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• .NET Properties - Use Private Set or ReadOnly Property?

  - by tgxiii

  In what situation should I use a Private Set on a property versus making it a ReadOnly property? Take into consideration the two very simplistic examples below. First example: Public Class Person Private _name As String Public Property Name As String Get Return _name End Get Private Set(ByVal value As String) _name = value End Set End Property Public Sub WorkOnName() Dim txtInfo As TextInfo = _ Threading.Thread.CurrentThread.CurrentCulture.TextInfo Me.Name = txtInfo.ToTitleCase(Me.Name) End Sub End Class // ---------- public class Person { private string _name; public string Name { get { return _name; } private set { _name = value; } } public void WorkOnName() { TextInfo txtInfo = System.Threading.Thread.CurrentThread.CurrentCulture.TextInfo; this.Name = txtInfo.ToTitleCase(this.Name); } } Second example: Public Class AnotherPerson Private _name As String Public ReadOnly Property Name As String Get Return _name End Get End Property Public Sub WorkOnName() Dim txtInfo As TextInfo = _ Threading.Thread.CurrentThread.CurrentCulture.TextInfo _name = txtInfo.ToTitleCase(_name) End Sub End Class // --------------- public class AnotherPerson { private string _name; public string Name { get { return _name; } } public void WorkOnName() { TextInfo txtInfo = System.Threading.Thread.CurrentThread.CurrentCulture.TextInfo; _name = txtInfo.ToTitleCase(_name); } } They both yield the same results. Is this a situation where there's no right and wrong, and it's just a matter of preference?

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• minecraft wont take keyboard input

  - by Drew S

  After upgrading to 13.10 FTB(minecraft) wont take keyboard input after login in. I can click the buttons but it will not let me type in a address on multiplayer, or copy/paste with mouse. Since upgrading I cannot run the other mod packs either, only the one I had installed from 13.04. I get this when running a new modpack: 2013-10-28 15:14:52 [INFO] [STDERR] Exception in thread "Minecraft main thread" java.lang.ExceptionInInitializerError 2013-10-28 15:14:52 [INFO] [STDERR] at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:355) 2013-10-28 15:14:52 [INFO] [STDERR] at net.minecraft.client.MinecraftAppletImpl.func_71384_a(SourceFile:56) 2013-10-28 15:14:52 [INFO] [STDERR] at net.minecraft.client.Minecraft.run(Minecraft.java:733) 2013-10-28 15:14:52 [INFO] [STDERR] at java.lang.Thread.run(Thread.java:724) 2013-10-28 15:14:52 [INFO] [STDERR] Caused by: java.lang.ArrayIndexOutOfBoundsException: 0 2013-10-28 15:14:52 [INFO] [STDERR] at org.lwjgl.opengl.XRandR$Screen.<init>(XRandR.java:234) 2013-10-28 15:14:52 [INFO] [STDERR] at org.lwjgl.opengl.XRandR$Screen.<init>(XRandR.java:196) 2013-10-28 15:14:52 [INFO] [STDERR] at org.lwjgl.opengl.XRandR.populate(XRandR.java:87) 2013-10-28 15:14:52 [INFO] [STDERR] at org.lwjgl.opengl.XRandR.access$100(XRandR.java:52) 2013-10-28 15:14:52 [INFO] [STDERR] at org.lwjgl.opengl.XRandR$1.run(XRandR.java:110) 2013-10-28 15:14:52 [INFO] [STDERR] at java.security.AccessController.doPrivileged(Native Method) 2013-10-28 15:14:52 [INFO] [STDERR] at org.lwjgl.opengl.XRandR.getConfiguration(XRandR.java:108) 2013-10-28 15:14:52 [INFO] [STDERR] at org.lwjgl.opengl.LinuxDisplay.init(LinuxDisplay.java:618) 2013-10-28 15:14:52 [INFO] [STDERR] at org.lwjgl.opengl.Display.<clinit>(Display.java:135) 2013-10-28 15:14:52 [INFO] [STDERR] ... 4 more

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• Feed the Beast Ultimate black screen after login 13.04?

  - by Drew S

  I get a black screen after login feed the beast ultimate splash animation. I have tried the manual LWJGL upgrading, using different versions of java (6 and 7 openJDK). no matter what I get this 2013-06-28 15:23:17 [INFO] [STDERR] Exception in thread "Minecraft main thread" java.lang.ExceptionInInitializerError 2013-06-28 15:23:17 [INFO] [STDERR] at net.minecraft.client.Minecraft.a(Minecraft.java:356) 2013-06-28 15:23:17 [INFO] [STDERR] at asq.a(SourceFile:56) 2013-06-28 15:23:17 [INFO] [STDERR] at net.minecraft.client.Minecraft.run(Minecraft.java:746) 2013-06-28 15:23:17 [INFO] [STDERR] at java.lang.Thread.run(Thread.java:722) 2013-06-28 15:23:17 [INFO] [STDERR] Caused by: java.lang.ArrayIndexOutOfBoundsException: 0 2013-06-28 15:23:17 [INFO] [STDERR] at org.lwjgl.opengl.XRandR$Screen.<init>(XRandR.java:234) 2013-06-28 15:23:17 [INFO] [STDERR] at org.lwjgl.opengl.XRandR$Screen.<init>(XRandR.java:196) 2013-06-28 15:23:17 [INFO] [STDERR] at org.lwjgl.opengl.XRandR.populate(XRandR.java:87) 2013-06-28 15:23:17 [INFO] [STDERR] at org.lwjgl.opengl.XRandR.access$100(XRandR.java:52) 2013-06-28 15:23:17 [INFO] [STDERR] at org.lwjgl.opengl.XRandR$1.run(XRandR.java:110) 2013-06-28 15:23:17 [INFO] [STDERR] at java.security.AccessController.doPrivileged(Native Method) 2013-06-28 15:23:17 [INFO] [STDERR] at org.lwjgl.opengl.XRandR.getConfiguration(XRandR.java:108) 2013-06-28 15:23:17 [INFO] [STDERR] at org.lwjgl.opengl.LinuxDisplay.init(LinuxDisplay.java:618) 2013-06-28 15:23:17 [INFO] [STDERR] at org.lwjgl.opengl.Display.<clinit>(Display.java:135) 2013-06-28 15:23:17 [INFO] [STDERR] ... 4 more

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• Android threads trouble wrapping my head around design

  - by semajhan

  I am having trouble wrapping my head around game design. On the android platform, I have an activity and set its content view with a custom surface view. The custom surface view acts as my panel and I create instances of all classes and do all the drawing and calculation in there. Question: Should I instead create the instances of other classes in my activity? Now I create a custom thread class that handles the game loop. Question: How do I use this one class in all my activities? Or do I have to create a separate instance of the extended thread class each time? In my previous game, I had multiple levels that had to create an instance of the thread class and in the thread class I had to set constructor methods for each separate level and in the loop use a switch statement to check which level it needs to render and update. Sorry if that sounds confusing. I just want to know if the method I am using is inefficient (which it probably is) and how to go about designing it the correct way. I have read many tutorials out there and I am still having lots of trouble with this particular topic. Maybe a link to a some tutorials that explain this? Thanks.

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• Minecraft in jdk 1.7.0_u2 x64

  - by Nela Drobná

  I have Ubuntu 11.10 64-bit and I installed JDK 1.7.0 update 2 x64 via webupd8 page. But currently I have problem with minecraft game. After downloading launcher from Minecraft.net and lauch the game by java -jar /home/zrebec/Downloads/minecraft.jar launcehr is launched normaly, after login the game download the updates but then I got just the black screen with this in terminal: Setting user: zrebec, -356009615199623309 Exception in thread "Minecraft main thread" java.lang.UnsatisfiedLinkError: /home/zrebec/.minecraft/bin/natives/liblwjgl.so: /home/zrebec/.minecraft/bin/natives/liblwjgl.so: wrong ELF class: ELFCLASS32 (Possible cause: architecture word width mismatch) at java.lang.ClassLoader$NativeLibrary.load(Native Method) at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1928) at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1825) at java.lang.Runtime.load0(Runtime.java:792) at java.lang.System.load(System.java:1059) at org.lwjgl.Sys$1.run(Sys.java:69) at java.security.AccessController.doPrivileged(Native Method) at org.lwjgl.Sys.doLoadLibrary(Sys.java:65) at org.lwjgl.Sys.loadLibrary(Sys.java:81) at org.lwjgl.Sys.<clinit>(Sys.java:98) at org.lwjgl.opengl.Display.<clinit>(Display.java:132) at net.minecraft.client.Minecraft.a(SourceFile:180) at net.minecraft.client.Minecraft.run(SourceFile:648) at java.lang.Thread.run(Thread.java:722) Please anyone can help me with this? I think that problem will be in architecture becase: liblwjgl.so: /home/zrebec/.minecraft/bin/natives/liblwjgl.so: wrong ELF class: ELFCLASS32 (Possible cause: architecture word width mismatch) Any idea please? I know, maybe this one is off topic because maybe its not Ubuntu problem maybe but in 64-bit works all perfectly and I think that accepted answer can help to many users and can make better playing games under linux. Really. Thank you very much for any idea.

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• Android threads trouble wrapping my head around design

  - by semajhan

  I am having trouble wrapping my head around game design. On the android platform, I have an activity and set its content view with a custom surface view. The custom surface view acts as my panel and I create instances of all classes and do all the drawing and calculation in there. Question: Should I instead create the instances of other classes in my activity? Now I create a custom thread class that handles the game loop. Question: How do I use this one class in all my activities? Or do I have to create a separate thread each time? In my previous game, I had multiple levels that had to create an instance of the thread class and in the thread class I had to set constructor methods for each separate level and in the loop use a switch statement to check which level it needs to render and update. Sorry if that sounds confusing. I just want to know if the method I am using is inefficient (which it probably is) and how to go about designing it the correct way. I have read many tutorials out there and I am still having lots of trouble with this particular topic. Maybe a link to a some tutorials that explain this? Thanks.

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• How can I save state from script in a multithreaded engine?

  - by Peter Ren

  We are building a multithreaded game engine and we've encountered some problems as described below. The engine have 3 threads in total: script, render, and audio. Each frame, we update these 3 threads simultaneously. As these threads updating themselves, they produce some tasks and put them into a public storage area. As all the threads finish their update, each thread go and copy the tasks for themselves one by one. After all the threads finish their task copying, we make the threads process those tasks and update these threads simultaneously as described before. So this is the general idea of the task schedule part of our engine. Ok, well, all the task schedule part work well, but here's the problem: For the simplest, I'll take Camera as an example: local oldPos = camera:getPosition() -- ( 0, 0, 0 ) camera:setPosition( 1, 1, 1 ) -- Won't work now, cuz the render thread will process the task at the beginning of the next frame local newPos = camera:getPosition() -- Still ( 0, 0, 0 ) So that's the problem: If you intend to change a property of an object in another thread, you have to wait until that thread process this property-changing message. As a result, what you get from the object is still the information in the last frame. So, is there a way to solve this problem? Or are we build the task schedule part in a wrong way? Thanks for your answers :)

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• How to manage long running background threads and report progress with DDD

  - by Mr Happy

  Title says most of it. I have found surprising little information about this. I have a long running operation of which the user wants to see the progress (as in, item x of y processed). I also need to be able to pause and stop the operation. (Stopping doesn't rollback the items already processed.) The thing is, it's not that each item takes a long time to get processed, it's that that there are usually a lot of items. And what I've read about so far is that it's somewhat of an anti-pattern to put something like a queue in the DB. I currently don't have any messaging system in place, and I've never worked with one either. Another thing I read somewhere is that progress reporting is something that belongs in the application layer, but it didn't go into the details. So having said all this, what I have in mind is the following. User request with list of items enters the application layer. Application layer gets some information from the domain needed to process the items. Application layer passes the items and the information off to some domain service (should the implementation of this service belong in the infrastructure layer?) This service spins up a worker thread with callbacks for both progress reporting and pausing/stopping it. This worker thread will process each item in it's own UoW. This means the domain information from earlier needs to be stored in some DTO. Since nothing is really persisted, the service should be singleton and thread safe Whenever a user requests a progress report or wants to pause/stop the operation, the application layer will ask the service. Would this be a correct solution? Or am I at least on the right track with this? Especially the singleton and thread safe part makes the whole thing feel icky.

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• Ubuntu 64bit Black Screen on Minecraft

  - by Signify

  I have tried posting on the forums, but I really need help (I'm a server admin and really don't want to have to switch to Windows just to run Minecraft). Anyhow, I originally was running openjdk6 as I was told that 7 was unstable and was getting periodical lag spikes while walking (at least once every 3 seconds the screen would freeze for a tenth of a second). After that, I attempted to install Sun's Java JDK7 (I couldn't get ahold of 6 without signing up for Oracle's newsletters). Upon attempting to run Minecraft, I got a black screen after logging in with this error message: 27 achievements 182 recipes Setting user: Thunder7102, -1618112820878091307 Exception in thread "Minecraft main thread" java.lang.UnsatisfiedLinkError: /home/noiro/.minecraft/bin/natives/liblwjgl.so: /home/noiro/.minecraft/bin/natives/liblwjgl.so: wrong ELF class: ELFCLASS32 (Possible cause: architecture word width mismatch) at java.lang.ClassLoader$NativeLibrary.load(Native Method) at java.lang.ClassLoader.loadLibrary1(ClassLoader.java:1939) at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1864) at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1825) at java.lang.Runtime.load0(Runtime.java:792) at java.lang.System.load(System.java:1059) at org.lwjgl.Sys$1.run(Sys.java:69) at java.security.AccessController.doPrivileged(Native Method) at org.lwjgl.Sys.doLoadLibrary(Sys.java:65) at org.lwjgl.Sys.loadLibrary(Sys.java:81) at org.lwjgl.Sys.<clinit>(Sys.java:98) at org.lwjgl.opengl.Display.<clinit>(Display.java:132) at net.minecraft.client.Minecraft.a(SourceFile:184) at net.minecraft.client.Minecraft.run(SourceFile:657) at java.lang.Thread.run(Thread.java:722) Now, this got me fed up, so I tried to install a Windows 7 virtual machine through virtualbox, I gave it 256mb of graphics memory with 2D and 3D acceleration and 3GB of RAM. I installed Java JDK7 for Windows (which does work from experience on my other Windows 7 partition). Once again, a black screen after login. What the heck is going on guys? My System Specs: Ubuntu 12.04 64bit Fully Updated running Gnome3 Nvidia GTS 450 1.3GB OC'd AMD Athlon II 4x 2.8Ghz 6GB of RAM So, what do you think?

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• How exactly to implement multiple threads in a game

  - by xerwin

  So I recently started learning Java, and having a interest in playing games as well as developing them, naturally I want to create game in Java. I have experience with games in C# and C++ but all of them were single-threaded simple games. But now, I learned how easy it is to make threads in Java, I want to take things to the next level. I started thinking about how would I actually implement threading in a game. I read couple of articles that say the same thing "Usually you have thread for rendering, for updating game logic, for AI, ..." but I haven't (or didn't look hard enough) found example of implementation. My idea how to make implementation is something like this (example for AI) public class AIThread implements Runnable{ private List<AI> ai; private Player player; /*...*/ public void run() { for (int i = 0; i < ai.size(); i++){ ai.get(i).update(player); } Thread.sleep(/* sleep until the next game "tick" */); } } I think this could work. If I also had a rendering and updating thread list of AI in both those threads, since I need to draw the AI and I need to calculate the logic between player and AI(But that could be moved to AIThread, but as an example) . Coming from C++ I'm used to do thing elegantly and efficiently, and this seems like neither of those. So what would be the correct way to handle this? Should I just keep multiple copies of resources in each thread or should I have the resources on one spot, declared with synchronized keyword? I'm afraid that could cause deadlocks, but I'm not yet qualified enough to know when a code will produce deadlock.

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• How to handle multiple pages of the same site with the same outlinks

  - by pandafromchina

  I am developing a back link tool for Chinese SEO (our web site URL is: http://link.aizhan.com just like ahrefs.com. I encountered a problem which is how to handle multiple pages of the same site with the same out links. For example: Most pages of bbs.chinaz.com have the same out links such as: bbs.chinaz.com/Tea/thread-6293993-1-1.html bbs.chinaz.com/Tea/list-1.html bbs.chinaz.com/alimama/thread-6265032-1-1.html bbs.chinaz.com/alimama/thread-6265032-2-1.html?userid=-1&extParms= bbs.chinaz.com/Shuiba/list-1.html bbs.chinaz.com/FeedBack/thread-4456753-1-1.html etc.. All of the pages have the same out links in the top of the page: www.cnzz.com(anchor text:????) www.313.com(????) www.idc123.com(????) Suppose I store these outlinks into database. The SEO will find there are six backlinks from bbs.chinaz.com of www.cnzz.com. This is obviously no sense for the SEO. Can you tell me how do you deal with this problem?

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• Marking Discussions as Answered

  As a contributor to a number of projects on CodePlex I really like the fact that the discussions feature exists but also I need ways to help me sort the discussions threads so I can make sure no-one is getting forgotten about. Seems like a lot of you agreed as the feature request Provide feature to allow Coordinators to mark Discussions threads as 'Answered' is our number 2 voted feature right now with 178 votes.  Today we rolled out the first iteration of “answer” support to discussions. In this first iteration we wanted to keep it simple and lightweight. The original poster of the thread along with project owners, developers or editors can mark any post to the thread as an answer. You can have any number of answers marked in a thread and it’s very quick to mark or unmark a post as an answer.  We deliberately keep the answers in the originally posted order so that you can see them in context with the discussion thread. When viewing discussions the default view is still to see everything, but you can easily filter by “Unanswered”.  You can even save that as a bookmark so as someone interested in the project can quickly jump to the unanswered discussion threads to go help out on. As I mention, we kept this first pass of the answering feature as simple and as lightweight as possible so that we can get some feedback on it. Head on over to the issue tracking this feature if you have any thoughts once you have used it for a bit or feel free to respond in the comments. I already have a couple of things I think we want to do such as a refresh of the look and feel of discussions in general along, make it easier to navigate to posts that are marked an answered and surface posts that you do that were marked as answered in your profile page - but if you have ideas then please let us know.

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• How to dynamically override a method in an object

  - by Ace Takwas

  If this is possible, how can I change what a method does after I might have created an instance of that class and wish to keep the reference to that object but override a public method in it's class' definition? Here's my code: package time_applet; public class TimerGroup implements Runnable{ private Timer hour, min, sec; private Thread hourThread, minThread, secThread; public TimerGroup(){ hour = new HourTimer(); min = new MinuteTimer(); sec = new SecondTimer(); } public void run(){ hourThread.start(); minThread.start(); secThread.start(); } /*Please pay close attention to this method*/ private Timer activateHourTimer(int start_time){ hour = new HourTimer(start_time){ public void run(){ while (true){ if(min.changed)//min.getTime() == 0) changeTime(); } } }; hourThread = new Thread(hour); return hour; } private Timer activateMinuteTimer(int start_time){ min = new MinuteTimer(start_time){ public void run(){ while (true){ if(sec.changed)//sec.getTime() == 0) changeTime(); } } }; minThread = new Thread(min); return min; } private Timer activateSecondTimer(int start_time){ sec = new SecondTimer(start_time); secThread = new Thread(sec); return sec; } public Timer addTimer(Timer timer){ if (timer instanceof HourTimer){ hour = timer; return activateHourTimer(timer.getTime()); } else if (timer instanceof MinuteTimer){ min = timer; return activateMinuteTimer(timer.getTime()); } else{ sec = timer; return activateSecondTimer(timer.getTime()); } } } So for example in the method activateHourTimer(), I would like to override the run() method of the hour object without having to create a new object. How do I go about that?

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• ??????????/??????????????|WebLogic Channel|??????

  - by ???02

  WebLogic Server???????????????????????????????????????????????????????????????????????????1???????????????????????????????????????????????????WebLogic Server???????????????????????????????????????????????????????????????????????·?????????????????????·??????????????????????????????????????????????????2011?11????????Oracle DBA & Developers Days 2011??????????????????????????WebLogic Server??????????????????WebLogic Server???????????????????????????????????????????????????·?????????????????????????????2??????????????????????????????????????????????·??????????(???)?WebLogic Server??????????????????????　WebLogic Server????????????????????????????OS???JVM???WebLogic Server????????????????5????????????????WebLogic Server??????????????????????????????????????　????????·????????????????????WebLogic Server????????????????　?????????????????????????????????????Listen????????????????Listen????????Muxer??????????????·????·????????????????????????????????????????·????????????????·?????????????????????????????????????????????????????????????????????????????????JDBC?????????????????????????????????????¦???????????·??????????――?????·??????·???????????WebLogic?????　?????????????????????·?????????????????????????3????????????1????????·?????????????¦????????????! ?????????????????JRockit Flight Recorder?????????1??????????????――?????????????????　1??????????????????　???????????????????????????????????????????????????????·?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????　??????????????????????CPU??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????　??????????????????????????????????????????????????????????????????????????????????????¦????????????WebLogic Server - ???????·??????　????????????????????????WebLogic Server?????????????????????????????????????????????????????????????3???　??????????????????????????(????????)??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????　??3??????????????????????????????????????????????????????????????????????　????????????50~600???????????????100~500???????????????????????????????????????????????300??????????????????????200?400???????????????????????????　???50?100???????????????????????????????????????????????????????????????????????????????????????????500?600????????????????????????????????????????????????????????????????　??????????????????????????????50?100????????????500?600???????????????????100~500?????????????????????????????????????????200~400?????????????????????????????　???????????????????????????????????????????????????????????????????"????????"??????????????????????????JDBC?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????¦????WebLogic Server(JRockit) - ????????????????????????????????2???????????????――???????? ? ??????????????????　2???????????????????????????????????????????????????????????????????????????????????????????????????????????1???????????400??????(???????????????????????????????domain.xsd????????????????????????????????????????)?　???????????????????????????????????????????????????????????????????????????????????????????????????????????????????Dweblogic.SelfTuningThreadPoolSizeMin={???????}Dweblogic.SelfTuningThreadPoolSizeMax={???????}?????????????????<server>　　<name>MANAGED_SRV</name>　　<self-tuning-thread-pool-size-min>{???????}</self-tuning-thread-pool-size-min>　　<self-tuning-thread-pool-size-max>{???????}</self-tuning-thread-pool-size-max>　　...?...</server>　????????????????????????????????????????????????????????　??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????¦????????????WebLogic Server - ????????/????　?????1?????????????·???????????????????????????????????????????????????·??????????????????????????????????·?????????????0~2????????????????????????????????????????????????????????????????????????????????????????·???????????????????????????????????????????????????????????????????????????????????　??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????·???????????????????????????????????　???????????????????????????????????????????????????????????????????????????????????????????????????????????·????????????　???????????????????????????????????????????????????????????????????????·???????????????????????????????　????????????????WebLogic Server??????????????????????????????????????????????????????????????????????????????????????????????????????????????·??????????????　??????????????????????????2????????·??????????????????????2?????????????¦Oracle DBA & Developers Days 2011????????????????????WebLogic Server??????????????¦????·????Oracle WebLogic Server 12c Forum - ????????Java??????????? -??2012?1?25?13:30~17:00 ?? ????????????13F?????

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• Hung JVM consuming 100% CPU

  - by Bogdan

  We have a JAVA server running on Sun JRE 6u20 on Linux 32-bit (CentOS). We use the Server Hotspot with CMS collector with the following options (I've only provided the relevant ones): -Xmx896m -Xss128k -XX:NewSize=384M -XX:MaxPermSize=96m -XX:+UseParNewGC -XX:+UseConcMarkSweepGC Sometimes, after running for a while, the JVM seems to slip into a hung state, whereby even though we don't make any requests to the application, the CPU continues to spin at 100% (we have 8 logical CPUs, so it looks like only one CPU does the spinning). In this state the JVM doesn't respond to SIGHUP signals (kill -3) and we can't connect to it normally with jstack. We CAN connect with "jstack -F", but the output is dodgy (we can see lots of NullPointerExceptions from JStack apparently because it wasn't able to 'walk' some stacks). So the "jstack -F" output seems to be useless. We have run a stack dump from "gdb" though, and we were able to match the thread id that spins the CPU (we found that using "top" with a per-thread view - "H" option) with a thread stack that appears in the gdb result and this is how it looks like: Thread 443 (Thread 0x7e5b90 (LWP 26310)): #0 0x0115ebd3 in CompactibleFreeListSpace::block_size(HeapWord const*) const () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #1 0x01160ff9 in CompactibleFreeListSpace::prepare_for_compaction(CompactPoint*) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #2 0x0123456c in Generation::prepare_for_compaction(CompactPoint*) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #3 0x01229b2c in GenCollectedHeap::prepare_for_compaction() () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #4 0x0122a7fc in GenMarkSweep::invoke_at_safepoint(int, ReferenceProcessor*, bool) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #5 0x01186024 in CMSCollector::do_compaction_work(bool) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #6 0x011859ee in CMSCollector::acquire_control_and_collect(bool, bool) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #7 0x01185705 in ConcurrentMarkSweepGeneration::collect(bool, bool, unsigned int, bool) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #8 0x01227f53 in GenCollectedHeap::do_collection(bool, bool, unsigned int, bool, int) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #9 0x0115c7b5 in GenCollectorPolicy::satisfy_failed_allocation(unsigned int, bool) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #10 0x0122859c in GenCollectedHeap::satisfy_failed_allocation(unsigned int, bool) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #11 0x0158a8ce in VM_GenCollectForAllocation::doit() () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #12 0x015987e6 in VM_Operation::evaluate() () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #13 0x01597c93 in VMThread::evaluate_operation(VM_Operation*) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #14 0x01597f0f in VMThread::loop() () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #15 0x015979f0 in VMThread::run() () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #16 0x0145c24e in java_start(Thread*) () from /usr/java/jdk1.6.0_20/jre/lib/i386/server/libjvm.so #17 0x00ccd46b in start_thread () from /lib/libpthread.so.0 #18 0x00bc2dbe in clone () from /lib/libc.so.6 It seems that a JVM thread is spinning while doing some CMS related work. We have checked the memory usage on the box, there seems to be enough memory available and the system is not swapping. Has anyone come across such a situation? Does it look like a JVM bug? UPDATE I've obtained some more information about this problem (it happened again on a server that has been running for more than 7 days). When the JVM entered the "hung" state it stayed like that for 2 hours until the server was manually restarted. We have obtained a core dump of the process and the gc log. We tried to get a heap dump as well, but "jmap" failed. We tried to use jmap -F but then only a 4Mb file was written before the program aborted with an exception (something about the a memory location not being accessible). So far I think the most interesting information comes from the gc log. It seems that the GC logging stopped as well (possibly at the time when the VM thread went into the long loop): 657501.199: [Full GC (System) 657501.199: [CMS: 400352K->313412K(524288K), 2.4024120 secs] 660634K->313412K(878208K), [CMS Perm : 29455K->29320K(68568K)], 2.4026470 secs] [Times: user=2.39 sys=0.01, real=2.40 secs] 657513.941: [GC 657513.941: [ParNew: 314624K->13999K(353920K), 0.0228180 secs] 628036K->327412K(878208K), 0.0230510 secs] [Times: user=0.08 sys=0.00, real=0.02 secs] 657523.772: [GC 657523.772: [ParNew: 328623K->17110K(353920K), 0.0244910 secs] 642036K->330523K(878208K), 0.0247140 secs] [Times: user=0.08 sys=0.00, real=0.02 secs] 657535.473: [GC 657535.473: [ParNew: 331734K->20282K(353920K), 0.0259480 secs] 645147K->333695K(878208K), 0.0261670 secs] [Times: user=0.11 sys=0.00, real=0.02 secs] .... .... 688346.765: [GC [1 CMS-initial-mark: 485248K(524288K)] 515694K(878208K), 0.0343730 secs] [Times: user=0.03 sys=0.00, real=0.04 secs] 688346.800: [CMS-concurrent-mark-start] 688347.964: [CMS-concurrent-mark: 1.083/1.164 secs] [Times: user=2.52 sys=0.09, real=1.16 secs] 688347.964: [CMS-concurrent-preclean-start] 688347.969: [CMS-concurrent-preclean: 0.004/0.005 secs] [Times: user=0.00 sys=0.01, real=0.01 secs] 688347.969: [CMS-concurrent-abortable-preclean-start] CMS: abort preclean due to time 688352.986: [CMS-concurrent-abortable-preclean: 2.351/5.017 secs] [Times: user=3.83 sys=0.38, real=5.01 secs] 688352.987: [GC[YG occupancy: 297806 K (353920 K)]688352.987: [Rescan (parallel) , 0.1815250 secs]688353.169: [weak refs processing, 0.0312660 secs] [1 CMS-remark: 485248K(524288K)] 783055K(878208K), 0.2131580 secs] [Times: user=1.13 sys =0.00, real=0.22 secs] 688353.201: [CMS-concurrent-sweep-start] 688353.903: [CMS-concurrent-sweep: 0.660/0.702 secs] [Times: user=0.91 sys=0.07, real=0.70 secs] 688353.903: [CMS-concurrent-reset-start] 688353.912: [CMS-concurrent-reset: 0.008/0.008 secs] [Times: user=0.01 sys=0.00, real=0.01 secs] 688354.243: [GC 688354.243: [ParNew: 344928K->30151K(353920K), 0.0305020 secs] 681955K->368044K(878208K), 0.0308880 secs] [Times: user=0.15 sys=0.00, real=0.03 secs] .... .... 688943.029: [GC 688943.029: [ParNew: 336531K->17143K(353920K), 0.0237360 secs] 813250K->494327K(878208K), 0.0241260 secs] [Times: user=0.10 sys=0.00, real=0.03 secs] 688950.620: [GC 688950.620: [ParNew: 331767K->22442K(353920K), 0.0344110 secs] 808951K->499996K(878208K), 0.0347690 secs] [Times: user=0.11 sys=0.00, real=0.04 secs] 688956.596: [GC 688956.596: [ParNew: 337064K->37809K(353920K), 0.0488170 secs] 814618K->515896K(878208K), 0.0491550 secs] [Times: user=0.18 sys=0.04, real=0.05 secs] 688961.470: [GC 688961.471: [ParNew (promotion failed): 352433K->332183K(353920K), 0.1862520 secs]688961.657: [CMS I suspect this problem has something to do with the last line in the log (I've added some "...." in order to skip some lines that were not interesting). The fact that the server stayed in the hung state for 2 hours (probably trying to GC and compact the old generation) seems quite strange to me. Also, the gc log stops suddenly with that message and nothing else gets printed any more, probably because the VM Thread gets into some sort of infinite loop (or something that takes 2+ hours).

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• Fail to analyze core dump with GDB when main.elf is dynamically linked (uses shared libs)

  - by dscTobi

  Hi all. I'm trying to analyze core dump, but i get following result: GNU gdb 6.6.0.20070423-cvs Copyright (C) 2006 Free Software Foundation, Inc. GDB is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Type "show copying" to see the conditions. There is absolutely no warranty for GDB. Type "show warranty" for details. This GDB was configured as "--host=mipsel-linux --target=mipsel-linux-uclibc". (gdb) file main.elf Reading symbols from /home/tobi/main.elf...Reading symbols from /home/tobi/main.dbg...done. done. (gdb) core-file /srv/tobi/core warning: .dynamic section for "/lib/libpthread.so.0" is not at the expected address (wrong library or version mismatch?) Error while mapping shared library sections: /lib/libdl.so.0: No such file or directory. Error while mapping shared library sections: /lib/librt.so.0: No such file or directory. Error while mapping shared library sections: /lib/libm.so.0: No such file or directory. Error while mapping shared library sections: /lib/libstdc++.so.6: No such file or directory. Error while mapping shared library sections: /lib/libc.so.0: No such file or directory. warning: .dynamic section for "/lib/libgcc_s.so.1" is not at the expected address (wrong library or version mismatch?) Error while mapping shared library sections: /lib/ld-uClibc.so.0: No such file or directory. Reading symbols from /lib/libpthread.so.0...done. Loaded symbols for /lib/libpthread.so.0 Symbol file not found for /lib/libdl.so.0 Symbol file not found for /lib/librt.so.0 Symbol file not found for /lib/libm.so.0 Symbol file not found for /lib/libstdc++.so.6 Symbol file not found for /lib/libc.so.0 Reading symbols from /lib/libgcc_s.so.1...done. Loaded symbols for /lib/libgcc_s.so.1 Symbol file not found for /lib/ld-uClibc.so.0 warning: Unable to find dynamic linker breakpoint function. GDB will be unable to debug shared library initializers and track explicitly loaded dynamic code. Core was generated by 'root/main.elf'. Program terminated with signal 11, Segmentation fault. #0 0x0046006c in NullPtr (parse_p=0x2ac9dc80, result_sym_p=0x13e3d6c "") at folder/my1.c:1624 1624 *ptr += 13; (gdb) bt #0 0x0046006c in NullPtr (parse_p=0x2ac9dc80, result_sym_p=0x13e3d6c "") at folder/my1.c:1624 #1 0x0047a31c in fn1 (line_ptr=0x2ac9dd18 "ccore_null_pointer", target_ptr=0x13e3d6c "", result_ptr=0x2ac9dd14) at folder/my2.c:980 #2 0x0047b9d0 in fn2 (macro_ptr=0x0, rtn_exp_ptr=0x0) at folder/my3.c:1483 /... some functions .../ #8 0x2aab7f9c in __nptl_setxid () from /lib/libpthread.so.0 Backtrace stopped: frame did not save the PC (gdb) thread apply all bt Thread 159 (process 1093): #0 0x2aac15dc in _Unwind_GetCFA () from /lib/libpthread.so.0 #1 0x2afdfde8 in ?? () warning: GDB cant find the start of the function at 0x2afdfde8. GDB is unable to find the start of the function at 0x2afdfde8 and thus cant determine the size of that functions stack frame. This means that GDB may be unable to access that stack frame, or the frames below it. This problem is most likely caused by an invalid program counter or stack pointer. However, if you think GDB should simply search farther back from 0x2afdfde8 for code which looks like the beginning of a function, you can increase the range of the search using the set heuristic-fence-post command. Backtrace stopped: previous frame inner to this frame (corrupt stack?) Thread 158 (process 1051): #0 0x2aac17bc in pthread_mutexattr_getprioceiling () from /lib/libpthread.so.0 #1 0x2aac17a0 in pthread_mutexattr_getprioceiling () from /lib/libpthread.so.0 Backtrace stopped: previous frame identical to this frame (corrupt stack?) Thread 157 (process 1057): #0 0x2aabf908 in ?? () from /lib/libpthread.so.0 #1 0x00000000 in ?? () Thread 156 (process 1090): #0 0x2aac17bc in pthread_mutexattr_getprioceiling () from /lib/libpthread.so.0 #1 0x2aac17a0 in pthread_mutexattr_getprioceiling () from /lib/libpthread.so.0 Backtrace stopped: previous frame identical to this frame (corrupt stack?) Thread 155 (process 1219): #0 0x2aabf908 in ?? () from /lib/libpthread.so.0 #1 0x00000000 in ?? () Thread 154 (process 1218): #0 0x2aabfb44 in connect () from /lib/libpthread.so.0 #1 0x00000000 in ?? () Thread 153 (process 1096): #0 0x2abc92b4 in ?? () warning: GDB cant find the start of the function at 0x2abc92b4. #1 0x2abc92b4 in ?? () warning: GDB cant find the start of the function at 0x2abc92b4. Backtrace stopped: previous frame identical to this frame (corrupt stack?) Thread 152 (process 1170): #0 0x2aabfb44 in connect () from /lib/libpthread.so.0 #1 0x00000000 in ?? () If i make main.elf statically linked everything is OK and i can see bt of all threads. Any ideas?

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• InternalsVisibleTo attribute and security vulnerability

  - by Sergey Litvinov

  I found one issue with InternalsVisibleTo attribute usage. The idea of InternalsVisibleTo attribute to allow some other assemblies to use internal classes\methods of this assembly. To make it work you need sign your assemblies. So, if other assemblies isn't specified in main assembly and if they have incorrect public key, then they can't use Internal members. But the issue in Reflection Emit type generation. For example, we have CorpLibrary1 assembly and it has such class: public class TestApi { internal virtual void DoSomething() { Console.WriteLine("Base DoSomething"); } public void DoApiTest() { // some internal logic // ... // call internal method DoSomething(); } } This assembly is marked with such attribute to allow another CorpLibrary2 to make inheritor for that TestAPI and override behaviour of DoSomething method. [assembly: InternalsVisibleTo("CorpLibrary2, PublicKey=0024000004800000940000000602000000240000525341310004000001000100434D9C5E1F9055BF7970B0C106AAA447271ECE0F8FC56F6AF3A906353F0B848A8346DC13C42A6530B4ED2E6CB8A1E56278E664E61C0D633A6F58643A7B8448CB0B15E31218FB8FE17F63906D3BF7E20B9D1A9F7B1C8CD11877C0AF079D454C21F24D5A85A8765395E5CC5252F0BE85CFEB65896EC69FCC75201E09795AAA07D0")] The issue is that I'm able to override this internal DoSomething method and break class logic. My steps to do it: Generate new assembly in runtime via AssemblyBuilder Get AssemblyName from CorpLibrary1 and copy PublikKey to new assembly Generate new assembly that will inherit TestApi class As PublicKey and name of generated assembly is the same as in InternalsVisibleTo, then we can generate new DoSomething method that will override internal method in TestAPI assembly Then we have another assembly that isn't related to this CorpLibrary1 and can't use internal members. We have such test code in it: class Program { static void Main(string[] args) { var builder = new FakeBuilder(InjectBadCode, "DoSomething", true); TestApi fakeType = builder.CreateFake(); fakeType.DoApiTest(); // it will display: // Inject bad code // Base DoSomething Console.ReadLine(); } public static void InjectBadCode() { Console.WriteLine("Inject bad code"); } } And this FakeBuilder class has such code: /// /// Builder that will generate inheritor for specified assembly and will overload specified internal virtual method /// /// Target type public class FakeBuilder { private readonly Action _callback; private readonly Type _targetType; private readonly string _targetMethodName; private readonly string _slotName; private readonly bool _callBaseMethod; public FakeBuilder(Action callback, string targetMethodName, bool callBaseMethod) { int randomId = new Random((int)DateTime.Now.Ticks).Next(); _slotName = string.Format("FakeSlot_{0}", randomId); _callback = callback; _targetType = typeof(TFakeType); _targetMethodName = targetMethodName; _callBaseMethod = callBaseMethod; } public TFakeType CreateFake() { // as CorpLibrary1 can't use code from unreferences assemblies, we need to store this Action somewhere. // And Thread is not bad place for that. It's not the best place as it won't work in multithread application, but it's just a sample LocalDataStoreSlot slot = Thread.AllocateNamedDataSlot(_slotName); Thread.SetData(slot, _callback); // then we generate new assembly with the same nameand public key as target assembly trusts by InternalsVisibleTo attribute var newTypeName = _targetType.Name + "Fake"; var targetAssembly = Assembly.GetAssembly(_targetType); AssemblyName an = new AssemblyName(); an.Name = GetFakeAssemblyName(targetAssembly); // copying public key to new generated assembly var assemblyName = targetAssembly.GetName(); an.SetPublicKey(assemblyName.GetPublicKey()); an.SetPublicKeyToken(assemblyName.GetPublicKeyToken()); AssemblyBuilder assemblyBuilder = Thread.GetDomain().DefineDynamicAssembly(an, AssemblyBuilderAccess.RunAndSave); ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule(assemblyBuilder.GetName().Name, true); // create inheritor for specified type TypeBuilder typeBuilder = moduleBuilder.DefineType(newTypeName, TypeAttributes.Public | TypeAttributes.Class, _targetType); // LambdaExpression.CompileToMethod can be used only with static methods, so we need to create another method that will call our Inject method // we can do the same via ILGenerator, but expression trees are more easy to use MethodInfo methodInfo = CreateMethodInfo(moduleBuilder); MethodBuilder methodBuilder = typeBuilder.DefineMethod(_targetMethodName, MethodAttributes.Public | MethodAttributes.Virtual); ILGenerator ilGenerator = methodBuilder.GetILGenerator(); // call our static method that will call inject method ilGenerator.EmitCall(OpCodes.Call, methodInfo, null); // in case if we need, then we put call to base method if (_callBaseMethod) { var baseMethodInfo = _targetType.GetMethod(_targetMethodName, BindingFlags.NonPublic | BindingFlags.Instance); // place this to stack ilGenerator.Emit(OpCodes.Ldarg_0); // call the base method ilGenerator.EmitCall(OpCodes.Call, baseMethodInfo, new Type[0]); // return ilGenerator.Emit(OpCodes.Ret); } // generate type, create it and return to caller Type cheatType = typeBuilder.CreateType(); object type = Activator.CreateInstance(cheatType); return (TFakeType)type; } /// /// Get name of assembly from InternalsVisibleTo AssemblyName /// private static string GetFakeAssemblyName(Assembly assembly) { var internalsVisibleAttr = assembly.GetCustomAttributes(typeof(InternalsVisibleToAttribute), true).FirstOrDefault() as InternalsVisibleToAttribute; if (internalsVisibleAttr == null) { throw new InvalidOperationException("Assembly hasn't InternalVisibleTo attribute"); } var ind = internalsVisibleAttr.AssemblyName.IndexOf(","); var name = internalsVisibleAttr.AssemblyName.Substring(0, ind); return name; } /// /// Generate such code: /// ((Action)Thread.GetData(Thread.GetNamedDataSlot(_slotName))).Invoke(); /// private LambdaExpression MakeStaticExpressionMethod() { var allocateMethod = typeof(Thread).GetMethod("GetNamedDataSlot", BindingFlags.Static | BindingFlags.Public); var getDataMethod = typeof(Thread).GetMethod("GetData", BindingFlags.Static | BindingFlags.Public); var call = Expression.Call(allocateMethod, Expression.Constant(_slotName)); var getCall = Expression.Call(getDataMethod, call); var convCall = Expression.Convert(getCall, typeof(Action)); var invokExpr = Expression.Invoke(convCall); var lambda = Expression.Lambda(invokExpr); return lambda; } /// /// Generate static class with one static function that will execute Action from Thread NamedDataSlot /// private MethodInfo CreateMethodInfo(ModuleBuilder moduleBuilder) { var methodName = "_StaticTestMethod_" + _slotName; var className = "_StaticClass_" + _slotName; TypeBuilder typeBuilder = moduleBuilder.DefineType(className, TypeAttributes.Public | TypeAttributes.Class); MethodBuilder methodBuilder = typeBuilder.DefineMethod(methodName, MethodAttributes.Static | MethodAttributes.Public); LambdaExpression expression = MakeStaticExpressionMethod(); expression.CompileToMethod(methodBuilder); var type = typeBuilder.CreateType(); return type.GetMethod(methodName, BindingFlags.Static | BindingFlags.Public); } } remarks about sample: as we need to execute code from another assembly, CorpLibrary1 hasn't access to it, so we need to store this delegate somewhere. Just for testing I stored it in Thread NamedDataSlot. It won't work in multithreaded applications, but it's just a sample. I know that we use Reflection to get private\internal members of any class, but within reflection we can't override them. But this issue is allows anyone to override internal class\method if that assembly has InternalsVisibleTo attribute. I tested it on .Net 3.5\4 and it works for both of them. How does it possible to just copy PublicKey without private key and use it in runtime? The whole sample can be found there - https://github.com/sergey-litvinov/Tests_InternalsVisibleTo UPDATE1: That test code in Program and FakeBuilder classes hasn't access to key.sn file and that library isn't signed, so it hasn't public key at all. It just copying it from CorpLibrary1 by using Reflection.Emit

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• Which functions in the C standard library commonly encourage bad practice?

  - by Ninefingers

  Hello all, This is inspired by this question and the comments on one particular answer in that I learnt that strncpy is not a very safe string handling function in C and that it pads zeros, until it reaches n, something I was unaware of. Specifically, to quote R.. strncpy does not null-terminate, and does null-pad the whole remainder of the destination buffer, which is a huge waste of time. You can work around the former by adding your own null padding, but not the latter. It was never intended for use as a "safe string handling" function, but for working with fixed-size fields in Unix directory tables and database files. snprintf(dest, n, "%s", src) is the only correct "safe strcpy" in standard C, but it's likely to be a lot slower. By the way, truncation in itself can be a major bug and in some cases might lead to privilege elevation or DoS, so throwing "safe" string functions that truncate their output at a problem is not a way to make it "safe" or "secure". Instead, you should ensure that the destination buffer is the right size and simply use strcpy (or better yet, memcpy if you already know the source string length). And from Jonathan Leffler Note that strncat() is even more confusing in its interface than strncpy() - what exactly is that length argument, again? It isn't what you'd expect based on what you supply strncpy() etc - so it is more error prone even than strncpy(). For copying strings around, I'm increasingly of the opinion that there is a strong argument that you only need memmove() because you always know all the sizes ahead of time and make sure there's enough space ahead of time. Use memmove() in preference to any of strcpy(), strcat(), strncpy(), strncat(), memcpy(). So, I'm clearly a little rusty on the C standard library. Therefore, I'd like to pose the question: What C standard library functions are used inappropriately/in ways that may cause/lead to security problems/code defects/inefficiencies? In the interests of objectivity, I have a number of criteria for an answer: Please, if you can, cite design reasons behind the function in question i.e. its intended purpose. Please highlight the misuse to which the code is currently put. Please state why that misuse may lead towards a problem. I know that should be obvious but it prevents soft answers. Please avoid: Debates over naming conventions of functions (except where this unequivocably causes confusion). "I prefer x over y" - preference is ok, we all have them but I'm interested in actual unexpected side effects and how to guard against them. As this is likely to be considered subjective and has no definite answer I'm flagging for community wiki straight away. I am also working as per C99.

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• Communicating between C# application and Android app via bluetooth

  - by Akki

  The android application acts as a server in this case. I have a main activity which creates a Thread to handle serverSocket and a different thread to handle the socket connection. I am using a uuid common to C# and android. I am using 32feet bluetooth library for C#. The errors i am facing are 1) My logcat shows this debug log Error while doing socket.connect()1 java.io.IOException: File descriptor in bad state Message: File descriptor in bad state Localized Message: File descriptor in bad state Received : Testing Connection Count of Thread is : 1 2) When i try to send something via C# app the second time, this exception is thrown: A first chance exception of type 'System.InvalidOperationException' occurred in System.dll System.InvalidOperationException: BeginConnect cannot be called while another asynchronous operation is in progress on the same Socket. at System.Net.Sockets.Socket.DoBeginConnect(EndPoint endPointSnapshot, SocketAddress socketAddress, LazyAsyncResult asyncResult) at System.Net.Sockets.Socket.BeginConnect(EndPoint remoteEP, AsyncCallback callback, Object state) at InTheHand.Net.Bluetooth.Msft.SocketBluetoothClient.BeginConnect(BluetoothEndPoint remoteEP, AsyncCallback requestCallback, Object state) at InTheHand.Net.Sockets.BluetoothClient.BeginConnect(BluetoothEndPoint remoteEP, AsyncCallback requestCallback, Object state) at InTheHand.Net.Sockets.BluetoothClient.BeginConnect(BluetoothAddress address, Guid service, AsyncCallback requestCallback, Object state) at BTSyncClient.Form1.connect() in c:\users\----\documents\visual studio 2010\Projects\TestClient\TestClient\Form1.cs:line 154 I only know android application programming and i designed the C# by learning bit and pieces. FYI, My android phone is galaxy s with ICS running on it.Please point out my mistakes.. Source codes : C# Code using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Threading; using System.Net.Sockets; using InTheHand.Net.Bluetooth; using InTheHand.Windows.Forms; using InTheHand.Net.Sockets; using InTheHand.Net; namespace BTSyncClient { public partial class Form1 : Form { BluetoothClient myself; BluetoothDeviceInfo bTServerDevice; private Guid uuid = Guid.Parse("00001101-0000-1000-8000-00805F9B34FB"); bool isConnected; public Form1() { InitializeComponent(); if (BluetoothRadio.IsSupported) { myself = new BluetoothClient(); } } private void Form1_Load(object sender, EventArgs e) { } private void button1_Click(object sender, EventArgs e) { connect(); } private void Form1_FormClosing(object sender, FormClosingEventArgs e) { try { myself.GetStream().Close(); myself.Dispose(); } catch (Exception ex) { Console.Out.WriteLine(ex); } } private void button2_Click(object sender, EventArgs e) { SelectBluetoothDeviceDialog dialog = new SelectBluetoothDeviceDialog(); DialogResult result = dialog.ShowDialog(this); if(result.Equals(DialogResult.OK)){ bTServerDevice = dialog.SelectedDevice; } } private void callback(IAsyncResult ar) { String msg = (String)ar.AsyncState; if (ar.IsCompleted) { isConnected = myself.Connected; if (myself.Connected) { UTF8Encoding encoder = new UTF8Encoding(); NetworkStream stream = myself.GetStream(); if (!stream.CanWrite) { MessageBox.Show("Stream is not Writable"); } System.IO.StreamWriter mywriter = new System.IO.StreamWriter(stream, Encoding.UTF8); mywriter.WriteLine(msg); mywriter.Flush(); } else MessageBox.Show("Damn thing isnt connected"); } } private void connect() { try { if (bTServerDevice != null) { myself.BeginConnect(bTServerDevice.DeviceAddress, uuid, new AsyncCallback(callback) , message.Text); } } catch (Exception e) { Console.Out.WriteLine(e); } } } } Server Thread import java.io.IOException; import java.util.UUID; import android.bluetooth.BluetoothAdapter; import android.bluetooth.BluetoothServerSocket; import android.bluetooth.BluetoothSocket; import android.util.Log; public class ServerSocketThread extends Thread { private static final String TAG = "TestApp"; private BluetoothAdapter btAdapter; private BluetoothServerSocket serverSocket; private boolean stopMe; private static final UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"); //private static final UUID uuid = UUID.fromString("6e58c9d5-b0b6-4009-ad9b-fd9481aef9b3"); private static final String SERVICE_NAME = "TestService"; public ServerSocketThread() { stopMe = false; btAdapter = BluetoothAdapter.getDefaultAdapter(); try { serverSocket = btAdapter.listenUsingRfcommWithServiceRecord(SERVICE_NAME, uuid); } catch (IOException e) { Log.d(TAG,e.toString()); } } public void signalStop(){ stopMe = true; } public void run(){ Log.d(TAG,"In ServerThread"); BluetoothSocket socket = null; while(!stopMe){ try { socket = serverSocket.accept(); } catch (IOException e) { break; } if(socket != null){ AcceptThread newClientConnection = new AcceptThread(socket); newClientConnection.start(); } } Log.d(TAG,"Server Thread now dead"); } // Will cancel the listening socket and cause the thread to finish public void cancel(){ try { serverSocket.close(); } catch (IOException e) { } } } Accept Thread import java.io.IOException; import java.io.InputStream; import java.util.Scanner; import android.bluetooth.BluetoothSocket; import android.util.Log; public class AcceptThread extends Thread { private BluetoothSocket socket; private String TAG = "TestApp"; static int count = 0; public AcceptThread(BluetoothSocket Socket) { socket = Socket; } volatile boolean isError; String output; String error; public void run() { Log.d(TAG, "AcceptThread Started"); isError = false; try { socket.connect(); } catch (IOException e) { Log.d(TAG,"Error while doing socket.connect()"+ ++count); Log.d(TAG, e.toString()); Log.d(TAG,"Message: "+e.getLocalizedMessage()); Log.d(TAG,"Localized Message: "+e.getMessage()); isError = true; } InputStream in = null; try { in = socket.getInputStream(); } catch (IOException e) { Log.d(TAG,"Error while doing socket.getInputStream()"); Log.d(TAG, e.toString()); Log.d(TAG,"Message: "+e.getLocalizedMessage()); Log.d(TAG,"Localized Message: "+e.getMessage()); isError = true; } Scanner istream = new Scanner(in); if (istream.hasNextLine()) { Log.d(TAG, "Received : "+istream.nextLine()); Log.d(TAG,"Count of Thread is : " + count); } istream.close(); try { in.close(); } catch (IOException e) { Log.d(TAG,"Error while doing in.close()"); Log.d(TAG, e.toString()); Log.d(TAG,"Message: "+e.getLocalizedMessage()); Log.d(TAG,"Localized Message: "+e.getMessage()); isError = true; } try { socket.close(); } catch (IOException e) { Log.d(TAG,"Error while doing socket.close()"); Log.d(TAG, e.toString()); Log.d(TAG,"Message: "+e.getLocalizedMessage()); Log.d(TAG,"Localized Message: "+e.getMessage()); isError = true; } } }

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• How to solve exception_priv _instruction exception while running destop project? [on hold]

  - by Haritha

  While running desktop project im getting exception_priv _instruction how to solve this??? while running this page is coming # # A fatal error has been detected by the Java Runtime Environment: # # EXCEPTION_PRIV_INSTRUCTION (0xc0000096) at pc=0x02f5a92b, pid=3012, tid=3104 # # JRE version: 7.0-b147 # Java VM: Java HotSpot(TM) Client VM (21.0-b17 mixed mode, sharing windows-x86 ) # Problematic frame: # C 0x02f5a92b # # Failed to write core dump. Minidumps are not enabled by default on client versions of Windows # # If you would like to submit a bug report, please visit: # http://bugreport.sun.com/bugreport/crash.jsp # The crash happened outside the Java Virtual Machine in native code. # See problematic frame for where to report the bug. # --------------- T H R E A D --------------- Current thread (0x02f5a800): JavaThread "LWJGL Application" [_thread_in_native, id=3104, stack(0x076f0000,0x07740000)] siginfo: ExceptionCode=0xc0000096 Registers: EAX=0x000df4f0, EBX=0x32afc180, ECX=0x000df4f0, EDX=0x00000020 ESP=0x0773f768, EBP=0x0773f790, ESI=0x32afc180, EDI=0x02f5a800 EIP=0x02f5a92b, EFLAGS=0x00010206 Top of Stack: (sp=0x0773f768) 0x0773f768: 02bd429c 02bd429c 0773f770 32afc180 0x0773f778: 0773f7b8 32b022c8 00000000 32afc180 0x0773f788: 00000000 0773f7a0 0773f7dc 00943187 0x0773f798: 229ec1c0 00948839 69081736 00000000 0x0773f7a8: 089b0048 00000000 00000014 00001406 0x0773f7b8: 00000002 0773f7bc 32afbeb0 0773f7f8 0x0773f7c8: 32b022c8 00000000 32afbf00 0773f7a0 0x0773f7d8: 0773f7f0 0773f81c 00943187 69081736 Instructions: (pc=0x02f5a92b) 0x02f5a90b: 00 43 00 00 00 00 f0 bc 02 e8 00 e9 22 40 f7 73 0x02f5a91b: 07 85 a5 94 00 90 f7 73 07 50 cc a0 6d d8 49 c0 0x02f5a92b: 6d 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x02f5a93b: 00 00 00 00 00 00 00 00 00 08 80 3d 37 00 00 00 Register to memory mapping: EAX=0x000df4f0 is an unknown value EBX=0x32afc180 is an oop {method} - klass: {other class} ECX=0x000df4f0 is an unknown value EDX=0x00000020 is an unknown value ESP=0x0773f768 is pointing into the stack for thread: 0x02f5a800 EBP=0x0773f790 is pointing into the stack for thread: 0x02f5a800 ESI=0x32afc180 is an oop {method} - klass: {other class} EDI=0x02f5a800 is a thread Stack: [0x076f0000,0x07740000], sp=0x0773f768, free space=317k Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code) C 0x02f5a92b j org.lwjgl.opengl.GL11.glVertexPointer(IILjava/nio/FloatBuffer;)V+48 j com.badlogic.gdx.backends.lwjgl.LwjglGL10.glVertexPointer(IIILjava/nio/Buffer;)V+53 j com.badlogic.gdx.graphics.glutils.VertexArray.bind()V+149 j com.badlogic.gdx.graphics.Mesh.bind()V+25 j com.badlogic.gdx.graphics.Mesh.render(IIIZ)V+32 j com.badlogic.gdx.graphics.Mesh.render(III)V+8 j com.badlogic.gdx.graphics.g2d.SpriteBatch.flush()V+197 j com.badlogic.gdx.graphics.g2d.SpriteBatch.switchTexture(Lcom/badlogic/gdx/graphics/Texture;)V+1 j com.badlogic.gdx.graphics.g2d.SpriteBatch.draw(Lcom/badlogic/gdx/graphics/Texture;FFFF)V+33 j sevenseas.game.WorldRenderer.drawBob()V+54 j sevenseas.game.WorldRenderer.render()V+12 j sevenseas.game.GameClass.render(F)V+38 j com.badlogic.gdx.Game.render()V+19 j com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop()V+642 j com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run()V+27 v ~StubRoutines::call_stub V [jvm.dll+0x122c7e] V [jvm.dll+0x1c9c0e] V [jvm.dll+0x122e73] V [jvm.dll+0x122ed7] V [jvm.dll+0xccd1f] V [jvm.dll+0x14433f] V [jvm.dll+0x171549] C [msvcr100.dll+0x5c6de] endthreadex+0x3a C [msvcr100.dll+0x5c788] endthreadex+0xe4 C [kernel32.dll+0xb713] GetModuleFileNameA+0x1b4 Java frames: (J=compiled Java code, j=interpreted, Vv=VM code) j org.lwjgl.opengl.GL11.nglVertexPointer(IIIJJ)V+0 j org.lwjgl.opengl.GL11.glVertexPointer(IILjava/nio/FloatBuffer;)V+48 j com.badlogic.gdx.backends.lwjgl.LwjglGL10.glVertexPointer(IIILjava/nio/Buffer;)V+53 j com.badlogic.gdx.graphics.glutils.VertexArray.bind()V+149 j com.badlogic.gdx.graphics.Mesh.bind()V+25 j com.badlogic.gdx.graphics.Mesh.render(IIIZ)V+32 j com.badlogic.gdx.graphics.Mesh.render(III)V+8 j com.badlogic.gdx.graphics.g2d.SpriteBatch.flush()V+197 j com.badlogic.gdx.graphics.g2d.SpriteBatch.switchTexture(Lcom/badlogic/gdx/graphics/Texture;)V+1 j com.badlogic.gdx.graphics.g2d.SpriteBatch.draw(Lcom/badlogic/gdx/graphics/Texture;FFFF)V+33 j sevenseas.game.WorldRenderer.drawBob()V+54 j sevenseas.game.WorldRenderer.render()V+12 j sevenseas.game.GameClass.render(F)V+38 j com.badlogic.gdx.Game.render()V+19 j com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop()V+642 j com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run()V+27 v ~StubRoutines::call_stub --------------- P R O C E S S --------------- Java Threads: ( => current thread ) 0x003d6c00 JavaThread "DestroyJavaVM" [_thread_blocked, id=3240, stack(0x008c0000,0x00910000)] =>0x02f5a800 JavaThread "LWJGL Application" [_thread_in_native, id=3104, stack(0x076f0000,0x07740000)] 0x02bcf000 JavaThread "Service Thread" daemon [_thread_blocked, id=2612, stack(0x02e00000,0x02e50000)] 0x02bc1000 JavaThread "C1 CompilerThread0" daemon [_thread_blocked, id=2776, stack(0x02db0000,0x02e00000)] 0x02bbf400 JavaThread "Attach Listener" daemon [_thread_blocked, id=2448, stack(0x02d60000,0x02db0000)] 0x02bbe000 JavaThread "Signal Dispatcher" daemon [_thread_blocked, id=1764, stack(0x02d10000,0x02d60000)] 0x02bb8000 JavaThread "Finalizer" daemon [_thread_blocked, id=3864, stack(0x02cc0000,0x02d10000)] 0x02bb3400 JavaThread "Reference Handler" daemon [_thread_blocked, id=2424, stack(0x02c70000,0x02cc0000)] Other Threads: 0x02bb1800 VMThread [stack: 0x02c20000,0x02c70000] [id=3076] 0x02bd1000 WatcherThread [stack: 0x02e50000,0x02ea0000] [id=3276] VM state:not at safepoint (normal execution) VM Mutex/Monitor currently owned by a thread: None Heap def new generation total 4928K, used 2571K [0x229c0000, 0x22f10000, 0x27f10000) eden space 4416K, 46% used [0x229c0000, 0x22bc2e38, 0x22e10000) from space 512K, 100% used [0x22e90000, 0x22f10000, 0x22f10000) to space 512K, 0% used [0x22e10000, 0x22e10000, 0x22e90000) tenured generation total 10944K, used 634K [0x27f10000, 0x289c0000, 0x329c0000) the space 10944K, 5% used [0x27f10000, 0x27faea60, 0x27faec00, 0x289c0000) compacting perm gen total 12288K, used 1655K [0x329c0000, 0x335c0000, 0x369c0000) the space 12288K, 13% used [0x329c0000, 0x32b5dc58, 0x32b5de00, 0x335c0000) ro space 10240K, 42% used [0x369c0000, 0x36dfc660, 0x36dfc800, 0x373c0000) rw space 12288K, 53% used [0x373c0000, 0x37a38180, 0x37a38200, 0x37fc0000) Code Cache [0x00940000, 0x009d8000, 0x02940000) total_blobs=305 nmethods=80 adapters=158 free_code_cache=32183Kb largest_free_block=32955904 Dynamic libraries: 0x00400000 - 0x0042f000 C:\Program Files\Java\jre7\bin\javaw.exe 0x7c900000 - 0x7c9af000 C:\WINDOWS\system32\ntdll.dll 0x7c800000 - 0x7c8f6000 C:\WINDOWS\system32\kernel32.dll 0x77dd0000 - 0x77e6b000 C:\WINDOWS\system32\ADVAPI32.dll 0x77e70000 - 0x77f02000 C:\WINDOWS\system32\RPCRT4.dll 0x77fe0000 - 0x77ff1000 C:\WINDOWS\system32\Secur32.dll 0x7e410000 - 0x7e4a1000 C:\WINDOWS\system32\USER32.dll 0x77f10000 - 0x77f59000 C:\WINDOWS\system32\GDI32.dll 0x773d0000 - 0x774d3000 C:\WINDOWS\WinSxS\x86_Microsoft.Windows.Common-Controls_6595b64144ccf1df_6.0.2600.5512_x-ww_35d4ce83\COMCTL32.dll 0x77c10000 - 0x77c68000 C:\WINDOWS\system32\msvcrt.dll 0x77f60000 - 0x77fd6000 C:\WINDOWS\system32\SHLWAPI.dll 0x76390000 - 0x763ad000 C:\WINDOWS\system32\IMM32.DLL 0x629c0000 - 0x629c9000 C:\WINDOWS\system32\LPK.DLL 0x74d90000 - 0x74dfb000 C:\WINDOWS\system32\USP10.dll 0x78aa0000 - 0x78b5e000 C:\Program Files\Java\jre7\bin\msvcr100.dll 0x6d940000 - 0x6dc61000 C:\Program Files\Java\jre7\bin\client\jvm.dll 0x71ad0000 - 0x71ad9000 C:\WINDOWS\system32\WSOCK32.dll 0x71ab0000 - 0x71ac7000 C:\WINDOWS\system32\WS2_32.dll 0x71aa0000 - 0x71aa8000 C:\WINDOWS\system32\WS2HELP.dll 0x76b40000 - 0x76b6d000 C:\WINDOWS\system32\WINMM.dll 0x76bf0000 - 0x76bfb000 C:\WINDOWS\system32\PSAPI.DLL 0x6d8d0000 - 0x6d8dc000 C:\Program Files\Java\jre7\bin\verify.dll 0x6d370000 - 0x6d390000 C:\Program Files\Java\jre7\bin\java.dll 0x6d920000 - 0x6d933000 C:\Program Files\Java\jre7\bin\zip.dll 0x6cec0000 - 0x6cf42000 C:\Documents and Settings\7stl0225\Local Settings\Temp\libgdx7stl0225\37fe1abc\gdx.dll 0x10000000 - 0x1004c000 C:\Documents and Settings\7stl0225\Local Settings\Temp\libgdx7stl0225\52d76f2b\lwjgl.dll 0x5ed00000 - 0x5edcc000 C:\WINDOWS\system32\OPENGL32.dll 0x68b20000 - 0x68b40000 C:\WINDOWS\system32\GLU32.dll 0x73760000 - 0x737ab000 C:\WINDOWS\system32\DDRAW.dll 0x73bc0000 - 0x73bc6000 C:\WINDOWS\system32\DCIMAN32.dll 0x77c00000 - 0x77c08000 C:\WINDOWS\system32\VERSION.dll 0x070b0000 - 0x07115000 C:\DOCUME~1\7stl0225\LOCALS~1\Temp\libgdx7stl0225\52d76f2b\OpenAL32.dll 0x7c9c0000 - 0x7d1d7000 C:\WINDOWS\system32\SHELL32.dll 0x774e0000 - 0x7761d000 C:\WINDOWS\system32\ole32.dll 0x5ad70000 - 0x5ada8000 C:\WINDOWS\system32\uxtheme.dll 0x76fd0000 - 0x7704f000 C:\WINDOWS\system32\CLBCATQ.DLL 0x77050000 - 0x77115000 C:\WINDOWS\system32\COMRes.dll 0x77120000 - 0x771ab000 C:\WINDOWS\system32\OLEAUT32.dll 0x73f10000 - 0x73f6c000 C:\WINDOWS\system32\dsound.dll 0x76c30000 - 0x76c5e000 C:\WINDOWS\system32\WINTRUST.dll 0x77a80000 - 0x77b15000 C:\WINDOWS\system32\CRYPT32.dll 0x77b20000 - 0x77b32000 C:\WINDOWS\system32\MSASN1.dll 0x76c90000 - 0x76cb8000 C:\WINDOWS\system32\IMAGEHLP.dll 0x72d20000 - 0x72d29000 C:\WINDOWS\system32\wdmaud.drv 0x72d10000 - 0x72d18000 C:\WINDOWS\system32\msacm32.drv 0x77be0000 - 0x77bf5000 C:\WINDOWS\system32\MSACM32.dll 0x77bd0000 - 0x77bd7000 C:\WINDOWS\system32\midimap.dll 0x73ee0000 - 0x73ee4000 C:\WINDOWS\system32\KsUser.dll 0x755c0000 - 0x755ee000 C:\WINDOWS\system32\msctfime.ime 0x69000000 - 0x691a9000 C:\WINDOWS\system32\sisgl.dll 0x73b30000 - 0x73b45000 C:\WINDOWS\system32\mscms.dll 0x73000000 - 0x73026000 C:\WINDOWS\system32\WINSPOOL.DRV 0x66e90000 - 0x66ed1000 C:\WINDOWS\system32\icm32.dll 0x07760000 - 0x0778d000 C:\Program Files\WordWeb\WHook.dll 0x74c80000 - 0x74cac000 C:\WINDOWS\system32\OLEACC.dll 0x76080000 - 0x760e5000 C:\WINDOWS\system32\MSVCP60.dll VM Arguments: jvm_args: -Dfile.encoding=Cp1252 java_command: sevenseas.game.MainDesktop Launcher Type: SUN_STANDARD Environment Variables: PATH=C:/Program Files/Java/jre7/bin/client;C:/Program Files/Java/jre7/bin;C:/Program Files/Java/jre7/lib/i386;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\Program Files\Java\jdk1.7.0\bin;C:\eclipse; USERNAME=7stl0225 OS=Windows_NT PROCESSOR_IDENTIFIER=x86 Family 15 Model 4 Stepping 1, GenuineIntel --------------- S Y S T E M --------------- OS: Windows XP Build 2600 Service Pack 3 CPU:total 1 (1 cores per cpu, 1 threads per core) family 15 model 4 stepping 1, cmov, cx8, fxsr, mmx, sse, sse2, sse3 Memory: 4k page, physical 2031088k(939252k free), swap 3969920k(3011396k free) vm_info: Java HotSpot(TM) Client VM (21.0-b17) for windows-x86 JRE (1.7.0-b147), built on Jun 27 2011 02:25:52 by "java_re" with unknown MS VC++:1600 time: Sat Oct 26 12:35:14 2013 elapsed time: 0 seconds

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• Why you need to learn async in .NET

  - by PSteele

  I had an opportunity to teach a quick class yesterday about what’s new in .NET 4.0.  One of the topics was the TPL (Task Parallel Library) and how it can make async programming easier.  I also stressed that this is the direction Microsoft is going with for C# 5.0 and learning the TPL will greatly benefit their understanding of the new async stuff.  We had a little time left over and I was able to show some code that uses the Async CTP to accomplish some stuff, but it wasn’t a simple demo that you could jump in to and understand so I thought I’d thrown one together and put it in a blog post. The entire solution file with all of the sample projects is located here. A Simple Example Let’s start with a super-simple example (WindowsApplication01 in the solution). I’ve got a form that displays a label and a button.  When the user clicks the button, I want to start displaying the current time for 15 seconds and then stop. What I’d like to write is this: lblTime.ForeColor = Color.Red; for (var x = 0; x < 15; x++) { lblTime.Text = DateTime.Now.ToString("HH:mm:ss"); Thread.Sleep(1000); } lblTime.ForeColor = SystemColors.ControlText; (Note that I also changed the label’s color while counting – not quite an ILM-level effect, but it adds something to the demo!) As I’m sure most of my readers are aware, you can’t write WinForms code this way.  WinForms apps, by default, only have one thread running and it’s main job is to process messages from the windows message pump (for a more thorough explanation, see my Visual Studio Magazine article on multithreading in WinForms).  If you put a Thread.Sleep in the middle of that code, your UI will be locked up and unresponsive for those 15 seconds.  Not a good UX and something that needs to be fixed.  Sure, I could throw an “Application.DoEvents()” in there, but that’s hacky. The Windows Timer Then I think, “I can solve that.  I’ll use the Windows Timer to handle the timing in the background and simply notify me when the time has changed”.  Let’s see how I could accomplish this with a Windows timer (WindowsApplication02 in the solution): public partial class Form1 : Form { private readonly Timer clockTimer; private int counter;   public Form1() { InitializeComponent(); clockTimer = new Timer {Interval = 1000}; clockTimer.Tick += UpdateLabel; }   private void UpdateLabel(object sender, EventArgs e) { lblTime.Text = DateTime.Now.ToString("HH:mm:ss"); counter++; if (counter == 15) { clockTimer.Enabled = false; lblTime.ForeColor = SystemColors.ControlText; } }   private void cmdStart_Click(object sender, EventArgs e) { lblTime.ForeColor = Color.Red; counter = 0; clockTimer.Start(); } } Holy cow – things got pretty complicated here.  I use the timer to fire off a Tick event every second.  Inside there, I can update the label.  Granted, I can’t use a simple for/loop and have to maintain a global counter for the number of iterations.  And my “end” code (when the loop is finished) is now buried inside the bottom of the Tick event (inside an “if” statement).  I do, however, get a responsive application that doesn’t hang or stop repainting while the 15 seconds are ticking away. But doesn’t .NET have something that makes background processing easier? The BackgroundWorker Next I try .NET’s BackgroundWorker component – it’s specifically designed to do processing in a background thread (leaving the UI thread free to process the windows message pump) and allows updates to be performed on the main UI thread (WindowsApplication03 in the solution): public partial class Form1 : Form { private readonly BackgroundWorker worker;   public Form1() { InitializeComponent(); worker = new BackgroundWorker {WorkerReportsProgress = true}; worker.DoWork += StartUpdating; worker.ProgressChanged += UpdateLabel; worker.RunWorkerCompleted += ResetLabelColor; }   private void StartUpdating(object sender, DoWorkEventArgs e) { var workerObject = (BackgroundWorker) sender; for (int x = 0; x < 15; x++) { workerObject.ReportProgress(0); Thread.Sleep(1000); } }   private void UpdateLabel(object sender, ProgressChangedEventArgs e) { lblTime.Text = DateTime.Now.ToString("HH:mm:ss"); }   private void ResetLabelColor(object sender, RunWorkerCompletedEventArgs e) { lblTime.ForeColor = SystemColors.ControlText; }   private void cmdStart_Click(object sender, EventArgs e) { lblTime.ForeColor = Color.Red; worker.RunWorkerAsync(); } } Well, this got a little better (I think).  At least I now have my simple for/next loop back.  Unfortunately, I’m still dealing with event handlers spread throughout my code to co-ordinate all of this stuff in the right order. Time to look into the future. The async way Using the Async CTP, I can go back to much simpler code (WindowsApplication04 in the solution): private async void cmdStart_Click(object sender, EventArgs e) { lblTime.ForeColor = Color.Red; for (var x = 0; x < 15; x++) { lblTime.Text = DateTime.Now.ToString("HH:mm:ss"); await TaskEx.Delay(1000); } lblTime.ForeColor = SystemColors.ControlText; } This code will run just like the Timer or BackgroundWorker versions – fully responsive during the updates – yet is way easier to implement.  In fact, it’s almost a line-for-line copy of the original version of this code.  All of the async plumbing is handled by the compiler and the framework.  My code goes back to representing the “what” of what I want to do, not the “how”. I urge you to download the Async CTP.  All you need is .NET 4.0 and Visual Studio 2010 sp1 – no need to set up a virtual machine with the VS2011 beta (unless, of course, you want to dive right in to the C# 5.0 stuff!).  Starting playing around with this today and see how much easier it will be in the future to write async-enabled applications.

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• Getting problem in collision detection in Java Game

  - by chetans

  Hi I am developing Spaceship Game in which i am getting problem in collision detection of moving images Game has a spaceship and number of asteroids(obstacles) i want to detect the collision between them How can i do this?`package Game; import java.applet.Applet; import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics; import java.awt.Image; import java.awt.MediaTracker; import java.awt.event.KeyEvent; import java.awt.event.KeyListener; import java.net.MalformedURLException; import java.net.URL; public class ThreadInApplet extends Applet implements KeyListener { private static final long serialVersionUID = 1L; Image[] asteroidImage; Image spaceshipImage; int[] XPosObst,YPosObst; int numberOfObstacles=0,XPosOfSpaceship,YPosOfSpaceship; int spaceButtnCntr=0,noOfObstaclesLevel=20; boolean gameStart=false,collideUp=false,collideDown=false,collideLeft=false,collideRight=false; private Image offScreenImage; private Dimension offScreenSize,d; private Graphics offScreenGraphics; int speedObstacles=1; String spaceshipImagePath="images/spaceship.png",obstacleImagepath="images/asteroid.png"; String buttonToStart="Press Space to start"; public void init() { try { asteroidImage=new Image[noOfObstaclesLevel]; XPosObst=new int[noOfObstaclesLevel]; YPosObst=new int[noOfObstaclesLevel]; XPosOfSpaceship=getWidth()/2-35; YPosOfSpaceship=getHeight()-100; spaceshipImage=getImage(new URL(getCodeBase(),spaceshipImagePath)); for(int i=0;i<noOfObstaclesLevel;i++) { asteroidImage[i]=getImage(new URL(getCodeBase(),obstacleImagepath)); XPosObst[i]=(int) (Math.random()*700); YPosObst[i]=0; } MediaTracker tracker = new MediaTracker (this); for(int i=0;i<noOfObstaclesLevel;i++) { tracker.addImage (asteroidImage[i], 0); } } catch (MalformedURLException e) { e.printStackTrace(); } setBackground(Color.black); addKeyListener(this); } public void paint(Graphics g) { g.setColor(Color.white); if(gameStart==false) { g.drawString(buttonToStart, (getWidth()/2)-60, getHeight()/2); } g.drawString("HEADfitted Solutions Pvt.Ltd.", (getWidth()/2)-80, getHeight()-20); for(int n=0;n<numberOfObstacles;n++) { if(n>0) g.drawImage(asteroidImage[n],XPosObst[n],YPosObst[n],this); } g.drawImage(spaceshipImage,XPosOfSpaceship,YPosOfSpaceship,this); } @SuppressWarnings("deprecation") public void update(Graphics g) { d = size(); if((offScreenImage == null) || (d.width != offScreenSize.width) || (d.height != offScreenSize.height)) { offScreenImage = createImage(d.width, d.height); offScreenSize = d; offScreenGraphics = offScreenImage.getGraphics(); } offScreenGraphics.clearRect(0, 0, d.width, d.height); paint(offScreenGraphics); g.drawImage(offScreenImage, 0, 0, null); } public void keyReleased(KeyEvent arg0){} public void keyTyped(KeyEvent arg0) {} Thread mainThread=new Thread() { synchronized public void run () { try { //System.out.println("in main thread"); if (gameStart==true) { moveObstacles.start(); if(collide()==false) { createObsThread.start(); } } } catch (Exception e) { e.printStackTrace(); } } }; Thread createObsThread=new Thread() { synchronized public void run () { if (spaceButtnCntr==1) { if (collide()==false) { for(int g=0;g<noOfObstaclesLevel;g++) { try { sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } numberOfObstacles++; } } } } }; Thread moveObstacles=new Thread() // Moving Obstacle images downwards after every 10 ms { synchronized public void run () { while(YPosObst[19]!=600) { if (collide()==false) { //createObsThread.start(); for(int l=0;l } repaint(); try { sleep(10); } catch (InterruptedException e) { e.printStackTrace(); } } } } }; public void keyPressed(KeyEvent e) { if(e.getKeyCode()==32) { gameStart=true; spaceButtnCntr++; if (spaceButtnCntr==1) { mainThread.start(); } } if(gameStart==true) { if(e.getKeyCode()==37 && collideLeft==false)//Spaceship movement left { new Thread () { synchronized public void run () { XPosOfSpaceship-=10; repaint(); } }.start(); } if(e.getKeyCode()==38 && collideUp==false)//Spaceship movement up { new Thread () { synchronized public void run () { YPosOfSpaceship-=10; repaint(); } }.start(); } if(e.getKeyCode()==39 && collideRight==false)//Spaceship movement right { new Thread () { synchronized public void run () { XPosOfSpaceship+=10; repaint(); } }.start(); } if(e.getKeyCode()==40 && collideDown==false)//Spaceship movement down { new Thread () { synchronized public void run () { YPosOfSpaceship+=10; repaint(); } }.start(); } } } /*public boolean collide() { int x0, y0, w0, h0, x2, y2, w2, h2; x0=XPosOfSpaceship; y0=YPosOfSpaceship; h0=spaceshipImage.getHeight(null); w0=spaceshipImage.getWidth(null); for(int i=0;i<20;i++) { x2=XPosObst[i]; y2=YPosObst[i]; h2=asteroidImage[i].getHeight(null); w2=asteroidImage[i].getWidth(null); if ((x0 > (x2 + w2)) || ((x0 + w0) < x2)) return false; System.out.println(x2+" "+y2+" "+h2+" "+w2); if ((y0 > (y2 + h2)) || ((y0 + h0) < y2)) return false; } return true; }*/ public boolean collide() { int x1,y1,x2,y2,x3,y3,x4,y4; //coordinates of obstacles int a1,b1,a2,b2,a3,b3,a4,b4; //coordinates of spaceship a1 =XPosOfSpaceship; b1=YPosOfSpaceship; a2=a1+spaceshipImage.getWidth(this); b2=b1; a3=a1; b3=b1+spaceshipImage.getHeight(this); a4=a2; b4=b3; for(int a=0;a if(x1>=a1 && x1<=a2 && x1<=b3 && x1>=b1) return (true); if(x2>=a1 && x2<=a2 && x2<=b3 && x2>=b1) return(true); //********checking asteroid touch spaceship from up direction******** if(y3==b1 && x4>=a1 && x4<=a2) { collideUp = true; return(true); } if(y3==b1 && x3>=a1 && x3<=a2) { collideUp = true; return(true); } //********checking asteroid touch spaceship from left direction****** if(x2==a1 && y4>=b1 && y4<=b3) { collideLeft=true; return(true); } if(x2==a1 && y2>=b1 && y2<=b3) { collideLeft=true; return(true); } //********checking asteroid touch spaceship from right direction***** if(x1==a2 && y3>=b2 && y3<=b4) { collideRight=true; return(true); } if(x1==a2 && y1>=b2 && y1<=b4) { collideRight=true; return(true); } //********checking asteroid touch spaceship from down direction***** if(y1==b3 && x2>=a3 && x2<=a4) { collideDown=true; return(true); } if(y1==b3 && x1>=a3 && x1<=a4) { collideDown=true; return(true); } else { collideUp=false; collideDown=false; collideLeft=false; collideRight=false; } } return(false); } } `

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• MySQL Connect 8 Days Away - Replication Sessions

  - by Mat Keep

  Following on from my post about MySQL Cluster sessions at the forthcoming Connect conference, its now the turn of MySQL Replication - another technology at the heart of scaling and high availability for MySQL. Unless you've only just returned from a 6-month alien abduction, you will know that MySQL 5.6 includes the largest set of replication enhancements ever packaged into a single new release: - Global Transaction IDs + HA utilities for self-healing cluster..(yes both automatic failover and manual switchover available!) - Crash-safe slaves and binlog - Binlog Group Commit and Multi-Threaded Slaves for high performance - Replication Event Checksums and Time-Delayed replication - and many more There are a number of sessions dedicated to learn more about these important new enhancements, delivered by the same engineers who developed them. Here is a summary Saturday 29th, 13.00 Replication Tips and Tricks, Mats Kindahl In this session, the developers of MySQL Replication present a bag of useful tips and tricks related to the MySQL 5.5 GA and MySQL 5.6 development milestone releases, including multisource replication, using logs for auditing, handling filtering, examining the binary log, using relay slaves, splitting the replication stream, and handling failover. Saturday 29th, 17.30 Enabling the New Generation of Web and Cloud Services with MySQL 5.6 Replication, Lars Thalmann This session showcases the new replication features, including • High performance (group commit, multithreaded slave) • High availability (crash-safe slaves, failover utilities) • Flexibility and usability (global transaction identifiers, annotated row-based replication [RBR]) • Data integrity (event checksums) Saturday 29th, 1900 MySQL Replication Birds of a Feather In this session, the MySQL Replication engineers discuss all the goodies, including global transaction identifiers (GTIDs) with autofailover; multithreaded, crash-safe slaves; checksums; and more. The team discusses the design behind these enhancements and how to get started with them. You will get the opportunity to present your feedback on how these can be further enhanced and can share any additional replication requirements you have to further scale your critical MySQL-based workloads. Sunday 30th, 10.15 Hands-On Lab, MySQL Replication, Luis Soares and Sven Sandberg But how do you get started, how does it work, and what are the best practices and tools? During this hands-on lab, you will learn how to get started with replication, how it works, architecture, replication prerequisites, setting up a simple topology, and advanced replication configurations. The session also covers some of the new features in the MySQL 5.6 development milestone releases. Sunday 30th, 13.15 Hands-On Lab, MySQL Utilities, Chuck Bell Would you like to learn how to more effectively manage a host of MySQL servers and manage high-availability features such as replication? This hands-on lab addresses these areas and more. Participants will get familiar with all of the MySQL utilities, using each of them with a variety of options to configure and manage MySQL servers. Sunday 30th, 14.45 Eliminating Downtime with MySQL Replication, Luis Soares The presentation takes a deep dive into new replication features such as global transaction identifiers and crash-safe slaves. It also showcases a range of Python utilities that, combined with the Release 5.6 feature set, results in a self-healing data infrastructure. By the end of the session, attendees will be familiar with the new high-availability features in the whole MySQL 5.6 release and how to make use of them to protect and grow their business. Sunday 30th, 17.45 Scaling for the Web and the Cloud with MySQL Replication, Luis Soares In a Replication topology, high performance directly translates into improving read consistency from slaves and reducing the risk of data loss if a master fails. MySQL 5.6 introduces several new replication features to enhance performance. In this session, you will learn about these new features, how they work, and how you can leverage them in your applications. In addition, you will learn about some other best practices that can be used to improve performance. So how can you make sure you don't miss out - the good news is that registration is still open ;-) And just to whet your appetite, listen to the On-Demand webinar that presents an overview of MySQL 5.6 Replication.  

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• Oracle TimesTen In-Memory Database Performance on SPARC T4-2

  - by Brian

  The Oracle TimesTen In-Memory Database is optimized to run on Oracle's SPARC T4 processor platforms running Oracle Solaris 11 providing unsurpassed scalability, performance, upgradability, protection of investment and return on investment. The following demonstrate the value of combining Oracle TimesTen In-Memory Database with SPARC T4 servers and Oracle Solaris 11: On a Mobile Call Processing test, the 2-socket SPARC T4-2 server outperforms: Oracle's SPARC Enterprise M4000 server (4 x 2.66 GHz SPARC64 VII+) by 34%. Oracle's SPARC T3-4 (4 x 1.65 GHz SPARC T3) by 2.7x, or 5.4x per processor. Utilizing the TimesTen Performance Throughput Benchmark (TPTBM), the SPARC T4-2 server protects investments with: 2.1x the overall performance of a 4-socket SPARC Enterprise M4000 server in read-only mode and 1.5x the performance in update-only testing. This is 4.2x more performance per processor than the SPARC64 VII+ 2.66 GHz based system. 10x more performance per processor than the SPARC T2+ 1.4 GHz server. 1.6x better performance per processor than the SPARC T3 1.65 GHz based server. In replication testing, the two socket SPARC T4-2 server is over 3x faster than the performance of a four socket SPARC Enterprise T5440 server in both asynchronous replication environment and the highly available 2-Safe replication. This testing emphasizes parallel replication between systems. Performance Landscape Mobile Call Processing Test Performance System Processor Sockets/Cores/Threads Tps SPARC T4-2 SPARC T4, 2.85 GHz 2 16 128 218,400 M4000 SPARC64 VII+, 2.66 GHz 4 16 32 162,900 SPARC T3-4 SPARC T3, 1.65 GHz 4 64 512 80,400 TimesTen Performance Throughput Benchmark (TPTBM) Read-Only System Processor Sockets/Cores/Threads Tps SPARC T3-4 SPARC T3, 1.65 GHz 4 64 512 7.9M SPARC T4-2 SPARC T4, 2.85 GHz 2 16 128 6.5M M4000 SPARC64 VII+, 2.66 GHz 4 16 32 3.1M T5440 SPARC T2+, 1.4 GHz 4 32 256 3.1M TimesTen Performance Throughput Benchmark (TPTBM) Update-Only System Processor Sockets/Cores/Threads Tps SPARC T4-2 SPARC T4, 2.85 GHz 2 16 128 547,800 M4000 SPARC64 VII+, 2.66 GHz 4 16 32 363,800 SPARC T3-4 SPARC T3, 1.65 GHz 4 64 512 240,500 TimesTen Replication Tests System Processor Sockets/Cores/Threads Asynchronous 2-Safe SPARC T4-2 SPARC T4, 2.85 GHz 2 16 128 38,024 13,701 SPARC T5440 SPARC T2+, 1.4 GHz 4 32 256 11,621 4,615 Configuration Summary Hardware Configurations: SPARC T4-2 server 2 x SPARC T4 processors, 2.85 GHz 256 GB memory 1 x 8 Gbs FC Qlogic HBA 1 x 6 Gbs SAS HBA 4 x 300 GB internal disks Sun Storage F5100 Flash Array (40 x 24 GB flash modules) 1 x Sun Fire X4275 server configured as COMSTAR head SPARC T3-4 server 4 x SPARC T3 processors, 1.6 GHz 512 GB memory 1 x 8 Gbs FC Qlogic HBA 8 x 146 GB internal disks 1 x Sun Fire X4275 server configured as COMSTAR head SPARC Enterprise M4000 server 4 x SPARC64 VII+ processors, 2.66 GHz 128 GB memory 1 x 8 Gbs FC Qlogic HBA 1 x 6 Gbs SAS HBA 2 x 146 GB internal disks Sun Storage F5100 Flash Array (40 x 24 GB flash modules) 1 x Sun Fire X4275 server configured as COMSTAR head Software Configuration: Oracle Solaris 11 11/11 Oracle TimesTen 11.2.2.4 Benchmark Descriptions TimesTen Performance Throughput BenchMark (TPTBM) is shipped with TimesTen and measures the total throughput of the system. The workload can test read-only, update-only, delete and insert operations as required. Mobile Call Processing is a customer-based workload for processing calls made by mobile phone subscribers. The workload has a mixture of read-only, update, and insert-only transactions. The peak throughput performance is measured from multiple concurrent processes executing the transactions until a peak performance is reached via saturation of the available resources. Parallel Replication tests using both asynchronous and 2-Safe replication methods. For asynchronous replication, transactions are processed in batches to maximize the throughput capabilities of the replication server and network. In 2-Safe replication, also known as no data-loss or high availability, transactions are replicated between servers immediately emphasizing low latency. For both environments, performance is measured in the number of parallel replication servers and the maximum transactions-per-second for all concurrent processes. See Also SPARC T4-2 Server oracle.com OTN Oracle TimesTen In-Memory Database oracle.com OTN Oracle Solaris oracle.com OTN Oracle Database 11g Release 2 Enterprise Edition oracle.com OTN Disclosure Statement Copyright 2012, Oracle and/or its affiliates. All rights reserved. Oracle and Java are registered trademarks of Oracle and/or its affiliates. Other names may be trademarks of their respective owners. Results as of 1 October 2012.

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• ASP.NET WebAPI Security 2: Identity Architecture

  - by Your DisplayName here!

  Pedro has beaten me to the punch with a detailed post (and diagram) about the WebAPI hosting architecture. So go read his post first, then come back so we can have a closer look at what that means for security. The first important takeaway is that WebAPI is hosting independent-  currently it ships with two host integration implementations – one for ASP.NET (aka web host) and WCF (aka self host). Pedro nicely shows the integration into the web host. Self hosting is not done yet so we will mainly focus on the web hosting case and I will point out security related differences when they exist. The interesting part for security (amongst other things of course) is the HttpControllerHandler (see Pedro’s diagram) – this is where the host specific representation of an HTTP request gets converted to the WebAPI abstraction (called HttpRequestMessage). The ConvertRequest method does the following: Create a new HttpRequestMessage. Copy URI, method and headers from the HttpContext. Copies HttpContext.User to the Properties<string, object> dictionary on the HttpRequestMessage. The key used for that can be found on HttpPropertyKeys.UserPrincipalKey (which resolves to “MS_UserPrincipal”). So the consequence is that WebAPI receives whatever IPrincipal has been set by the ASP.NET pipeline (in the web hosting case). Common questions are: Are there situations where is property does not get set? Not in ASP.NET – the DefaultAuthenticationModule in the HTTP pipeline makes sure HttpContext.User (and Thread.CurrentPrincipal – more on that later) are always set. Either to some authenticated user – or to an anonymous principal. This may be different in other hosting environments (again more on that later). Why so generic? Keep in mind that WebAPI is hosting independent and may run on a host that materializes identity completely different compared to ASP.NET (or .NET in general). This gives them a way to evolve the system in the future. How does WebAPI code retrieve the current client identity? HttpRequestMessage has an extension method called GetUserPrincipal() which returns the property as an IPrincipal. A quick look at self hosting shows that the moral equivalent of HttpControllerHandler.ConvertRequest() is HttpSelfHostServer.ProcessRequestContext(). Here the principal property gets only set when the host is configured for Windows authentication (inconsisteny). Do I like that? Well – yes and no. Here are my thoughts: I like that it is very straightforward to let WebAPI inherit the client identity context of the host. This might not always be what you want – think of an ASP.NET app that consists of UI and APIs – the UI might use Forms authentication, the APIs token based authentication. So it would be good if the two parts would live in a separate security world. It makes total sense to have this generic hand off point for identity between the host and WebAPI. It also makes total sense for WebAPI plumbing code (especially handlers) to use the WebAPI specific identity abstraction. But – c’mon we are running on .NET. And the way .NET represents identity is via IPrincipal/IIdentity. That’s what every .NET developer on this planet is used to. So I would like to see a User property of type IPrincipal on ApiController. I don’t like the fact that Thread.CurrentPrincipal is not populated. T.CP is a well established pattern as a one stop shop to retrieve client identity on .NET.  That makes a lot of sense – even if the name is misleading at best. There might be existing library code you want to call from WebAPI that makes use of T.CP (e.g. PrincipalPermission, or a simple .Name or .IsInRole()). Having the client identity as an ambient property is useful for code that does not have access to the current HTTP request (for calling GetUserPrincipal()). I don’t like the fact that that the client identity conversion from host to WebAPI is inconsistent. This makes writing security plumbing code harder. I think the logic should always be: If the host has a client identity representation, copy it. If not, set an anonymous principal on the request message. Btw – please don’t annoy me with the “but T.CP is static, and static is bad for testing” chant. T.CP is a getter/setter and, in fact I find it beneficial to be able to set different security contexts in unit tests before calling in some logic. And, in case you have wondered – T.CP is indeed thread static (and the name comes from a time where a logical operation was bound to a thread – which is not true anymore). But all thread creation APIs in .NET actually copy T.CP to the new thread they create. This is the case since .NET 2.0 and is certainly an improvement compared to how Win32 does things. So to sum it up: The host plumbing copies the host client identity to WebAPI (this is not perfect yet, but will surely be improved). or in other words: The current WebAPI bits don’t ship with any authentication plumbing, but solely use whatever authentication (and thus client identity) is set up by the host. WebAPI developers can retrieve the client identity from the HttpRequestMessage. Hopefully my proposed changes around T.CP and the User property on ApiController will be added. In the next post, I will detail how to add WebAPI specific authentication support, e.g. for Basic Authentication and tokens. This includes integrating the notion of claims based identity. After that we will look at the built-in authorization bits and how to improve them as well. Stay tuned.

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