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  • PHP/Java bridge problem

    - by Jack
    I am using tomcat 6 on windows. Here is the code I am testing. import java.io.ByteArrayOutputStream; import java.io.Closeable; import java.io.StringReader; import javax.script.Invocable; import javax.script.ScriptEngine; import javax.script.ScriptEngineManager; /** * Create and run THREAD_COUNT PHP threads, concurrently accessing a * shared resource. * * Create 5 script engines, passing each a shared resource allocated * from Java. Each script engine has to implement Runnable. * * Java accesses the Runnable script engine using * scriptEngine.getInterface() and calls thread.start() to invoke each * PHP Runnable implementations concurrently. */ class PhpThreads { public static final String runnable = new String("<?php\n" + "function run() {\n" + " $out = java_context()->getAttribute('sharedResource', 100);\n" + " $nr = (string)java_context()->getAttribute('nr', 100);\n" + " echo \"started thread: $nr\n\";\n" + " for($i=0; $i<100; $i++) {\n" + " $out->write(ord($nr));\n" + " java('java.lang.Thread')->sleep(1);\n" + " }\n" + "}\n" + "?>\n"); static final int THREAD_COUNT = 5; public static void main(String[] args) throws Exception { ScriptEngineManager manager = new ScriptEngineManager(); Thread threads[] = new Thread[THREAD_COUNT]; ScriptEngine engines[] = new ScriptEngine[THREAD_COUNT]; ByteArrayOutputStream sharedResource = new ByteArrayOutputStream(); StringReader runnableReader = new StringReader(runnable); // create THREAD_COUNT PHP threads for (int i=0; i<THREAD_COUNT; i++) { engines[i] = manager.getEngineByName("php-invocable"); if (engines[i] == null) throw new NullPointerException ("php script engine not found"); engines[i].put("nr", new Integer(i+1)); engines[i].put("sharedResource", sharedResource); engines[i].eval(runnableReader); runnableReader.reset(); // cast the whole script to Runnable; note also getInterface(specificClosure, type) Runnable r = (Runnable) ((Invocable)engines[i]).getInterface(Runnable.class); threads[i] = new Thread(r); } // run the THREAD_COUNT PHP threads for (int i=0; i<THREAD_COUNT; i++) { threads[i].start(); } // wait for the THREAD_COUNT PHP threads to finish for (int i=0; i<THREAD_COUNT; i++) { threads[i].join(); ((Closeable)engines[i]).close(); } // print the output generated by the THREAD_COUNT concurrent threads String result = sharedResource.toString(); System.out.println(result); // Check result Object res=manager.getEngineByName("php").eval( "<?php " + "exit((int)('10011002100310041005'!=" + "@system(\"echo -n "+result+"|sed 's/./&\\\n/g'|sort|uniq -c|tr -d ' \\\n'\")));" + "?>"); System.exit(((Number)res).intValue()); } } I have added all the libraries. When I run the file I get the following error - run: Exception in thread "main" javax.script.ScriptException: java.io.IOException: Cannot run program "php-cgi": CreateProcess error=2, The system cannot find the file specified at php.java.script.InvocablePhpScriptEngine.eval(InvocablePhpScriptEngine.java:209) at php.java.script.SimplePhpScriptEngine.eval(SimplePhpScriptEngine.java:178) at javax.script.AbstractScriptEngine.eval(AbstractScriptEngine.java:232) at PhpThreads.main(NewClass.java:53) Caused by: java.io.IOException: Cannot run program "php-cgi": CreateProcess error=2, The system cannot find the file specified at java.lang.ProcessBuilder.start(ProcessBuilder.java:459) at java.lang.Runtime.exec(Runtime.java:593) at php.java.bridge.Util$Process.start(Util.java:1064) at php.java.bridge.Util$ProcessWithErrorHandler.start(Util.java:1166) at php.java.bridge.Util$ProcessWithErrorHandler.start(Util.java:1217) at php.java.script.CGIRunner.doRun(CGIRunner.java:126) at php.java.script.HttpProxy.doRun(HttpProxy.java:63) at php.java.script.CGIRunner.run(CGIRunner.java:111) at php.java.bridge.ThreadPool$Delegate.run(ThreadPool.java:60) Caused by: java.io.IOException: CreateProcess error=2, The system cannot find the file specified at java.lang.ProcessImpl.create(Native Method) at java.lang.ProcessImpl.<init>(ProcessImpl.java:81) at java.lang.ProcessImpl.start(ProcessImpl.java:30) at java.lang.ProcessBuilder.start(ProcessBuilder.java:452) ... 8 more What am I missing?

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  • C#: System.Collections.Concurrent.ConcurrentQueue vs. Queue

    - by James Michael Hare
    I love new toys, so of course when .NET 4.0 came out I felt like the proverbial kid in the candy store!  Now, some people get all excited about the IDE and it’s new features or about changes to WPF and Silver Light and yes, those are all very fine and grand.  But me, I get all excited about things that tend to affect my life on the backside of development.  That’s why when I heard there were going to be concurrent container implementations in the latest version of .NET I was salivating like Pavlov’s dog at the dinner bell. They seem so simple, really, that one could easily overlook them.  Essentially they are implementations of containers (many that mirror the generic collections, others are new) that have either been optimized with very efficient, limited, or no locking but are still completely thread safe -- and I just had to see what kind of an improvement that would translate into. Since part of my job as a solutions architect here where I work is to help design, develop, and maintain the systems that process tons of requests each second, the thought of extremely efficient thread-safe containers was extremely appealing.  Of course, they also rolled out a whole parallel development framework which I won’t get into in this post but will cover bits and pieces of as time goes by. This time, I was mainly curious as to how well these new concurrent containers would perform compared to areas in our code where we manually synchronize them using lock or some other mechanism.  So I set about to run a processing test with a series of producers and consumers that would be either processing a traditional System.Collections.Generic.Queue or a System.Collection.Concurrent.ConcurrentQueue. Now, I wanted to keep the code as common as possible to make sure that the only variance was the container, so I created a test Producer and a test Consumer.  The test Producer takes an Action<string> delegate which is responsible for taking a string and placing it on whichever queue we’re testing in a thread-safe manner: 1: internal class Producer 2: { 3: public int Iterations { get; set; } 4: public Action<string> ProduceDelegate { get; set; } 5: 6: public void Produce() 7: { 8: for (int i = 0; i < Iterations; i++) 9: { 10: ProduceDelegate(“Hello”); 11: } 12: } 13: } Then likewise, I created a consumer that took a Func<string> that would read from whichever queue we’re testing and return either the string if data exists or null if not.  Then, if the item doesn’t exist, it will do a 10 ms wait before testing again.  Once all the producers are done and join the main thread, a flag will be set in each of the consumers to tell them once the queue is empty they can shut down since no other data is coming: 1: internal class Consumer 2: { 3: public Func<string> ConsumeDelegate { get; set; } 4: public bool HaltWhenEmpty { get; set; } 5: 6: public void Consume() 7: { 8: bool processing = true; 9: 10: while (processing) 11: { 12: string result = ConsumeDelegate(); 13: 14: if(result == null) 15: { 16: if (HaltWhenEmpty) 17: { 18: processing = false; 19: } 20: else 21: { 22: Thread.Sleep(TimeSpan.FromMilliseconds(10)); 23: } 24: } 25: else 26: { 27: DoWork(); // do something non-trivial so consumers lag behind a bit 28: } 29: } 30: } 31: } Okay, now that we’ve done that, we can launch threads of varying numbers using lambdas for each different method of production/consumption.  First let's look at the lambdas for a typical System.Collections.Generics.Queue with locking: 1: // lambda for putting to typical Queue with locking... 2: var productionDelegate = s => 3: { 4: lock (_mutex) 5: { 6: _mutexQueue.Enqueue(s); 7: } 8: }; 9:  10: // and lambda for typical getting from Queue with locking... 11: var consumptionDelegate = () => 12: { 13: lock (_mutex) 14: { 15: if (_mutexQueue.Count > 0) 16: { 17: return _mutexQueue.Dequeue(); 18: } 19: } 20: return null; 21: }; Nothing new or interesting here.  Just typical locks on an internal object instance.  Now let's look at using a ConcurrentQueue from the System.Collections.Concurrent library: 1: // lambda for putting to a ConcurrentQueue, notice it needs no locking! 2: var productionDelegate = s => 3: { 4: _concurrentQueue.Enqueue(s); 5: }; 6:  7: // lambda for getting from a ConcurrentQueue, once again, no locking required. 8: var consumptionDelegate = () => 9: { 10: string s; 11: return _concurrentQueue.TryDequeue(out s) ? s : null; 12: }; So I pass each of these lambdas and the number of producer and consumers threads to launch and take a look at the timing results.  Basically I’m timing from the time all threads start and begin producing/consuming to the time that all threads rejoin.  I won't bore you with the test code, basically it just launches code that creates the producers and consumers and launches them in their own threads, then waits for them all to rejoin.  The following are the timings from the start of all threads to the Join() on all threads completing.  The producers create 10,000,000 items evenly between themselves and then when all producers are done they trigger the consumers to stop once the queue is empty. These are the results in milliseconds from the ordinary Queue with locking: 1: Consumers Producers 1 2 3 Time (ms) 2: ---------- ---------- ------ ------ ------ --------- 3: 1 1 4284 5153 4226 4554.33 4: 10 10 4044 3831 5010 4295.00 5: 100 100 5497 5378 5612 5495.67 6: 1000 1000 24234 25409 27160 25601.00 And the following are the results in milliseconds from the ConcurrentQueue with no locking necessary: 1: Consumers Producers 1 2 3 Time (ms) 2: ---------- ---------- ------ ------ ------ --------- 3: 1 1 3647 3643 3718 3669.33 4: 10 10 2311 2136 2142 2196.33 5: 100 100 2480 2416 2190 2362.00 6: 1000 1000 7289 6897 7061 7082.33 Note that even though obviously 2000 threads is quite extreme, the concurrent queue actually scales really well, whereas the traditional queue with simple locking scales much more poorly. I love the new concurrent collections, they look so much simpler without littering your code with the locking logic, and they perform much better.  All in all, a great new toy to add to your arsenal of multi-threaded processing!

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  • Thread vs ThreadPool - .Net 2.0

    - by NLV
    Hello I'm not able to understand the difference between Thread vs ThreadPool. Consider i've to manipulate 50,000 records using threads. In case of threads i need to either predefine no of threads or no of records per threads. Either of them has to be constant. In case of threadpool we dont need to set any of them theoretically. But practically we need to assign the number of records per thread, because the no of threads may grow extremely large if the input no of records is huge. Any insights on this?

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  • Java threadpool functionality

    - by cpf
    Hi stackoverflow, I need to make a program with a limited amount of threads (currently using newFixedThreadPool) but I have the problem that all threads get created from start, filling up memory at alarming rate. I wish to prevent this. Threads should only be created shortly before they are executed. e.g.: I call the program and instruct it to use 2 threads in the pool. The program should create & launch the first 2 Threads immediately (obviously), create the next 2 to wait for the previous 2, and at that point wait until one or both of the first 2 ended executing. I thought about extending executor or FixedThreadPool or such. However I have no clue on how to start there and doubt it is the best solution. Easiest would have my main Thread sleeping on intervals, which is not really good either... Thanks in advance!

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  • How do I use SDl_Threads properly?

    - by Anoymonous
    I am new to threads,SDL and how graphic work in general. I've been looking through all of LazyFoo's SDL tutorials, and had helped me greatly. But in his tutorials about multi threading, he commented that you should never use video functions in separate threads, or might cause problem. I am curious how it should be done, as I still have a vague understanding of graphics and threads. As one of my projects is a shoot'em up, I was wondering if I should create one thread that displays all the graphics, one threads receives all the player input for his ship, and another thread for the enemy AI. If this is NOT how it should be done, (I think it's wrong) does anyone have any advice of how graphics should be implemented with user input and enemy AI with threads? For the Lazyfoo's tutorials, this is the link: http://lazyfoo.net/SDL_tutorials/

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  • Can you dynamically resize a java.util.concurrent.ThreadPoolExecutor while it still has tasks waitin

    - by Edward Shtern
    I'm working with a java.util.concurrent.ThreadPoolExecutor to process a number of items in parallel. Although the threading itself works fine, at times we've run into other resource constraints due to actions happening in the threads, which made us want to dial down the number of Threads in the pool. I'd like to know if there's a way to dial down the number of the threads while the threads area actually working. I know that you can call setMaximumPoolSize() and/or setCorePoolSize(), but these only resize the pool once threads become idle, but they don't become idle until there are no tasks waiting in the queue.

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  • Avoding multiple thread spawns in pthreads

    - by madman
    Hi StackOverflow, I have an application that is parallellized using pthreads. The application has a iterative routine call and a thread spawn within the rountine (pthread_create and pthread_join) to parallelize the computation intensive section in the routine. When I use an instrumenting tool like PIN to collect the statistics the tool reports statistics for several threads(no of threads x no of iterations). I beleive it is because it is spawning new set of threads each time the routine is called. How can I ensure that I create the thread only once and all successive calls use the threads that have been created first. When I do the same with OpenMP and then try to collect the statistics, I see that the threads are created only once. Is it beacause of the OpenMP runtime ? Thanks.

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  • Thread Jobs in Java

    - by Bragaadeesh
    Hi, I want to spawn 200 threads simultaneously in Java. What I'm doing right now is running into a loop and creating 200 threads and starting them. After these 200 gets completed, I want to spawn another 200 set of threads and so on. The gist here is that the first 200 threads I spawned need to be FINISHED before spawning the next set. I tried the code below, but its not working for(int i=0;i<200;i++){ Thread myThread = new Thread(runnableInstance); myThread.start(); } for(int i=0;i<200;i++){ Thread myThread = new Thread(runnableInstance); myThread.start(); } Note: I have intentionally put the for loop Twice, but the desired effect I intend is not happening simply because the second for loop is executed before the first set of threads end their execution. Please advise

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  • Regarding Notify()

    - by user1334074
    I was going through threads and I read that ..The notify() method is used to send a signal to one and only one of the threads that are waiting in that same object's waiting pool. The method notifyAll() works in the same way as notify(), only it sends the signal to all of the threads waiting on the object.... Now my query is that if Lets say I have 5 threads and one main thread , so initially the main thread starts and then five other threads start , Now I want to send notification to third thread only , How could it be possible with the use of notify(), since here I am sending notification to third thread only , please advise.

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  • Sun Fire X4270 M3 SAP Enhancement Package 4 for SAP ERP 6.0 (Unicode) Two-Tier Standard Sales and Distribution (SD) Benchmark

    - by Brian
    Oracle's Sun Fire X4270 M3 server achieved 8,320 SAP SD Benchmark users running SAP enhancement package 4 for SAP ERP 6.0 with unicode software using Oracle Database 11g and Oracle Solaris 10. The Sun Fire X4270 M3 server using Oracle Database 11g and Oracle Solaris 10 beat both IBM Flex System x240 and IBM System x3650 M4 server running DB2 9.7 and Windows Server 2008 R2 Enterprise Edition. The Sun Fire X4270 M3 server running Oracle Database 11g and Oracle Solaris 10 beat the HP ProLiant BL460c Gen8 server using SQL Server 2008 and Windows Server 2008 R2 Enterprise Edition by 6%. The Sun Fire X4270 M3 server using Oracle Database 11g and Oracle Solaris 10 beat Cisco UCS C240 M3 server running SQL Server 2008 and Windows Server 2008 R2 Datacenter Edition by 9%. The Sun Fire X4270 M3 server running Oracle Database 11g and Oracle Solaris 10 beat the Fujitsu PRIMERGY RX300 S7 server using SQL Server 2008 and Windows Server 2008 R2 Enterprise Edition by 10%. Performance Landscape SAP-SD 2-Tier Performance Table (in decreasing performance order). SAP ERP 6.0 Enhancement Pack 4 (Unicode) Results (benchmark version from January 2009 to April 2012) System OS Database Users SAPERP/ECCRelease SAPS SAPS/Proc Date Sun Fire X4270 M3 2xIntel Xeon E5-2690 @2.90GHz 128 GB Oracle Solaris 10 Oracle Database 11g 8,320 20096.0 EP4(Unicode) 45,570 22,785 10-Apr-12 IBM Flex System x240 2xIntel Xeon E5-2690 @2.90GHz 128 GB Windows Server 2008 R2 EE DB2 9.7 7,960 20096.0 EP4(Unicode) 43,520 21,760 11-Apr-12 HP ProLiant BL460c Gen8 2xIntel Xeon E5-2690 @2.90GHz 128 GB Windows Server 2008 R2 EE SQL Server 2008 7,865 20096.0 EP4(Unicode) 42,920 21,460 29-Mar-12 IBM System x3650 M4 2xIntel Xeon E5-2690 @2.90GHz 128 GB Windows Server 2008 R2 EE DB2 9.7 7,855 20096.0 EP4(Unicode) 42,880 21,440 06-Mar-12 Cisco UCS C240 M3 2xIntel Xeon E5-2690 @2.90GHz 128 GB Windows Server 2008 R2 DE SQL Server 2008 7,635 20096.0 EP4(Unicode) 41,800 20,900 06-Mar-12 Fujitsu PRIMERGY RX300 S7 2xIntel Xeon E5-2690 @2.90GHz 128 GB Windows Server 2008 R2 EE SQL Server 2008 7,570 20096.0 EP4(Unicode) 41,320 20,660 06-Mar-12 Complete benchmark results may be found at the SAP benchmark website http://www.sap.com/benchmark. Configuration and Results Summary Hardware Configuration: Sun Fire X4270 M3 2 x 2.90 GHz Intel Xeon E5-2690 processors 128 GB memory Sun StorageTek 6540 with 4 * 16 * 300GB 15Krpm 4Gb FC-AL Software Configuration: Oracle Solaris 10 Oracle Database 11g SAP enhancement package 4 for SAP ERP 6.0 (Unicode) Certified Results (published by SAP): Number of benchmark users: 8,320 Average dialog response time: 0.95 seconds Throughput: Fully processed order line: 911,330 Dialog steps/hour: 2,734,000 SAPS: 45,570 SAP Certification: 2012014 Benchmark Description The SAP Standard Application SD (Sales and Distribution) Benchmark is a two-tier ERP business test that is indicative of full business workloads of complete order processing and invoice processing, and demonstrates the ability to run both the application and database software on a single system. The SAP Standard Application SD Benchmark represents the critical tasks performed in real-world ERP business environments. SAP is one of the premier world-wide ERP application providers, and maintains a suite of benchmark tests to demonstrate the performance of competitive systems on the various SAP products. See Also SAP Benchmark Website Sun Fire X4270 M3 Server oracle.com OTN Oracle Solaris oracle.com OTN Oracle Database 11g Release 2 Enterprise Edition oracle.com OTN Disclosure Statement Two-tier SAP Sales and Distribution (SD) standard SAP SD benchmark based on SAP enhancement package 4 for SAP ERP 6.0 (Unicode) application benchmark as of 04/11/12: Sun Fire X4270 M3 (2 processors, 16 cores, 32 threads) 8,320 SAP SD Users, 2 x 2.90 GHz Intel Xeon E5-2690, 128 GB memory, Oracle 11g, Solaris 10, Cert# 2012014. IBM Flex System x240 (2 processors, 16 cores, 32 threads) 7,960 SAP SD Users, 2 x 2.90 GHz Intel Xeon E5-2690, 128 GB memory, DB2 9.7, Windows Server 2008 R2 EE, Cert# 2012016. IBM System x3650 M4 (2 processors, 16 cores, 32 threads) 7,855 SAP SD Users, 2 x 2.90 GHz Intel Xeon E5-2690, 128 GB memory, DB2 9.7, Windows Server 2008 R2 EE, Cert# 2012010. Cisco UCS C240 M3 (2 processors, 16 cores, 32 threads) 7,635 SAP SD Users, 2 x 2.90 GHz Intel Xeon E5-2690, 128 GB memory, SQL Server 2008, Windows Server 2008 R2 DE, Cert# 2012011. Fujitsu PRIMERGY RX300 S7 (2 processors, 16 cores, 32 threads) 7,570 SAP SD Users, 2 x 2.90 GHz Intel Xeon E5-2690, 128 GB memory, SQL Server 2008, Windows Server 2008 R2 EE, Cert# 2012008. HP ProLiant DL380p Gen8 (2 processors, 16 cores, 32 threads) 7,865 SAP SD Users, 2 x 2.90 GHz Intel Xeon E5-2690, 128 GB memory, SQL Server 2008, Windows Server 2008 R2 EE, Cert# 2012012. SAP, R/3, reg TM of SAP AG in Germany and other countries. More info www.sap.com/benchmark

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  • SQL SERVER – SOS_SCHEDULER_YIELD – Wait Type – Day 8 of 28

    - by pinaldave
    This is a very interesting wait type and quite often seen as one of the top wait types. Let us discuss this today. From Book On-Line: Occurs when a task voluntarily yields the scheduler for other tasks to execute. During this wait the task is waiting for its quantum to be renewed. SOS_SCHEDULER_YIELD Explanation: SQL Server has multiple threads, and the basic working methodology for SQL Server is that SQL Server does not let any “runnable” thread to starve. Now let us assume SQL Server OS is very busy running threads on all the scheduler. There are always new threads coming up which are ready to run (in other words, runnable). Thread management of the SQL Server is decided by SQL Server and not the operating system. SQL Server runs on non-preemptive mode most of the time, meaning the threads are co-operative and can let other threads to run from time to time by yielding itself. When any thread yields itself for another thread, it creates this wait. If there are more threads, it clearly indicates that the CPU is under pressure. You can fun the following DMV to see how many runnable task counts there are in your system. SELECT scheduler_id, current_tasks_count, runnable_tasks_count, work_queue_count, pending_disk_io_count FROM sys.dm_os_schedulers WHERE scheduler_id < 255 GO If you notice a two-digit number in runnable_tasks_count continuously for long time (not once in a while), you will know that there is CPU pressure. The two-digit number is usually considered as a bad thing; you can read the description of the above DMV over here. Additionally, there are several other counters (%Processor Time and other processor related counters), through which you can refer to so you can validate CPU pressure along with the method explained above. Reducing SOS_SCHEDULER_YIELD wait: This is the trickiest part of this procedure. As discussed, this particular wait type relates to CPU pressure. Increasing more CPU is the solution in simple terms; however, it is not easy to implement this solution. There are other things that you can consider when this wait type is very high. Here is the query where you can find the most expensive query related to CPU from the cache Note: The query that used lots of resources but is not cached will not be caught here. SELECT SUBSTRING(qt.TEXT, (qs.statement_start_offset/2)+1, ((CASE qs.statement_end_offset WHEN -1 THEN DATALENGTH(qt.TEXT) ELSE qs.statement_end_offset END - qs.statement_start_offset)/2)+1), qs.execution_count, qs.total_logical_reads, qs.last_logical_reads, qs.total_logical_writes, qs.last_logical_writes, qs.total_worker_time, qs.last_worker_time, qs.total_elapsed_time/1000000 total_elapsed_time_in_S, qs.last_elapsed_time/1000000 last_elapsed_time_in_S, qs.last_execution_time, qp.query_plan FROM sys.dm_exec_query_stats qs CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) qt CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) qp ORDER BY qs.total_worker_time DESC -- CPU time You can find the most expensive queries that are utilizing lots of CPU (from the cache) and you can tune them accordingly. Moreover, you can find the longest running query and attempt to tune them if there is any processor offending code. Additionally, pay attention to total_worker_time because if that is also consistently higher, then  the CPU under too much pressure. You can also check perfmon counters of compilations as they tend to use good amount of CPU. Index rebuild is also a CPU intensive process but we should consider that main cause for this query because that is indeed needed on high transactions OLTP system utilized to reduce fragmentations. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All of the discussions of Wait Stats in this blog is generic and varies from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • Are CQRS/DDD/Event Sourcing and REST compatible?

    - by Robin Green
    REST seems to promote the idea of a canonical URL for a resource, and PUTing/POSTing back a modified representation of that resource in order to change it. However, with CQRS - Command Query Responsibility Segregation - one can theoretically have a completely different "API" for reading and for writing, which seems to conflict with the REST ideal of one URL for a resource, and no RPC-style "verbs inside the request body". DDD and Event Sourcing sometimes go together with CQRS, which is why I mention them in this question. So, can CQRS be used together with REST? Or is it against the REST way of doing things? What about DDD? And Event Sourcing? Can they be used with REST?

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  • Box2d too much for Circle/Circle collision detection?

    - by Joey Green
    I'm using cocos2d to program a game and am using box2d for collision detection. Everything in my game is a circle and for some reason I'm having a problem with some times things are not being detected as a collision when they should be. I'm thinking of rolling up my own collision detection since I don't think it would be too hard. Questions are: Would this approach work for collision detection between circles? a. get radius of circle A and circle B. b. get distance of the center of circle A and circle B c. if the distance is greater than or equal to the sum of circle A radius and circle B radius then we have a hit Should box2d be used for such simple collision detection? There are no physics in this game.

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  • Cocos2d: Changing b2Body x val every frame causes jitter

    - by Joey Green
    So, I have a jumping mechanism similar to what you would see in doodle jump where character jumps and you use the accelerometer to make character change direction left or right. I have a player object with position and a box2d b2Body with position. I'm changing the player X position via the accelerometer and the Y position according to box2d. pseudocode for this is like so -----accelerometer acceleration------ player.position = new X -----world update--------- physicsWorld-step() //this will get me the new Y according to the physics similation //so we keep the bodys Y value but change x to new X according to accelerometer data playerPhysicsBody.position = new pos(player.position.x, keepYval) player.position = playerPhysicsBody.position Now this is simplifying my code, but I'm doing the position conversion back and forth via mult or divide by PTM_. Well, I'm getting a weird jitter effect after I get big jump in acceleration data. So, my questions are: 1) Is this the right approach to have the accelerometer control the x pos and box2d control the y pos and just sync everthing up every frame? 2) Is there some issue with updating a b2body x position every frame? 3) Any idea what might be creating this jitter effect? I've collecting some data while running the game. Pre-body is before I set the x value on the b2Body in my update method after I world-step(). Post of course is afterwards. As you can see there is definitively a pattern. 012-06-19 08:14:13.118 Game[1073:707] pre-body pos 5.518720~24.362963 2012-06-19 08:14:13.120 Game[1073:707] post-body pos 5.060156~24.362963 2012-06-19 08:14:13.131 Game[1073:707] player velocity x: -31.833529 2012-06-19 08:14:13.133 Game[1073:707] delta 0.016669 2012-06-19 08:14:13.135 Game[1073:707] pre-body pos 5.060156~24.689455 2012-06-19 08:14:13.137 Game[1073:707] post-body pos 5.502138~24.689455 2012-06-19 08:14:13.148 Game[1073:707] player velocity x: -31.833529 2012-06-19 08:14:13.150 Game[1073:707] delta 0.016667 2012-06-19 08:14:13.151 Game[1073:707] pre-body pos 5.502138~25.006948 2012-06-19 08:14:13.153 Game[1073:707] post-body pos 5.043575~25.006948 2012-06-19 08:14:13.165 Game[1073:707] player velocity x: -31.833529 2012-06-19 08:14:13.167 Game[1073:707] delta 0.016644 2012-06-19 08:14:13.169 Game[1073:707] pre-body pos 5.043575~25.315441 2012-06-19 08:14:13.170 Game[1073:707] post-body pos 5.485580~25.315441 2012-06-19 08:14:13.180 Game[1073:707] player velocity x: -31.833529 2012-06-19 08:14:13.182 Game[1073:707] delta 0.016895 2012-06-19 08:14:13.185 Game[1073:707] pre-body pos 5.485580~25.614935 2012-06-19 08:14:13.188 Game[1073:707] post-body pos 5.026768~25.614935 2012-06-19 08:14:13.198 Game[1073:707] player velocity x: -31.833529 2012-06-19 08:14:13.199 Game[1073:707] delta 0.016454 2012-06-19 08:14:13.207 Game[1073:707] pre-body pos 5.026768~25.905428 2012-06-19 08:14:13.211 Game[1073:707] post-body pos 5.469213~25.905428 2012-06-19 08:14:13.217 Game[1073:707] acceleration x -0.137421 2012-06-19 08:14:13.223 Game[1073:707] player velocity x: -65.022644 2012-06-19 08:14:13.229 Game[1073:707] delta 0.016603

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  • Spreadsheets in Game Design?

    - by Joey Green
    There have been two instances from the past two weeks that I've heard from well known successful game developers that they use spreadsheets when designing games. The first being David Whatley in this GDCVault video: http://gdcvault.com/play/1012372/From-Zero-to-Time-Magazine The second being the guys that do Walled Garden Weekly: http://walledgardenweekly.com/ David said he models everything out and uses excel models to see how everything plays out. What on earth is he talking about? Is it seeing how the game mechanics react to each other? Is there somewhere where I can learn more about how to do this? Thanks

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  • Software Architecture and Design vs Psychology of HCI class

    - by Joey Green
    I have two classes to choose from and I'm wanting to get an opinion from the more experienced game devs which might be better for someone who wants to be an indie game dev. The first is a Software Architecture and Design course and the second is a course titled Psychology of HCI. I've previously have taken a Software Design course that was focused only on design patterns. I've also taken an Introduction to HCI course. Software Architecture and Design Description Topics include software architectures, methodologies, model representations, component-based design ,patterns,frameworks, CASE-based desgins, and case studies. Psychology of HCI Description Exploration of psychological factors that interact with computer interface usablilty. Interface design techniques and usability evaluation methods are emphasized. I know I would find both interesting, but my concern is really which one might be easier to pick up on my own. I know HCI is relevant to game dev, but am un-sure if the topics in the Software Architecture class would be more for big software projects that go beyond the scope of games. Also, I'm not able to take both because the overlap.

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  • Oracle Certification at OpenWorld + JavaOne 2012 [VIDEO]

    - by Harold Green
    Oracle Certification will again be at this year's Oracle OpenWorld and JavaOne conferences in San Francisco. We'll have two locations - the Oracle Certification Lounge at OpenWorld, and the Java Certification Zone at JavaOne. Watch this quick video (1:46) to learn more about these, Oracle University pre-conference training, some mini-sessions on several certification topics, and previews of our new Exam Preparation Seminars. ORACLE CERTIFICATION PROGRAM LOUNGE Location: Moscone South, Mezzanine, Room 250 Hours: Monday, 9:00 a.m.–5:00 p.m. Tuesday, 9:00 a.m.–5:00 p.m. Wednesday, 9:00 a.m.–5:00 p.m. Thursday, 9:00 a.m.–1:00 p.m. JAVA CERTIFICATION ZONE Location: The Zone/Taylor Street Café Hours: Sunday, 7:00 p.m.–9:00 p.m. Monday, 11:00 a.m.–6:00 p.m. Tuesday, 11:00 a.m.–6:This i00 p.m. Wednesday, 11:00 a.m.–6:00 p.m. Thursday, 11:00 a.m.–2:00 p.m. CERTIFICATION SESSIONS Monday, 1:00 p.m - JavaOne (Java Certification Zone) Monday, 3:00 p.m - Oracle OpenWorld (Oracle Certification Lounge) QUICK LINKS: Oracle OpenWorld Certification Lounge Details Oracle University at Oracle OpenWorld 2012 (Pre-Conference Training) Java University at JavaOne 2012 (Pre-Conference Training) Self Test Software Oracle Press Oracle Certification on Twitter: https://twitter.com/oraclecert Oracle Certification on Facebook: facebook.com/OracleCertification

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  • Cocos2d: Tongue effect like in Munch Time

    - by Joey Green
    I'm wanting to do a tongue effect for my character like the one in Munch Time( shown in pic ). The player does some action and his tongue attaches to the nearest platform. I'm thinking this is simply a get distance to platform and keep player at that distance as he moves back and forth giving him the swinging effect. For the drawing, I'm wanting the same effect where the tongue sprite is the skinniest in the middle of the distance between the character and platform. I know how to do this in a shader( I'm using cocos2d v2 btw ), but I'm wondering if there is some built-in functionality to allow me to do this. First, is this the right approach using distance? Second, is their an easy way to do the tongue sprite effect without a shader? Third, I'm wanting to have the player spring up at will in the direction of the platform. I'm using Box2D. Would there be a way to do this using force's or would it be easier to write my own code?

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  • Mobile Apps for Hospitals?

    - by Joey Green
    I currently work for a pretty large hospital and have been dabbling in iPhone development for a couple years. The CEO is wanting to get together a group to see what mobile technology we could create. I was contacted to be the main developer. I wanted to gather some ideas of what kind of mobile apps people have seen deployed in hospitals. Not necessarily medical apps that you can get on the app store, but rather apps built specifically for a hospital. Any ideas? If this is not the appropriate forum for a question like this, can someone point me to a forum where it would be appropriate?

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  • Do employers hiring for Software jobs care about the classes you took in CS masters program?

    - by Joey Green
    I'm torn between two classes right now for next semester( Software Design and Advanced Computer Graphics ). I would enjoy Advanced Computer Graphics more, but I feel the software design class would help me when approaching anything I ever build for the rest of my career. I feel though I could just buy the book( I already have both books actually ) of the Software Design class and go through it, if I wanted. But think it would be a bit tougher to pick up the Advanced Computer Graphics class on my own. So do employers look at the graduate classes you've taken to decide if you would be a good fit or not? I think more importantly what I'm wanting to know is if I wanted to work for a high-end software company like Apple or Google would a company like that be more impressed by someone that took software engineering classes or hardcore CS classes?

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  • Linking Libraries in iOS?

    - by Joey Green
    This is probably a totally noob question but I have missing links in my mind when thinking about linking libraries in iOS. I usually just add a new library that's been cross compiled and set the build and linker paths without really know what I'm doing. I'm hoping someone can help me fill in some gaps. Let's take the OpenCV library for instance. I have this totally working btw because of a really well written tutorial( http://niw.at/articles/2009/03/14/using-opencv-on-iphone/en ), but I'm just wanting to know what is exactly going on. What I'm thinking is happening is that when I build OpenCV for iOS is that your creating object code that gets placed in the .a files. This object code is just the implementation files( .m ) compiled. One reason you would want to do this is to make it hard to see the source code and so that you don't have to compile that source code every time. The .h files won't be put in the library ( .a ). You include the .h in your source files and these header files communicate with the object code library ( .a ) in some way. You also have to include the header files for your library in the Build Path and the Library itself in the Linker Path. So, is the way I view linking libraries correct? If , not can someone correct me on this ?

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  • Which data structure should I use for dynamically generated platforms?

    - by Joey Green
    I'm creating a platform type of game with various types of platforms. Platforms that move, shake, rotate, etc. Multiple types and multiple of each type can be on the screen at once. The platforms will be procedural generated. I'm trying to figure out which of the following would be a better platform system: Pre-allocate all platforms when the scene loads, storing each platform type into different platform type arrays( i.e. regPlatformArray ), and just getting one when I need one. The other option is to allocate and load what I need when my code needs it. The problem with 1 is keeping up with the indices that are in use on screen and which aren't. The problem with 2 is I'm having a hard time wrapping my head around how I would store these platforms so that I can call the update/draw methods on them and managing that data structure that holds them. The data structure would constantly be growing and shrinking. It seems there could be too much complexity. I'm using the cocos2d iPhone game engine. Anyways, which option would be best or is there a better option?

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  • Coding Dynamic Events?

    - by Joey Green
    I have no idea what the title of this question should be so bare with me. My game has turns. On a turn a player does something and this can result in a random number of explosions that occur at different times. I know when the explosions are done. I need to know when ALL are done and then do some other action. Also, each explosion is the same amount of time, say 3 seconds.. Right now I'm thinking of using a counter to hold how many explosions are happening. Then once the explosion is finished decrement this counter. Once the counter is zero, do my action. This idea is inspired by objective-c memory management btw. Anyways, does this sound like a good approach or would there be another way. An alternative might be to figure out the explosion who happened last and let it be responsible for calling this subsequent action. I'm asking mostly, because I haven't done this before and am trying to figure out if there are bugs that may occur that I'm not foreseeing.

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  • What is the best way to learn Cocos2D?

    - by Joey Green
    I've messed around with iPhone development for a couple years now. I've done some contract work. I want to get into Cocos2D to develop a game idea that I have. I was wondering what might be the best/quickest way to get up in running in cocos2d? I've thought about a book, but I wondering if that is needed? I'm the type of guy that just wants to know what everything does and is suppose to be used for. Any ideas?

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  • When to roll your own game engine?

    - by Joey Green
    I've been a software developer for 5 years now and wanting to get into iOS game development. I've played around with the iOS SDK for about 2 years now, attending cocoaheads meetings and feel I have a good grasp on objective-c/cocoa and even c/c++. I have a game idea and know that I will use Box2D but I'm wondering if I should use cocos2D or not. The main reasons are: I may want to do things graphics wise that aren't available in cocos2d. If I roll my own game engine I'll have more control. Of course the main reason for using a already existing game engine is the time it saves and it makes the hard stuff easier, but for someone who has the technical chops to roll his own does it make sense?

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