get me to the player faster than the terrain around me?" Because of time, I'm also debating reusing my Bresenham algorithm for the enemies. Unfortunately, the different terrain movement bonuses won't be used by the AI, which will make the game suck. :/ I'd really like to have this in for the prototype, but I'm not a developer by trade nor am I a computer scientist. :D If you know of any code that does what I'm looking for, please share! Sanity check tips for this are also appreciated.

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• Organization &amp; Architecture UNISA Studies &ndash; Chap 13

  - by MarkPearl

  Learning Outcomes Explain the advantages of using a large number of registers Discuss the way in which compilers optimize register usage Discuss the evolution of CISC machines Describe the characteristics of RISC architecture Discuss the RISC vs. CISC controversy Describe the way in which RISC and CISC design principles can be combined Instruction Execution Characteristics To understand the the line of reasoning of RISC advocates, we need a brief overview of instruction execution characteristics. These include… Operations Operands Procedure Calls These three sections can be studied in depth in the textbook at pages 503 - 505 A number of groups have come up with the conclusion that the attempt to make the instruction set architecture closer to HLLs (High Level Languages) is not the most effective design strategy. Rather HLL’s can be best supported by optimizing performance of the most time-consuming features of typical HLL programs. Generally 3 main characteristics came up to improve performance… Use a large number of registers or use a compiler to optimize register usage Careful attention needs to be paid to the design of instruction pipelines A simplified (reduced) instruction set is indicated The use of a large register optimization One of the most important design principles of RISC machines is the use of a large number of registers. The concept of register windows and the use of a large register file versus the use of cache memory are discussed. On the face of it, the use of a large set of registers should decrease the need to access memory. The design task is to organize the registers in such a fashion that this goal is realized. Read page 507 – 510 for a detailed explanation. Compiler-based register optimization   Reduced Instructions Set Architecture There are two advantages to smaller programs… Because the program takes up less memory, there is a savings in that resource (this was more compelling when memory was more expensive) Smaller programs should improve performance, and this will happen in two ways – fewer instructions means fewer instruction bytes to be fetched and in a paging environment smaller programs occupy fewer pages, reducing page faults. Certain characteristics are common to RISC processors… One instruction per cycle Register-to-register operations Simple addressing modes Simple instruction formats RISC vs. CISC After initial enthusiasm for RISC machines, there has been a growing realization that RISC designs may benefit from the inclusion of some CISC features CISC designs may benefit from the inclusion of some RISC features

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• 2d, Top-down map with different levels

  - by Ktash

  So, I'm creating a 2d, top down, sprite based (tiled) game, and right now I'm working on maps (well, a map editor at the moment, but it will be creating my maps, so basically the same thing). The scenario So, I'm thinking about efficiency and creating a map in pieces. In each piece, I plan on having 'layers'. Basically, I plan on rendering it down to a 'below hero' level, and an 'above hero' level, with the hero rendered in between obviously. There will likely also be a 'on level with hero' layer, but I'm not quite there yet. Not even worrying about events or interaction yet. Just looking to get a hero on the screen. Now for movement, I obviously need to know what tiles can be moved and in what direction. My plan at the moment is each tile getting 8 bits (4 'can enter in direction' bits, 4 'can leave in direction'). This will allow me to limit movement and even allow one way directional movement. The dilemma This works great for a lot of scenarios. It will allow me to store a map in essentially 3 layers, a string, and gives me flexibility going forward. However, I can't create maps that themselves have layers. A good example is a bridge where the user can go under or over the bridge without invalid moves being allowed. I can't create a platform and allow movement underneath. These are things I would like to be able to include in my game. My idea In theory, I could allow multiple hero layers and then allow multiple sets of 'below' and 'above' layers (or sandwich layers). But this complicates my system, and makes movement between maps potentially tricky (If the hero is on the third layer at the edge of a map, but that corresponds to the second layer on the other map, how can I allow or disallow movement). My question Is there a better way to manage multiple maps with multiple levels like this where a users level may be 'connected' on different levels on different maps? Or even... Am I doing this the hard way? Is there a more standard way to handle top-down 2d tiled maps that I am just not aware of? Things to note or that might be helpful This will be done in Javascript (transferred around in JSON) State will need to be transferred quickly, so a map-id and x/y/direction should be enough to get me a boolean 'can move' value Maps will not be standard sized (though they will be in a certain number of tiles) Making an editor tool so that I can have others help, so something that I can create in a tool would be helpful 'Teleportation' locations will likely need to exist to get into building maps and to and from different map sets (which will not necessarily be connected), but have not been created yet (lumping in with events at the moment).

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• ADF Mobile Released!!

  - by Denis T

  ADFmfAnnounce We are pleased to announce the general availability of the newest version of Oracle’s ADF Mobile framework. This new framework provides the much anticipated on-device capabilities that the latest mobile applications require.  Feature Highlights Java - Oracle brings a Java VM embedded with each application so you can develop all your business logic in the platform neutral language you know and love! (Yes, even iOS!) JDBC - Since we give you Java, we also provide JDBC along with a SQLite driver and engine that also supports encryption out of the box. Multi-Platform - Truly develop your application only once and deploy to multiple platforms. iOS and Android platforms are supported for both phone and tablet. Flexible - You can decide how to implement the UI: (a) Use existing server-based UI framework like JSF. (b) Use your own favorite HTML5 framework like JQuery. (c) Use our declarative HTML5 component set provided with the framework. ADF Mobile XML or AMX for short, provides all the normal input and layout controls you expect and we also add charts/maps/gauges along with it to provide a very comprehensive UI controls. You can also mix and match any of the three for ultimate flexibility! Device Feature Access - You can get access to device features from either Java or JavaScript to invoke features like camera, GPS, email, SMS, contacts, etc. Secure - ADF Mobile provides integrated security that works with your server back-end as well. Whether you’re using remote URLs, local HTML or AMX, you can secure any/all of your features with a single consistent login page. Since we also give you SQLite encryption, we are assured that your data is safe. Rapid - Using the same development techniques that ADF developers are already used to, you can quickly create mobile applications without ever learning another language! Architecture ADF Mobile is a “hybrid” architecture that employs a natively built “container” on each platform that hosts a number of browser windows that are used to display the application content. We add the Java VM as a natively built library to the container for business logic.   How To Get Started ADF Mobile is an extension to the recently released JDeveloper version 11.1.2.3.0. Simple get the latest JDeveloper from Oracle Technology Network and use the Check for Updates feature to get the ADF Mobile extension. Note: ADF Mobile does not require developers to learn any other languages or frameworks but to build/deploy to iOS, you must be on an Apple MacintoshTM and have Xcode installed. To build/deploy to Android™ you must have the Android SDK installed.

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• High-Powered Sites for low Cost

  - by HighAltitudeCoder

  Ahh, I am experiencing the intimidation of my very first post - visible by the whole world. Ok, here goes.   This first post is nothing exceptional.  It is simply a recommendation based (fittingly, I suppose) upon the job search you may be gearing up for.  I find myself in this very situation right now.  And, I will take my own recommendation after posting this entry. Job-Seekers: To the left you will notice two links under "Recommended Learning".  I have found these links to be invaluable when it comes to re-tooling, re-familiarizing, or otherwise resharping my skills when looking for that next job. Often, you will find job-postings with the text, usually posted after a laborious list of qualifications indicating the company's desire to hire candidates who know what they are doing: "...Looking for a candidate who can hit the ground running...".  The interesting thing about this post to me is I've encountered many individuals who, after speaking and working with them for some time, I've realized are perfectly capable of hitting the ground running - and FAST.  But what if they speed off in the wrong direction? The next time you spearhead a major task in your job, ask yourself: Am I headed in the wrong direction?  There are many ways to do this.  In fact, I've found in this new field there are more tempting ways to steer your project in the wrong direction than there are good ones.  I don't want to suggest that every one of my posts will fall into the "right direction" category, however I do think a healthy dose of introspection of the pros and cons will always be beneficial before you set off. That said, allow me to expound on the previously mentioned links. These web sites are invaluable.  They demonstrate the capabilities of existing as well as new and upcoming tools available in several IDE's.  I've viewed many tutorials in LearnVisualStudio.NET, and only one or two so far in TrainingSpot, however I've been delighted in their simplicity and straightforward approach to proper usage of the particular tool or concept being discussed.  They have not (so far in my experience) demonstrated ways in which to use the tools that become cumbersome, impractical, or error-prone. Each website has step-by-step videos that can be paused, replayed, and most importantly, they are done in real time.  As the author is typing, the viewer gets to experience the coding experience from a first-person perspective, including syntax errors, unexpected behaviors, IDE setup idiosyncracies, everything.  A subtle value I've gained from these videos is that a certain degree of confusion and introspection is normal when working with new tools and exploring new paths.  They (as well as your own experience) are not to be feared, but enjoyed.  I highly recommend them. Good work, guys!

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• Why C++ people loves multithreading when it comes to performances?

  - by user1849534

  I have a question, it's about why programmers seems to love concurrency and multi-threaded programs in general. I'm considering 2 main approach here: an async approach basically based on signals, or just an async approach as called by many papers and languages like the new C# 5.0 for example, and a "companion thread" that maanges the policy of your pipeline a concurrent approach or multi-threading approach I will just say that I'm thinking about the hardware here and the worst case scenario, and I have tested this 2 paradigms myself, the async paradigm is a winner at the point that I don't get why people 90% of the time talk about concurrency when they wont to speed up things or make a good use of their resources. I have tested multi-threaded programs and async program on an old machine with an Intel quad-core that doesn't offer a memory controller inside the CPU, the memory is managed entirely by the motherboard, well in this case performances are horrible with a multi-threaded application, even a relatively low number of threads like 3-4-5 can be a problem, the application is unresponsive and is just slow and unpleasant. A good async approach is, on the other hand, probably not faster but it's not worst either, my application just waits for the result and doesn't hangs, it's responsive and there is a much better scaling going on. I have also discovered that a context change in the threading world it's not that cheap in real world scenario, it's infact quite expensive especially when you have more than 2 threads that need to cycle and swap among each other to be computed. On modern CPUs the situation it's not really that different, the memory controller it's integrated but my point is that an x86 CPUs is basically a serial machine and the memory controller works the same way as with the old machine with an external memory controller on the motherboard. The context switch is still a relevant cost in my application and the fact that the memory controller it's integrated or that the newer CPU have more than 2 core it's not bargain for me. For what i have experienced the concurrent approach is good in theory but not that good in practice, with the memory model imposed by the hardware, it's hard to make a good use of this paradigm, also it introduces a lot of issues ranging from the use of my data structures to the join of multiple threads. Also both paradigms do not offer any security abut when the task or the job will be done in a certain point in time, making them really similar from a functional point of view. According to the X86 memory model, why the majority of people suggest to use concurrency with C++ and not just an async aproach ? Also why not considering the worst case scenario of a computer where the context switch is probably more expensive than the computation itself ?

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• EF Doesn't Like Same Named Tables

  - by Anthony Trudeau

  Originally posted on: http://geekswithblogs.net/tonyt/archive/2013/07/02/153327.aspxIt's another week and another restriction imposed by the Entity Framework (EF). Don't get me wrong. I like EF, but I don't like how it restricts you in different ways. At this point you may be asking yourself the question: how can you have more than one table with the same name?The answer is to have tables in different schemas. I do this to partition the data based on the area of concern. It allows security to be assigned conveniently. A lot of people don't use schemas. I love them. But this article isn't about schemas.In the situation I have two tables:Contact.PersonEmployee.PersonThe first contains the basic, more public information such as the name. The second contains mostly HR specific information. I then mapped these tables to two classes. I stuck to a Table per Class (TPC) mapping, because of problems I've had in the past implementing inheritance with EF. The following code gives you the basic contents of the classes.[Table("Person", Schema = "Employee")]public class Employee {   ...   public int PersonId { get; set; }   [ForeignKey("PersonId")]   public virtual Person Person { get; set; }}[Table("Person", Schema = "Contact")]public class Person {   [Key]   public int Id { get; set; }   ...}This seemingly simple scenario just doesn't work. The problem occurs when you try to add a Person to the DbContext. You get an InvalidOperationException with the following text:The entity types 'Employee' and 'Person' cannot share table 'People' because they are not in the same type hierarchy or do not have a valid one to one foreign key relationship with matching primary keys between them..This is interesting for a couple of reasons. First, there is no People table in my database. Second, I have used the SetInitializer method to stop a database from being created, so it shouldn't be thinking about new tables.The solution to my problem was to change the name of my Employee.Person table. I decided to name it Employee.Employee. It's not ideal, but it gets me past the EF limitation. I hope that this article will help someone else that has the same problem.

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• Let&rsquo;s keep informed with &ldquo;Data Explorer&rdquo;

  - by Luca Zavarella

  At Pass Summit 2011 a new project was announced. It’s a Microsoft SQL Azure Lab and its codename is Microsoft “Data Explorer”. According to the official blog (http://blogs.msdn.com/b/dataexplorer/), this new tool provides an innovative way to acquire new knowledge from the data that interest you. In a nutshell, Data Explorer allows you to combine data from multiple sources, to publish and share the result. In addition, you can generate data streams in the RESTful open format (Open Data Protocol), and they can then be used by other applications. Nonetheless we can still use Excel or PowerPivot to analyze the results. Sources can be varied: Excel spreadsheets, text files, databases, Windows Azure Marketplace, etc.. For those who are not familiar with this resource, I strongly suggest you to keep an eye on the data services available to the Marketplace: https://datamarket.azure.com/browse/Data To tell the truth, as I read the above blog post, I was tempted to think of the Data Explorer as a "SSIS on Azure" addressed to the Power User. In fact, reading the response from Tim Mallalieu (Group Program Manager of Data Explorer) to the comment made to his post, I had a positive response to my first impression: “…we originally thinking of ourselves as Self-Service ETL. As we talked to more folks and started partnering with other teams we realized that would be an area that we can add value but that there were more opportunities emerging.” The typical operations of the ETL phase ( processing and organization of data in different formats) can be obtained thanks to Data Explorer Mashup. This is an image of the tool: The flexibility in the manipulation of information is given by Data Explorer Formula Language. This is a formula-based Excel-style specific language: Anyone wishing to know more can check the project page in addition to aforementioned blog: http://www.microsoft.com/en-us/sqlazurelabs/labs/dataexplorer.aspx In light of this new project, there is no doubt about the intention of Microsoft to get closer and closer to the Power User, providing him flexible and very easy to use tools for data analysis. The prime example of this is PowerPivot. The question that remains is always the same: having in a company more Power User will implicitly mean having different data models representing the same reality. But this would inevitably lead to anarchical data management... What do you think about that?

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• Building Enterprise Smartphone App &ndash; Part 3: Key Concerns

  - by Tim Murphy

  This is part 3 in a series of posts based on a talk I gave recently at the Chicago Information Technology Architects Group.  Feel free to leave feedback. Keys Concerns Of Smartphones In The Enterprise These are the factors that you need to be aware of and address in order to build successful enterprise smartphone applications.  Most of them have nothing to do with the application itself as you will see here. Managing Devices Managing devices is a factor that is going to effect how much your company will have to spend outside of developing the applications.  How will you track the devices within the corporation?  How often will you have to replace phones and as a consequence have to upgrade your applications to support new phones?  The devices can represent a significant investment of capital.  If these questions are not addressed you will find a number of hidden costs throughout the life of your solution. Purchase or BYOD We have seen the trend of Bring Your Own Device (BYOD) lately within the enterprise.  How many meetings have you been in where someone is on their personal iPad, iPhone, Android phone or Windows Phone?  The issue is if you can afford to support everyone's choice in device? That is a lot to take on even if you only support the current release of each platform. Do you go with the most popular device or do you pick a platform that best matches your current ecosystem and distribute company owned devices?  There is no easy answer here, but you should be able give some dollar value to both hardware and development costs related to platform coverage. Asset Tracking/Insurance Smartphones are devices that are easier to lose or have stolen than laptops and desktops. Not only do you have your normal asset management concerns but also assignment of financial responsibility. You also will need to insure them against damage and theft and add legal documents that spell out the responsibilities of the employees that use these devices. Personal vs. Corporate Data What happens when you terminate an employee?  How do you recover the device?  What happens when they have put personal data on the device?  These are all situation that can cause possible loss of corporate intellectual property or legal repercussions of reclaiming a device with personal data on it.  Policies need to be put in place that protect the company from being exposed to type of loss.  This can mean significant legal and procedural cost that you need to consider. Coming Up In the last installment of this series I will cover application development considerations. del.icio.us Tags: Smartphones,Enterprise Smartphone Apps,Architecture

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• How to run WordPress and Java web app running on Tomcat on the same server?

  - by Chantz

  I have to run a WordPress site served via Apache2 & Java-based webapp using Tomcat on the same server. When users come to example.com or example.com/public-pages they need to served from WordPress but when they come to example.com/private-pages they need to be served from the Tomcat. I have asked this question on serverfault where they suggested using different port, different IP & sub-domain. I want to go for different port solution since it will mean I need to buy only one SSL certificate. I tried doing the reverse proxy method by having the following in my default-ssl.conf <VirtualHost _default_:443> ServerAdmin webmaster@localhost ServerName localhost:443 DocumentRoot /var/www <Directory /var/www> #For Wordpress Options FollowSymLinks AllowOverride All </Directory> <Proxy *> Order deny,allow Allow from all </Proxy> ProxyRequests Off ProxyPass /private-pages ajp://localhost:8009/ ProxyPassReverse /private-pages ajp://localhost:8009/ SSLEngine on SSLProxyEngine On SSLCertificateFile /etc/apache2/ssl/apache.crt SSLCertificateKeyFile /etc/apache2/ssl/apache.key </VirtualHost> As you have noticed I am using mod_proxy_ajp in Apache2 for this. And that my Tomcat is listening to port 8009 and then serving content. So now when I go to example.com/private-pages I am seeing the content from my Tomcat. But 2 issues are happening. All my static resources are getting 404-ed, so none of my images, CSS, js are getting loaded. I see that the browser is requesting for the resources using URL example.com/css/* This will clearly not work because it translates to example.com:80/css/* instead of example.com:8009/css/* & there are no such resources in the WordPress directory. If I go to example.com/private-pages/abcd I am somehow kicked to the WordPress site (which obviously displays a 404 page). I can understand why #1 is happening but have no clue why the #2 is happening. Regardless, if there is another clean solution for resolving this, I would appreciate y'alls help.

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• Developing web sites that imitate desktop apps. How to fight that paradigm? [closed]

  - by user1598390

  Supposse there's a company where web sites/apps are designed to resemble desktop apps. They struggle to add: Splash screens Drop-down menus Tab-pages Pages that don't grow downward with content, context is inside scrollable area so page is of a fixed size, as if resembling the one-screen limitation of desktop apps. Modal windows, pop-ups, etc. Tree views Absolutely no access to content unless you login-first, even with non-sensitive content. After splash screen desapears, you are presented with a login screen. No links - just simulated buttons. Fixed page-size. Cannot open a linked in other tab Print button that prints directly ( not showing printable page so the user can't print via the browser's print command ) Progress bars for loading content even when the browser indicates it with its own animation Fonts and color amulate a desktop app made with Visual Basic, PowerBuilder etc. Every app seems almost as if were made in Visual Basic. They reject this elements: Breadcrumbs Good old underlined links Generated/dynamic navigation, usage-based suggestions Ability to open links in multiple tabs Pagination Printable pages Ability to produce a URL you can save or share that links to an item, like when you send someone the link to an especific StackExchange question. The only URL is the main one. Back button To achieve this, tons of javascript code is needed. Lots and lots of Javascript and Ajax code for things not related with the business but with the necessity to hide/show that button, refresh this listbox, grey-out that label, etc. The coplexity generated by forcing one paradigm into another means most lines of code are dedicated to maintain the illusion of a desktop app. What is the best way to change this mindset, and make them embrace the web, and start producing modern, web apps instead of desktop imitations ? EDIT: These sites are intranet sites. Users hate these apps. They constantly whine about them, but they have to use them to do their daily work. These sites are in-house solutions, the end-users have no choice but to use them. They are a "captive audience". Also, substitution will not happen because of high costs. But at least if that mindset is changed, new developments would be more web-like.

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• I have a performance problem

  - by Alan

  (copied from my wordpress blog). So start 95% of the performance calls that I receive. They usually continue something like: I have gathered some *stat data for you (eg the guds tool from Document 1285485.1), can you please root cause our problem? So, do you think you could? Neither can I, based on this my answer inevitably has to be "No". Given this kind of problem statement, I have no idea about the expectations, the boundary conditions, or even the application. The answer may as well be "Performance problems? Consult your local Doctor for Viagra". It's really not a lot to go on. So, What kind of problem description is going to allow me to start work on the issue that is being seen? I don't doubt that there really is an issue, it just needs to be pinned down somewhat. What behavior exactly are you expecting to see? Be specific and use business metrics. For example "run-time", "response-time" and "throughput". This helps us define exit criterea. Now, let's look at the system that is having problems. How is what you are seeing different? Use the same type of metrics. The answers to these two questions take us a long way towards being able to work a call. Even more helpful are answers to questions like Has this system ever worked to expectation? If so, when did it start exhibiting this behavior? Is the problem always present, or does it sometimes work to expectation? If it sometimes works to expectation, when are you seeing the problem? Is there any discernible pattern? Is the impact of the problem getting better, worse, or remaining constant? What kind of differences are there between when the system was performing to expectation and when it is not? Are there other machines where we could expect to see the same issue (eg similar usage and load), but are not? Again, differences? Once we start to gather information like this we start to build up a much clearer picture of exactly what we need to investigate, and what we need to achieve so that both you and me agree that the problem has been solved. Please help get that figure of poorly defined problem statements down from it's current 95% value.

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• IPv6, isn't it just a few extra bits?

  - by rclewis

  It's always an interesting task, to try and explain what you do to family and friends. I have described IPv6 as the "Next Generation Internet"  or "Second Internet" but the hollow expressions on my kids faces scream for the instant relief of the latest video game.  Never one to give up easily, I have formulated a new example - the Post Office... Similar to the Post Office the Internet delivers mail and packages based on addresses. As the number of residences, businesses, and delivery locations increased, the 5 digit ZIP Code (Washington, DC 20005) was expanded to ZIP+4  allowing for more precise delivery points (Postmaster General, Washington, DC 20260-3100). Ah, if only computers were as simple.  IPv6 isn't an add-on or expansion of the existing IPv4 Addressing, it is a new addressing model which will allow the internet to grow from a single computer in the basement of a university or your parents kitchen table, to support the multitude of smart phones, smart TV's, tablets, dvr's, and disk players, all clambering to connect for information. Unfortunetly there are only a finite number of IPv4 public addresses left, and those are being consumed at an ever increasing rate. Few people could have predicted the explosive growth of the internet or the shortage of IPv4 addresses we now face - but there is a "Plan B" and that is the vastly larger address space of IPv6.  Many in the industry have labeled this a "business continuity" problem,  when in fact most companies will be able to continue conducting business once they run out of existing IPv4 Addresses. The problem is really a Customer Continuity problem, how will businesses communicate with existing customers and reach new customers online who's only option is to adopt IPv6 when IPv4 is depleted? Perhaps a first step is publishing a blog that is also accessible via IPv6, it's just a few extra bits. Join us for the Oracle OpenWorld 2012 Session:   Navigating IPv6 @ Oracle Thursday, Oct. 4th 2:15PM - 3:15PM  Palace Hotel - Concert   Learn more about IPv6 Technologies at Oracle

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• Are we queueing and serializing properly?

  - by insta

  We process messages through a variety of services (one message will touch probably 9 services before it's done, each doing a specific IO-related function). Right now we have a combination of the worst-case (XML data contract serialization) and best-case (in-memory MSMQ) for performance. The nature of the message means that our serialized data ends up about 12-15 kilobytes, and we process about 4 million messages per week. Persistent messages in MSMQ were too slow for us, and as the data grows we are feeling the pressure from MSMQ's memory-mapped files. The server is at 16GB of memory usage and growing, just for queueing. Performance also suffers when the memory usage is high, as the machine starts swapping. We're already doing the MSMQ self-cleanup behavior. I feel like there's a part we're doing wrong here. I tried using RavenDB to persist the messages and just queueing an identifier, but the performance there was very slow (1000 messages per minute, at best). I'm not sure if that's a result of using the development version or what, but we definitely need a higher throughput[1]. The concept worked very well in theory but performance was not up to the task. The usage pattern has one service acting as a router, which does all reads. The other services will attach information based on their 3rd party hook, and forward back to the router. Most objects are touched 9-12 times, although about 10% are forced to loop around in this system for awhile until the 3rd parties respond appropriately. The services right now account for this and have appropriate sleeping behaviors, as we utilize the priority field of the message for this reason. So, my question, is what is an ideal stack for message passing between discrete-but-LAN'ed machines in a C#/Windows environment? I would normally start with BinaryFormatter instead of XML serialization, but that's a rabbit hole if a better way is to offload serialization to a document store. Hence, my question. [1]: The nature of our business means the sooner we process messages, the more money we make. We've empirically proven that processing a message later in the week means we are less likely to make that money. While performance of "1000 per minute" sounds plenty fast, we really need that number upwards of 10k/minute. Just because I'm giving numbers in messages per week doesn't mean we have a whole week to process those messages.

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• Application workflow

  - by manseuk

  I am in the planning process for a new application, the application will be written in PHP (using the Symfony 2 framework) but I'm not sure how relevant that is. The application will be browser based, although there will eventually be API access for other systems to interact with the data stored within the application, again probably not relavent at this point. The application manages SIM cards for lots of different providers - each SIM card belongs to a single provider but a single customer might have many SIM cards across many providers. The application allows the user to perform actions against the SIM card - for example Activate it, Barr it, Check on its status etc Some of the providers provide an API for doing this - so a single access point with multiple methods eg activateSIM, getStatus, barrSIM etc. The method names differ for each provider and some providers offer methods for extra functions that others don't. Some providers don't have APIs but do offer these methods by sending emails with attachments - the attachments are normally a CSV file that contains the SIM reference and action required - the email is processed by the provider and replied to once the action has been complete. To give you an example - the front end of my application will provide a customer with a list of SIM cards they own and give them access to the actions that are provided by the provider of each specific SIM card - some methods may require extra data which will either be stored in the backend or collected from the user frontend. Once the user has selected their action and added any required data I will handle the process in the backend and provide either instant feedback, in the case of the providers with APIs, or start the process off by sending an email and waiting for its reply before processing it and updating the backend so that next time the user checks the SIM card its status is correct (ie updated by a backend process). My reason for creating this question is because I'm stuck !! I'm confused about how to approach the actual workflow logic. I was thinking about creating a Provider Interface with the most common methods getStatus, activateSIM and barrSIM and then implementing that interface for each provider. So class Provider1 implements Provider - Then use a Factory to create the required class depending on user selected SIM card and invoking the method selected. This would work fine if all providers offered the same methods but they don't - there are a subset which are common but some providers offer extra methods - how can I implement that flexibly ? How can I deal with the processes where the workflow is different - ie some methods require and API call and value returned and some require an email to be sent and the next stage of the process doesn't start until the email reply is recieved ... Please help ! (I hope this is a readable question and that this is the correct place to be asking) Update I guess what I'm trying to avoid is a big if or switch / case statement - some design pattern that gives me a flexible approach to implementing this kind of fluid workflow .. anyone ?

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• IPC in C under linux

  - by poly

  I'm building a messaging solution with the followingsetup: all the messages are saved on a DB, two or more reader processes will read from this DB and send data to other process(es) which will send it over the network. My approach is depicted below, The following have 4 sender process with 4 fifos, and 2 readers with 2 fifos reader0 ? read data from DB reader1 ? read data from DB sending part network_handler0 ? network_handler_fifo0 ? reader0 network_handler1 ? network_handler_fifo1 ? reader1 network_handler2 ? network_handler_fifo2 ? reader0 network_handler3 ? network_handler_fifo3 ? reader1 receiving part network_handler0 ? reader_fifo0 ? reader0 ? write to DB network_handler1 ? reader_fifo1 ? reader1 ? write to DB network_handler2 ? reader_fifo0 ? reader0 ? write to DB network_handler3 ? reader_fifo1 ? reader1 ? write to DB I have few problem with this setup, and please note that the number of processes could be more than that based on the environment, so I could make it 20 readers and 10 network_handlers or it it could as shown above. The size of the buffer is 64K and the message size is 200k, is this small enough to make the write/read to/from fifo atomic? How can make the processes aware of each other, so for example, reader 0 writes to network_handler_fifo0 and network_handler_fifo2, how can I make it start writing on other fifo if the current ones are full or their network_handlers are dea d I thought about making the reader process writing more general in writing, so for example it writes to all network fifos using lock mechanism and stop writing on the one that its process dead, I didn't use it as lock mechanism could slow thing down. BTW, each network_handler is an SCTP association, so network_handler0 is association 0, network_handler1 is association 1 and so on. Any idea is appreciated. I mean even if I have to change the setup above.

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• Are there software options (preferabbly .NET) for doing distance and speed analysis of footballers moving on video?

  - by Anonymous Type

  Editing Question for Clarity Thanks for feedback so far, very insightful. I'm not sure how far along this part of the software community is, and what if any libraries exist for me to leverage from. Heres what I'm trying to do. Problem: Take an existing video of a game of rugby league. The Rugby League field is 100 metres long, 70 metres wide, and has white line markings every 10 metres running along the width of the field, as well as along the sidelines. Each side has 13 players on the field. Players on each team have identical jerseys that normally constrast strongly against background colours (green/brown field colour) and the referee's colour (usually yellow) and the designated water runner (orange). All players have a unique number in thick white lettering on their backs for identification. Video is taken with a high definition camera. Currently only one camera is used (2D) and existing video does not contain a foreground object of fixed spatial dimensions (as suggested in one answer for comparision measurements, however I could add this to future filming sessions if it is worthwhile). The player's do not run in a straight line 50% of the time but will go sideways on on a diagonal to the play the ball. The distance measured always starts from the spot of the previous "tackle", which ends where the player stops forward movement. It is not always possible to determine the players number from the video (facing other direction, sunlight, others standing in the way of the camera). But this isn't important as the software could allow for manual inputting of unknown "runs" at a later point after analysis. Determine the distance between two points (i.e. where the player started his "run" and where he finished it). I'm guessing that this would be quite doable if I manually marked the start and end point in the video. But how would I use landmarks in the background to determine the distance (assuming the person taking the video has kept it from jerking around). Question: Do software packages or libraries exist that are specialised enough to assist with writing analysis software to determine a sports persons distance travelled based on video taken of the performance?

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• Protobuf design patterns

  - by Monster Truck

  I am evaluating Google Protocol Buffers for a Java based service (but am expecting language agnostic patterns). I have two questions: The first is a broad general question: What patterns are we seeing people use? Said patterns being related to class organization (e.g., messages per .proto file, packaging, and distribution) and message definition (e.g., repeated fields vs. repeated encapsulated fields*) etc. There is very little information of this sort on the Google Protobuf Help pages and public blogs while there is a ton of information for established protocols such as XML. I also have specific questions over the following two different patterns: Represent messages in .proto files, package them as a separate jar, and ship it to target consumers of the service --which is basically the default approach I guess. Do the same but also include hand crafted wrappers (not sub-classes!) around each message that implement a contract supporting at least these two methods (T is the wrapper class, V is the message class (using generics but simplified syntax for brevity): public V toProtobufMessage() { V.Builder builder = V.newBuilder(); for (Item item : getItemList()) { builder.addItem(item); } return builder.setAmountPayable(getAmountPayable()). setShippingAddress(getShippingAddress()). build(); } public static T fromProtobufMessage(V message_) { return new T(message_.getShippingAddress(), message_.getItemList(), message_.getAmountPayable()); } One advantage I see with (2) is that I can hide away the complexities introduced by V.newBuilder().addField().build() and add some meaningful methods such as isOpenForTrade() or isAddressInFreeDeliveryZone() etc. in my wrappers. The second advantage I see with (2) is that my clients deal with immutable objects (something I can enforce in the wrapper class). One disadvantage I see with (2) is that I duplicate code and have to sync up my wrapper classes with .proto files. Does anyone have better techniques or further critiques on any of the two approaches? *By encapsulating a repeated field I mean messages such as this one: message ItemList { repeated item = 1; } message CustomerInvoice { required ShippingAddress address = 1; required ItemList = 2; required double amountPayable = 3; } instead of messages such as this one: message CustomerInvoice { required ShippingAddress address = 1; repeated Item item = 2; required double amountPayable = 3; } I like the latter but am happy to hear arguments against it.

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• Running MS Access Programs

  - by fredhappier

  I have an old program developed in MS Access and would like to convert it to Kexi somehow. The program on Windows is launched with Access. Is there any way that Kexi can launch this program? I know my way around Ubuntu and the terminal, but not well versed on databases. Once you make something in Kexi how do you "run" it or "view" what you've made? So far I am able to import the MDB file into Kexi and see all of the database data, but that is as far I have gone. The program was made by a relative years ago for my dad. I myself am an Ubuntu only user for 6+ years now and have no intentions to touch Windows and am looking for a linux solution. My dad is also an Ubuntu user, hence why Im looking for a solution. If Kexi cannot launch and run an MDB file, what else can I try? Anything browser based? Any tips or direction would be extremely helpful. I spoke to my brother who originally made the program. I told him about Kexi and here is what he said. Does any of this make sense? Thanks. This is how I would try to get them to work: Stand alone setup - after import, look for an option where you designate which form object you want to open upon startup. It might be in the tools tab in the picture below. After you save that change, it re-start it and it should work. Front end/back end setup - Do what I suggested for the stand alone setup to the "front-end" MDB file. After you do that, put the other file (table MDB file) where you want it to reside on the network. Now, open back up the "front end" file and look for an option that will allow you to "connect" to those tables in the other file. It looks like it could be in the "External data" tab in the picture below. For this setup, you may need to do these two tasks in the reverse order I just mentioned. Thanks! Fred

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• How should I refactor switch statements like this (Switching on type) to be more OO?

  - by Taytay

  I'm seeing some code like this in our code base, and want to refactor it: (Typescript psuedocode follows): class EntityManager{ private findEntityForServerObject(entityType:string, serverObject:any):IEntity { var existingEntity:IEntity = null; switch(entityType) { case Types.UserSetting: existingEntity = this.getUserSettingByUserIdAndSettingName(serverObject.user_id, serverObject.setting_name); break; case Types.Bar: existingEntity = this.getBarByUserIdAndId(serverObject.user_id, serverObject.id); break; //Lots more case statements here... } return existingEntity; } } The downsides of switching on type are self-explanatory. Normally, when switching behavior based on type, I try to push the behavior into subclasses so that I can reduce this to a single method call, and let polymorphism take care of the rest. However, the following two things are giving me pause: 1) I don't want to couple the serverObject with the class that is storing all of these objects. It doesn't know where to look for entities of a certain type. And unfortunately, the identity of a type of ServerObject varies with the type of ServerObject. (So sometimes it's just an ID, other times it's a combination of an id and a uniquely identifying string, etc). And this behavior doesn't belong down there on those subclasses. It is the responsibility of the EntityManager and its delegates. 2) In this case, I can't modify the ServerObject classes since they're plain old data objects. It should be mentioned that I've got other instances of the above method that take a parameter like "IEntity" and proceed to do almost the same thing (but slightly modify the name of the methods they're calling to get the identity of the entity). So, we might have: case Types.Bar: existingEntity = this.getBarByUserIdAndId(entity.getUserId(), entity.getId()); break; So in that case, I can change the entity interface and subclasses, but this isn't behavior that belongs in that class. So, I think that points me to some sort of map. So eventually I will call: private findEntityForServerObject(entityType:string, serverObject:any):IEntity { return aMapOfSomeSort[entityType].findByServerObject(serverObject); } private findEntityForEntity(someEntity:IEntity):IEntity { return aMapOfSomeSort[someEntity.entityType].findByEntity(someEntity); } Which means I need to register some sort of strategy classes/functions at runtime with this map. And again, I darn well better remember to register one for each my my types, or I'll get a runtime exception. Is there a better way to refactor this? I feel like I'm missing something really obvious here.

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• Trying to find resources to learn how to test software [closed]

  - by Davek804

  First off, yes this is a general question, and I'd be perfectly happy to move this to another portion of SE, but I didn't see a more fitting sub. Basically, I am hoping a more experienced QA tester can come along and really fill in some basics for me. So far, websites seem to be sparse in terms of explaining languages involved, basic practices, etc. So, I'm sorry in advance if this is too general, but towards the end of this post I ask some specific questions if it's just absolutely unacceptable to speak in general terms. I just landed a position as Junior Systems and QA Engineer with a social media startup. Their QA and testing is almost nonexistent, so if I do a good job, I imagine I'll find a lot of bugs and have a secure role in the business. I'm pretty good with the systems aspect of my role, but I need to learn more about the QA and testing aspects. We run hardware that's touchscreen based - the user can use and interact with the devices. So, in terms of my QA role, in the short term, I need to build scripts to test the hardware/software as a 'user' to try to uncover bugs. First off, what language should these scripts be written in? Does anyone have some examples? What about the longer term 'automated testing'? I'm familiar with regression testing as the developer adds in new features, sure, but the 50,000 other types of testing, not so much. Most of our hardware runs dotnet/C# code, with some of the servers running Java - but I don't expect to need to run tests on the Java side at this point. I hope to meet with one developer today and try to get a good idea of the output from the hardware so that I can 'mock' this data that gets sent to servers, to try to bugtest. Eventually, we will be moving the hardware to be closer to where I live and work, so that I can test virtually and on real hardware. So a lot of the bugs we're dealing with now are like this: the Local Server, which kiosks report their data to gets updated from the kiosks, but the remote server does not. Or, vis versa when the user registers on a kiosk, the remote server updates but the local server does not. But yeah, without much more detail, I imagine a lot of this info isn't helpful. I've bought a book "How Google Tests Software", but it's really a book more about 'how their software testing is different from Microsoft'. It doesn't teach how to test so much as why their methods are better. Does anyone have a good book that I can buy? An ebook maybe? My local Barnes and Noble kinda had a terrible selection. I also figure a book from 2005 is not necessarily that good either.

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• How to check if a variable is an integer? [closed]

  - by FyrePlanet

  I'm going through my C++ book and have currently made a working Guess The Number game. The game generates a random number based on current time, has the user input their guess, and then tells them whether it was too high, too low, or the correct number. The game functions fine if you enter a number, but returns 'Too High' if you enter something that is not a number (such as a letter or punctuation). Not only does it return 'too high', but it also continually returns it. I was wondering what I could do to check if the guess, as input by the user, is an integer and if it is not, to return 'Not a number. Guess again.' Here is the code. #include <iostream> #include <cstdlib> #include <ctime> using namespace std; int main() { srand(time(0)); // seed the random number generator int theNumber = rand() % 100 + 1; // random number between 1 and 100 int tries = 0, guess; cout << "\tWelcome to Guess My Number!\n\n"; do { cout << "Enter a guess: "; cin >> guess; ++tries; if (guess > theNumber) cout << "Too high!\n\n"; if (guess < theNumber) cout << "Too low!\n\n"; } while (guess != theNumber); cout << "\nThat's it! You got it in " << tries << " guesses!\n"; cout << "\nPress Enter to exit.\n"; cin.ignore(cin.rdbuf()->in_avail() + 1); return 0; }

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• HAProxy reqrep remove URI on backend request

  - by Jim

  real quick question regarding HAProxy reqrep. I am trying to rewrite/replace the request that gets sent to the backend. I have the following example domain and URIs http://domain/web1 http://domain/web2 I want web1 to go to backend webfarm1, and web2 to go to webfarm2. Currently this does happen. However I want to strip off the web1 or web2 URI when the request is sent to the backend. Here is my haproxy.cfg frontend webVIP_80 mode http bind :80 #acl routing to backend acl web1_path path_beg /web1 acl web2_path path_beg /web2 #which backend use_backend webfarm1 if web1_path use_backend webfarm2 if web2_path default_backend webfarm1 backend webfarm1 mode http reqrep ^([^\ ]*)\ /web1/(.*) \1\ /\2 balance roundrobin option httpchk HEAD /index HTTP/1.1\r\nHost:\ example.com server webtest1 10.0.0.10:80 weight 5 check slowstart 5000ms server webtest2 10.0.0.20:80 weight 5 check slowstart 5000ms backend webfarm2 mode http reqrep ^([^\ ]*)\ /web2/(.*) \1\ /\2 balance roundrobin option httpchk HEAD /index HTTP/1.1\r\nHost:\ example.com server webtest1-farm2 10.0.0.110:80 weight 5 check slowstart 5000ms server webtest2-farm2 10.0.0.120:80 weight 5 check slowstart 5000ms If I go to http://domain/web1 or http://domain/web2 I see it in the error logs that the request on a server in each backend that the requst is for the resource /web1 or /web2 respectively. Therefore I believe there to be something wrong with my regular expression, even though I copied and pasted it from the Documentation. http://code.google.com/p/haproxy-docs/wiki/reqrep Summary: I'm trying to route traffic based on URI, however I want to strip the URI on the backend side. Go to http://domain/web1 -- backend request of / to webfarm1 Thank you! -Jim

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• SSTP client disconnects shortly after successfully connected to VPN

  - by Eran Betzalel

  I'm successfully authenticating and connecting to a SSTP VPN (on windows 2008) from my windows 7 machine, but for some reason, the connection is disconnected about a 1-2 seconds after it's established. I've done the following: Defined a SSTP VPN on my windows server 2008. Defined the same machine as CA. Issued the needed certificates and published them on the client. I'm currently testing this VPN inside my LAN so all the needed ports are opened. Here are the event log entries when trying to connect: Error Log (Client): The user HOME\User dialed a connection named Home VPN which has terminated. The reason code returned on termination is 829. Error Log (Server-VPN): The user HOME\User connected on port VPN0-0 on 7/27/2012 at 1:57 AM and disconnected on 7/27/2012 at 1:57 AM. The user was active for 0 minutes 0 seconds. 312 bytes were sent and 4528 bytes were received. The reason for disconnecting was user request. What would be the issue? How can I resolve or debug it? UPDATE: I've found an event log (Log=System, Source=RasSstp) message on the windows 7 machine that tries to connect to the VPN: The SSTP-based VPN connection to the remote access server was terminated because of a security check failure. Security settings on the remote access server do not match settings on this computer. Contact the system administrator of the remote access server and relay the following information: SHA1 Certificate Hash: 065D681...520375552F SHA256 Certificate Hash: 18DED363...EEEE28CFD00

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• Ubuntu boot hangs after message "Running /scripts/init-bottom ... done"

  - by Douglas B. Staple

  I've been trying to copy a Proxmox container based on the Ubuntu Precise Standard template to a VirtualBox VM. I am now stuck at a point where my new Ubuntu/VirtualBox VM hangs after the message "Running /scripts/init-bottom ... done" during boot. I started by installing Ubuntu Server 12.04.4 LTS on a VirtualBox VM. Ubuntu Server 12.04.4 LTS was the closest "official" Ubuntu ISO to the Proxmox container OS I could find. I installed all updates on both the Proxmox container and on the VirtualBox VM. The idea was to get same version kernal running on the ProxMox container and VirtualBox VM. sudo apt-get update ; sudo apt-get upgrade ; sudo apt-get dist-upgrade sudo reboot rsync the entire proxmox container to a temporary directory in the VirtualBox VM: cd / mkdir /tmp/backup rsync -e ssh -av --exclude={/dev,/proc,/sys,/tmp,/run,/mnt,/media,/lost+found,/boot,/selinux} root@my_proxmox_container_hostname:/ /tmp/backup Shut down the virtual machine, and boot the VM with a bootable linux image. I used the Desktop image of Ubuntu 12.04 LTS, ubuntu-12.04.4-desktop-i386.iso Drop to a root prompt. Mount the VM root filesystem: sudo mount /dev/sda1 /mnt Remove files from most of /mnt cd /mnt sudo rm -rf bin etc home lib opt sbin root usr var Move all of the files from /mnt/backup into /mnt sudo mv /mnt/tmp/backup/* /mnt Rebooted system. For me, at this point the system freezes after starting, after the message: Running /scripts/init-bottom ... done I've tried reinstalling GRUB and all manner of other thing. I am almost ready to give up.

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