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• What happens if an asynchronous delegate call never returns?

  - by RichardHowells

  I found a decent looking example of how to call a delegate asynchronously with a timeout... http://www.eggheadcafe.com/tutorials/aspnet/847c94bf-4b8d-4a66-9ae5-5b61f049019f/basics-make-any-method-c.aspx. In summary it uses WaitOne with a timeout to determine if the call does not return before the timeout expires. I also know that you should have an EndInvoke to match each BeginInvoke. So what happens if the wait timeout expires? We (presumably) DON'T want to call EndInvoke as that will block. The code can go on to do 'other things', but have we leaked anything? Is there some poor thread someplace blocked waiting for a return that's never going to happen? Have we leaked some memory where the result-that-will-never-return was going to be placed?

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• How can I delete a row in the view only if the AJAX call & db deletion was successful?

  - by user1760663

  I have a table where each row has a button for deletion. Actually I delete the row everytime without checking if the ajax call was successfull. How can I achieve that, so that the row will only be deleted if the ajax call was ok. Here is my clickhandler on each row $("body").on('click', ".ui-icon-trash" ,function(){ var $closestTr = $(this).closest('tr'); // This will give the closest tr // If the class element is the child of tr deleteRowFromDB(oTable, closestTr); $closestTr.remove() ; // Will delete that }); And here my ajax call function deleteRowFromDB(oTable, sendallproperty){ var deleteEntryRoute = #{jsRoute @Application.deleteConfigurationEntry() /} console.log("route is: " + deleteEntryRoute.url) $.ajax({ url: deleteEntryRoute.url({id: sendallproperty}), type: deleteEntryRoute.method, data: 'id=' + sendallproperty });

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• How does a cmdlet know when it really should call WriteVerbose()?

  - by Roman Kuzmin

  How does a cmdlet know when it really should call WriteVerbose(), WriteDebug() and etc.? Perhaps I miss something simple but I cannot find the answer. All cmdlet implementations I have seen so far just call WriteVerbose() without any hesitation. I know that it is correct to do so, but it is not effective. Performance suffers when verbose mode is off but a cmdlet still prepares data for WriteVerbose() call, that is, for nothing. In other words, in a cmdlet I would like to be able to: if (<VerboseMode>) { .... data preparation, sometimes expensive ... WriteVerbose(...); } But I don't know how to get this if (<VerboseMode>). Any ideas?

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• Does the API call ExitProcess() work OK in VB6 if you follow the MS caveats?

  - by Clay Nichols

  Microsoft indicates that VB6 doesn't support ExitProcess (to exit and return a value). However, it indicates that this call can fail under certain circumstances (if a thread hasn't been completed, etc.) so I'm wondering whether this call will work OK (consistently :-) as long as you obey the caveats in the article. I could go a step further and call ExitProcess() from the Sub Main or Form which stared the app. Update: after some more reading (I really did research this a bit before asking ) I found a suggestion to use the TerminateProcess API instead. I'm investigating that option. Any thoughts?

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• How to develop asp.net web service to create the web method which can take the parameter of type win

  - by Shailesh Jaiswal

  I am developing asp.net web service. I am developing this web service so that OPC ( OLE for process control) client application can use it. In this web service I am using the built-in functions provided by the namespaces using OPC, using OPCDA, using OPCDA.NET. I have also added the namespace using System.Windows.Forms in this web service so that I can use the windows form control. In that we service I have created on web method which takes the parameter of type windows form control as given below. public void getOPCServerItems(TreeView tvServerItems, ListView lvBranchItems) { ArrayList ArrlstObj = new ArrayList(); ItemShowTreeList = OpcSrv.ShowBrowseTreeList(tvServerItems, lvBranchItems); ItemShowTreeList.BrowseModeOneLevel = true; // browse hierachy levels when selected. (default) ItemShowTreeList.Show(OpcSrv.ServerName); } In the above web method I need to pass the values to the built-in function ShowBrowseTreeList() (found in OPC, OPCDA, OPCDA.NET namespaces). This function takes the two parameter of windows form control type. These parameters are Treeview & ListView control of the windows form. In the above web method ShowBrowseTreeList() method automatically create the treeview & listview structure of the available items. Now as I am consuming the web service so I need to pass the values to the webmethod getOPCServerItems(). But as I my consuming application is asp.net application there is no such windows form control. In asp.net application there are also & control. I want to display The data returned in these asp.net controls rather than windows form control. I am not getting the way what should I need to do or how should I pass the values form my client application to this web service ? In the above method getOPCServerItems() when I use the parameter of type treeview & listview it generate s error "Cannot serialize member System.ComponentModel.Component.Site of type System.ComponentModel.ISite because it is an interface.". Can you provide me the the way In which I can write the above web method & how should I pass parameter to the Treeview & Listview control (windows form control) from my asp.net application ? which controls I should use to pass parameters ? Is there any need to do any type of casting ? Can you provide me the the code for above web method so that I can resolve the above issue ?

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• How do I convert this Crystal Report IF statement for use in a WHERE clause in Reporting Services?

  - by Spacehamster

  I'm trying to translate this Crystal Reports IF Statement for use in a WHERE clause - {@receipt_datetime_daylight} in {?DateRange} and (if {?Call Sign} = "All Call Signs" Then {cacs_incident_task.resource_or_class_id} = {cacs_incident_task.resource_or_class_id} Else If {?Call Sign} = "All Sierra Call Signs" Then {cacs_incident_task.resource_or_class_id} in ["S10", "S11", "S12"] Else If {?Call Sign} = "All Whiskey Call Signs" Then {cacs_incident_task.resource_or_class_id} in ["W01", "W02", "W03"] Else {cacs_incident_task.resource_or_class_id} = {?Call Sign}) and (if {?OffenceType} = "All Offences" Then {cacs_inc_type.description} = {cacs_inc_type.description} else {cacs_inc_type.description} = {?OffenceType}) CASE statements don't work in Reporting Services, so I need to find a why of translating this into a WHERE clause. Does anyone know a way?

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• Proxied calls not working as expected

  - by AndyH

  I have been modifying an application to have a cleaner client/server split to allow for load splitting and resource sharing etc. Everything is written to an interface so it was easy to add a remoting layer to the interface using a proxy. Everything worked fine. The next phase was to add a caching layer to the interface and again this worked fine and speed was improved but not as much as I would have expected. On inspection it became very clear what was going on. I feel sure that this behavior has been seen many times before and there is probably a design pattern to solve the problem but it eludes me and I'm not even sure how to describe it. It is easiest explained with an example. Let's imagine the interface is interface IMyCode { List<IThing> getLots( List<String> ); IThing getOne( String id ); } The getLots() method calls getOne() and fills up the list before returning. The interface is implemented at the client which is proxied to a remoting client which then calls the remoting server which in turn calls the implementation at the server. At the client and the server layers there is also a cache. So we have :- Client interface | Client cache | Remote client | Remote server | Server cache | Server interface If we call getOne("A") at the client interface, the call is passed to the client cache which faults. This then calls the remote client which passes the call to the remote server. This then calls the server cache which also faults and so the call is eventually passed to the server interface which actually gets the IThing. In turn the server cache is filled and finally the client cache also. If getOne("A") is again called at the client interface the client cache has the data and it gets returned immediately. If a second client called getOne("B") it would fill the server cache with "B" as well as it's own client cache. Then, when the first client calls getOne("B") the client cache faults but the server cache has the data. This is all as one would expect and works well. Now lets call getLots( [ "C", "D" ] ). This works as you would expect by calling getOne() twice but there is a subtlety here. The call to getLots() cannot directly make use of the cache. Therefore the sequence is to call the client interface which in turn calls the remote client, then the remote server and eventually the server interface. This then calls getOne() to fill the list before returning. The problem is that the getOne() calls are being satisfied at the server when ideally they should be satisfied at the client. If you imagine that the client/server link is really slow then it becomes clear why the client call is more efficient than the server call once the client cache has the data. This example is contrived to illustrate the point. The more general problem is that you cannot just keep adding proxied layers to an interface and expect it to work as you would imagine. As soon as the call goes 'through' the proxy any subsequent calls are on the proxied side rather than 'self' side. Have I failed to learn or not learned something correctly? All this is implemented in Java and I haven't used EJBs. It seems that the example may be confusing. The problem is nothing to do with cache efficiencies. It is more to do with an illusion created by the use of proxies or AOP techniques in general. When you have an object whose class implements an interface there is an assumption that a call on that object might make further calls on that same object. For example, public String getInternalString() { return InetAddress.getLocalHost().toString(); } public String getString() { return getInternalString(); } If you get an object and call getString() the result depends where the code is running. If you add a remoting proxy to the class then the result could be different for calls to getString() and getInternalString() on the same object. This is because the initial call gets 'deproxied' before the actual method is called. I find this not only confusing but I wonder how I can control this behavior especially as the use of the proxy may be by a third party. The concept is fine but the practice is certainly not what I expected. Have I missed the point somewhere?

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• java.lang.IllegalAccessException during Ant jwsc webservice build

  - by KevB

  Hi. I have a large application, part of which relies on a set of 3 webservices. I'm currently in the process of writing an Ant build script to build and package the application into an EAR file. When building the web sub-project for this application I use the <jwsc> task in Ant to compile the webservices. This causes an IllegalAccessException, as outlined in the stack trace below: [jwsc] warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=last; set to false for repeatable builds [jwsc] JWS: processing module weboutput [jwsc] Parsing source files [jwsc] Parsing source files [jwsc] 3 JWS files being processed for module weboutput [jwsc] JWS: C:\dev\ir\irWeb\src\webservices\DailyRun.java Validated. [jwsc] JWS: C:\dev\ir\irWeb\src\webservices\PendingRegistrationsSweep.java Validated. [jwsc] JWS: C:\dev\ir\irWeb\src\webservices\RegistrationsGoLive.java Validated. [jwsc] Compiling 6 source files to C:\DOCUME~1\KEVIN~1.BRE\LOCALS~1\Temp\_5l950r [jwsc] An exception has occurred in the compiler (1.6.0_23). Please file a bug at the Java Developer Connection (http://java.sun.com/webapps/bugreport) after checking the Bug Parade for duplicates. Include your program and the following diagnostic in your report. Thank you. [jwsc] java.lang.IllegalAccessError: tried to access class com.sun.tools.javac.jvm.ClassReader$AnnotationDefaultCompleter from class com.sun.tools.javac.jvm.ClassReader [jwsc] at com.sun.tools.javac.jvm.ClassReader.attachAnnotationDefault(ClassReader.java:1128) [jwsc] at com.sun.tools.javac.jvm.ClassReader.readMemberAttr(ClassReader.java:906) [jwsc] at com.sun.tools.javac.jvm.ClassReader.readMemberAttrs(ClassReader.java:1027) [jwsc] at com.sun.tools.javac.jvm.ClassReader.readMethod(ClassReader.java:1490) [jwsc] at com.sun.tools.javac.jvm.ClassReader.readClass(ClassReader.java:1586) [jwsc] at com.sun.tools.javac.jvm.ClassReader.readClassFile(ClassReader.java:1658) [jwsc] at com.sun.tools.javac.jvm.ClassReader.fillIn(ClassReader.java:1845) [jwsc] at com.sun.tools.javac.jvm.ClassReader.complete(ClassReader.java:1777) [jwsc] at com.sun.tools.javac.code.Symbol.complete(Symbol.java:386) [jwsc] at com.sun.tools.javac.code.Symbol$ClassSymbol.complete(Symbol.java:763) [jwsc] at com.sun.tools.javac.jvm.ClassReader.loadClass(ClassReader.java:1951) [jwsc] at com.sun.tools.javac.comp.Resolve.loadClass(Resolve.java:842) [jwsc] at com.sun.tools.javac.comp.Resolve.findIdentInPackage(Resolve.java:1011) [jwsc] at com.sun.tools.javac.comp.Attr.selectSym(Attr.java:1921) [jwsc] at com.sun.tools.javac.comp.Attr.visitSelect(Attr.java:1835) [jwsc] at com.sun.tools.javac.tree.JCTree$JCFieldAccess.accept(JCTree.java:1522) [jwsc] at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:360) [jwsc] at com.sun.tools.javac.comp.Attr.attribType(Attr.java:390) [jwsc] at com.sun.tools.javac.comp.MemberEnter.attribImportType(MemberEnter.java:681) [jwsc] at com.sun.tools.javac.comp.MemberEnter.visitImport(MemberEnter.java:545) [jwsc] at com.sun.tools.javac.tree.JCTree$JCImport.accept(JCTree.java:495) [jwsc] at com.sun.tools.javac.comp.MemberEnter.memberEnter(MemberEnter.java:387) [jwsc] at com.sun.tools.javac.comp.MemberEnter.memberEnter(MemberEnter.java:399) [jwsc] at com.sun.tools.javac.comp.MemberEnter.visitTopLevel(MemberEnter.java:512) [jwsc] at com.sun.tools.javac.tree.JCTree$JCCompilationUnit.accept(JCTree.java:446) [jwsc] at com.sun.tools.javac.comp.MemberEnter.memberEnter(MemberEnter.java:387) [jwsc] at com.sun.tools.javac.comp.MemberEnter.complete(MemberEnter.java:819) [jwsc] at com.sun.tools.javac.code.Symbol.complete(Symbol.java:386) [jwsc] at com.sun.tools.javac.code.Symbol$ClassSymbol.complete(Symbol.java:763) [jwsc] at com.sun.tools.javac.comp.Enter.complete(Enter.java:464) [jwsc] at com.sun.tools.javac.comp.Enter.main(Enter.java:442) [jwsc] at com.sun.tools.javac.main.JavaCompiler.enterTrees(JavaCompiler.java:819) [jwsc] at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:727) [jwsc] at com.sun.tools.javac.main.Main.compile(Main.java:353) [jwsc] at com.sun.tools.javac.main.Main.compile(Main.java:279) [jwsc] at com.sun.tools.javac.main.Main.compile(Main.java:270) [jwsc] at com.sun.tools.javac.Main.compile(Main.java:69) [jwsc] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [jwsc] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.taskdefs.compilers.Javac13.execute(Javac13.java:56) [jwsc] at org.apache.tools.ant.taskdefs.Javac.compile(Javac.java:1097) [jwsc] at weblogic.wsee.tools.anttasks.DelegatingJavacTask$ExposingJavac.compile(DelegatingJavacTask.java:343) [jwsc] at weblogic.wsee.tools.anttasks.DelegatingJavacTask.compile(DelegatingJavacTask.java:286) [jwsc] at weblogic.wsee.tools.anttasks.JwscTask.javac(JwscTask.java:335) [jwsc] at weblogic.wsee.tools.anttasks.JwsModule.compile(JwsModule.java:390) [jwsc] at weblogic.wsee.tools.anttasks.JwsModule.build(JwsModule.java:262) [jwsc] at weblogic.wsee.tools.anttasks.JwscTask.execute(JwscTask.java:227) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.Target.execute(Target.java:390) [jwsc] at org.apache.tools.ant.Target.performTasks(Target.java:411) [jwsc] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1397) [jwsc] at org.apache.tools.ant.helper.SingleCheckExecutor.executeTargets(SingleCheckExecutor.java:38) [jwsc] at org.apache.tools.ant.Project.executeTargets(Project.java:1249) [jwsc] at org.apache.tools.ant.taskdefs.Ant.execute(Ant.java:442) [jwsc] at org.apache.tools.ant.taskdefs.CallTarget.execute(CallTarget.java:105) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.Target.execute(Target.java:390) [jwsc] at org.apache.tools.ant.Target.performTasks(Target.java:411) [jwsc] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1397) [jwsc] at org.apache.tools.ant.Project.executeTarget(Project.java:1366) [jwsc] at com.bea.workshop.cmdline.antlib.AntExTask.execute(AntExTask.java:406) [jwsc] at com.bea.workshop.cmdline.antlib.AntCallExTask.execute(AntCallExTask.java:118) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.Target.execute(Target.java:390) [jwsc] at org.apache.tools.ant.Target.performTasks(Target.java:411) [jwsc] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1397) [jwsc] at org.apache.tools.ant.Project.executeTarget(Project.java:1366) [jwsc] at com.bea.workshop.cmdline.antlib.AntExTask.execute(AntExTask.java:406) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:68) [jwsc] at net.sf.antcontrib.logic.IfTask.execute(IfTask.java:217) [jwsc] at sun.reflect.GeneratedMethodAccessor44.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.TaskAdapter.execute(TaskAdapter.java:154) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:68) [jwsc] at net.sf.antcontrib.logic.IfTask.execute(IfTask.java:197) [jwsc] at sun.reflect.GeneratedMethodAccessor44.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.TaskAdapter.execute(TaskAdapter.java:154) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:68) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.taskdefs.MacroInstance.execute(MacroInstance.java:398) [jwsc] at net.sf.antcontrib.logic.ForTask.doSequentialIteration(ForTask.java:259) [jwsc] at net.sf.antcontrib.logic.ForTask.doToken(ForTask.java:268) [jwsc] at net.sf.antcontrib.logic.ForTask.doTheTasks(ForTask.java:299) [jwsc] at net.sf.antcontrib.logic.ForTask.execute(ForTask.java:244) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:68) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.taskdefs.MacroInstance.execute(MacroInstance.java:398) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.Target.execute(Target.java:390) [jwsc] at org.apache.tools.ant.Target.performTasks(Target.java:411) [jwsc] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1397) [jwsc] at org.apache.tools.ant.helper.SingleCheckExecutor.executeTargets(SingleCheckExecutor.java:38) [jwsc] at org.apache.tools.ant.Project.executeTargets(Project.java:1249) [jwsc] at org.apache.tools.ant.taskdefs.Ant.execute(Ant.java:442) [jwsc] at org.apache.tools.ant.taskdefs.CallTarget.execute(CallTarget.java:105) [jwsc] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291) [jwsc] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) [jwsc] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [jwsc] at java.lang.reflect.Method.invoke(Method.java:597) [jwsc] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106) [jwsc] at org.apache.tools.ant.Task.perform(Task.java:348) [jwsc] at org.apache.tools.ant.Target.execute(Target.java:390) [jwsc] at org.apache.tools.ant.Target.performTasks(Target.java:411) [jwsc] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1397) [jwsc] at org.apache.tools.ant.Project.executeTarget(Project.java:1366) [jwsc] at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41) [jwsc] at org.apache.tools.ant.Project.executeTargets(Project.java:1249) [jwsc] at org.apache.tools.ant.Main.runBuild(Main.java:801) [jwsc] at org.apache.tools.ant.Main.startAnt(Main.java:218) [jwsc] at org.apache.tools.ant.launch.Launcher.run(Launcher.java:280) [jwsc] at org.apache.tools.ant.launch.Launcher.main(Launcher.java:109) [AntUtil.deleteDir] Deleting directory C:\DOCUME~1\KEVIN~1.BRE\LOCALS~1\Temp_5l950r The Ant target that uses the <jwsc> task is this: <target name="webservice.build" depends="init,generated.root.init"> <path id="jwsc.srcpath"> <path path="${java.sourcepath}" /> <pathelement path="build/assembly/.src" /> </path> <taskdef name="jwsc" classname="weblogic.wsee.tools.anttasks.JwscTask" > <classpath> <path refid="weblogic.jar.classpath" /> </classpath> </taskdef> <property name="jwsc.module.root" value="${project.dir}/build/weboutput"/> <property name="jwsc.contextpath" value="irWeb"/> <property name="jwsc.srcpath.prop" refid="jwsc.srcpath"/> <path id="jwsc.classpath"> <path refid="weblogic.jar.classpath" /> <path refid="java.classpath" /> <pathelement path="${java.outpath}" /> </path> <jwsc destdir="${project.dir}/build" classpathref="jwsc.classpath"> <module name="weboutput" explode="true" contextPath="${jwsc.contextpath}" > <jwsFileSet srcdir="${webservices.dir}" type="JAXRPC"> <include name="**/*.java"/> </jwsFileSet> <descriptor file="${jwsc.module.root}/WEB-INF/web.xml" /> <descriptor file="${jwsc.module.root}/WEB-INF/weblogic.xml" /> </module> </jwsc> </target> I have no idea what could be causing the compiler to throw this error at build time, and a day of google searching has turned up other instances of this error caused by different triggers, and solutions for those propblems didn't work for me. I also found a single report on the Oracle forums that seemed to be a carbon copy of this issue, but there were no replies. The application is written in Weblogic Workshop 10, runs on Weblogic Server 10.3, and uses Beehive / NetUI. Not sure if that would make a difference or not though. The build scripts were automatically generated by Weblogic Workshop, with some tweaks and fixes made to other aspects of the files by myself to fix other compatability issues. I am using Java 1.6.0_23 from Sun, and Ant 1.8.1 Any help or advice would be greatly appreciated.

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• is it right to call ejb bean from thread by ThreadPoolExecutor?

  - by kislo_metal

  I trying to call some ejb bean method from tread. and getting error : (as is glassfish v3) Log Level SEVERE Logger javax.enterprise.system.std.com.sun.enterprise.v3.services.impl Name-Value Pairs {_ThreadName=Thread-1, _ThreadID=42} Record Number 928 Message ID java.lang.NullPointerException at ua.co.rufous.server.broker.TempLicService.run(TempLicService.java Complete Message 35) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:637) here is tread public class TempLicService implements Runnable { String hash; //it`s Stateful bean @EJB private LicActivatorLocal lActivator; public TempLicService(String hash) { this.hash= hash; } @Override public void run() { lActivator.proccessActivation(hash); } } my ThreadPoolExecutor public class RequestThreadPoolExecutor extends ThreadPoolExecutor { private boolean isPaused; private ReentrantLock pauseLock = new ReentrantLock(); private Condition unpaused = pauseLock.newCondition(); private static RequestThreadPoolExecutor threadPool; private RequestThreadPoolExecutor() { super(1, Integer.MAX_VALUE, 10, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); System.out.println("RequestThreadPoolExecutor created"); } public static RequestThreadPoolExecutor getInstance() { if (threadPool == null) threadPool = new RequestThreadPoolExecutor(); return threadPool; } public void runService(Runnable task) { threadPool.execute(task); } protected void beforeExecute(Thread t, Runnable r) { super.beforeExecute(t, r); pauseLock.lock(); try { while (isPaused) unpaused.await(); } catch (InterruptedException ie) { t.interrupt(); } finally { pauseLock.unlock(); } } public void pause() { pauseLock.lock(); try { isPaused = true; } finally { pauseLock.unlock(); } } public void resume() { pauseLock.lock(); try { isPaused = false; unpaused.signalAll(); } finally { pauseLock.unlock(); } } public void shutDown() { threadPool.shutdown(); } //<<<<<< creating thread here public void runByHash(String hash) { Runnable service = new TempLicService(hash); threadPool.runService(service); } } and method where i call it (it is gwt servlet, but there is no proble to call thread that not contain ejb) : @Override public Boolean submitHash(String hash) { System.out.println("submiting hash"); try { if (tBoxService.getTempLicStatus(hash) == 1) { //<<< here is the call RequestThreadPoolExecutor.getInstance().runByHash(hash); return true; } } catch (NoResultException e) { e.printStackTrace(); } return false; } I need to organize some pool of submitting hash to server (calls of LicActivator bean), is ThreadPoolExecutor design good idea and why it is not working in my case? (as I know we can`t create thread inside bean, but could we call bean from different threads? ). If No, what is the bast practice for organize such request pool? Thanks. << Answer: I am using DI (EJB 3.1) soo i do not need any look up here. (application packed in ear and both modules in it (web module and ejb), it works perfect for me). But I can use it only in managed classes. So.. 2.Can I use manual look up in Tread ? Could I use Bean that extends ThreadPoolExecutor and calling another bean that implements Runnable ? Or it is not allowed ?

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• Problem in creation MDB Queue connection at Jboss StartUp

  - by Amit Ruwali

  I am not able to create a Queue connection in JBOSS4.2.3GA Version & Java1.5, as I am using MDB as per the below details. I am putting this MDB in a jar file(named utsJar.jar) and copied it in deploy folder of JBOSS, In the test env. this MDB works well but in another env. [ env settings and jboss/java ver is same ] it is throwing error at jboss start up [attached below ]. I have searched for this error but couldn't find any solution till now; was there any issue of port confict or something related with configurations ? UTSMessageListner.java @MessageDriven(activationConfig = { @ActivationConfigProperty(propertyName="destinationType", propertyValue="javax.jms.Queue"), @ActivationConfigProperty(propertyName="destination", propertyValue="queue/UTSQueue") }) @TransactionAttribute(TransactionAttributeType.NOT_SUPPORTED) public class UTSMessageListner implements MessageListener { public void onMessage(Message msg) { ObjectMessage objmsg = (ObjectMessage) msg; try { UTSListVO utsMessageListVO = (UTSListVO) objmsg.getObject(); if(utsMessageListVO.getUtsMessageList()!=null) { UtsWebServiceLogger.logMessage("UTSMessageListner:onMessage: SIZE Of UTSMessage List =[" +utsMessageListVO.getUtsMessageList().size() + "]"); UTSDataLayerImpl.getInstance().insertUTSMessage(utsMessageListVO); } else { UtsWebServiceLogger.logMessage("UTSMessageListner:onMessage: Message List is NULL"); } } catch (Exception ex) { UtsWebServiceLogger.logMessage("UTSMessageListner:onMessage: Error Receiving Message"+ExceptionUtility.getStackTrace(ex)); } } } [ I have also attached whole server.log as an attach] /// ///////////////////////////////// Error Trace is Below while starting the server /////////////////////////// 2010-03-12 07:05:40,061 WARN [org.jboss.ejb3.mdb.MessagingContainer] Could not find the queue destination-jndi-name=queue/UTSQueue 2010-03-12 07:05:40,061 WARN [org.jboss.ejb3.mdb.MessagingContainer] destination not found: queue/UTSQueue reason: javax.naming.NameNotFoundException: queue not bound 2010-03-12 07:05:40,061 WARN [org.jboss.ejb3.mdb.MessagingContainer] creating a new temporary destination: queue/UTSQueue 2010-03-12 07:05:40,071 WARN [org.jboss.system.ServiceController] Problem starting service jboss.j2ee:ear=uts.ear,jar=utsJar.jar,name=UTSMessageListner,service=EJB3 java.lang.NullPointerException at org.jboss.mq.server.jmx.DestinationManager.createDestination(DestinationManager.java:336) at org.jboss.mq.server.jmx.DestinationManager.createQueue(DestinationManager.java:293) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.server.Invocation.invoke(Invocation.java:86) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.ejb3.JmxClientKernelAbstraction.invoke(JmxClientKernelAbstraction.java:44) at org.jboss.ejb3.jms.DestinationManagerJMSDestinationFactory.createDestination(DestinationManagerJMSDestinationFactory.java:75) at org.jboss.ejb3.mdb.MessagingContainer.createTemporaryDestination(MessagingContainer.java:573) at org.jboss.ejb3.mdb.MessagingContainer.createDestination(MessagingContainer.java:512) at org.jboss.ejb3.mdb.MessagingContainer.innerCreateQueue(MessagingContainer.java:438) at org.jboss.ejb3.mdb.MessagingContainer.jmsCreate(MessagingContainer.java:400) at org.jboss.ejb3.mdb.MessagingContainer.innerStart(MessagingContainer.java:166) at org.jboss.ejb3.mdb.MessagingContainer.start(MessagingContainer.java:152) at org.jboss.ejb3.mdb.MDB.start(MDB.java:126) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.ejb3.ServiceDelegateWrapper.startService(ServiceDelegateWrapper.java:103) at org.jboss.system.ServiceMBeanSupport.jbossInternalStart(ServiceMBeanSupport.java:289) at org.jboss.system.ServiceMBeanSupport.jbossInternalLifecycle(ServiceMBeanSupport.java:245) at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.server.Invocation.invoke(Invocation.java:86) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.system.ServiceController$ServiceProxy.invoke(ServiceController.java:978) at $Proxy0.start(Unknown Source) at org.jboss.system.ServiceController.start(ServiceController.java:417) at sun.reflect.GeneratedMethodAccessor10.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.server.Invocation.invoke(Invocation.java:86) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:210) at $Proxy53.start(Unknown Source) at org.jboss.ejb3.JmxKernelAbstraction.install(JmxKernelAbstraction.java:120) at org.jboss.ejb3.Ejb3Deployment.registerEJBContainer(Ejb3Deployment.java:301) at org.jboss.ejb3.Ejb3Deployment.start(Ejb3Deployment.java:362) at org.jboss.ejb3.Ejb3Module.startService(Ejb3Module.java:91) at org.jboss.system.ServiceMBeanSupport.jbossInternalStart(ServiceMBeanSupport.java:289) at org.jboss.system.ServiceMBeanSupport.jbossInternalLifecycle(ServiceMBeanSupport.java:245) at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.server.Invocation.invoke(Invocation.java:86) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.system.ServiceController$ServiceProxy.invoke(ServiceController.java:978) at $Proxy0.start(Unknown Source) at org.jboss.system.ServiceController.start(ServiceController.java:417) at sun.reflect.GeneratedMethodAccessor10.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.server.Invocation.invoke(Invocation.java:86) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:210) at $Proxy33.start(Unknown Source) at org.jboss.ejb3.EJB3Deployer.start(EJB3Deployer.java:512) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.interceptor.AbstractInterceptor.invoke(AbstractInterceptor.java:133) at org.jboss.mx.server.Invocation.invoke(Invocation.java:88) at org.jboss.mx.interceptor.ModelMBeanOperationInterceptor.invoke(ModelMBeanOperationInterceptor.java:142) at org.jboss.mx.interceptor.DynamicInterceptor.invoke(DynamicInterceptor.java:97) at org.jboss.system.InterceptorServiceMBeanSupport.invokeNext(InterceptorServiceMBeanSupport.java:238) at org.jboss.wsf.container.jboss42.DeployerInterceptor.start(DeployerInterceptor.java:87) at org.jboss.deployment.SubDeployerInterceptorSupport$XMBeanInterceptor.start(SubDeployerInterceptorSupport.java:188) at org.jboss.deployment.SubDeployerInterceptor.invoke(SubDeployerInterceptor.java:95) at org.jboss.mx.server.Invocation.invoke(Invocation.java:88) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:210) at $Proxy34.start(Unknown Source) at org.jboss.deployment.MainDeployer.start(MainDeployer.java:1025) at org.jboss.deployment.MainDeployer.start(MainDeployer.java:1015) at org.jboss.deployment.MainDeployer.deploy(MainDeployer.java:819) at org.jboss.deployment.MainDeployer.deploy(MainDeployer.java:782) at sun.reflect.GeneratedMethodAccessor20.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.interceptor.AbstractInterceptor.invoke(AbstractInterceptor.java:133) at org.jboss.mx.server.Invocation.invoke(Invocation.java:88) at org.jboss.mx.interceptor.ModelMBeanOperationInterceptor.invoke(ModelMBeanOperationInterceptor.java:142) at org.jboss.mx.server.Invocation.invoke(Invocation.java:88) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:210) at $Proxy9.deploy(Unknown Source) at org.jboss.deployment.scanner.URLDeploymentScanner.deploy(URLDeploymentScanner.java:421) at org.jboss.deployment.scanner.URLDeploymentScanner.scan(URLDeploymentScanner.java:634) at org.jboss.deployment.scanner.AbstractDeploymentScanner$ScannerThread.doScan(AbstractDeploymentScanner.java:263) at org.jboss.deployment.scanner.AbstractDeploymentScanner.startService(AbstractDeploymentScanner.java:336) at org.jboss.system.ServiceMBeanSupport.jbossInternalStart(ServiceMBeanSupport.java:289) at org.jboss.system.ServiceMBeanSupport.jbossInternalLifecycle(ServiceMBeanSupport.java:245) at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.server.Invocation.invoke(Invocation.java:86) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.system.ServiceController$ServiceProxy.invoke(ServiceController.java:978) at $Proxy0.start(Unknown Source) at org.jboss.system.ServiceController.start(ServiceController.java:417) at sun.reflect.GeneratedMethodAccessor10.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.server.Invocation.invoke(Invocation.java:86) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:210) at $Proxy4.start(Unknown Source) at org.jboss.deployment.SARDeployer.start(SARDeployer.java:304) at org.jboss.deployment.MainDeployer.start(MainDeployer.java:1025) at org.jboss.deployment.MainDeployer.deploy(MainDeployer.java:819) at org.jboss.deployment.MainDeployer.deploy(MainDeployer.java:782) at org.jboss.deployment.MainDeployer.deploy(MainDeployer.java:766) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155) at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94) at org.jboss.mx.interceptor.AbstractInterceptor.invoke(AbstractInterceptor.java:133) at org.jboss.mx.server.Invocation.invoke(Invocation.java:88) at org.jboss.mx.interceptor.ModelMBeanOperationInterceptor.invoke(ModelMBeanOperationInterceptor.java:142) at org.jboss.mx.server.Invocation.invoke(Invocation.java:88) at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659) at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:210) at $Proxy5.deploy(Unknown Source) at org.jboss.system.server.ServerImpl.doStart(ServerImpl.java:482) at org.jboss.system.server.ServerImpl.start(ServerImpl.java:362) at org.jboss.Main.boot(Main.java:200) at org.jboss.Main$1.run(Main.java:508) at java.lang.Thread.run(Thread.java:595)

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• Several ways to call a windows batch file from another one or from prompt. Which one in which case?

  - by dim

  A windows batch file (called.bat or called.cmd) can be called from another batch file (caller.bat or caller.cmd) or interactive cmd.exe prompt in several ways: direct call: called.bat using call command: call called.bat using cmd command: cmd /c called.bat using start command: start called.bat I'm quite in trouble to differentiate their intended usage based on their help text: when to use which one? e.g. why I might use 'call' command instead of direct call. What's different? I'm interested on some summary report that analyze all 4 possibilities (and others if any missing) from various point of views: recommended use cases for which they are designed to fit, process spawning, execution context, environment, return code processing. Note: I'm using Windows XP SP3.

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• Java: Cannot find a method's symbol even though that method is declared later in the class. The remaining code is looking for a class.

  - by Midimistro

  This is an assignment that we use strings in Java to analyze a phone number. The error I am having is anything below tester=invalidCharacters(c); does not compile because every line past tester=invalidCharacters(c); is looking for a symbol or the class. In get invalidResults, all I am trying to do is evaluate a given string for non-alphabetical characters such as *,(,^,&,%,@,#,), and so on. What to answer: Why is it producing an error, what will work, and is there an easier method WITHOUT using regex. Here is the link to the assignment: http://cis.csuohio.edu/~hwang/teaching/cis260/assignments/assignment9.html public class PhoneNumber { private int areacode; private int number; private int ext; /////Constructors///// //Third Constructor (given one string arg) "xxx-xxxxxxx" where first three are numbers and the remaining (7) are numbers or letters public PhoneNumber(String newNumber){ //Note: Set default ext to 0 ext=0; ////Declare Temporary Storage and other variables//// //for the first three numbers String areaCodeString; //for the remaining seven characters String newNumberString; //For use in testing the second half of the string boolean containsLetters; boolean containsInvalid; /////Separate the two parts of string///// //Get the area code part of the string areaCodeString=newNumber.substring(0,2); //Convert the string and set it to the area code areacode=Integer.parseInt(areaCodeString); //Skip the "-" and Get the remaining part of the string newNumberString=newNumber.substring(4); //Create an array of characters from newNumberString to reuse in later methods for int length=newNumberString.length(); char [] myCharacters= new char [length]; int i; for (i=0;i<length;i++){ myCharacters [i]=newNumberString.charAt(i); } //Test if newNumberString contains letters & converting them into numbers String reNewNumber=""; //Test for invalid characters containsInvalid=getInvalidResults(newNumberString,length); if (containsInvalid==false){ containsLetters=getCharResults(newNumberString,length); if (containsLetters==true){ for (i=0;i<length;i++){ myCharacters [i]=(char)convertLetNum((myCharacters [i])); reNewNumber=reNewNumber+myCharacters[i]; } } } if (containsInvalid==false){ number=Integer.parseInt(reNewNumber); } else{ System.out.println("Error!"+"\t"+newNumber+" contains illegal characters. This number will be ignored and skipped."); } } //////Primary Methods/Behaviors/////// //Compare this phone number with the one passed by the caller public boolean equals(PhoneNumber pn){ boolean equal; String concat=(areacode+"-"+number); String pN=pn.toString(); if (concat==pN){ equal=true; } else{ equal=false; } return equal; } //Convert the stored number to a certain string depending on extension public String toString(){ String returned; if(ext==0){ returned=(areacode+"-"+number); } else{ returned=(areacode+"-"+number+" ext "+ext); } return returned; } //////Secondary Methods/////// //Method for testing if the second part of the string contains any letters public static boolean getCharResults(String newNumString,int getLength){ //Recreate a character array int i; char [] myCharacters= new char [getLength]; for (i=0;i<getLength;i++){ myCharacters [i]=newNumString.charAt(i); } boolean doesContainLetter=false; int j; for (j=0;j<getLength;j++){ if ((Character.isDigit(myCharacters[j])==true)){ doesContainLetter=false; } else{ doesContainLetter=true; return doesContainLetter; } } return doesContainLetter; } //Method for testing if the second part of the string contains any letters public static boolean getInvalidResults(String newNumString,int getLength){ boolean doesContainInvalid=false; int i; char c; boolean tester; char [] invalidCharacters= new char [getLength]; for (i=0;i<getLength;i++){ invalidCharacters [i]=newNumString.charAt(i); c=invalidCharacters [i]; tester=invalidCharacters(c); if(tester==true)){ doesContainInvalid=false; } else{ doesContainInvalid=true; return doesContainInvalid; } } return doesContainInvalid; } //Method for evaluating string for invalid characters public boolean invalidCharacters(char letter){ boolean returnNum=false; switch (letter){ case 'A': return returnNum; case 'B': return returnNum; case 'C': return returnNum; case 'D': return returnNum; case 'E': return returnNum; case 'F': return returnNum; case 'G': return returnNum; case 'H': return returnNum; case 'I': return returnNum; case 'J': return returnNum; case 'K': return returnNum; case 'L': return returnNum; case 'M': return returnNum; case 'N': return returnNum; case 'O': return returnNum; case 'P': return returnNum; case 'Q': return returnNum; case 'R': return returnNum; case 'S': return returnNum; case 'T': return returnNum; case 'U': return returnNum; case 'V': return returnNum; case 'W': return returnNum; case 'X': return returnNum; case 'Y': return returnNum; case 'Z': return returnNum; default: return true; } } //Method for converting letters to numbers public int convertLetNum(char letter){ int returnNum; switch (letter){ case 'A': returnNum=2;return returnNum; case 'B': returnNum=2;return returnNum; case 'C': returnNum=2;return returnNum; case 'D': returnNum=3;return returnNum; case 'E': returnNum=3;return returnNum; case 'F': returnNum=3;return returnNum; case 'G': returnNum=4;return returnNum; case 'H': returnNum=4;return returnNum; case 'I': returnNum=4;return returnNum; case 'J': returnNum=5;return returnNum; case 'K': returnNum=5;return returnNum; case 'L': returnNum=5;return returnNum; case 'M': returnNum=6;return returnNum; case 'N': returnNum=6;return returnNum; case 'O': returnNum=6;return returnNum; case 'P': returnNum=7;return returnNum; case 'Q': returnNum=7;return returnNum; case 'R': returnNum=7;return returnNum; case 'S': returnNum=7;return returnNum; case 'T': returnNum=8;return returnNum; case 'U': returnNum=8;return returnNum; case 'V': returnNum=8;return returnNum; case 'W': returnNum=9;return returnNum; case 'X': returnNum=9;return returnNum; case 'Y': returnNum=9;return returnNum; case 'Z': returnNum=9;return returnNum; default: return 0; } } } Note: Please Do not use this program to cheat in your own class. To ensure of this, I will take this question down if it has not been answered by the end of 2013, if I no longer need an explanation for it, or if the term for the class has ended.

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• ActionResult types in MVC2

  - by rajbk

  In ASP.NET MVC, incoming browser requests gets mapped to a controller action method. The action method returns a type of ActionResult in response to the browser request. A basic example is shown below: public class HomeController : Controller { public ActionResult Index() { return View(); } } Here we have an action method called Index that returns an ActionResult. Inside the method we call the View() method on the base Controller. The View() method, as you will see shortly, is a method that returns a ViewResult. The ActionResult class is the base class for different controller results. The following diagram shows the types derived from the ActionResult type. ASP.NET has a description of these methods ContentResult – Represents a text result. EmptyResult – Represents no result. FileContentResult – Represents a downloadable file (with the binary content). FilePathResult – Represents a downloadable file (with a path). FileStreamResult – Represents a downloadable file (with a file stream). JavaScriptResult – Represents a JavaScript script. JsonResult – Represents a JavaScript Object Notation result that can be used in an AJAX application. PartialViewResult – Represents HTML and markup rendered by a partial view. RedirectResult – Represents a redirection to a new URL. RedirectToRouteResult – Represents a result that performs a redirection by using the specified route values dictionary. ViewResult – Represents HTML and markup rendered by a view. To return the types shown above, you call methods that are available in the Controller base class. A list of these methods are shown below.   Methods without an ActionResult return type The MVC framework will translate action methods that do not return an ActionResult into one. Consider the HomeController below which has methods that do not return any ActionResult types. The methods defined return an int, object and void respectfully. public class HomeController : Controller { public int Add(int x, int y) { return x + y; }   public Employee GetEmployee() { return new Employee(); }   public void DoNothing() { } } When a request comes in, the Controller class hands internally uses a ControllerActionInvoker class which inspects the action parameters and invokes the correct action method. The CreateActionResult method in the ControllerActionInvoker class is used to return an ActionResult. This method is shown below. If the result of the action method is null, an EmptyResult instance is returned. If the result is not of type ActionResult, the result is converted to a string and returned as a ContentResult. protected virtual ActionResult CreateActionResult(ControllerContext controllerContext, ActionDescriptor actionDescriptor, object actionReturnValue) { if (actionReturnValue == null) { return new EmptyResult(); }   ActionResult actionResult = (actionReturnValue as ActionResult) ?? new ContentResult { Content = Convert.ToString(actionReturnValue, CultureInfo.InvariantCulture) }; return actionResult; }   In the HomeController class above, the DoNothing method will return an instance of the EmptyResult() Renders an empty webpage the GetEmployee() method will return a ContentResult which contains a string that represents the current object Renders the text “MyNameSpace.Controllers.Employee” without quotes. the Add method for a request of /home/add?x=3&y=5 returns a ContentResult Renders the text “8” without quotes. Unit Testing The nice thing about the ActionResult types is in unit testing the controller. We can, without starting a web server, create an instance of the Controller, call the methods and verify that the type returned is the expected ActionResult type. We can then inspect the returned type properties and confirm that it contains the expected values. Enjoy! Sulley: Hey, Mike, this might sound crazy but I don't think that kid's dangerous. Mike: Really? Well, in that case, let's keep it. I always wanted a pet that could kill me.

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• Optional Parameters and Named Arguments in C# 4 (and a cool scenario w/ ASP.NET MVC 2)

  - by ScottGu

  [In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] This is the seventeenth in a series of blog posts I’m doing on the upcoming VS 2010 and .NET 4 release. Today’s post covers two new language feature being added to C# 4.0 – optional parameters and named arguments – as well as a cool way you can take advantage of optional parameters (both in VB and C#) with ASP.NET MVC 2. Optional Parameters in C# 4.0 C# 4.0 now supports using optional parameters with methods, constructors, and indexers (note: VB has supported optional parameters for awhile). Parameters are optional when a default value is specified as part of a declaration.  For example, the method below takes two parameters – a “category” string parameter, and a “pageIndex” integer parameter.  The “pageIndex” parameter has a default value of 0, and as such is an optional parameter: When calling the above method we can explicitly pass two parameters to it: Or we can omit passing the second optional parameter – in which case the default value of 0 will be passed:   Note that VS 2010’s Intellisense indicates when a parameter is optional, as well as what its default value is when statement completion is displayed: Named Arguments and Optional Parameters in C# 4.0 C# 4.0 also now supports the concept of “named arguments”.  This allows you to explicitly name an argument you are passing to a method – instead of just identifying it by argument position.  For example, I could write the code below to explicitly identify the second argument passed to the GetProductsByCategory method by name (making its usage a little more explicit): Named arguments come in very useful when a method supports multiple optional parameters, and you want to specify which arguments you are passing.  For example, below we have a method DoSomething that takes two optional parameters: We could use named arguments to call the above method in any of the below ways: Because both parameters are optional, in cases where only one (or zero) parameters is specified then the default value for any non-specified arguments is passed. ASP.NET MVC 2 and Optional Parameters One nice usage scenario where we can now take advantage of the optional parameter support of VB and C# is with ASP.NET MVC 2’s input binding support to Action methods on Controller classes. For example, consider a scenario where we want to map URLs like “Products/Browse/Beverages” or “Products/Browse/Deserts” to a controller action method.  We could do this by writing a URL routing rule that maps the URLs to a method like so: We could then optionally use a “page” querystring value to indicate whether or not the results displayed by the Browse method should be paged – and if so which page of the results should be displayed.  For example: /Products/Browse/Beverages?page=2. With ASP.NET MVC 1 you would typically handle this scenario by adding a “page” parameter to the action method and make it a nullable int (which means it will be null if the “page” querystring value is not present).  You could then write code like below to convert the nullable int to an int – and assign it a default value if it was not present in the querystring: With ASP.NET MVC 2 you can now take advantage of the optional parameter support in VB and C# to express this behavior more concisely and clearly.  Simply declare the action method parameter as an optional parameter with a default value: C# VB If the “page” value is present in the querystring (e.g. /Products/Browse/Beverages?page=22) then it will be passed to the action method as an integer.  If the “page” value is not in the querystring (e.g. /Products/Browse/Beverages) then the default value of 0 will be passed to the action method.  This makes the code a little more concise and readable. Summary There are a bunch of great new language features coming to both C# and VB with VS 2010.  The above two features (optional parameters and named parameters) are but two of them.  I’ll blog about more in the weeks and months ahead. If you are looking for a good book that summarizes all the language features in C# (including C# 4.0), as well provides a nice summary of the core .NET class libraries, you might also want to check out the newly released C# 4.0 in a Nutshell book from O’Reilly: It does a very nice job of packing a lot of content in an easy to search and find samples format. Hope this helps, Scott

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• Fed Authentication Methods in OIF / IdP

  - by Damien Carru

  This article is a continuation of my previous entry where I explained how OIF/IdP leverages OAM to authenticate users at runtime: OIF/IdP internally forwards the user to OAM and indicates which Authentication Scheme should be used to challenge the user if needed OAM determine if the user should be challenged (user already authenticated, session timed out or not, session authentication level equal or higher than the level of the authentication scheme specified by OIF/IdP…) After identifying the user, OAM internally forwards the user back to OIF/IdP OIF/IdP can resume its operation In this article, I will discuss how OIF/IdP can be configured to map Federation Authentication Methods to OAM Authentication Schemes: When processing an Authn Request, where the SP requests a specific Federation Authentication Method with which the user should be challenged When sending an Assertion, where OIF/IdP sets the Federation Authentication Method in the Assertion Enjoy the reading! Overview The various Federation protocols support mechanisms allowing the partners to exchange information on: How the user should be challenged, when the SP/RP makes a request How the user was challenged, when the IdP/OP issues an SSO response When a remote SP partner redirects the user to OIF/IdP for Federation SSO, the message might contain data requesting how the user should be challenged by the IdP: this is treated as the Requested Federation Authentication Method. OIF/IdP will need to map that Requested Federation Authentication Method to a local Authentication Scheme, and then invoke OAM for user authentication/challenge with the mapped Authentication Scheme. OAM would authenticate the user if necessary with the scheme specified by OIF/IdP. Similarly, when an IdP issues an SSO response, most of the time it will need to include an identifier representing how the user was challenged: this is treated as the Federation Authentication Method. When OIF/IdP issues an Assertion, it will evaluate the Authentication Scheme with which OAM identified the user: If the Authentication Scheme can be mapped to a Federation Authentication Method, then OIF/IdP will use the result of that mapping in the outgoing SSO response: AuthenticationStatement in the SAML Assertion OpenID Response, if PAPE is enabled If the Authentication Scheme cannot be mapped, then OIF/IdP will set the Federation Authentication Method as the Authentication Scheme name in the outgoing SSO response: AuthenticationStatement in the SAML Assertion OpenID Response, if PAPE is enabled Mappings In OIF/IdP, the mapping between Federation Authentication Methods and Authentication Schemes has the following rules: One Federation Authentication Method can be mapped to several Authentication Schemes In a Federation Authentication Method <-> Authentication Schemes mapping, a single Authentication Scheme is marked as the default scheme that will be used to authenticate a user, if the SP/RP partner requests the user to be authenticated via a specific Federation Authentication Method An Authentication Scheme can be mapped to a single Federation Authentication Method Let’s examine the following example and the various use cases, based on the SAML 2.0 protocol: Mappings defined as: urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport mapped to LDAPScheme, marked as the default scheme used for authentication BasicScheme urn:oasis:names:tc:SAML:2.0:ac:classes:X509 mapped to X509Scheme, marked as the default scheme used for authentication Use cases: SP sends an AuthnRequest specifying urn:oasis:names:tc:SAML:2.0:ac:classes:X509 as the RequestedAuthnContext: OIF/IdP will authenticate the use with X509Scheme since it is the default scheme mapped for that method. SP sends an AuthnRequest specifying urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport as the RequestedAuthnContext: OIF/IdP will authenticate the use with LDAPScheme since it is the default scheme mapped for that method, not the BasicScheme SP did not request any specific methods, and user was authenticated with BasisScheme: OIF/IdP will issue an Assertion with urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport as the FederationAuthenticationMethod SP did not request any specific methods, and user was authenticated with LDAPScheme: OIF/IdP will issue an Assertion with urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport as the FederationAuthenticationMethod SP did not request any specific methods, and user was authenticated with BasisSessionlessScheme: OIF/IdP will issue an Assertion with BasisSessionlessScheme as the FederationAuthenticationMethod, since that scheme could not be mapped to any Federation Authentication Method (in this case, the administrator would need to correct that and create a mapping) Configuration Mapping Federation Authentication Methods to OAM Authentication Schemes is protocol dependent, since the methods are defined in the various protocols (SAML 2.0, SAML 1.1, OpenID 2.0). As such, the WLST commands to set those mappings will involve: Either the SP Partner Profile and affect all Partners referencing that profile, which do not override the Federation Authentication Method to OAM Authentication Scheme mappings Or the SP Partner entry, which will only affect the SP Partner It is important to note that if an SP Partner is configured to define one or more Federation Authentication Method to OAM Authentication Scheme mappings, then all the mappings defined in the SP Partner Profile will be ignored. Authentication Schemes As discussed in the previous article, during Federation SSO, OIF/IdP will internally forward the user to OAM for authentication/verification and specify which Authentication Scheme to use. OAM will determine if a user needs to be challenged: If the user is not authenticated yet If the user is authenticated but the session timed out If the user is authenticated, but the authentication scheme level of the original authentication is lower than the level of the authentication scheme requested by OIF/IdP So even though an SP requests a specific Federation Authentication Method to be used to challenge the user, if that method is mapped to an Authentication Scheme and that at runtime OAM deems that the user does not need to be challenged with that scheme (because the user is already authenticated, session did not time out, and the session authn level is equal or higher than the one for the specified Authentication Scheme), the flow won’t result in a challenge operation. Protocols SAML 2.0 The SAML 2.0 specifications define the following Federation Authentication Methods for SAML 2.0 flows: urn:oasis:names:tc:SAML:2.0:ac:classes:unspecified urn:oasis:names:tc:SAML:2.0:ac:classes:InternetProtocol urn:oasis:names:tc:SAML:2.0:ac:classes:Telephony urn:oasis:names:tc:SAML:2.0:ac:classes:MobileOneFactorUnregistered urn:oasis:names:tc:SAML:2.0:ac:classes:PersonalTelephony urn:oasis:names:tc:SAML:2.0:ac:classes:PreviousSession urn:oasis:names:tc:SAML:2.0:ac:classes:MobileOneFactorContract urn:oasis:names:tc:SAML:2.0:ac:classes:Smartcard urn:oasis:names:tc:SAML:2.0:ac:classes:Password urn:oasis:names:tc:SAML:2.0:ac:classes:InternetProtocolPassword urn:oasis:names:tc:SAML:2.0:ac:classes:X509 urn:oasis:names:tc:SAML:2.0:ac:classes:TLSClient urn:oasis:names:tc:SAML:2.0:ac:classes:PGP urn:oasis:names:tc:SAML:2.0:ac:classes:SPKI urn:oasis:names:tc:SAML:2.0:ac:classes:XMLDSig urn:oasis:names:tc:SAML:2.0:ac:classes:SoftwarePKI urn:oasis:names:tc:SAML:2.0:ac:classes:Kerberos urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport urn:oasis:names:tc:SAML:2.0:ac:classes:SecureRemotePassword urn:oasis:names:tc:SAML:2.0:ac:classes:NomadTelephony urn:oasis:names:tc:SAML:2.0:ac:classes:AuthenticatedTelephony urn:oasis:names:tc:SAML:2.0:ac:classes:MobileTwoFactorUnregistered urn:oasis:names:tc:SAML:2.0:ac:classes:MobileTwoFactorContract urn:oasis:names:tc:SAML:2.0:ac:classes:SmartcardPKI urn:oasis:names:tc:SAML:2.0:ac:classes:TimeSyncToken Out of the box, OIF/IdP has the following mappings for the SAML 2.0 protocol: Only urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport is defined This Federation Authentication Method is mapped to: LDAPScheme, marked as the default scheme used for authentication FAAuthScheme BasicScheme BasicFAScheme This mapping is defined in the saml20-sp-partner-profile SP Partner Profile which is the default OOTB SP Partner Profile for SAML 2.0 An example of an AuthnRequest message sent by an SP to an IdP with the SP requesting a specific Federation Authentication Method to be used to challenge the user would be: <samlp:AuthnRequest xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol" Destination="https://idp.com/oamfed/idp/samlv20" ID="id-8bWn-A9o4aoMl3Nhx1DuPOOjawc-" IssueInstant="2014-03-21T20:51:11Z" Version="2.0">  <saml:Issuer ...>https://acme.com/sp</saml:Issuer>  <samlp:NameIDPolicy AllowCreate="false" Format="urn:oasis:names:tc:SAML:1.1:nameid-format:unspecified"/>  <samlp:RequestedAuthnContext Comparison="minimum">    <saml:AuthnContextClassRef xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion">      urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport </saml:AuthnContextClassRef>  </samlp:RequestedAuthnContext></samlp:AuthnRequest> An example of an Assertion issued by an IdP would be: <samlp:Response ...>    <saml:Issuer ...>https://idp.com/oam/fed</saml:Issuer>    <samlp:Status>        <samlp:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Success"/>    </samlp:Status>    <saml:Assertion ...>        <saml:Issuer ...>https://idp.com/oam/fed</saml:Issuer>        <dsig:Signature>            ...        </dsig:Signature>        <saml:Subject>            <saml:NameID ...>[email protected]</saml:NameID>            <saml:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer">                <saml:SubjectConfirmationData .../>            </saml:SubjectConfirmation>        </saml:Subject>        <saml:Conditions ...>            <saml:AudienceRestriction>                <saml:Audience>https://acme.com/sp</saml:Audience>            </saml:AudienceRestriction>        </saml:Conditions>        <saml:AuthnStatement AuthnInstant="2014-03-21T20:53:55Z" SessionIndex="id-6i-Dm0yB-HekG6cejktwcKIFMzYE8Yrmqwfd0azz" SessionNotOnOrAfter="2014-03-21T21:53:55Z">            <saml:AuthnContext>                <saml:AuthnContextClassRef>                    urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport                </saml:AuthnContextClassRef>            </saml:AuthnContext>        </saml:AuthnStatement>    </saml:Assertion></samlp:Response> An administrator would be able to specify a mapping between a SAML 2.0 Federation Authentication Method and one or more OAM Authentication Schemes SAML 1.1 The SAML 1.1 specifications define the following Federation Authentication Methods for SAML 1.1 flows: urn:oasis:names:tc:SAML:1.0:am:unspecified urn:oasis:names:tc:SAML:1.0:am:HardwareToken urn:oasis:names:tc:SAML:1.0:am:password urn:oasis:names:tc:SAML:1.0:am:X509-PKI urn:ietf:rfc:2246 urn:oasis:names:tc:SAML:1.0:am:PGP urn:oasis:names:tc:SAML:1.0:am:SPKI urn:ietf:rfc:3075 urn:oasis:names:tc:SAML:1.0:am:XKMS urn:ietf:rfc:1510 urn:ietf:rfc:2945 Out of the box, OIF/IdP has the following mappings for the SAML 1.1 protocol: Only urn:oasis:names:tc:SAML:1.0:am:password is defined This Federation Authentication Method is mapped to: LDAPScheme, marked as the default scheme used for authentication FAAuthScheme BasicScheme BasicFAScheme This mapping is defined in the saml11-sp-partner-profile SP Partner Profile which is the default OOTB SP Partner Profile for SAML 1.1 An example of an Assertion issued by an IdP would be: <samlp:Response ...>    <samlp:Status>        <samlp:StatusCode Value="samlp:Success"/>    </samlp:Status>    <saml:Assertion Issuer="https://idp.com/oam/fed" ...>        <saml:Conditions ...>            <saml:AudienceRestriction>                <saml:Audience>https://acme.com/sp/ssov11</saml:Audience>            </saml:AudienceRestriction>        </saml:Conditions>        <saml:AuthnStatement AuthenticationInstant="2014-03-21T20:53:55Z" AuthenticationMethod="urn:oasis:names:tc:SAML:1.0:am:password">            <saml:Subject>                <saml:NameID ...>[email protected]</saml:NameID>                <saml:SubjectConfirmation>                   <saml:ConfirmationMethod>                       urn:oasis:names:tc:SAML:1.0:cm:bearer                   </saml:ConfirmationMethod>                </saml:SubjectConfirmation>            </saml:Subject>        </saml:AuthnStatement>        <dsig:Signature>            ...        </dsig:Signature>    </saml:Assertion></samlp:Response> Note: SAML 1.1 does not define an AuthnRequest message. An administrator would be able to specify a mapping between a SAML 1.1 Federation Authentication Method and one or more OAM Authentication Schemes OpenID 2.0 The OpenID 2.0 PAPE specifications define the following Federation Authentication Methods for OpenID 2.0 flows: http://schemas.openid.net/pape/policies/2007/06/phishing-resistant http://schemas.openid.net/pape/policies/2007/06/multi-factor http://schemas.openid.net/pape/policies/2007/06/multi-factor-physical Out of the box, OIF/IdP does not define any mappings for the OpenID 2.0 Federation Authentication Methods. For OpenID 2.0, the configuration will involve mapping a list of OpenID 2.0 policies to a list of Authentication Schemes. An example of an OpenID 2.0 Request message sent by an SP/RP to an IdP/OP would be: https://idp.com/openid?openid.ns=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0&openid.mode=checkid_setup&openid.claimed_id=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0%2Fidentifier_select&openid.identity=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0%2Fidentifier_select&openid.assoc_handle=id-6a5S6zhAKaRwQNUnjTKROREdAGSjWodG1el4xyz3&openid.return_to=https%3A%2F%2Facme.com%2Fopenid%3Frefid%3Did-9PKVXZmRxAeDYcgLqPm36ClzOMA-&openid.realm=https%3A%2F%2Facme.com%2Fopenid&openid.ns.ax=http%3A%2F%2Fopenid.net%2Fsrv%2Fax%2F1.0&openid.ax.mode=fetch_request&openid.ax.type.attr0=http%3A%2F%2Faxschema.org%2Fcontact%2Femail&openid.ax.if_available=attr0&openid.ns.pape=http%3A%2F%2Fspecs.openid.net%2Fextensions%2Fpape%2F1.0&openid.pape.max_auth_age=0 An example of an Open ID 2.0 SSO Response issued by an IdP/OP would be: https://acme.com/openid?refid=id-9PKVXZmRxAeDYcgLqPm36ClzOMA-&openid.ns=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0&openid.mode=id_res&openid.op_endpoint=https%3A%2F%2Fidp.com%2Fopenid&openid.claimed_id=https%3A%2F%2Fidp.com%2Fopenid%3Fid%3Did-38iCmmlAVEXPsFjnFVKArfn5RIiF75D5doorhEgqqPM%3D&openid.identity=https%3A%2F%2Fidp.com%2Fopenid%3Fid%3Did-38iCmmlAVEXPsFjnFVKArfn5RIiF75D5doorhEgqqPM%3D&openid.return_to=https%3A%2F%2Facme.com%2Fopenid%3Frefid%3Did-9PKVXZmRxAeDYcgLqPm36ClzOMA-&openid.response_nonce=2014-03-24T19%3A20%3A06Zid-YPa2kTNNFftZkgBb460jxJGblk2g--iNwPpDI7M1&openid.assoc_handle=id-6a5S6zhAKaRwQNUnjTKROREdAGSjWodG1el4xyz3&openid.ns.ax=http%3A%2F%2Fopenid.net%2Fsrv%2Fax%2F1.0&openid.ax.mode=fetch_response&openid.ax.type.attr0=http%3A%2F%2Fsession%2Fcount&openid.ax.value.attr0=1&openid.ax.type.attr1=http%3A%2F%2Fopenid.net%2Fschema%2FnamePerson%2Ffriendly&openid.ax.value.attr1=My+name+is+Bobby+Smith&openid.ax.type.attr2=http%3A%2F%2Fschemas.openid.net%2Fax%2Fapi%2Fuser_id&openid.ax.value.attr2=bob&openid.ax.type.attr3=http%3A%2F%2Faxschema.org%2Fcontact%2Femail&openid.ax.value.attr3=bob%40oracle.com&openid.ax.type.attr4=http%3A%2F%2Fsession%2Fipaddress&openid.ax.value.attr4=10.145.120.253&openid.ns.pape=http%3A%2F%2Fspecs.openid.net%2Fextensions%2Fpape%2F1.0&openid.pape.auth_time=2014-03-24T19%3A20%3A05Z&openid.pape.auth_policies=http%3A%2F%2Fschemas.openid.net%2Fpape%2Fpolicies%2F2007%2F06%2Fphishing-resistant&openid.signed=op_endpoint%2Cclaimed_id%2Cidentity%2Creturn_to%2Cresponse_nonce%2Cassoc_handle%2Cns.ax%2Cax.mode%2Cax.type.attr0%2Cax.value.attr0%2Cax.type.attr1%2Cax.value.attr1%2Cax.type.attr2%2Cax.value.attr2%2Cax.type.attr3%2Cax.value.attr3%2Cax.type.attr4%2Cax.value.attr4%2Cns.pape%2Cpape.auth_time%2Cpape.auth_policies&openid.sig=mYMgbGYSs22l8e%2FDom9NRPw15u8%3D In the next article, I will provide examples on how to configure OIF/IdP for the various protocols, to map OAM Authentication Schemes to Federation Authentication Methods.Cheers,Damien Carru

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• It’s On! Oracle Open World 2012 Opens Call for Papers is Open

  - by David Hope-Ross

  Oracle OpenWorld is among the world’s largest industry events for good reason. It offers a vast array of learning and networking opportunities in one of the planet’s great cities.  And one of the key reasons for its popularity among procurement and supply chain professionals is the prominence of presentations by customers.   If you’d like to deliver a presentation based on your experience, now is the time to submit your abstract for review by the selection panel. The competition is strong: roughly 18% of entries are accepted each year from more than 3,000 submissions. Review panels are made up of experts both internal and external to Oracle. Successful submissions often (but not exclusively) focus on customer successes, how-tos, or best practices. What’s in it for you? Recognition, for one thing. Accepted sessions are publicized in the content catalog, which goes live in mid-June, and sessions given by external speakers often prove the most popular. Plus, accepted speakers get a complimentary pass to Oracle OpenWorld with access to all sessions and networking events- that could save you up to $2,595!   Be sure designate your session for inclusion in the correct track by selecting  “APPLICATIONS: Supply Chain Management” or “APPLICATIONS: Sourcing and Procurement” from the Primary Track drop down menu.   We look forward to seeing you in San Francisco!

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• An abundance of LINQ queries and expressions using both the query and method syntax.

  - by nikolaosk

  In this post I will be writing LINQ queries against an array of strings, an array of integers.Moreover I will be using LINQ to query an SQL Server database. I can use LINQ against arrays since the array of strings/integers implement the IENumerable interface. I thought it would be a good idea to use both the method syntax and the query syntax. There are other places on the net where you can find examples of LINQ queries but I decided to create a big post using as many LINQ examples as possible. We...(read more)

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• Unable to uninstall or reinstall Ubuntu desktop

  - by sherwyngsw

  The uninstall-wubi option doesn't work. When I try reinstalling it they show an error and tells me to check "wubi 12.04 rev266" log Everything goes fine till the bottom which shows this There is another file or directory with this name. Please remove it before continuing. Traceback (most recent call last): File "\lib\wubi\backends\common\tasklist.py", line 197, in __call__ File "\lib\wubi\backends\win32\backend.py", line 81, in select_target_dir Exception: Cannot install into C:\ubuntu. There is another file or directory with this name. Please remove it before continuing. 05-25 15:20 DEBUG TaskList: # Cancelling tasklist 05-25 15:20 DEBUG TaskList: # Finished tasklist 05-25 15:20 ERROR root: Cannot install into C:\ubuntu. There is another file or directory with this name. Please remove it before continuing. Traceback (most recent call last): File "\lib\wubi\application.py", line 58, in run File "\lib\wubi\application.py", line 132, in select_task File "\lib\wubi\application.py", line 158, in run_installer File "\lib\wubi\backends\common\tasklist.py", line 197, in __call__ File "\lib\wubi\backends\win32\backend.py", line 81, in select_target_dir Exception: Cannot install into C:\ubuntu. There is another file or directory with this name. Please remove it before continuing. What do I do? I've tried the uninstall wubi option but all it shows is "reinstall using recommended settings which doesn't do anything" okay i've tried installing it into another hardrive and i got this Traceback (most recent call last): File "\lib\wubi\backends\common\tasklist.py", line 197, in call File "\lib\wubi\backends\win32\backend.py", line 117, in create_uninstaller File "\lib\wubi\backends\win32\registry.py", line 45, in set_value WindowsError: [Errno 5] Access is denied 05-26 16:12 DEBUG TaskList: # Cancelling tasklist 05-26 16:12 DEBUG TaskList: # Finished tasklist 05-26 16:12 ERROR root: [Errno 5] Access is denied Traceback (most recent call last): File "\lib\wubi\application.py", line 58, in run File "\lib\wubi\application.py", line 132, in select_task File "\lib\wubi\application.py", line 158, in run_installer File "\lib\wubi\backends\common\tasklist.py", line 197, in call File "\lib\wubi\backends\win32\backend.py", line 117, in create_uninstaller File "\lib\wubi\backends\win32\registry.py", line 45, in set_value WindowsError: [Errno 5] Access is denied

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• Understanding C# async / await (2) Awaitable / Awaiter Pattern

  - by Dixin

  What is awaitable Part 1 shows that any Task is awaitable. Actually there are other awaitable types. Here is an example: Task<int> task = new Task<int>(() => 0); int result = await task.ConfigureAwait(false); // Returns a ConfiguredTaskAwaitable<TResult>. The returned ConfiguredTaskAwaitable<TResult> struct is awaitable. And it is not Task at all: public struct ConfiguredTaskAwaitable<TResult> { private readonly ConfiguredTaskAwaiter m_configuredTaskAwaiter; internal ConfiguredTaskAwaitable(Task<TResult> task, bool continueOnCapturedContext) { this.m_configuredTaskAwaiter = new ConfiguredTaskAwaiter(task, continueOnCapturedContext); } public ConfiguredTaskAwaiter GetAwaiter() { return this.m_configuredTaskAwaiter; } } It has one GetAwaiter() method. Actually in part 1 we have seen that Task has GetAwaiter() method too: public class Task { public TaskAwaiter GetAwaiter() { return new TaskAwaiter(this); } } public class Task<TResult> : Task { public new TaskAwaiter<TResult> GetAwaiter() { return new TaskAwaiter<TResult>(this); } } Task.Yield() is a another example: await Task.Yield(); // Returns a YieldAwaitable. The returned YieldAwaitable is not Task either: public struct YieldAwaitable { public YieldAwaiter GetAwaiter() { return default(YieldAwaiter); } } Again, it just has one GetAwaiter() method. In this article, we will look at what is awaitable. The awaitable / awaiter pattern By observing different awaitable / awaiter types, we can tell that an object is awaitable if It has a GetAwaiter() method (instance method or extension method); Its GetAwaiter() method returns an awaiter. An object is an awaiter if: It implements INotifyCompletion or ICriticalNotifyCompletion interface; It has an IsCompleted, which has a getter and returns a Boolean; it has a GetResult() method, which returns void, or a result. This awaitable / awaiter pattern is very similar to the iteratable / iterator pattern. Here is the interface definitions of iteratable / iterator: public interface IEnumerable { IEnumerator GetEnumerator(); } public interface IEnumerator { object Current { get; } bool MoveNext(); void Reset(); } public interface IEnumerable<out T> : IEnumerable { IEnumerator<T> GetEnumerator(); } public interface IEnumerator<out T> : IDisposable, IEnumerator { T Current { get; } } In case you are not familiar with the out keyword, please find out the explanation in Understanding C# Covariance And Contravariance (2) Interfaces. The “missing” IAwaitable / IAwaiter interfaces Similar to IEnumerable and IEnumerator interfaces, awaitable / awaiter can be visualized by IAwaitable / IAwaiter interfaces too. This is the non-generic version: public interface IAwaitable { IAwaiter GetAwaiter(); } public interface IAwaiter : INotifyCompletion // or ICriticalNotifyCompletion { // INotifyCompletion has one method: void OnCompleted(Action continuation); // ICriticalNotifyCompletion implements INotifyCompletion, // also has this method: void UnsafeOnCompleted(Action continuation); bool IsCompleted { get; } void GetResult(); } Please notice GetResult() returns void here. Task.GetAwaiter() / TaskAwaiter.GetResult() is of such case. And this is the generic version: public interface IAwaitable<out TResult> { IAwaiter<TResult> GetAwaiter(); } public interface IAwaiter<out TResult> : INotifyCompletion // or ICriticalNotifyCompletion { bool IsCompleted { get; } TResult GetResult(); } Here the only difference is, GetResult() return a result. Task<TResult>.GetAwaiter() / TaskAwaiter<TResult>.GetResult() is of this case. Please notice .NET does not define these IAwaitable / IAwaiter interfaces at all. As an UI designer, I guess the reason is, IAwaitable interface will constraint GetAwaiter() to be instance method. Actually C# supports both GetAwaiter() instance method and GetAwaiter() extension method. Here I use these interfaces only for better visualizing what is awaitable / awaiter. Now, if looking at above ConfiguredTaskAwaitable / ConfiguredTaskAwaiter, YieldAwaitable / YieldAwaiter, Task / TaskAwaiter pairs again, they all “implicitly” implement these “missing” IAwaitable / IAwaiter interfaces. In the next part, we will see how to implement awaitable / awaiter. Await any function / action In C# await cannot be used with lambda. This code: int result = await (() => 0); will cause a compiler error: Cannot await 'lambda expression' This is easy to understand because this lambda expression (() => 0) may be a function or a expression tree. Obviously we mean function here, and we can tell compiler in this way: int result = await new Func<int>(() => 0); It causes an different error: Cannot await 'System.Func<int>' OK, now the compiler is complaining the type instead of syntax. With the understanding of the awaitable / awaiter pattern, Func<TResult> type can be easily made into awaitable. GetAwaiter() instance method, using IAwaitable / IAwaiter interfaces First, similar to above ConfiguredTaskAwaitable<TResult>, a FuncAwaitable<TResult> can be implemented to wrap Func<TResult>: internal struct FuncAwaitable<TResult> : IAwaitable<TResult> { private readonly Func<TResult> function; public FuncAwaitable(Func<TResult> function) { this.function = function; } public IAwaiter<TResult> GetAwaiter() { return new FuncAwaiter<TResult>(this.function); } } FuncAwaitable<TResult> wrapper is used to implement IAwaitable<TResult>, so it has one instance method, GetAwaiter(), which returns a IAwaiter<TResult>, which wraps that Func<TResult> too. FuncAwaiter<TResult> is used to implement IAwaiter<TResult>: public struct FuncAwaiter<TResult> : IAwaiter<TResult> { private readonly Task<TResult> task; public FuncAwaiter(Func<TResult> function) { this.task = new Task<TResult>(function); this.task.Start(); } bool IAwaiter<TResult>.IsCompleted { get { return this.task.IsCompleted; } } TResult IAwaiter<TResult>.GetResult() { return this.task.Result; } void INotifyCompletion.OnCompleted(Action continuation) { new Task(continuation).Start(); } } Now a function can be awaited in this way: int result = await new FuncAwaitable<int>(() => 0); GetAwaiter() extension method As IAwaitable shows, all that an awaitable needs is just a GetAwaiter() method. In above code, FuncAwaitable<TResult> is created as a wrapper of Func<TResult> and implements IAwaitable<TResult>, so that there is a  GetAwaiter() instance method. If a GetAwaiter() extension method  can be defined for Func<TResult>, then FuncAwaitable<TResult> is no longer needed: public static class FuncExtensions { public static IAwaiter<TResult> GetAwaiter<TResult>(this Func<TResult> function) { return new FuncAwaiter<TResult>(function); } } So a Func<TResult> function can be directly awaited: int result = await new Func<int>(() => 0); Using the existing awaitable / awaiter - Task / TaskAwaiter Remember the most frequently used awaitable / awaiter - Task / TaskAwaiter. With Task / TaskAwaiter, FuncAwaitable / FuncAwaiter are no longer needed: public static class FuncExtensions { public static TaskAwaiter<TResult> GetAwaiter<TResult>(this Func<TResult> function) { Task<TResult> task = new Task<TResult>(function); task.Start(); return task.GetAwaiter(); // Returns a TaskAwaiter<TResult>. } } Similarly, with this extension method: public static class ActionExtensions { public static TaskAwaiter GetAwaiter(this Action action) { Task task = new Task(action); task.Start(); return task.GetAwaiter(); // Returns a TaskAwaiter. } } an action can be awaited as well: await new Action(() => { }); Now any function / action can be awaited: await new Action(() => HelperMethods.IO()); // or: await new Action(HelperMethods.IO); If function / action has parameter(s), closure can be used: int arg0 = 0; int arg1 = 1; int result = await new Action(() => HelperMethods.IO(arg0, arg1)); Using Task.Run() The above code is used to demonstrate how awaitable / awaiter can be implemented. Because it is a common scenario to await a function / action, so .NET provides a built-in API: Task.Run(): public class Task2 { public static Task Run(Action action) { // The implementation is similar to: Task task = new Task(action); task.Start(); return task; } public static Task<TResult> Run<TResult>(Func<TResult> function) { // The implementation is similar to: Task<TResult> task = new Task<TResult>(function); task.Start(); return task; } } In reality, this is how we await a function: int result = await Task.Run(() => HelperMethods.IO(arg0, arg1)); and await a action: await Task.Run(() => HelperMethods.IO());

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• What do the 4 keyboard input method systems in 10.04 mean?

  - by Android Eve

  I am trying to install another language support (in addition to the default US). Checking that language checkbox in "Install / Remove Languages..." wasn't too difficult. :) But now I want to add keyboard support, too, for that language. Again, I am prompted with a nice listbox with the following 4 options: none ibus lo-gtk th-gtk But I have no idea what these mean. I googled "ubuntu 10.04 keyboard input method system none ibus lo-gtk th-gtk" but all I could find was descriptions of problems, not an actual definition. Could you please point me to a webpage where I can learn about the meanings of these 4 different methods and +'s and -'s of each?

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• Z600 Workstation ACPI Fan Noise

  - by dpb

  Hi -- I have an HP z600 workstation that has the FAN running full when idle. In fact, after the boot, the fan never slows down or varies. I looked in dmesg, and noticed this: [ 1.516778] ACPI Error (dsfield-0143): [CAPD] Namespace lookup failure, AE_ALREADY_EXISTS [ 1.516781] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0._OSC] (Node ffff8801b8c4e3e0), AE_ALREADY_EXISTS [ 1.516786] ACPI: Marking method _OSC as Serialized because of AE_ALREADY_EXISTS error [ 1.519868] ACPI Error (dsfield-0143): [CAPD] Namespace lookup failure, AE_ALREADY_EXISTS [ 1.519872] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0._OSC] (Node ffff8801b8c4e3e0), AE_ALREADY_EXISTS [ 1.624638] ACPI Error (dsfield-0143): [CAPD] Namespace lookup failure, AE_ALREADY_EXISTS [ 1.624642] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0._OSC] (Node ffff8801b8c4e3e0), AE_ALREADY_EXISTS [ 1.624726] ACPI Error (dsfield-0143): [CAPD] Namespace lookup failure, AE_ALREADY_EXISTS [ 1.624729] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0._OSC] (Node ffff8801b8c4e3e0), AE_ALREADY_EXISTS [ 1.624802] ACPI Error (dsfield-0143): [CAPD] Namespace lookup failure, AE_ALREADY_EXISTS [ 1.624805] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0._OSC] (Node ffff8801b8c4e3e0), AE_ALREADY_EXISTS [ 1.624895] ACPI Error (dsfield-0143): [CAPD] Namespace lookup failure, AE_ALREADY_EXISTS [ 1.624898] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0._OSC] (Node ffff8801b8c4e3e0), AE_ALREADY_EXISTS [ 1.624977] ACPI Error (dsfield-0143): [CAPD] Namespace lookup failure, AE_ALREADY_EXISTS [ 1.624981] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0._OSC] (Node ffff8801b8c4e3e0), AE_ALREADY_EXISTS [ 1.625070] ACPI Error (dsfield-0143): [CAPD] Namespace lookup failure, AE_ALREADY_EXISTS [ 1.625074] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0._OSC] (Node ffff8801b8c4e3e0), AE_ALREADY_EXISTS [ 1.625153] ACPI Error (dsfield-0143): [CAPD] Namespace lookup failure, AE_ALREADY_EXISTS [ 1.625157] ACPI Error (psparse-0537): Method parse/execution failed [\_SB_.PCI0._OSC] (Node ffff8801b8c4e3e0), AE_ALREADY_EXISTS Anyone know what could be done to fix this?

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• Collaboration Nation Call to Action! Calling All SQL Server Bloggers and Twitterers

  - by KKline

  Help build a brand new shiny centralized reference with a full compendium to everyone blog & twitter hyperlinks who are active in the SQL Server space...(read more)

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• Understanding C# async / await (1) Compilation

  - by Dixin

  Now the async / await keywords are in C#. Just like the async and ! in F#, this new C# feature provides great convenience. There are many nice documents talking about how to use async / await in specific scenarios, like using async methods in ASP.NET 4.5 and in ASP.NET MVC 4, etc. In this article we will look at the real code working behind the syntax sugar. According to MSDN: The async modifier indicates that the method, lambda expression, or anonymous method that it modifies is asynchronous. Since lambda expression / anonymous method will be compiled to normal method, we will focus on normal async method. Preparation First of all, Some helper methods need to make up. internal class HelperMethods { internal static int Method(int arg0, int arg1) { // Do some IO. WebClient client = new WebClient(); Enumerable.Repeat("http://weblogs.asp.net/dixin", 10) .Select(client.DownloadString).ToArray(); int result = arg0 + arg1; return result; } internal static Task<int> MethodTask(int arg0, int arg1) { Task<int> task = new Task<int>(() => Method(arg0, arg1)); task.Start(); // Hot task (started task) should always be returned. return task; } internal static void Before() { } internal static void Continuation1(int arg) { } internal static void Continuation2(int arg) { } } Here Method() is a long running method doing some IO. Then MethodTask() wraps it into a Task and return that Task. Nothing special here. Await something in async method Since MethodTask() returns Task, let’s try to await it: internal class AsyncMethods { internal static async Task<int> MethodAsync(int arg0, int arg1) { int result = await HelperMethods.MethodTask(arg0, arg1); return result; } } Because we used await in the method, async must be put on the method. Now we get the first async method. According to the naming convenience, it is called MethodAsync. Of course a async method can be awaited. So we have a CallMethodAsync() to call MethodAsync(): internal class AsyncMethods { internal static async Task<int> CallMethodAsync(int arg0, int arg1) { int result = await MethodAsync(arg0, arg1); return result; } } After compilation, MethodAsync() and CallMethodAsync() becomes the same logic. This is the code of MethodAsyc(): internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MethodAsync(int arg0, int arg1) { MethodAsyncStateMachine methodAsyncStateMachine = new MethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; methodAsyncStateMachine.Builder.Start(ref methodAsyncStateMachine); return methodAsyncStateMachine.Builder.Task; } } It just creates and starts a state machine MethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Result; private TaskAwaiter<int> awaitor; void IAsyncStateMachine.MoveNext() { try { if (this.State != 0) { this.awaitor = HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaitor.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaitor, ref this); return; } } else { this.State = -1; } this.Result = this.awaitor.GetResult(); } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); return; } this.State = -2; this.Builder.SetResult(this.Result); } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine param0) { this.Builder.SetStateMachine(param0); } } The generated code has been cleaned up so it is readable and can be compiled. Several things can be observed here: The async modifier is gone, which shows, unlike other modifiers (e.g. static), there is no such IL/CLR level “async” stuff. It becomes a AsyncStateMachineAttribute. This is similar to the compilation of extension method. The generated state machine is very similar to the state machine of C# yield syntax sugar. The local variables (arg0, arg1, result) are compiled to fields of the state machine. The real code (await HelperMethods.MethodTask(arg0, arg1)) is compiled into MoveNext(): HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(). CallMethodAsync() will create and start its own state machine CallMethodAsyncStateMachine: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(CallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> CallMethodAsync(int arg0, int arg1) { CallMethodAsyncStateMachine callMethodAsyncStateMachine = new CallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; callMethodAsyncStateMachine.Builder.Start(ref callMethodAsyncStateMachine); return callMethodAsyncStateMachine.Builder.Task; } } CallMethodAsyncStateMachine has the same logic as MethodAsyncStateMachine above. The detail of the state machine will be discussed soon. Now it is clear that: async /await is a C# level syntax sugar. There is no difference to await a async method or a normal method. A method returning Task will be awaitable. State machine and continuation To demonstrate more details in the state machine, a more complex method is created: internal class AsyncMethods { internal static async Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; } } In this method: There are multiple awaits. There are code before the awaits, and continuation code after each await After compilation, this multi-await method becomes the same as above single-await methods: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; multiCallMethodAsyncStateMachine.Builder.Start(ref multiCallMethodAsyncStateMachine); return multiCallMethodAsyncStateMachine.Builder.Task; } } It creates and starts one single state machine, MultiCallMethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Arg2; public int Arg3; public int ResultOfAwait1; public int ResultOfAwait2; public int ResultToReturn; private TaskAwaiter<int> awaiter; void IAsyncStateMachine.MoveNext() { try { switch (this.State) { case -1: HelperMethods.Before(); this.awaiter = AsyncMethods.MethodAsync(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 0: this.ResultOfAwait1 = this.awaiter.GetResult(); HelperMethods.Continuation1(this.ResultOfAwait1); this.awaiter = AsyncMethods.MethodAsync(this.Arg2, this.Arg3).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 1; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 1: this.ResultOfAwait2 = this.awaiter.GetResult(); HelperMethods.Continuation2(this.ResultOfAwait2); this.ResultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; this.State = -2; this.Builder.SetResult(this.ResultToReturn); break; } } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); } } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { this.Builder.SetStateMachine(stateMachine); } } The above code is already cleaned up, but there are still a lot of things. More clean up can be done, and the state machine can be very simple: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { // State: // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End public int State; public TaskCompletionSource<int> ResultToReturn; // int resultToReturn ... public int Arg0; // int Arg0 public int Arg1; // int arg1 public int Arg2; // int arg2 public int Arg3; // int arg3 public int ResultOfAwait1; // int resultOfAwait1 ... public int ResultOfAwait2; // int resultOfAwait2 ... private Task<int> currentTaskToAwait; /// <summary> /// Moves the state machine to its next state. /// </summary> void IAsyncStateMachine.MoveNext() { try { switch (this.State) { // Orginal code is splitted by "case"s: // case -1: // HelperMethods.Before(); // MethodAsync(Arg0, arg1); // case 0: // int resultOfAwait1 = await ... // HelperMethods.Continuation1(resultOfAwait1); // MethodAsync(arg2, arg3); // case 1: // int resultOfAwait2 = await ... // HelperMethods.Continuation2(resultOfAwait2); // int resultToReturn = resultOfAwait1 + resultOfAwait2; // return resultToReturn; case -1: // -1 is begin. HelperMethods.Before(); // Code before 1st await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg0, this.Arg1); // 1st task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 0. this.State = 0; IAsyncStateMachine this1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this1.MoveNext()); // Callback break; case 0: // Now 1st await is done. this.ResultOfAwait1 = this.currentTaskToAwait.Result; // Get 1st await's result. HelperMethods.Continuation1(this.ResultOfAwait1); // Code after 1st await and before 2nd await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg2, this.Arg3); // 2nd task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 1. this.State = 1; IAsyncStateMachine this2 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this2.MoveNext()); // Callback break; case 1: // Now 2nd await is done. this.ResultOfAwait2 = this.currentTaskToAwait.Result; // Get 2nd await's result. HelperMethods.Continuation2(this.ResultOfAwait2); // Code after 2nd await. int resultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; // Code after 2nd await. // End with resultToReturn. this.State = -2; // -2 is end. this.ResultToReturn.SetResult(resultToReturn); break; } } catch (Exception exception) { // End with exception. this.State = -2; // -2 is end. this.ResultToReturn.SetException(exception); } } /// <summary> /// Configures the state machine with a heap-allocated replica. /// </summary> /// <param name="stateMachine">The heap-allocated replica.</param> [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { // No core logic. } } Only Task and TaskCompletionSource are involved in this version. And MultiCallMethodAsync() can be simplified to: [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync_(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, ResultToReturn = new TaskCompletionSource<int>(), // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End State = -1 }; (multiCallMethodAsyncStateMachine as IAsyncStateMachine).MoveNext(); // Original code are in this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clear - it is about callback: Original code are split into pieces by “await”s, and each piece is put into each “case” in the state machine. Here the 2 awaits split the code into 3 pieces, so there are 3 “case”s. The “piece”s are chained by callback, that is done by Builder.AwaitUnsafeOnCompleted(callback), or currentTaskToAwait.ContinueWith(callback) in the simplified code. A previous “piece” will end with a Task (which is to be awaited), when the task is done, it will callback the next “piece”. The state machine’s state works with the “case”s to ensure the code “piece”s executes one after another. Callback Since it is about callback, the simplification  can go even further – the entire state machine can be completely purged. Now MultiCallMethodAsync() becomes: internal static Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>(); try { // Oringinal code begins. HelperMethods.Before(); MethodAsync(arg0, arg1).ContinueWith(await1 => { int resultOfAwait1 = await1.Result; HelperMethods.Continuation1(resultOfAwait1); MethodAsync(arg2, arg3).ContinueWith(await2 => { int resultOfAwait2 = await2.Result; HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; // Oringinal code ends. taskCompletionSource.SetResult(resultToReturn); }); }); } catch (Exception exception) { taskCompletionSource.SetException(exception); } return taskCompletionSource.Task; } Please compare with the original async / await code: HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; Yeah that is the magic of C# async / await: Await is literally pretending to wait. In a await expression, a Task object will be return immediately so that caller is not blocked. The continuation code is compiled as that Task’s callback code. When that task is done, continuation code will execute. Please notice that many details inside the state machine are omitted for simplicity, like context caring, etc. If you want to have a detailed picture, please do check out the source code of AsyncTaskMethodBuilder and TaskAwaiter.

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• is it a bad practice to call a View from another View in MVC?

  - by marcos.borunda

  I have some plain Views, they don't have any logic behind them (there is no action or controller behind them), their only propouse is to alert the user about something like "We have sent you an email to confirm your account", "You have no access to this resource", etc... These views are really simple, and calling them through a Controller/Action seems to be too much overhead, but somehow I feel like it is not quite correct. What do you think? How do you handle this kind of situations?? I guess this question will apply to any MVC Framework, but in my case I'm using the ASP.NET MVC 3 framework.

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• Understanding C# async / await (1) Compilation

  - by Dixin

  Now the async / await keywords are in C#. Just like the async and ! in F#, this new C# feature provides great convenience. There are many nice documents talking about how to use async / await in specific scenarios, like using async methods in ASP.NET 4.5 and in ASP.NET MVC 4, etc. In this article we will look at the real code working behind the syntax sugar. According to MSDN: The async modifier indicates that the method, lambda expression, or anonymous method that it modifies is asynchronous. Since lambda expression / anonymous method will be compiled to normal method, we will focus on normal async method. Preparation First of all, Some helper methods need to make up. internal class HelperMethods { internal static int Method(int arg0, int arg1) { // Do some IO. WebClient client = new WebClient(); Enumerable.Repeat("http://weblogs.asp.net/dixin", 10) .Select(client.DownloadString).ToArray(); int result = arg0 + arg1; return result; } internal static Task<int> MethodTask(int arg0, int arg1) { Task<int> task = new Task<int>(() => Method(arg0, arg1)); task.Start(); // Hot task (started task) should always be returned. return task; } internal static void Before() { } internal static void Continuation1(int arg) { } internal static void Continuation2(int arg) { } } Here Method() is a long running method doing some IO. Then MethodTask() wraps it into a Task and return that Task. Nothing special here. Await something in async method Since MethodTask() returns Task, let’s try to await it: internal class AsyncMethods { internal static async Task<int> MethodAsync(int arg0, int arg1) { int result = await HelperMethods.MethodTask(arg0, arg1); return result; } } Because we used await in the method, async must be put on the method. Now we get the first async method. According to the naming convenience, it is named MethodAsync. Of course a async method can be awaited. So we have a CallMethodAsync() to call MethodAsync(): internal class AsyncMethods { internal static async Task<int> CallMethodAsync(int arg0, int arg1) { int result = await MethodAsync(arg0, arg1); return result; } } After compilation, MethodAsync() and CallMethodAsync() becomes the same logic. This is the code of MethodAsyc(): internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MethodAsync(int arg0, int arg1) { MethodAsyncStateMachine methodAsyncStateMachine = new MethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; methodAsyncStateMachine.Builder.Start(ref methodAsyncStateMachine); return methodAsyncStateMachine.Builder.Task; } } It just creates and starts a state machine, MethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Result; private TaskAwaiter<int> awaitor; void IAsyncStateMachine.MoveNext() { try { if (this.State != 0) { this.awaitor = HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaitor.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaitor, ref this); return; } } else { this.State = -1; } this.Result = this.awaitor.GetResult(); } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); return; } this.State = -2; this.Builder.SetResult(this.Result); } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine param0) { this.Builder.SetStateMachine(param0); } } The generated code has been refactored, so it is readable and can be compiled. Several things can be observed here: The async modifier is gone, which shows, unlike other modifiers (e.g. static), there is no such IL/CLR level “async” stuff. It becomes a AsyncStateMachineAttribute. This is similar to the compilation of extension method. The generated state machine is very similar to the state machine of C# yield syntax sugar. The local variables (arg0, arg1, result) are compiled to fields of the state machine. The real code (await HelperMethods.MethodTask(arg0, arg1)) is compiled into MoveNext(): HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(). CallMethodAsync() will create and start its own state machine CallMethodAsyncStateMachine: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(CallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> CallMethodAsync(int arg0, int arg1) { CallMethodAsyncStateMachine callMethodAsyncStateMachine = new CallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; callMethodAsyncStateMachine.Builder.Start(ref callMethodAsyncStateMachine); return callMethodAsyncStateMachine.Builder.Task; } } CallMethodAsyncStateMachine has the same logic as MethodAsyncStateMachine above. The detail of the state machine will be discussed soon. Now it is clear that: async /await is a C# language level syntax sugar. There is no difference to await a async method or a normal method. As long as a method returns Task, it is awaitable. State machine and continuation To demonstrate more details in the state machine, a more complex method is created: internal class AsyncMethods { internal static async Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; } } In this method: There are multiple awaits. There are code before the awaits, and continuation code after each await After compilation, this multi-await method becomes the same as above single-await methods: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; multiCallMethodAsyncStateMachine.Builder.Start(ref multiCallMethodAsyncStateMachine); return multiCallMethodAsyncStateMachine.Builder.Task; } } It creates and starts one single state machine, MultiCallMethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Arg2; public int Arg3; public int ResultOfAwait1; public int ResultOfAwait2; public int ResultToReturn; private TaskAwaiter<int> awaiter; void IAsyncStateMachine.MoveNext() { try { switch (this.State) { case -1: HelperMethods.Before(); this.awaiter = AsyncMethods.MethodAsync(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 0: this.ResultOfAwait1 = this.awaiter.GetResult(); HelperMethods.Continuation1(this.ResultOfAwait1); this.awaiter = AsyncMethods.MethodAsync(this.Arg2, this.Arg3).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 1; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 1: this.ResultOfAwait2 = this.awaiter.GetResult(); HelperMethods.Continuation2(this.ResultOfAwait2); this.ResultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; this.State = -2; this.Builder.SetResult(this.ResultToReturn); break; } } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); } } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { this.Builder.SetStateMachine(stateMachine); } } Once again, the above state machine code is already refactored, but it still has a lot of things. More clean up can be done if we only keep the core logic, and the state machine can become very simple: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { // State: // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End public int State; public TaskCompletionSource<int> ResultToReturn; // int resultToReturn ... public int Arg0; // int Arg0 public int Arg1; // int arg1 public int Arg2; // int arg2 public int Arg3; // int arg3 public int ResultOfAwait1; // int resultOfAwait1 ... public int ResultOfAwait2; // int resultOfAwait2 ... private Task<int> currentTaskToAwait; /// <summary> /// Moves the state machine to its next state. /// </summary> public void MoveNext() // IAsyncStateMachine member. { try { switch (this.State) { // Original code is split by "await"s into "case"s: // case -1: // HelperMethods.Before(); // MethodAsync(Arg0, arg1); // case 0: // int resultOfAwait1 = await ... // HelperMethods.Continuation1(resultOfAwait1); // MethodAsync(arg2, arg3); // case 1: // int resultOfAwait2 = await ... // HelperMethods.Continuation2(resultOfAwait2); // int resultToReturn = resultOfAwait1 + resultOfAwait2; // return resultToReturn; case -1: // -1 is begin. HelperMethods.Before(); // Code before 1st await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg0, this.Arg1); // 1st task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 0. this.State = 0; MultiCallMethodAsyncStateMachine that1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => that1.MoveNext()); break; case 0: // Now 1st await is done. this.ResultOfAwait1 = this.currentTaskToAwait.Result; // Get 1st await's result. HelperMethods.Continuation1(this.ResultOfAwait1); // Code after 1st await and before 2nd await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg2, this.Arg3); // 2nd task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 1. this.State = 1; MultiCallMethodAsyncStateMachine that2 = this; this.currentTaskToAwait.ContinueWith(_ => that2.MoveNext()); break; case 1: // Now 2nd await is done. this.ResultOfAwait2 = this.currentTaskToAwait.Result; // Get 2nd await's result. HelperMethods.Continuation2(this.ResultOfAwait2); // Code after 2nd await. int resultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; // Code after 2nd await. // End with resultToReturn. this.State = -2; // -2 is end. this.ResultToReturn.SetResult(resultToReturn); break; } } catch (Exception exception) { // End with exception. this.State = -2; // -2 is end. this.ResultToReturn.SetException(exception); } } /// <summary> /// Configures the state machine with a heap-allocated replica. /// </summary> /// <param name="stateMachine">The heap-allocated replica.</param> [DebuggerHidden] public void SetStateMachine(IAsyncStateMachine stateMachine) // IAsyncStateMachine member. { // No core logic. } } Only Task and TaskCompletionSource are involved in this version. And MultiCallMethodAsync() can be simplified to: [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, ResultToReturn = new TaskCompletionSource<int>(), // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End State = -1 }; multiCallMethodAsyncStateMachine.MoveNext(); // Original code are moved into this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clean - it is about callback: Original code are split into pieces by “await”s, and each piece is put into each “case” in the state machine. Here the 2 awaits split the code into 3 pieces, so there are 3 “case”s. The “piece”s are chained by callback, that is done by Builder.AwaitUnsafeOnCompleted(callback), or currentTaskToAwait.ContinueWith(callback) in the simplified code. A previous “piece” will end with a Task (which is to be awaited), when the task is done, it will callback the next “piece”. The state machine’s state works with the “case”s to ensure the code “piece”s executes one after another. Callback If we focus on the point of callback, the simplification  can go even further – the entire state machine can be completely purged, and we can just keep the code inside MoveNext(). Now MultiCallMethodAsync() becomes: internal static Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>(); try { // Oringinal code begins. HelperMethods.Before(); MethodAsync(arg0, arg1).ContinueWith(await1 => { int resultOfAwait1 = await1.Result; HelperMethods.Continuation1(resultOfAwait1); MethodAsync(arg2, arg3).ContinueWith(await2 => { int resultOfAwait2 = await2.Result; HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; // Oringinal code ends. taskCompletionSource.SetResult(resultToReturn); }); }); } catch (Exception exception) { taskCompletionSource.SetException(exception); } return taskCompletionSource.Task; } Please compare with the original async / await code: HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; Yeah that is the magic of C# async / await: Await is not to wait. In a await expression, a Task object will be return immediately so that execution is not blocked. The continuation code is compiled as that Task’s callback code. When that task is done, continuation code will execute. Please notice that many details inside the state machine are omitted for simplicity, like context caring, etc. If you want to have a detailed picture, please do check out the source code of AsyncTaskMethodBuilder and TaskAwaiter.

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