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  • Java EE @ No Fluff Just Stuff Tour

    - by reza_rahman
    If you work in the US and still don't know what the No Fluff Just Stuff (NFJS) Tour is, you are doing yourself a very serious disfavor. NFJS is by far the cheapest and most effective way to stay up to date through some world class speakers and talks. This is most certainly true for US enterprise Java developers in particular. Following the US cultural tradition of old-fashioned roadshows, NFJS is basically a set program of speakers and topics offered at major US cities year round. Many now famous world class technology speakers can trace their humble roots to NFJS. Via NFJS you basically get to have amazing training without paying for an expensive venue, lodging or travel. The events are usually on the weekends so you don't need to even skip work if you want (a great feature for consultants on tight budgets and deadlines). I am proud to share with you that I recently joined the NFJS troupe. My hope is that this will help solve the lingering problem of effectively spreading the Java EE message here in the US. For NFJS I hope my joining will help beef up perhaps much desired Java content. In any case, simply being accepted into this legendary program is an honor I could have perhaps only dreamed of a few years ago. I am very grateful to Jay Zimmerman for seeing the value in me and the Java EE content. The current speaker line-up consists of the likes of Neal Ford, Venkat Subramaniam, Nathaniel Schutta, Tim Berglund and many other great speakers. I actually had my tour debut on April 4-5 with the NFJS New York Software Symposium - basically a short train commute away from my home office. The show is traditionally one of the smaller ones and it was not that bad for a start. I look forward to doing a few more in the coming months (more on that a bit later). I had four talks back to back (really my most favorite four at the moment). The first one was a talk on JMS 2 - some of you might already know JMS is one of my most favored Java EE APIs. The slides for the talk are posted below: What’s New in Java Message Service 2 from Reza Rahman The next talk I delivered was my Cargo Tracker/Java EE + DDD talk. This talk basically overviews DDD and describes how DDD maps to Java EE using code examples/demos from the Cargo Tracker Java EE Blue Prints project. Applied Domain-Driven Design Blue Prints for Java EE from Reza Rahman The third talk I delivered was our flagship Java EE 7/8 talk. As you may know, currently the talk is basically about Java EE 7. I'll probably slowly evolve this talk to gradually transform it into a Java EE 8 talk as we move forward (I'll blog about that separately shortly). The following is the slide deck for the talk: JavaEE.Next(): Java EE 7, 8, and Beyond from Reza Rahman My last talk for the show was my JavaScript+Java EE 7 talk. This talk is basically about aligning EE 7 with the emerging JavaScript ecosystem (specifically AngularJS). The slide deck for the talk is here: JavaScript/HTML5 Rich Clients Using Java EE 7 from Reza Rahman Unsurprisingly this talk was well-attended. The demo application code is posted on GitHub. The code should be a helpful resource if this development model is something that interests you. Do let me know if you need help with it but the instructions should be fairly self-explanatory. My next NFJS show is the Central Ohio Software Symposium in Columbus on June 6-8 (sorry for the late notice - it's been a really crazy few weeks). Here's my tour schedule so far, I'll keep you up-to-date as the tour goes forward: June 6 - 8, Columbus Ohio. June 24 - 27, Denver Colorado (UberConf) - my most extensive agenda on the tour so far. July 18 - 20, Austin Texas. I hope you'll take this opportunity to get some updates on Java EE as well as the other awesome content on the tour?

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  • Displaying wait cursor in while backgroundworker is running

    - by arc1880
    During the start of my windows application, I have to make a call to a web service to retrieve some default data to load onto my application. During the load of the form, I run a backgroundworker to retrieve this data. I want to display the wait cursor until this data is retrieved. How would I do this? I've tried setting the wait cursor before calling the backgroundworker to run. When I report a progress of 100 then I set it back to the default cursor. The wait cursor comes up but when I move the mouse it disappears. Environment: Windows 7 Pro 64-bit VS2010 C# .NET 4.0 Windows Forms EDIT: I am setting the cursor the way Jay Riggs suggested. It only works if I don't move the mouse. **UPDATE: I have created a button click which does the following: When I do the button click and move my mouse, the wait cursor appears regardless if I move my mouse or not. void BtnClick() { Cursor = Cursors.WaitCursor; Thread.Sleep(8000); Cursor = Cursors.Default; } If I do the following: I see the wait cursor and when I move the mouse it disappears inside the form. If I move to my status bar or the menu bar the wait cursor appears. Cursor = Cursors.WaitCursor; if (!backgroundWorker.IsBusy) { backGroundWorker.RunWorkerAsync(); } void backGroundWorkerDoWork(object sender, DoWorkEventArgs e) { Thread.Sleep(8000); } void backGroundWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { Cursor = Cursors.Default; } If I do the following: The wait cursor appears and when I move the mouse it still appears but will sometimes flicker off and on when moving in text fields. if (!backgroundWorker.IsBusy) { backGroundWorker.RunWorkerAsync(); } void backGroundWorkerDoWork(object sender, DoWorkEventArgs e) { UseWaitCursor = true; Thread.Sleep(8000); } void backGroundWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { UseWaitCursor = false; }

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  • What's Your Biggest Visual Studio 2008 Annoyance?

    - by Kyle West
    I love Visual Studio about 90% of the time, but that last 10% it is such a PITA it makes me want to launch my monitor off the desk. My latest annoyances: It won't remember my toolbar settings. I don't want any toolbars, ever. Quit popping open the CSS editor or XML editor or text editor everytime I open a file. Doesn't remember which regions I had expanded or collapsed and as far as I know there is no way to tell it to always open files with the regions expanded. When editing CSS or HTML the damn error list wants to pop up each time I start a tag and haven't finished it yet. First of all, don't pop up at all. And if you're going to ... give me a couple seconds to finish what I'm doing. The best part ... ReSharper :) EDIT [Jay Bazuzi]: It seems like this discussion is only productive if it's focused on the latest released version. Set the title to VS2008.

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  • Passing a list of ints to WebMethod using jQuery and ajax.

    - by birdus
    I'm working on a web page (ASP.NET 4.0) and am just starting simple to try and get this ajax call working (I'm an ajax/jQuery neophyte) and I'm getting an error on the call. Here's the js: var TestParams = new Object; TestParams.Items = new Object; TestParams.Items[0] = 1; TestParams.Items[1] = 5; TestParams.Items[2] = 10; var finalObj = JSON.stringify(TestParams); var _url = 'AdvancedSearch.aspx/TestMethod'; $(document).ready(function () { $.ajax({ type: "POST", url: _url, data: finalObj, contentType: "application/json; charset=utf-8", dataType: "json", success: function (msg) { $(".main").html(msg.d); }, error: function (xhr, ajaxOptions, thrownError) { alert(thrownError.toString()); } }); Here's the method in my code behind file: [Serializable] public class TestParams { public List<int> Items { get; set; } } public partial class Search : Page { [WebMethod] public static string TestMethod(TestParams testParams) { // I never hit a breakpoint in here // do some stuff // return some stuff return ""; } } Here's the stringified json I'm sending back: {"Items":{"0":1,"1":5,"2":10}} When I run it, I get this error: Microsoft JScript runtime error: 'undefined' is null or not an object It breaks on the error function. I've also tried this variation on building the json (based on a sample on a website) with this final json: var TestParams = new Object; TestParams.Positions = new Object; TestParams.Positions[0] = 1; TestParams.Positions[1] = 5; TestParams.Positions[2] = 10; var DTO = new Object; DTO.positions = TestParams; var finalObj = JSON.stringify(DTO) {"positions":{"Positions":{"0":1,"1":5,"2":10}}} Same error message. It doesn't seem like it should be hard to send a list of ints from a web page to my webmethod. Any ideas? Thanks, Jay

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  • image not displaying in midlet

    - by user316843
    Hello all,am new here. i have a slight problem; PLease look at the following code and tell me if am doing something wrong because the image is not displaying. i have made it really small so it should fit but its not displaying. i have images displaying in other screens but this main midlet would not. Here is the code: import java.io.IOException; import javax.microedition.midlet.*; import javax.microedition.lcdui.*; /** * @author jay */ public class WShop extends MIDlet implements CommandListener { /* Declare display variables*/ private Form mainForm; private Display display; private Command OK,Exit,wView, mView, myView; /* */ Categories categories = new Categories(this); Image image; public WShop() { /* initialize Screen and Command buttons that will be used when the application starts in the class constructor*/ mainForm = new Form("Wind Shopper"); OK = new Command("OK", Command.OK, 2); Exit = new Command("Exit", Command.EXIT, 0); wview= new Command("wview", Command.OK, 0); mview= new Command("mview", Command.OK, 0); try { /* retrieving the main image of the application*/ image = Image.createImage("/main.png"); } catch (IOException ex) { ex.printStackTrace(); } mainForm.addCommand(OK); mainForm.addCommand(Exit); mainForm.addCommand(wView); mainForm.addCommand(mView); mainForm.setCommandListener(this); } public void startApp() { /* checks to see if the display is currently empty and then sets it to the current screen */ if (display == null) { display = Display.getDisplay(this); } display.setCurrent(mainForm); } /* paused state of the application*/ public void pauseApp() { } /* Destroy Midlet state*/ public void destroyApp(boolean unconditional) { } Thanks in advance.

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  • How to format the Facebook news feed description of grouped app posts?

    - by JcFx
    I have an app which posts a message like this to a user's Facebook timeline: This is working fine, but if I post a few times, my posts get grouped on my news feed, and I get this: What settings should I use to control the way this news report appears? Instead of 'All about periods' and the page link in the box at the top, I'd like 'Body iQ Quiz' and the app description. Where would I set these values? And is it possible to make the grouped report say 'Jay cee Effex shared a link via Body iQ Quiz', the way the original post does? I'm posting from the Facebook AS3 API, and my post code looks like this: var auth:FacebookAuthResponse = Facebook.getAuthResponse(); var token:String = auth.accessToken; var user:String = auth.uid; var values:Object = { access_token: token, name: "Body iQ Quiz", picture: "http://a7.sphotos.ak.fbcdn.net/hphotos-ak-snc6/282950_427728213914009_630526316_n.jpg", link:"http://www.lil-lets.co.uk/en-GB/Wellbeing", description: "Women, how well do we know our bodies? Click here to find out what your Body iQ is.", message: result.FacebookBody + " " + result.FacebookTitle }; Facebook.api("/" + user + "/feed", handleSubmitFeed, values, URLRequestMethod.POST); ... but I'm not sure if this is something I can fix in code, or if the app configuration needs tweaking? NOTE: Some users report getting the latter format in their news feed even with a single post (I can't reproduce this), so perhaps grouping is a red herring, and the real question is how to format the news feed report of a timeline post?

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  • Generic InBetween Function.

    - by Luiscencio
    I am tired of writing x > min && x < max so i wawnt to write a simple function but I am not sure if I am doing it right... actually I am not cuz I get an error: bool inBetween<T>(T x, T min, T max) where T:IComparable { return (x > min && x < max); } errors: Operator '>' cannot be applied to operands of type 'T' and 'T' Operator '<' cannot be applied to operands of type 'T' and 'T' may I have a bad understanding of the where part in the function declaring note: for those who are going to tell me that I will be writing more code than before... think on readability =) any help will be appreciated EDIT deleted cuz it was resolved =) ANOTHER EDIT so after some headache I came out with this (ummm) thing following @Jay Idea of extreme readability: public static class test { public static comparision Between<T>(this T a,T b) where T : IComparable { var ttt = new comparision(); ttt.init(a); ttt.result = a.CompareTo(b) > 0; return ttt; } public static bool And<T>(this comparision state, T c) where T : IComparable { return state.a.CompareTo(c) < 0 && state.result; } public class comparision { public IComparable a; public bool result; public void init<T>(T ia) where T : IComparable { a = ia; } } } now you can compare anything with extreme readability =) what do you think.. I am no performance guru so any tweaks are welcome

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  • What are the attributes that are need to Send with this FEDEX shipping script?

    - by Fero
    could any one please tell me what are the attributes that are send with $ship_data ? I am too confused about it. I know that ORIGIN ADDRESS, DESTINATION ADDRESS, NAME etc.. need to be send. But how the data should be aligned. Like name is FIRST, address is SECOND etc... Any help will be useful ** // create new fedex object $fed = new FedExDC('#########','#########'); $ship_data = array( 75= 'LBS', 16= 'Ma' , 13= '44 Main street' , 5= '312 stuart st', 1273= '01', 1274= '01', 18= '6173335555', 15= 'Boston', 23= '1', 9= '02134', 183= '6175556985', 8= 'MA', 117= 'US', 17= '02116', 50= 'US', 4= 'Vermonster LLC', 7= 'Boston', 1369= '1', 12= 'Jay Powers', 1333= '1', 1401= '1.0', 116= 1, 68= 'USD', 1368= 1, 1369= 1, 1370= 5 ); // Ship example $ship_Ret = $fed-ship_express($ship_data); if ($error = $fed-getError()) { echo "ERROR :". $error; } else { // Save the label to disk $fed-label('mylabel.png'); } /* tracking example $track_Ret = $fed-track( array( 29 = 790344664540, )); echo $fed-debug_str. "\n"; echo "Price ".$ship_Ret[1419];*/ echo ""; if ($error = $fed-getError()) { die("ERROR: ". $error); } else { // decode and save label $fed-label('myLabel.png'); echo $fed-debug_str. "\n"; echo "\n\n"; echo "Price $".$ship_Ret[1419]; echo "\n"; echo "Tracking# ".$ship_Ret[29]; } echo ""; ?** Thanks Fero

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  • ASP can't connect to SQL Server database

    - by birdus
    I'm trying to get a classic ASP application to connect to a local SQL Server 2008 database. The app and database were built by someone else. I'm just trying to get them installed and running on my machine (Windows 7). I'm getting the following error when when the ASP app tries to connect to the database: Could not connect to database: Error Number: -2147467259 Error Message: [ConnectionOpen (Connect()).] does not exist or access denied. I don't see any messages in the Windows Event Viewer. I'm looking at: Event Viewer-Windows Logs-Application. It's a fresh database install using a simple restore. The SQL Server install uses the default instance. SQL Server and Windows authentication are both allowed. I left the existing connection string (in the ASP code) in tact and just tried adding that to my SQL Server installation. Here's the connection string: strConn = "PROVIDER=SQLOLEDB;SERVER=localhost;UID=TheUser;PWD=ThePassword;DATABASE=TheDatabase;" To add that user to SQL Server, I went to Security/Logins in SSMS and added the user and the password. I selected the database in question as the Default database. I thought that might do the trick, but it didn't. Then, I went into TheDatabase, then went into Security there. I added a new user there, referencing the new user I had already added in server Security. Under Owned Schemas, I clicked db_owner and under Role Members I checked db_accessadmin and db_owner. None of this gave the ASP application access to the database. The sid values match in sys.database_principals and sys.server_principals for the login in question. I am able to login to SSMS using this login. The app needs to execute selects against the database like this: oConn.Execute('select * from someTable') I'm not a DBA and am sort of grasping at straws here. How do I get this thing connected? Thanks, Jay

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  • Fasted way to develop data entry screens for a .NET backend ?

    - by jay23
    I am a .NET / C# back end guy. I am working on a app that will have about 200 different data entry screens. For me exposing DTO as a collection for CRUD (IUpdatable and IQueryable) is the easy part, can do it in sleep :-). What I am trying to decide is what type of front end technology will allow me to develop these data entry screens fast. They don't have to be fancy but they are not just plain grid either and on average they have about 15 form fields and some client side data validation (no db look up) Options I am looking at are Use ExtJS on the front and REST / JSON on the back. ASP.NET RIA but I do not know SL (Well XAML) Plain ASP.NET / MVC One idea I had was the DTO will contain the meta data about the form (As Attributes) and the form can be dynamically generated, but i do not want to reinvent the wheel if their is an easy way. I have looked at RAD software but all of them look at the DB and generate screens. I rather want some thing that can look at my DTO and generate screens. Jay

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  • A Visual Studio Release Grows in Brooklyn

    - by andrewbrust
    Yesterday, Microsoft held its flagship launch event for Office 2010 in Manhattan.  Today, the Redmond software company is holding a local launch event for Visual Studio (VS) 2010, in Brooklyn.  How come information workers get the 212 treatment and developers are relegated to 718? Well, here’s the thing: the Brooklyn Marriott is actually a great place for an event, but you need some intimate knowledge of New York City to know that.  NBC’s Studio 8H, where the Office launch was held yesterday (and from where SNL is broadcast) is a pretty small venue, but you’d need some inside knowledge to recognize that.  Likewise, while Office 2010 is a product whose value is apparent.  Appreciating VS 2010’s value takes a bit more savvy.  Setting aside its year-based designation, this release of VS, counting the old Visual Basic releases, is the 10th version of the product.  How can a developer audience get excited about an integrated development environment when it reaches double-digit version numbers?  Well, it can be tough.  Luckily, Microsoft sent Jay Schmelzer, a Group Program Manager from the Visual Studio team in Redmond, to come tell the Brooklyn audience why they should be excited. Turns out there’s a lot of reasons.  Support fro SharePoint development is a big one.  In previous versions of VS, that support has been anemic, at best.  Shortage of SharePoint developers is a huge issue in the industry, and this should help.  There’s also built in support for Windows Azure (Microsoft’s cloud platform) and, through a download, support for the forthcoming Windows Phone 7 platform.  ASP.NET MVC, a “close-to-the-metal” Web development option that does away with the Web Forms abstraction layer, has a first-class presence in VS.  So too does jQuery, the Open Source environment that makes JavaScript development a breeze.  The jQuery support is so good that Microsoft now contributes to that Open Source project and offers IntelliSense support for it in the code editor. Speaking of the VS code editor, it now supports multi-monitor setups, zoom-in, and block selection.  If you’re not a developer, this may sound confusing and minute.  I’ll just say that for people who are developers these are little things that really contribute to productivity, and that translates into lower development costs. The really cool demo, though, was around Visual Studio 2010’s new debugging features.  This stuff is hard to showcase, but I believe it’s truly breakthrough technology: imagine being able to step backwards in time to see what might have caused a bug.  Cool?  Now imagine being able to do that, even if you weren’t the tester and weren’t present while the testing was being done.  Then imagine being able to see a video screen capture of what the tester was doing with your app when the bug occurred.  VS 2010 allows all that.  This could be the demise of the IWOMM (“it works on my machine”) syndrome. After the keynote, I asked Schmelzer if any of Microsoft’s competitors have debugging tools that come close to VS 2010’s.  His answer was an earnest “we don’t think so.”  If that’s true, that’s a big deal, and a huge advantage for developer teams who adopt it.  It will make software development much cheaper and more efficient.  Kind of like holding a launch event at the Brooklyn Marriott instead of 30 Rock in Manhattan! VS 2010 (version 10) and Office 2010 (version 14) aren’t the only new product versions Microsoft is releasing right now.  There’s also SQL Server 2008 R2 (version 10.5), Exchange 2010 (version 8, I believe), SharePoint 2010 (version 4) and, of course, Windows 7.  With so many new versions at such levels of maturity, I think it’s fair to say Microsoft has reached middle-age.  How does a company stave off a potential mid-life crisis, especially when with young Turks like Google coming along and competing so fiercely?  Hard to say.  But if focusing on core value, including value that’s hard to play into a sexy demo, is part oft the answer, then Microsoft’s doing OK.  And if some new tricks, like Windows Phone 7, can gain some traction, that might round things out nicely. Are the legacy products old tricks, or are they revised classics?  I honestly don’t know, because it’s the market’s prerogative to pass that judgement.  I can say this though: based on today’s show, I think Microsoft’s been doing its homework.

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  • hello-1.mod.c:14: warning: missing initializer (near initialization for '__this_module.arch.unw_sec_init')

    - by Sompom
    I am trying to write a module for an sbc1651. Since the device is ARM, this requires a cross-compile. As a start, I am trying to compile the "Hello Kernel" module found here. This compiles fine on my x86 development system, but when I try to cross-compile I get the below error. /home/developer/HelloKernel/hello-1.mod.c:14: warning: missing initializer /home/developer/HelloKernel/hello-1.mod.c:14: warning: (near initialization for '__this_module.arch.unw_sec_init') Since this is in the .mod.c file, which is autogenerated I have no idea what's going on. The mod.c file seems to be generated by the module.h file. As far as I can tell, the relevant parts are the same between my x86 system's module.h and the arm kernel header's module.h. Adding to my confusion, this problem is either not googleable (by me...) or hasn't happened to anyone before. Or I'm just doing something clueless that anyone with any sense wouldn't do. The cross-compiler I'm using was supplied by Freescale (I think). I suppose it could be a problem with the compiler. Would it be worth trying to build the toolchain myself? Obviously, since this is a warning, I could ignore it, but since it's so strange, I am worried about it, and would like to at least know the cause... Thanks very much, Sompom Here are the source files hello-1.mod.c #include <linux/module.h> #include <linux/vermagic.h> #include <linux/compiler.h> MODULE_INFO(vermagic, VERMAGIC_STRING); struct module __this_module __attribute__((section(".gnu.linkonce.this_module"))) = { .name = KBUILD_MODNAME, .init = init_module, #ifdef CONFIG_MODULE_UNLOAD .exit = cleanup_module, #endif .arch = MODULE_ARCH_INIT, }; static const struct modversion_info ____versions[] __used __attribute__((section("__versions"))) = { { 0x3972220f, "module_layout" }, { 0xefd6cf06, "__aeabi_unwind_cpp_pr0" }, { 0xea147363, "printk" }, }; static const char __module_depends[] __used __attribute__((section(".modinfo"))) = "depends="; hello-1.c (modified slightly from the given link) /* hello-1.c - The simplest kernel module. * * Copyright (C) 2001 by Peter Jay Salzman * * 08/02/2006 - Updated by Rodrigo Rubira Branco <[email protected]> */ /* Kernel Programming */ #ifndef MODULE #define MODULE #endif #ifndef LINUX #define LINUX #endif #ifndef __KERNEL__ #define __KERNEL__ #endif #include <linux/module.h> /* Needed by all modules */ #include <linux/kernel.h> /* Needed for KERN_ALERT */ static int hello_init_module(void) { printk(KERN_ALERT "Hello world 1.\n"); /* A non 0 return means init_module failed; module can't be loaded.*/ return 0; } static void hello_cleanup_module(void) { printk(KERN_ALERT "Goodbye world 1.\n"); } module_init(hello_init_module); module_exit(hello_cleanup_module); MODULE_LICENSE("GPL"); Makefile export ARCH:=arm export CCPREFIX:=/opt/freescale/usr/local/gcc-4.4.4-glibc-2.11.1-multilib-1.0/arm-fsl-linux-gnueabi/bin/arm-linux- export CROSS_COMPILE:=${CCPREFIX} TARGET := hello-1 WARN := -W -Wall -Wstrict-prototypes -Wmissing-prototypes -Wno-sign-compare -Wno-unused -Werror UNUSED_FLAGS := -std=c99 -pedantic EXTRA_CFLAGS := -O2 -DMODULE -D__KERNEL__ ${WARN} ${INCLUDE} KDIR ?= /home/developer/src/ltib-microsys/ltib/rpm/BUILD/linux-2.6.35.3 ifneq ($(KERNELRELEASE),) # kbuild part of makefile obj-m := $(TARGET).o else # normal makefile default: clean $(MAKE) -C $(KDIR) M=$$PWD .PHONY: clean clean: -rm built-in.o -rm $(TARGET).ko -rm $(TARGET).ko.unsigned -rm $(TARGET).mod.c -rm $(TARGET).mod.o -rm $(TARGET).o -rm modules.order -rm Module.symvers endif

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  • Following the Thread in OSB

    - by Antony Reynolds
    Threading in OSB The Scenario I recently led an OSB POC where we needed to get high throughput from an OSB pipeline that had the following logic: 1. Receive Request 2. Send Request to External System 3. If Response has a particular value   3.1 Modify Request   3.2 Resend Request to External System 4. Send Response back to Requestor All looks very straightforward and no nasty wrinkles along the way.  The flow was implemented in OSB as follows (see diagram for more details): Proxy Service to Receive Request and Send Response Request Pipeline   Copies Original Request for use in step 3 Route Node   Sends Request to External System exposed as a Business Service Response Pipeline   Checks Response to Check If Request Needs to Be Resubmitted Modify Request Callout to External System (same Business Service as Route Node) The Proxy and the Business Service were each assigned their own Work Manager, effectively giving each of them their own thread pool. The Surprise Imagine our surprise when, on stressing the system we saw it lock up, with large numbers of blocked threads.  The reason for the lock up is due to some subtleties in the OSB thread model which is the topic of this post.   Basic Thread Model OSB goes to great lengths to avoid holding on to threads.  Lets start by looking at how how OSB deals with a simple request/response routing to a business service in a route node. Most Business Services are implemented by OSB in two parts.  The first part uses the request thread to send the request to the target.  In the diagram this is represented by the thread T1.  After sending the request to the target (the Business Service in our diagram) the request thread is released back to whatever pool it came from.  A multiplexor (muxer) is used to wait for the response.  When the response is received the muxer hands off the response to a new thread that is used to execute the response pipeline, this is represented in the diagram by T2. OSB allows you to assign different Work Managers and hence different thread pools to each Proxy Service and Business Service.  In out example we have the “Proxy Service Work Manager” assigned to the Proxy Service and the “Business Service Work Manager” assigned to the Business Service.  Note that the Business Service Work Manager is only used to assign the thread to process the response, it is never used to process the request. This architecture means that while waiting for a response from a business service there are no threads in use, which makes for better scalability in terms of thread usage. First Wrinkle Note that if the Proxy and the Business Service both use the same Work Manager then there is potential for starvation.  For example: Request Pipeline makes a blocking callout, say to perform a database read. Business Service response tries to allocate a thread from thread pool but all threads are blocked in the database read. New requests arrive and contend with responses arriving for the available threads. Similar problems can occur if the response pipeline blocks for some reason, maybe a database update for example. Solution The solution to this is to make sure that the Proxy and Business Service use different Work Managers so that they do not contend with each other for threads. Do Nothing Route Thread Model So what happens if there is no route node?  In this case OSB just echoes the Request message as a Response message, but what happens to the threads?  OSB still uses a separate thread for the response, but in this case the Work Manager used is the Default Work Manager. So this is really a special case of the Basic Thread Model discussed above, except that the response pipeline will always execute on the Default Work Manager.   Proxy Chaining Thread Model So what happens when the route node is actually calling a Proxy Service rather than a Business Service, does the second Proxy Service use its own Thread or does it re-use the thread of the original Request Pipeline? Well as you can see from the diagram when a route node calls another proxy service then the original Work Manager is used for both request pipelines.  Similarly the response pipeline uses the Work Manager associated with the ultimate Business Service invoked via a Route Node.  This actually fits in with the earlier description I gave about Business Services and by extension Route Nodes they “… uses the request thread to send the request to the target”. Call Out Threading Model So what happens when you make a Service Callout to a Business Service from within a pipeline.  The documentation says that “The pipeline processor will block the thread until the response arrives asynchronously” when using a Service Callout.  What this means is that the target Business Service is called using the pipeline thread but the response is also handled by the pipeline thread.  This implies that the pipeline thread blocks waiting for a response.  It is the handling of this response that behaves in an unexpected way. When a Business Service is called via a Service Callout, the calling thread is suspended after sending the request, but unlike the Route Node case the thread is not released, it waits for the response.  The muxer uses the Business Service Work Manager to allocate a thread to process the response, but in this case processing the response means getting the response and notifying the blocked pipeline thread that the response is available.  The original pipeline thread can then continue to process the response. Second Wrinkle This leads to an unfortunate wrinkle.  If the Business Service is using the same Work Manager as the Pipeline then it is possible for starvation or a deadlock to occur.  The scenario is as follows: Pipeline makes a Callout and the thread is suspended but still allocated Multiple Pipeline instances using the same Work Manager are in this state (common for a system under load) Response comes back but all Work Manager threads are allocated to blocked pipelines. Response cannot be processed and so pipeline threads never unblock – deadlock! Solution The solution to this is to make sure that any Business Services used by a Callout in a pipeline use a different Work Manager to the pipeline itself. The Solution to My Problem Looking back at my original workflow we see that the same Business Service is called twice, once in a Routing Node and once in a Response Pipeline Callout.  This was what was causing my problem because the response pipeline was using the Business Service Work Manager, but the Service Callout wanted to use the same Work Manager to handle the responses and so eventually my Response Pipeline hogged all the available threads so no responses could be processed. The solution was to create a second Business Service pointing to the same location as the original Business Service, the only difference was to assign a different Work Manager to this Business Service.  This ensured that when the Service Callout completed there were always threads available to process the response because the response processing from the Service Callout had its own dedicated Work Manager. Summary Request Pipeline Executes on Proxy Work Manager (WM) Thread so limited by setting of that WM.  If no WM specified then uses WLS default WM. Route Node Request sent using Proxy WM Thread Proxy WM Thread is released before getting response Muxer is used to handle response Muxer hands off response to Business Service (BS) WM Response Pipeline Executes on Routed Business Service WM Thread so limited by setting of that WM.  If no WM specified then uses WLS default WM. No Route Node (Echo functionality) Proxy WM thread released New thread from the default WM used for response pipeline Service Callout Request sent using proxy pipeline thread Proxy thread is suspended (not released) until the response comes back Notification of response handled by BS WM thread so limited by setting of that WM.  If no WM specified then uses WLS default WM. Note this is a very short lived use of the thread After notification by callout BS WM thread that thread is released and execution continues on the original pipeline thread. Route/Callout to Proxy Service Request Pipeline of callee executes on requestor thread Response Pipeline of caller executes on response thread of requested proxy Throttling Request message may be queued if limit reached. Requesting thread is released (route node) or suspended (callout) So what this means is that you may get deadlocks caused by thread starvation if you use the same thread pool for the business service in a route node and the business service in a callout from the response pipeline because the callout will need a notification thread from the same thread pool as the response pipeline.  This was the problem we were having. You get a similar problem if you use the same work manager for the proxy request pipeline and a business service callout from that request pipeline. It also means you may want to have different work managers for the proxy and business service in the route node. Basically you need to think carefully about how threading impacts your proxy services. References Thanks to Jay Kasi, Gerald Nunn and Deb Ayers for helping to explain this to me.  Any errors are my own and not theirs.  Also thanks to my colleagues Milind Pandit and Prasad Bopardikar who travelled this road with me. OSB Thread Model Great Blog Post on Thread Usage in OSB

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  • Mass Ball-to-Ball Collision Handling (as in, lots of balls)

    - by BlueThen
    Update: Found out that I was using the radius as the diameter, which was why the mtd was overcompensating. Hi, StackOverflow. I've written a Processing program awhile back simulating ball physics. Basically, I have a large number of balls (1000), with gravity turned on. Detection works great, but my issue is that they start acting weird when they're bouncing against other balls in all directions. I'm pretty confident this involves the handling. For the most part, I'm using Jay Conrod's code. One part that's different is if (distance > 1.0) return; which I've changed to if (distance < 1.0) return; because the collision wasn't even being performed with the first bit of code, I'm guessing that's a typo. The balls overlap when I use his code, which isn't what I was looking for. My attempt to fix it was to move the balls to the edge of each other: float angle = atan2(y - collider.y, x - collider.x); float distance = dist(x,y, balls[ID2].x,balls[ID2].y); x = collider.x + radius * cos(angle); y = collider.y + radius * sin(angle); This isn't correct, I'm pretty sure of that. I tried the correction algorithm in the previous ball-to-ball topic: // get the mtd Vector2d delta = (position.subtract(ball.position)); float d = delta.getLength(); // minimum translation distance to push balls apart after intersecting Vector2d mtd = delta.multiply(((getRadius() + ball.getRadius())-d)/d); // resolve intersection -- // inverse mass quantities float im1 = 1 / getMass(); float im2 = 1 / ball.getMass(); // push-pull them apart based off their mass position = position.add(mtd.multiply(im1 / (im1 + im2))); ball.position = ball.position.subtract(mtd.multiply(im2 / (im1 + im2))); except my version doesn't use vectors, and every ball's weight is 1. The resulting code I get is this: PVector delta = new PVector(collider.x - x, collider.y - y); float d = delta.mag(); PVector mtd = new PVector(delta.x * ((radius + collider.radius - d) / d), delta.y * ((radius + collider.radius - d) / d)); // push-pull apart based on mass x -= mtd.x * 0.5; y -= mtd.y * 0.5; collider.x += mtd.x * 0.5; collider.y += mtd.y * 0.5; This code seems to over-correct collisions. Which doesn't make sense to me because in no other way do I modify the x and y values of each ball, other than this. Some other part of my code could be wrong, but I don't know. Here's the snippet of the entire ball-to-ball collision handling I'm using: if (alreadyCollided.contains(new Integer(ID2))) // if the ball has already collided with this, then we don't need to reperform the collision algorithm return; Ball collider = (Ball) objects.get(ID2); PVector collision = new PVector(x - collider.x, y - collider.y); float distance = collision.mag(); if (distance == 0) { collision = new PVector(1,0); distance = 1; } if (distance < 1) return; PVector velocity = new PVector(vx,vy); PVector velocity2 = new PVector(collider.vx, collider.vy); collision.div(distance); // normalize the distance float aci = velocity.dot(collision); float bci = velocity2.dot(collision); float acf = bci; float bcf = aci; vx += (acf - aci) * collision.x; vy += (acf - aci) * collision.y; collider.vx += (bcf - bci) * collision.x; collider.vy += (bcf - bci) * collision.y; alreadyCollided.add(new Integer(ID2)); collider.alreadyCollided.add(new Integer(ID)); PVector delta = new PVector(collider.x - x, collider.y - y); float d = delta.mag(); PVector mtd = new PVector(delta.x * ((radius + collider.radius - d) / d), delta.y * ((radius + collider.radius - d) / d)); // push-pull apart based on mass x -= mtd.x * 0.2; y -= mtd.y * 0.2; collider.x += mtd.x * 0.2; collider.y += mtd.y * 0.2; Thanks. (Apologies for lack of sources, stackoverflow thinks I'm a spammer)

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  • C++ Linked List - Reading data from a file with a sentinel

    - by Nick
    So I've done quite a bit of research on this and can't get my output to work correctly. I need to read in data from a file and have it stored into a Linked List. The while loop used should stop once it hits the $$$$$ sentinel. Then I am to display the data (by searching by ID Number[user input]) I am not that far yet I just want to properly display the data and get it read in for right now. My problem is when it displays the data is isn't stopping at the $$$$$ (even if I do "inFile.peek() != EOF and omit the $$$$$) I am still getting an extra garbage record. I know it has something to do with my while loop and how I am creating a new Node but I can't get it to work any other way. Any help would be appreciated. students.txt Nick J Cooley 324123 60 70 80 90 Jay M Hill 412254 70 80 90 100 $$$$$ assign6.h file #pragma once #include <iostream> #include <string> using namespace std; class assign6 { public: assign6(); // constructor void displayStudents(); private: struct Node { string firstName; string midIni; string lastName; int idNum; int sco1; //Test score 1 int sco2; //Test score 2 int sco3; //Test score 3 int sco4; //Test score 4 Node *next; }; Node *head; Node *headPtr; }; assign6Imp.cpp // Implementation File #include "assign6.h" #include <fstream> #include <iostream> #include <string> using namespace std; assign6::assign6() //constructor { ifstream inFile; inFile.open("students.txt"); head = NULL; head = new Node; headPtr = head; while (inFile.peek() != EOF) //reading in from file and storing in linked list { inFile >> head->firstName >> head->midIni >> head->lastName; inFile >> head->idNum; inFile >> head->sco1; inFile >> head->sco2; inFile >> head->sco3; inFile >> head->sco4; if (inFile != "$$$$$") { head->next = NULL; head->next = new Node; head = head->next; } } head->next = NULL; inFile.close(); } void assign6::displayStudents() { int average = 0; for (Node *cur = headPtr; cur != NULL; cur = cur->next) { cout << cur->firstName << " " << cur->midIni << " " << cur->lastName << endl; cout << cur->idNum << endl; average = (cur->sco1 + cur->sco2 + cur->sco3 + cur->sco4)/4; cout << cur->sco1 << " " << cur->sco2 << " " << cur->sco3 << " " << cur->sco4 << " " << "average: " << average << endl; } }

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