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  • That Escalated Quickly

    - by Jesse Taber
    Originally posted on: http://geekswithblogs.net/GruffCode/archive/2014/05/17/that-escalated-quickly.aspxI have been working remotely out of my home for over 4 years now. All of my coworkers during that time have also worked remotely. Lots of folks have written about the challenges inherent in facilitating communication on remote teams and strategies for overcoming them. A popular theme around this topic is the notion of “escalating communication”. In this context “escalating” means taking a conversation from one mode of communication to a different, higher fidelity mode of communication. Here are the five modes of communication I use at work in order of increasing fidelity: Email – This is the “lowest fidelity” mode of communication that I use. I usually only check it a few times a day (and I’m trying to check it even less frequently than that) and I only keep items in my inbox if they represent an item I need to take action on that I haven’t tracked anywhere else. Forums / Message boards – Being a developer, I’ve gotten into the habit of having other people look over my code before it becomes part of the product I’m working on. These code reviews often happen in “real time” via screen sharing, but I also always have someone else give all of the changes another look using pull requests. A pull request takes my code and lets someone else see the changes I’ve made side-by-side with the existing code so they can see if I did anything dumb. Pull requests can facilitate a conversation about the code changes in an online-forum like style. Some teams I’ve worked on also liked using tools like Trello or Google Groups to have on-going conversations about a topic or task that was being worked on. Chat & Instant Messaging  - Chat and instant messaging are the real workhorses for communication on the remote teams I’ve been a part of. I know some teams that are co-located that also use it pretty extensively for quick messages that don’t warrant walking across the office to talk with someone but reqire more immediacy than an e-mail. For the purposes of this post I think it’s important to note that the terms “chat” and “instant messaging” might insinuate that the conversation is happening in real time, but that’s not always true. Modern chat and IM applications maintain a searchable history so people can easily see what might have been discussed while they were away from their computers. Voice, Video and Screen sharing – Everyone’s got a camera and microphone on their computers now, and there are an abundance of services that will let you use them to talk to other people who have cameras and microphones on their computers. I’m including screen sharing here as well because, in my experience, these discussions typically involve one or more people showing the other participants something that’s happening on their screen. Obviously, this mode of communication is much higher-fidelity than any of the ones listed above. Scheduled meetings are typically conducted using this mode of communication. In Person – No matter how great communication tools become, there’s no substitute for meeting with someone face-to-face. However, opportunities for this kind of communcation are few and far between when you work on a remote team. When a conversation gets escalated that usually means it moves up one or more positions on this list. A lot of people advocate jumping to #4 sooner than later. Like them, I used to believe that, if it was possible, organizing a call with voice and video was automatically better than any kind of text-based communication could be. Lately, however, I’m becoming less convinced that escalating is always the right move. Working Asynchronously Last year I attended a talk at our local code camp given by Drew Miller. Drew works at GitHub and was talking about how they use GitHub internally. Many of the folks at GitHub work remotely, so communication was one of the main themes in Drew’s talk. During the talk Drew used the phrase, “asynchronous communication” to describe their use of chat and pull request comments. That phrase stuck in my head because I hadn’t heard it before but I think it perfectly describes the way in which remote teams often need to communicate. You don’t always know when your co-workers are at their computers or what hours (if any) they are working that day. In order to work this way you need to assume that the person you’re talking to might not respond right away. You can’t always afford to wait until everyone required is online and available to join a voice call, so you need to use text-based, persistent forms of communication so that people can receive and respond to messages when they are available. Going back to my list from the beginning of this post for a second, I characterize items #1-3 as being “asynchronous” modes of communication while we could call items #4 and #5 “synchronous”. When communication gets escalated it’s almost always moving from an asynchronous mode of communication to a synchronous one. Now, to the point of this post: I’ve become increasingly reluctant to escalate from asynchronous to synchronous communication for two primary reasons: 1 – You can often find a higher fidelity way to convey your message without holding a synchronous conversation 2 - Asynchronous modes of communication are (usually) persistent and searchable. You Don’t Have to Broadcast Live Let’s start with the first reason I’ve listed. A lot of times you feel like you need to escalate to synchronous communication because you’re having difficulty describing something that you’re seeing in words. You want to provide the people you’re conversing with some audio-visual aids to help them understand the point that you’re trying to make and you think that getting on Skype and sharing your screen with them is the best way to do that. Firing up a screen sharing session does work well, but you can usually accomplish the same thing in an asynchronous manner. For example, you could take a screenshot and annotate it with some text and drawings to illustrate what it is you’re seeing. If a screenshot won’t work, taking a short screen recording while your narrate over it and posting the video to your forum or chat system along with a text-based description of what’s in the recording that can be searched for later can be a great way to effectively communicate with your team asynchronously. I Said What?!? Now for the second reason I listed: most asynchronous modes of communication provide a transcript of what was said and what decisions might have been made during the conversation. There have been many occasions where I’ve used the search feature of my team’s chat application to find a conversation that happened several weeks or months ago to remember what was decided. Unfortunately, I think the benefits associated with the persistence of communicating asynchronously often get overlooked when people decide to escalate to a in-person meeting or voice/video call. I’m becoming much more reluctant to suggest a voice or video call if I suspect that it might lead to codifying some kind of design decision because everyone involved is going to hang up the call and immediately forget what was decided. I recognize that you can record and archive these types of interactions, but without being able to search them the recordings aren’t terribly useful. When and How To Escalate I don’t mean to imply that communicating via voice/video or in person is never a good idea. I probably jump on a Skype call with a co-worker at least once a day to quickly hash something out or show them a bit of code that I’m working on. Also, meeting in person periodically is really important for remote teams. There’s no way around the fact that sometimes it’s easier to jump on a call and show someone my screen so they can see what I’m seeing. So when is it right to escalate? I think the simplest way to answer that is when the communication starts to feel painful. Everyone’s tolerance for that pain is different, but I think you need to let it hurt a little bit before jumping to synchronous communication. When you do escalate from asynchronous to synchronous communication, there are a couple of things you can do to maximize the effectiveness of the communication: Takes notes – This is huge and yet I’ve found that a lot of teams don’t do this. If you’re holding a meeting with  > 2 people you should have someone taking notes. Taking notes while participating in a meeting can be difficult but there are a few strategies to deal with this challenge that probably deserve a short post of their own. After the meeting, make sure the notes are posted to a place where all concerned parties (including those that might not have attended the meeting) can review and search them. Persist decisions made ASAP – If any decisions were made during the meeting, persist those decisions to a searchable medium as soon as possible following the conversation. All the teams I’ve worked on used a web-based system for tracking the on-going work and a backlog of work to be done in the future. I always try to make sure that all of the cards/stories/tasks/whatever in these systems always reflect the latest decisions that were made as the work was being planned and executed. If held a quick call with your team lead and decided that it wasn’t worth the effort to build real-time validation into that new UI you were working on, go and codify that decision in the story associated with that work immediately after you hang up. Even better, write it up in the story while you are both still on the phone. That way when the folks from your QA team pick up the story to test a few days later they’ll know why the real-time validation isn’t there without having to invoke yet another conversation about the work. Communicating Well is Hard At this point you might be thinking that communicating asynchronously is more difficult than having a live conversation. You’re right: it is more difficult. In order to communicate effectively this way you need to very carefully think about the message that you’re trying to convey and craft it in a way that’s easy for your audience to understand. This is almost always harder than just talking through a problem in real time with someone; this is why escalating communication is such a popular idea. Why wouldn’t we want to do the thing that’s easier? Easier isn’t always better. If you and your team can get in the habit of communicating effectively in an asynchronous manner you’ll find that, over time, all of your communications get less painful because you don’t need to re-iterate previously made points over and over again. If you communicate right the first time, you often don’t need to rehash old conversations because you can go back and find the decisions that were made laid out in plain language. You’ll also find that you get better at doing things like writing useful comments in your code, creating written documentation about how the feature that you just built works, or persuading your team to do things in a certain way.

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  • How to make Asynchronous(AJAX) File Upload using iframe ?

    - by BugKiller
    Hi, I'm trying to make ajax file upload . I read that it is not possible to do that without using iframe . I wrote : <iframe id="uploadTrg" name="uploadTrg" height="0" width="0" frameborder="0" scrolling="yes"></iframe> <form id="myForm" action="file-component" method="post" enctype="multipart/form-data" target="uploadTrg"> File: <input type="file" name="file"> <input type="submit" value="Submit" id="submitBtn"/> </form> and using jquery form plugin : $('#myForm').ajaxForm({ dataType: 'json', success: function(data){ alert(data.toSource()); } }); The Result : the file is uploaded successfully and I can see the uploaded file , but a dialog box appears : since I send back a json result to display the file name + size etc .. My Question : How can I use the iFrame to be able to make " ajax file upload".

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  • How can I get jQuery to perform a synchronous, rather than asynchronous, AJAX request?

    - by Artem Tikhomirov
    Hello. I have a javascript widget witch provides standard extension points. One of them is the beforecreate function. It should return false to prevent an item from being created. I've added an AJAX call into this function using jQuery: beforecreate: function(node,targetNode,type,to) { jQuery.get('http://example.com/catalog/create/' + targetNode.id + '?name=' + encode(to.inp[0].value), function(result) { if(result.isOk == false) alert(result.message); }); } But I want to prevent my widget from creating the item, so I should return false in the mother-function, not in the callback. Is there any way to perform a synchronized AJAX request using jQuery or any other API? Thanks.

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  • Detect if HTTP request is from browser / Flex asynchronous request?

    - by Andree
    Hi there! When Flex application make an asynchronus HTTP request, does it add a special header to the request, like some JavaScript framework does? Something that indicates whether this request is an AJAX call/not. I just want my server side code to return different response format, depending on whether the request is made from browser/flex. Regards, Andree.

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  • How do I run asynchronous code in asp.net mvc 2?

    - by SLC
    I tried this: BackgroundWorker bw = new BackgroundWorker(); bw.DoWork += (o, e) => { SendConfEmail(); }; bw.RunWorkerAsync(); but it didn't work. SendConfEmail takes a while to run. I guess it's because BackgroundWorker is designed for winforms not webforms. Any ideas how I can solve the problem?

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  • Jersey non blocking client

    - by Pavel Bucek
    Although Jersey already have support for making asynchronous requests, it is implemented by standard blocking way - every asynchronous request is handled by one thread and that thread is released only after request is completely processed. That is OK for lots of cases, but imagine how that will work when you need to do lots of parallel requests. Of course you can limit (and its really wise thing to do, you do want control your resources) number of threads used for asynchronous requests, but you'll get another maybe not pleasant consequence - obviously processing time will incerase. There are few projects which are trying to deal with that problem, commonly named as async http clients. I didn't want to "re-implement a wheel" and I decided I'll use AHC - Async Http Client made by Jeanfrancois Arcand. There is also interesting implementation from Apache - HttpAsyncClient, but it is still in "very early stages of development" and others haven't been in similar or better shape as AHC. How this works? Non-blocking clients allow users to make same asynchronous requests as we can do with standard approach but implementation is different - threads are better utilized, they don't spend most of time in idle state. Simply described - when you make a request (send it over the network), you are waiting for reply from other side. And there comes main advantage of non-blocking approach - it uses these threads for further work, like making other requests or processing responses etc.. Idle time is minimized and your resources (threads) will be far better used. Who should consider using this? Everyone who is making lots of asynchronous requests. I haven't done proper benchmark yet, but some simple dumb tests are showing huge improvement in cases where lots of concurrent asynchronous requests are made in short period. Last but not least - this module is still experimental, so if you don't like something or if you have ideas for improvements/any feedback, feel free to comment this blog post, send mail to [email protected] or contact me personally. All feedback is greatly appreciated! maven dependency (will be present in java.net maven 2 repo by the end of the day): link: http://download.java.net/maven/2/com/sun/jersey/experimental/jersey-non-blocking-client <dependency> <groupId>com.sun.jersey.experimental</groupId> <artifactId>jersey-non-blocking-client</artifactId> <version>1.9-SNAPSHOT</version> </dependency> code snippet: ClientConfig cc = new DefaultNonBlockingClientConfig(); cc.getProperties().put(NonBlockingClientConfig.PROPERTY_THREADPOOL_SIZE, 10); // default value, feel free to change Client c = NonBlockingClient.create(cc); AsyncWebResource awr = c.asyncResource("http://oracle.com"); Future<ClientResponse> responseFuture = awr.get(ClientResponse.class); // or awr.get(new TypeListener<ClientResponse>(ClientResponse.class) { @Override public void onComplete(Future<ClientResponse> f) throws InterruptedException { ... } }); javadoc (temporary location, won't be updated): http://anise.cz/~paja/jersey-non-blocking-client/

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  • C# 5 Async, Part 3: Preparing Existing code For Await

    - by Reed
    While the Visual Studio Async CTP provides a fantastic model for asynchronous programming, it requires code to be implemented in terms of Task and Task<T>.  The CTP adds support for Task-based asynchrony to the .NET Framework methods, and promises to have these implemented directly in the framework in the future.  However, existing code outside the framework will need to be converted to using the Task class prior to being usable via the CTP. Wrapping existing asynchronous code into a Task or Task<T> is, thankfully, fairly straightforward.  There are two main approaches to this. Code written using the Asynchronous Programming Model (APM) is very easy to convert to using Task<T>.  The TaskFactory class provides the tools to directly convert APM code into a method returning a Task<T>.  This is done via the FromAsync method.  This method takes the BeginOperation and EndOperation methods, as well as any parameters and state objects as arguments, and returns a Task<T> directly. For example, we could easily convert the WebRequest BeginGetResponse and EndGetResponse methods into a method which returns a Task<WebResponse> via: Task<WebResponse> task = Task.Factory .FromAsync<WebResponse>( request.BeginGetResponse, request.EndGetResponse, null); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Event-based Asynchronous Pattern (EAP) code can also be wrapped into a Task<T>, though this requires a bit more effort than the one line of code above.  This is handled via the TaskCompletionSource<T> class.  MSDN provides a detailed example of using this to wrap an EAP operation into a method returning Task<T>.  It demonstrates handling cancellation and exception handling as well as the basic operation of the asynchronous method itself. The basic form of this operation is typically: Task<YourResult> GetResultAsync() { var tcs = new TaskCompletionSource<YourResult>(); // Handle the event, and setup the task results... this.GetResultCompleted += (o,e) => { if (e.Error != null) tcs.TrySetException(e.Error); else if (e.Cancelled) tcs.TrySetCanceled(); else tcs.TrySetResult(e.Result); }; // Call the asynchronous method this.GetResult(); // Return the task from the TaskCompletionSource return tcs.Task; } We can easily use these methods to wrap our own code into a method that returns a Task<T>.  Existing libraries which cannot be edited can be extended via Extension methods.  The CTP uses this technique to add appropriate methods throughout the framework. The suggested naming for these methods is to define these methods as “Task<YourResult> YourClass.YourOperationAsync(…)”.  However, this naming often conflicts with the default naming of the EAP.  If this is the case, the CTP has standardized on using “Task<YourResult> YourClass.YourOperationTaskAsync(…)”. Once we’ve wrapped all of our existing code into operations that return Task<T>, we can begin investigating how the Async CTP can be used with our own code.

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  • C# 5.0 Async/Await Demo Code

    - by Paulo Morgado
    I’ve published the sample code I use to demonstrate the use of async/await in C# 5.0. You can find it here. Projects PauloMorgado.AyncDemo.WebServer This project is a simple web server implemented as a console application using Microsoft ASP.NET Web API self hosting and serves an image (with a delay) that is accessed by the other projects. This project has a dependency on Json.NET due to the fact the the Microsoft ASP.NET Web API hosting has a dependency on Json.NET. The application must be run on a command prompt with administrative privileges or a urlacl must be added to allow the use of the following command: netsh http add urlacl url=http://+:9090/ user=machine\username To remove the urlacl, just use the following command: netsh http delete urlacl url=http://+:9090/ PauloMorgado.AsyncDemo.WindowsForms This Windows Forms project contains three regions that must be uncommented one at a time: Sync with WebClient This code retrieves the image through a synchronous call using the WebClient class. Async with WebClient This code retrieves the image through an asynchronous call using the WebClient class. Async with HttpClient with cancelation This code retrieves the image through an asynchronous call with cancelation using the HttpClient class. PauloMorgado.AsyncDemo.Wpf This WPF project contains three regions that must be uncommented one at a time: Sync with WebClient This code retrieves the image through a synchronous call using the WebClient class. Async with WebClient This code retrieves the image through an asynchronous call using the WebClient class. Async with HttpClient with cancelation This code retrieves the image through an asynchronous call with cancelation using the HttpClient class.

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  • Can you preload images in a dojo animation.

    - by asynchronous-challenged
    I have a dojo animation object of about 15 images. I'm also using dojo.fx.chain to link them all together. Right before I create all my dojo.fadeIn's and dojo.fadeOut's I added in some basic javascript to preload each image. My question is: Am I doing this the hard way or is there some function/attr I can set in the animation object to do this?

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  • Someone explain to me the meanings behind the naming conventions used in .net?

    - by IbrarMumtaz
    I need someone to explain the following names; Asynchronous Delegates. Asynchronous methods. Asynchronous events. I'm currently going over this for my 70-536 exam and I am covering all my bases so far. The threading chapter and online resources have been good to me on my second read through. Still though, the names used above mean absolutely nothing to me? I would really appreciate the meaning behind the word 'Asynchronous' and its relevance to Delegates, methods and events. Feel free to go into as much detail as you like. Thanks, Ibrar

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  • Programming user interfaces using F# workflows

    F# asynchronous workflows can be used to solve a wide range of programming problems. In this article we'll look how to use asynchronous workflows for elegantly expressing the control flow of interaction with the user. We'll also look at clear functional way for encoding drag&drop-like algorithm.

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  • C# 5: At last, async without the pain

    - by Alex.Davies
    For me, the best feature in Visual Studio 11 is the async and await keywords that come with C# 5. I am a big fan of asynchronous programming: it frees up resources, in particular the thread that a piece of code needs to run in. That lets that thread run something else, while waiting for your long-running operation to complete. That's really important if that thread is the UI thread, or if it's holding a lock because it accesses some data structure. Before C# 5, I think I was about the only person in the world who really cared about asynchronous programming. The trouble was that you had to go to extreme lengths to make code asynchronous. I would forever be writing methods that, instead of returning a value, accepted an extra argument that is a "continuation". Then, when calling the method, I'd have to pass a lambda in to it, which contained all the stuff that needed to happen after the method finished. Here is a real snippet of code that is in .NET Demon: m_BuildControl.FilterEnabledForBuilding(     projects,     enabledProjects = m_OutOfDateProjectFinder.FilterNeedsBuilding(         enabledProjects,         newDirtyProjects =         {             // Mark any currently broken projects as dirty             newDirtyProjects.UnionWith(m_BrokenProjects);             // Copy what we found into the set of dirty things             m_DirtyProjects = newDirtyProjects;             RunSomeBuilds();         })); It's just obtuse. Who puts a lambda inside a lambda like that? Well, me obviously. But surely enabledProjects should just be the return value of FilterEnabledForBuilding? And newDirtyProjects should just be the return value of FilterNeedsBuilding? C# 5 async/await lets you write asynchronous code without it looking so stupid. Here's what I plan to change that code to, once we upgrade to VS 11: var enabledProjects = await m_BuildControl.FilterEnabledForBuilding(projects); var newDirtyProjects = await m_OutOfDateProjectFinder.FilterNeedsBuilding(enabledProjects); // Mark any currently broken projects as dirty newDirtyProjects.UnionWith(m_BrokenProjects); // Copy what we found into the set of dirty things m_DirtyProjects = newDirtyProjects; RunSomeBuilds(); Much easier to read! But how is this the same code? If we were on the UI thread, doesn't the UI thread have to block while FilterEnabledForBuilding runs? No, it doesn't, and that's the magic of the await keyword! It cuts your method up into its constituent pieces, much like I did manually with lambdas before. When you run it, only the piece up to the first await actually runs. The rest is passed to FilterEnabledForBuilding as a continuation, which will get called back whenever that method is finished. In the meantime, our thread returns, and can go back to making the UI responsive, or whatever else threads do in their spare time. This is actually a massive simplification, and if you're interested in all the gory details, and speed hacks that the await keyword actually does for you, I recommend Jon Skeet's blog posts about it.

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  • CLR via C# 3rd Edition is out

    - by Abhijeet Patel
    Time for some book news update. CLR via C#, 3rd Edition seems to have been out for a little while now. The book was released in early Feb this year, and needless to say my copy is on it’s way. I can barely wait to dig in and chew on the goodies that one of the best technical authors and software professionals I respect has in store. The 2nd edition of the book was an absolute treat and this edition promises to be no less. Here is a brief description of what’s new and updated from the 2nd edition. Part I – CLR Basics Chapter 1-The CLR’s Execution Model Added about discussion about C#’s /optimize and /debug switches and how they relate to each other. Chapter 2-Building, Packaging, Deploying, and Administering Applications and Types Improved discussion about Win32 manifest information and version resource information. Chapter 3-Shared Assemblies and Strongly Named Assemblies Added discussion of TypeForwardedToAttribute and TypeForwardedFromAttribute. Part II – Designing Types Chapter 4-Type Fundamentals No new topics. Chapter 5-Primitive, Reference, and Value Types Enhanced discussion of checked and unchecked code and added discussion of new BigInteger type. Also added discussion of C# 4.0’s dynamic primitive type. Chapter 6-Type and Member Basics No new topics. Chapter 7-Constants and Fields No new topics. Chapter 8-Methods Added discussion of extension methods and partial methods. Chapter 9-Parameters Added discussion of optional/named parameters and implicitly-typed local variables. Chapter 10-Properties Added discussion of automatically-implemented properties, properties and the Visual Studio debugger, object and collection initializers, anonymous types, the System.Tuple type and the ExpandoObject type. Chapter 11-Events Added discussion of events and thread-safety as well as showing a cool extension method to simplify the raising of an event. Chapter 12-Generics Added discussion of delegate and interface generic type argument variance. Chapter 13-Interfaces No new topics. Part III – Essential Types Chapter 14-Chars, Strings, and Working with Text No new topics. Chapter 15-Enums Added coverage of new Enum and Type methods to access enumerated type instances. Chapter 16-Arrays Added new section on initializing array elements. Chapter 17-Delegates Added discussion of using generic delegates to avoid defining new delegate types. Also added discussion of lambda expressions. Chapter 18-Attributes No new topics. Chapter 19-Nullable Value Types Added discussion on performance. Part IV – CLR Facilities Chapter 20-Exception Handling and State Management This chapter has been completely rewritten. It is now about exception handling and state management. It includes discussions of code contracts and constrained execution regions (CERs). It also includes a new section on trade-offs between writing productive code and reliable code. Chapter 21-Automatic Memory Management Added discussion of C#’s fixed state and how it works to pin objects in the heap. Rewrote the code for weak delegates so you can use them with any class that exposes an event (the class doesn’t have to support weak delegates itself). Added discussion on the new ConditionalWeakTable class, GC Collection modes, Full GC notifications, garbage collection modes and latency modes. I also include a new sample showing how your application can receive notifications whenever Generation 0 or 2 collections occur. Chapter 22-CLR Hosting and AppDomains Added discussion of side-by-side support allowing multiple CLRs to be loaded in a single process. Added section on the performance of using MarshalByRefObject-derived types. Substantially rewrote the section on cross-AppDomain communication. Added section on AppDomain Monitoring and first chance exception notifications. Updated the section on the AppDomainManager class. Chapter 23-Assembly Loading and Reflection Added section on how to deploy a single file with dependent assemblies embedded inside it. Added section comparing reflection invoke vs bind/invoke vs bind/create delegate/invoke vs C#’s dynamic type. Chapter 24-Runtime Serialization This is a whole new chapter that was not in the 2nd Edition. Part V – Threading Chapter 25-Threading Basics Whole new chapter motivating why Windows supports threads, thread overhead, CPU trends, NUMA Architectures, the relationship between CLR threads and Windows threads, the Thread class, reasons to use threads, thread scheduling and priorities, foreground thread vs background threads. Chapter 26-Performing Compute-Bound Asynchronous Operations Whole new chapter explaining the CLR’s thread pool. This chapter covers all the new .NET 4.0 constructs including cooperative cancelation, Tasks, the aralle class, parallel language integrated query, timers, how the thread pool manages its threads, cache lines and false sharing. Chapter 27-Performing I/O-Bound Asynchronous Operations Whole new chapter explaining how Windows performs synchronous and asynchronous I/O operations. Then, I go into the CLR’s Asynchronous Programming Model, my AsyncEnumerator class, the APM and exceptions, Applications and their threading models, implementing a service asynchronously, the APM and Compute-bound operations, APM considerations, I/O request priorities, converting the APM to a Task, the event-based Asynchronous Pattern, programming model soup. Chapter 28-Primitive Thread Synchronization Constructs Whole new chapter discusses class libraries and thread safety, primitive user-mode, kernel-mode constructs, and data alignment. Chapter 29-Hybrid Thread Synchronization Constructs Whole new chapter discussion various hybrid constructs such as ManualResetEventSlim, SemaphoreSlim, CountdownEvent, Barrier, ReaderWriterLock(Slim), OneManyResourceLock, Monitor, 3 ways to solve the double-check locking technique, .NET 4.0’s Lazy and LazyInitializer classes, the condition variable pattern, .NET 4.0’s concurrent collection classes, the ReaderWriterGate and SyncGate classes.

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  • SOA Suite 11g Dynamic Payload Testing with soapUI Free Edition

    - by Greg Mally
    Overview Many web service developers use soapUI for various tests like: smoke test, unit test, and load testing because you can get a free edition that is fairly robust. However, if you need to venture into more complex testing that requires a dynamic payload, then the free edition doesn't necessarily make it easy. This feature does exist in soapUI, but for obvious reasons it is in the Pro version. In this blog I will show you how to use soapUI free edition for dynamic payloads in a simplified example. Hopefully this will open the doors for you to expand into more complex scenarios. The following assumes that you have a working knowledge of soapUI and will not go into concepts like setting up a project etc. For the basics, please review the documentation for soapUI: http://www.soapui.org/Getting-Started/. Additionally, we will be using asynchronous web services and you can review the setup for this in my blog: SOA Suite 11g Asynchronous Testing with soapUI. Features in soapUI Free Edition Relating to this Topic The soapUI test tool provides a very feature rich environment that can do many things provided you are willing to go beyond point and click. For this example, we will be leveraging just a couple features for our dynamic payload example: Test Case Properties Scripting with Groovy Basically, we will be using a property as a global variable and we will manipulate that property using a Groovy script. Setting Up Our Property Properties are available throughout soapUI and here is a snippet from the soapUI website defining the locations: Projects : for handling Project scope values, for example a subscription ID TestSuite : for handling TestSuite scoped values, can be seen as "arguments" to a TestSuite TestCases : for handling TestCase scoped values, can be seen as "arguments" to a TestCase Properties TestStep : for providing local values/state within a TestCase Local TestStep properties : several TestStep types maintain their own list of properties specific to their functionality : DataSource, DataSink, Run TestCase MockServices : for handling MockService scoped values/arguments MockResponses : for handling MockResponse scoped values Global Properties : for handling Global properties, optionally from an external source For our example, we will be defining a custom property in a TestCase called SimpleAsyncPayload. The property can be created in either the Custom Properties tab located at the bottom of the Navigator panel when the TestCase is selected in the Navigator or the Properties label in the TestCase editor: Navigator Panel TestCase Editor You will notice that I set a value of “0” for the custom property. For this simplified example, we will need to retrieve that value and manipulate it prior to making the web service request invocation. In order to accomplish this, we will need to get Groovy ;) Let's Get Groovy We will now add a new Groovy Script step to the TestCase called Manipulate Payload: TestCase Editor > Append Step > Groovy Script Once we have added the Groovy Script step to our TestCase, we can open the Groovy Script editor to add the code to: Get the current value of the property we created called SimpleAsyncPayload. Convert the value of the property to an integer. Increment the value. Store the incremented value back into the TestCase property called SimpleAsyncPayload. The script should look something like the following: Groovy Script Editor – Manipulate Payload At this point we can test the script to see if it is working by simply running the TestCase (left-click on the green triangle in the upper left-hand corner of the TestCase editor). To verify if it ran correctly, we can look at the value of the SimpleAsyncPayload property which should now be 1: TestCase Editor – Run Results All that is left to complete the TestCase is to append another step of type Test Request. The information required to append the request is a name and an operation to invoke. In this example we will use the default name and select the SimpleAsyncBPELProcessBingd -> process as the operation (any other information being requested, simply use the defaults unless you are calling an asynchronous operation then do not add any assertions). We are now in familiar ground with the Test Request editor. Depending upon the type of operation you are invoking (synchronous or asynchronous), please update the request with the necessary information (e.g., callback information for asynchronous operations). We will now tweak the Test Request payload to retrieve the value of the SimpleAsyncPayload property. The soapUI editor makes this very simple: right-click in the payload and navigate to the property (e.g., right-click > Get Data.. > TestCase: [Groovy TestCase] > Property [SimpleAsyncPayload]): Test Request Editor – Insert Property Value Your payload should now look something like the following: Test Request Editor – Inserted Property Value Just like before, we are now ready to run the TestCase. If everything goes as expected we should see a response like the following: Message Viewer – Results of TestCase Run We are now setup to be able to run a stress test where the payload will change for each request. This simple example can be expanded to include multiple payload values, complex calculations in the scripts, or whatever can be done via the soapUI scripting. Hopefully you have found this useful and happy testing to you :)

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  • How to implement Comet in database side?

    - by Morgan Cheng
    I have been searched for this question for a long time. How to implement Comet in database side? To support Comet, we'd better have a web server stack that supports asynchronous operation. So, Apache is not a option. There are some open source web server such as tornado can do asynchronous http handling. This is in web server level. In database level, how to make web server know that some event happens in database? There should be a asynchronous way to let web server know that something updated in database. Polling is not a option. Is there any example available?

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  • How do I get a Dane-Elec mp3/mp4 player working?

    - by user40432
    My MP3/MP4 does not plug-in and play and therefore I can not transfer any file to the MP3/MP4 dane-elec music my touch or only dane-elec with 8 gb in memory and perhapses model zt1 with radio,..and microsdhc card slot following the above link the mp3/mp4 is there and it is MP3 Player: TOUCH MY MUSIC and the complete information is on this site http://www.danedigital.com/8-Music-Media-Players/2-music-touch.html as the Technical Specifications MP3 Player: TOUCH MY MUSIC The Mp4 player has a very classy. It allows its users to play music and view photos and video. His fluent interface, its touch-pad, his radio and RDS Micro SDHC reader makes him a very complete device will become the ideal musical companion. ubuntu i am with is ubuntu 11.10 kernel 3.0.0-14-generic the latest I tried to install many applications but nothing worked. With disk utility I can see that Ubuntu can recognize something, that as a peripheral device named rockchip usbdisk user and rockchip usbdisk sd, and i can plug and play other devices, and only this mp3/mp4 do not connect to the computer with ubuntu and the device as no problem working disconnected to computer I try to see if work on Windows and it does! I can see the device and transfer files to the MP3/MP4 dane-elec folder device and use FAT32. So why can not do on Ubuntu!? What can I do and why does not work on Ubuntu? What is wrong with it? Here are the logs: Jan 4 17:27:34 a-ubuntu kernel: [ 141.948863] init: apport pre-start process (1970) terminated with status 1 Jan 4 17:27:34 a-ubuntu kernel: [ 141.963202] init: apport post-stop process (1994) terminated with status 1 Jan 4 17:30:02 a-ubuntu kernel: [ 289.564049] usb 2-4: new high speed USB device number 3 using ehci_hcd Jan 4 17:30:02 a-ubuntu kernel: [ 289.988706] usbcore: registered new interface driver uas Jan 4 17:30:02 a-ubuntu kernel: [ 289.992056] Initializing USB Mass Storage driver... Jan 4 17:30:02 a-ubuntu kernel: [ 289.992272] scsi6 : usb-storage 2-4:1.0 Jan 4 17:30:02 a-ubuntu kernel: [ 289.993082] usbcore: registered new interface driver usb-storage Jan 4 17:30:02 a-ubuntu kernel: [ 289.993088] USB Mass Storage support registered. Jan 4 17:30:03 a-ubuntu kernel: [ 290.996887] scsi 6:0:0:0: Direct-Access RockChip USBDISK User 1.00 PQ: 0 ANSI: 0 Jan 4 17:30:03 a-ubuntu kernel: [ 290.997372] scsi 6:0:0:1: Direct-Access RockChip USBDISK SD 1.00 PQ: 0 ANSI: 0 Jan 4 17:30:03 a-ubuntu kernel: [ 290.997478] scsi: killing requests for dead queue Jan 4 17:30:03 a-ubuntu kernel: [ 291.002712] scsi: killing requests for dead queue Jan 4 17:30:03 a-ubuntu kernel: [ 291.002880] scsi: killing requests for dead queue Jan 4 17:30:04 a-ubuntu kernel: [ 291.016249] scsi: killing requests for dead queue Jan 4 17:30:04 a-ubuntu kernel: [ 291.032252] scsi: killing requests for dead queue Jan 4 17:30:04 a-ubuntu kernel: [ 291.048182] scsi: killing requests for dead queue Jan 4 17:30:04 a-ubuntu kernel: [ 291.060178] scsi: killing requests for dead queue Jan 4 17:30:04 a-ubuntu kernel: [ 291.060357] scsi: killing requests for dead queue Jan 4 17:30:04 a-ubuntu kernel: [ 291.080381] sd 6:0:0:0: Attached scsi generic sg2 type 0 Jan 4 17:30:04 a-ubuntu kernel: [ 291.080646] sd 6:0:0:1: Attached scsi generic sg3 type 0 Jan 4 17:30:04 a-ubuntu kernel: [ 291.088381] sd 6:0:0:0: [sdb] 16015360 512-byte logical blocks: (8.19 GB/7.63 GiB) Jan 4 17:30:04 a-ubuntu kernel: [ 291.088988] sd 6:0:0:1: [sdc] Attached SCSI removable disk Jan 4 17:30:04 a-ubuntu kernel: [ 291.200050] usb 2-4: reset high speed USB device number 3 using ehci_hcd Jan 4 17:30:04 a-ubuntu kernel: [ 291.448044] usb 2-4: reset high speed USB device number 3 using ehci_hcd Jan 4 17:30:04 a-ubuntu kernel: [ 291.696055] usb 2-4: reset high speed USB device number 3 using ehci_hcd Jan 4 17:30:04 a-ubuntu kernel: [ 291.832046] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled Jan 4 17:30:04 a-ubuntu kernel: [ 291.832994] sd 6:0:0:0: [sdb] Asking for cache data failed Jan 4 17:30:04 a-ubuntu kernel: [ 291.833001] sd 6:0:0:0: [sdb] Assuming drive cache: write through Jan 4 17:30:04 a-ubuntu kernel: [ 291.834378] sdb: detected capacity change from 8199864320 to 0 Jan 4 17:30:04 a-ubuntu kernel: [ 291.835367] sd 6:0:0:0: [sdb] Attached SCSI removable disk Jan 4 17:30:06 a-ubuntu kernel: [ 293.004741] sd 6:0:0:0: [sdb] 16015360 512-byte logical blocks: (8.19 GB/7.63 GiB) Jan 4 17:30:06 a-ubuntu kernel: [ 293.116051] usb 2-4: reset high speed USB device number 3 using ehci_hcd Jan 4 17:30:21 a-ubuntu kernel: [ 308.228043] usb 2-4: device descriptor read/64, error -110 Jan 4 17:30:36 a-ubuntu kernel: [ 323.444072] usb 2-4: device descriptor read/64, error -110 Jan 4 17:30:36 a-ubuntu kernel: [ 323.660047] usb 2-4: reset high speed USB device number 3 using ehci_hcd Jan 4 17:30:51 a-ubuntu kernel: [ 338.772085] usb 2-4: device descriptor read/64, error -110 Jan 4 17:31:06 a-ubuntu kernel: [ 353.988064] usb 2-4: device descriptor read/64, error -110 Jan 4 17:31:07 a-ubuntu kernel: [ 354.204058] usb 2-4: reset high speed USB device number 3 using ehci_hcd Jan 4 17:31:12 a-ubuntu kernel: [ 359.224115] usb 2-4: device descriptor read/8, error -110 Jan 4 17:31:17 a-ubuntu kernel: [ 364.344136] usb 2-4: device descriptor read/8, error -110 Jan 4 17:31:17 a-ubuntu kernel: [ 364.560037] usb 2-4: reset high speed USB device number 3 using ehci_hcd Jan 4 17:31:22 a-ubuntu kernel: [ 369.580132] usb 2-4: device descriptor read/8, error -110 Jan 4 17:31:27 a-ubuntu kernel: [ 374.700126] usb 2-4: device descriptor read/8, error -110 Jan 4 17:31:27 a-ubuntu kernel: [ 374.804121] usb 2-4: USB disconnect, device number 3 Jan 4 17:31:27 a-ubuntu kernel: [ 374.804518] sd 6:0:0:0: Device offlined - not ready after error recovery Jan 4 17:31:27 a-ubuntu kernel: [ 374.804600] sd 6:0:0:0: [sdb] No Caching mode page present Jan 4 17:31:27 a-ubuntu kernel: [ 374.804606] sd 6:0:0:0: [sdb] Assuming drive cache: write through Jan 4 17:31:27 a-ubuntu kernel: [ 374.804693] sd 6:0:0:0: [sdb] READ CAPACITY failed Jan 4 17:31:27 a-ubuntu kernel: [ 374.804698] sd 6:0:0:0: [sdb] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK Jan 4 17:31:27 a-ubuntu kernel: [ 374.804704] sd 6:0:0:0: [sdb] Sense not available. Jan 4 17:31:27 a-ubuntu kernel: [ 374.804744] sd 6:0:0:0: [sdb] No Caching mode page present Jan 4 17:31:27 a-ubuntu kernel: [ 374.804748] sd 6:0:0:0: [sdb] Assuming drive cache: write through Jan 4 17:31:27 a-ubuntu kernel: [ 374.804754] sdb: detected capacity change from 8199864320 to 0 Jan 4 17:31:27 a-ubuntu kernel: [ 374.820273] scsi: killing requests for dead queue Jan 4 17:31:27 a-ubuntu kernel: [ 374.852240] scsi: killing requests for dead queue Jan 4 17:31:27 a-ubuntu kernel: [ 374.980054] usb 2-4: new high speed USB device number 4 using ehci_hcd Jan 4 17:31:43 a-ubuntu kernel: [ 390.092059] usb 2-4: device descriptor read/64, error -110 Jan 4 17:31:58 a-ubuntu kernel: [ 405.308070] usb 2-4: device descriptor read/64, error -110 Jan 4 17:31:58 a-ubuntu kernel: [ 405.524078] usb 2-4: new high speed USB device number 5 using ehci_hcd and the other post is: http://pastebin.ubuntu.com/792915/ and the other bDeviceSubClass 2 ? bDeviceProtocol 1 Interface Association bMaxPacketSize0 64 idVendor 0x04f2 Chicony Electronics Co., Ltd idProduct 0xb008 USB 2.0 Camera bcdDevice 93.27 iManufacturer 2 Chicony Electronics Co., Ltd. iProduct 1 Chicony USB 2.0 Camera iSerial 3 SN0001 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 565 bNumInterfaces 2 bConfigurationValue 1 iConfiguration 0 bmAttributes 0x80 (Bus Powered) MaxPower 500mA Interface Association: bLength 8 bDescriptorType 11 bFirstInterface 0 bInterfaceCount 2 bFunctionClass 14 Video bFunctionSubClass 3 Video Interface Collection bFunctionProtocol 0 iFunction 1 Chicony USB 2.0 Camera Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 14 Video bInterfaceSubClass 1 Video Control bInterfaceProtocol 0 iInterface 1 Chicony USB 2.0 Camera VideoControl Interface Descriptor: bLength 13 bDescriptorType 36 bDescriptorSubtype 1 (HEADER) bcdUVC 1.00 wTotalLength 77 dwClockFrequency 15.000000MHz bInCollection 1 baInterfaceNr( 0) 1 VideoControl Interface Descriptor: bLength 9 bDescriptorType 36 bDescriptorSubtype 3 (OUTPUT_TERMINAL) bTerminalID 2 wTerminalType 0x0101 USB Streaming bAssocTerminal 0 bSourceID 4 iTerminal 0 VideoControl Interface Descriptor: bLength 26 bDescriptorType 36 bDescriptorSubtype 6 (EXTENSION_UNIT) bUnitID 4 guidExtensionCode {7033f028-1163-2e4a-ba2c-6890eb334016} bNumControl 1 bNrPins 1 baSourceID( 0) 3 bControlSize 1 bmControls( 0) 0x01 iExtension 0 VideoControl Interface Descriptor: bLength 18 bDescriptorType 36 bDescriptorSubtype 2 (INPUT_TERMINAL) bTerminalID 1 wTerminalType 0x0201 Camera Sensor bAssocTerminal 0 iTerminal 0 wObjectiveFocalLengthMin 0 wObjectiveFocalLengthMax 0 wOcularFocalLength 0 bControlSize 3 bmControls 0x00000000 VideoControl Interface Descriptor: bLength 11 bDescriptorType 36 bDescriptorSubtype 5 (PROCESSING_UNIT) Warning: Descriptor too short bUnitID 3 bSourceID 1 wMaxMultiplier 0 bControlSize 2 bmControls 0x0000053f Brightness Contrast Hue Saturation Sharpness Gamma Backlight Compensation Power Line Frequency iProcessing 0 bmVideoStandards 0x a NTSC - 525/60 SECAM - 625/50 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x83 EP 3 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0010 1x 16 bytes bInterval 6 Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 1 bAlternateSetting 0 bNumEndpoints 0 bInterfaceClass 14 Video bInterfaceSubClass 2 Video Streaming bInterfaceProtocol 0 iInterface 0 VideoStreaming Interface Descriptor: bLength 14 bDescriptorType 36 bDescriptorSubtype 1 (INPUT_HEADER) bNumFormats 1 wTotalLength 345 bEndPointAddress 129 bmInfo 0 bTerminalLink 2 bStillCaptureMethod 0 bTriggerSupport 1 bTriggerUsage 0 bControlSize 1 bmaControls( 0) 27 VideoStreaming Interface Descriptor: bLength 27 bDescriptorType 36 bDescriptorSubtype 4 (FORMAT_UNCOMPRESSED) bFormatIndex 1 bNumFrameDescriptors 7 guidFormat {59555932-0000-1000-8000-00aa00389b71} bBitsPerPixel 16 bDefaultFrameIndex 1 bAspectRatioX 0 bAspectRatioY 0 bmInterlaceFlags 0x00 Interlaced stream or variable: No Fields per frame: 2 fields Field 1 first: No Field pattern: Field 1 only bCopyProtect 0 VideoStreaming Interface Descriptor: bLength 46 bDescriptorType 36 bDescriptorSubtype 5 (FRAME_UNCOMPRESSED) bFrameIndex 1 bmCapabilities 0x00 Still image unsupported wWidth 640 wHeight 480 dwMinBitRate 614400 dwMaxBitRate 18432000 dwMaxVideoFrameBufferSize 614400 dwDefaultFrameInterval 333333 bFrameIntervalType 5 dwFrameInterval( 0) 333333 dwFrameInterval( 1) 500000 dwFrameInterval( 2) 666666 dwFrameInterval( 3) 1000000 dwFrameInterval( 4) 2000000 VideoStreaming Interface Descriptor: bLength 46 bDescriptorType 36 bDescriptorSubtype 5 (FRAME_UNCOMPRESSED) bFrameIndex 2 bmCapabilities 0x00 Still image unsupported wWidth 352 wHeight 288 dwMinBitRate 202752 dwMaxBitRate 6082560 dwMaxVideoFrameBufferSize 202752 dwDefaultFrameInterval 333333 bFrameIntervalType 5 dwFrameInterval( 0) 333333 dwFrameInterval( 1) 500000 dwFrameInterval( 2) 666666 dwFrameInterval( 3) 1000000 dwFrameInterval( 4) 2000000 VideoStreaming Interface Descriptor: bLength 46 bDescriptorType 36 bDescriptorSubtype 5 (FRAME_UNCOMPRESSED) bFrameIndex 3 bmCapabilities 0x00 Still image unsupported wWidth 320 wHeight 240 dwMinBitRate 153600 dwMaxBitRate 4608000 dwMaxVideoFrameBufferSize 153600 dwDefaultFrameInterval 333333 bFrameIntervalType 5 dwFrameInterval( 0) 333333 dwFrameInterval( 1) 500000 dwFrameInterval( 2) 666666 dwFrameInterval( 3) 1000000 dwFrameInterval( 4) 2000000 VideoStreaming Interface Descriptor: bLength 46 bDescriptorType 36 bDescriptorSubtype 5 (FRAME_UNCOMPRESSED) bFrameIndex 4 bmCapabilities 0x00 Still image unsupported wWidth 176 wHeight 144 dwMinBitRate 50688 dwMaxBitRate 1520640 dwMaxVideoFrameBufferSize 50688 dwDefaultFrameInterval 333333 bFrameIntervalType 5 dwFrameInterval( 0) 333333 dwFrameInterval( 1) 500000 dwFrameInterval( 2) 666666 dwFrameInterval( 3) 1000000 dwFrameInterval( 4) 2000000 VideoStreaming Interface Descriptor: bLength 46 bDescriptorType 36 bDescriptorSubtype 5 (FRAME_UNCOMPRESSED) bFrameIndex 5 bmCapabilities 0x00 Still image unsupported wWidth 160 wHeight 120 dwMinBitRate 38400 dwMaxBitRate 1152000 dwMaxVideoFrameBufferSize 38400 dwDefaultFrameInterval 333333 bFrameIntervalType 5 dwFrameInterval( 0) 333333 dwFrameInterval( 1) 500000 dwFrameInterval( 2) 666666 dwFrameInterval( 3) 1000000 dwFrameInterval( 4) 2000000 VideoStreaming Interface Descriptor: bLength 34 bDescriptorType 36 bDescriptorSubtype 5 (FRAME_UNCOMPRESSED) bFrameIndex 6 bmCapabilities 0x00 Still image unsupported wWidth 1280 wHeight 800 dwMinBitRate 2048000 dwMaxBitRate 18432000 dwMaxVideoFrameBufferSize 2048000 dwDefaultFrameInterval 1333333 bFrameIntervalType 2 dwFrameInterval( 0) 1333333 dwFrameInterval( 1) 2000000 VideoStreaming Interface Descriptor: bLength 34 bDescriptorType 36 bDescriptorSubtype 5 (FRAME_UNCOMPRESSED) bFrameIndex 7 bmCapabilities 0x00 Still image unsupported wWidth 1280 wHeight 1024 dwMinBitRate 2621440 dwMaxBitRate 23592960 dwMaxVideoFrameBufferSize 2621440 dwDefaultFrameInterval 1333333 bFrameIntervalType 2 dwFrameInterval( 0) 1333333 dwFrameInterval( 1) 2000000 VideoStreaming Interface Descriptor: bLength 6 bDescriptorType 36 bDescriptorSubtype 13 (COLORFORMAT) bColorPrimaries 1 (BT.709,sRGB) bTransferCharacteristics 1 (BT.709) bMatrixCoefficients 4 (SMPTE 170M (BT.601)) Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 1 bAlternateSetting 1 bNumEndpoints 1 bInterfaceClass 14 Video bInterfaceSubClass 2 Video Streaming bInterfaceProtocol 0 iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 5 Transfer Type Isochronous Synch Type Asynchronous Usage Type Data wMaxPacketSize 0x0080 1x 128 bytes bInterval 1 Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 1 bAlternateSetting 2 bNumEndpoints 1 bInterfaceClass 14 Video bInterfaceSubClass 2 Video Streaming bInterfaceProtocol 0 iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 5 Transfer Type Isochronous Synch Type Asynchronous Usage Type Data wMaxPacketSize 0x0100 1x 256 bytes bInterval 1 Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 1 bAlternateSetting 3 bNumEndpoints 1 bInterfaceClass 14 Video bInterfaceSubClass 2 Video Streaming bInterfaceProtocol 0 iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 5 Transfer Type Isochronous Synch Type Asynchronous Usage Type Data wMaxPacketSize 0x0320 1x 800 bytes bInterval 1 Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 1 bAlternateSetting 4 bNumEndpoints 1 bInterfaceClass 14 Video bInterfaceSubClass 2 Video Streaming bInterfaceProtocol 0 iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 5 Transfer Type Isochronous Synch Type Asynchronous Usage Type Data wMaxPacketSize 0x0b20 2x 800 bytes bInterval 1 Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 1 bAlternateSetting 5 bNumEndpoints 1 bInterfaceClass 14 Video bInterfaceSubClass 2 Video Streaming bInterfaceProtocol 0 iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 5 Transfer Type Isochronous Synch Type Asynchronous Usage Type Data wMaxPacketSize 0x1320 3x 800 bytes bInterval 1 Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 1 bAlternateSetting 6 bNumEndpoints 1 bInterfaceClass 14 Video bInterfaceSubClass 2 Video Streaming bInterfaceProtocol 0 iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 5 Transfer Type Isochronous Synch Type Asynchronous Usage Type Data wMaxPacketSize 0x13e8 3x 1000 bytes bInterval 1 Device Qualifier (for other device speed): bLength 10 bDescriptorType 6 bcdUSB 2.00 bDeviceClass 239 Miscellaneous Device bDeviceSubClass 2 ? bDeviceProtocol 1 Interface Association bMaxPacketSize0 64 bNumConfigurations 1 Device Status: 0x0000 (Bus Powered) Bus 006 Device 002: ID 04d9:1503 Holtek Semiconductor, Inc. Shortboard Lefty Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 1.10 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 8 idVendor 0x04d9 Holtek Semiconductor, Inc. idProduct 0x1503 Shortboard Lefty bcdDevice 3.10 iManufacturer 1 iProduct 2 USB Keyboard iSerial 0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 59 bNumInterfaces 2 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xa0 (Bus Powered) Remote Wakeup MaxPower 100mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 3 Human Interface Device bInterfaceSubClass 1 Boot Interface Subclass bInterfaceProtocol 1 Keyboard iInterface 0 HID Device Descriptor: bLength 9 bDescriptorType 33 bcdHID 1.10 bCountryCode 0 Not supported bNumDescriptors 1 bDescriptorType 34 Report wDescriptorLength 62 Report Descriptors: ** UNAVAILABLE ** Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0008 1x 8 bytes bInterval 10 Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 1 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 3 Human Interface Device bInterfaceSubClass 0 No Subclass bInterfaceProtocol 0 None iInterface 0 HID Device Descriptor: bLength 9 bDescriptorType 33 bcdHID 1.10 bCountryCode 0 Not supported bNumDescriptors 1 bDescriptorType 34 Report wDescriptorLength 101 Report Descriptors: ** UNAVAILABLE ** Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x82 EP 2 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0008 1x 8 bytes bInterval 10 Device Status: 0x0000 (Bus Powered)

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  • Workflows not starting after fresh install

    - by Greg McGuffey
    I just installed Dynamics CRM 4.0. It is working nicely except for workflows. They won't start. I turned on tracing and it appears that there is an IO error. The server is setup with IFD and SSL. No issues accessing it internally or externally. Here is the trace: # CRM Tracing Version 2.0 # LocalTime: 2010-06-08 11:34:58.2 # Categories: # CallStackOn: No # ComputerName: FOX-CRM1 # CRMVersion: 4.0.7333.2741 # DeploymentType: OnPremise # ScaleGroup: # ServerRole: AppServer, AsyncService, DiscoveryService, WebService, ApiServer, HelpServer, DeploymentService [2010-06-08 11:34:58.2] Process:CrmAsyncService |Organization:821a137e-7191-49a4-86cc-69101e2b6d20 |Thread: 24 |Category: Platform.Async |User: 00000000-0000-0000-0000-000000000000 |Level: Error | AsyncOperationCommand.Execute >Exception while trying to execute AsyncOperationId: {DF68F483-2C73-DF11-9A34-18A9053B7B38} AsyncOperationType: 1 - System.Net.WebException: The underlying connection was closed: An unexpected error occurred on a send. ---> System.IO.IOException: The handshake failed due to an unexpected packet format. at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.ForceAuthentication(Boolean receiveFirst, Byte[] buffer, AsyncProtocolRequest asyncRequest) at System.Net.Security.SslState.ProcessAuthentication(LazyAsyncResult lazyResult) at System.Net.TlsStream.CallProcessAuthentication(Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Net.TlsStream.ProcessAuthentication(LazyAsyncResult result) at System.Net.TlsStream.Write(Byte[] buffer, Int32 offset, Int32 size) at System.Net.PooledStream.Write(Byte[] buffer, Int32 offset, Int32 size) at System.Net.ConnectStream.WriteHeaders(Boolean async) --- End of inner exception stack trace --- at System.Web.Services.Protocols.WebClientProtocol.GetWebResponse(WebRequest request) at System.Web.Services.Protocols.HttpWebClientProtocol.GetWebResponse(WebRequest request) at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters) at Microsoft.Crm.SdkTypeProxy.CrmService.Retrieve(String entityName, Guid id, ColumnSetBase columnSet) at Microsoft.Crm.Asynchronous.SdkTypeProxyCrmServiceWrapper.Retrieve(String entityName, Guid id, ColumnSetBase columnSet) at Microsoft.Crm.Asynchronous.SdkPluginDescriptionProvider.GetPluginTypeDescription(Guid pluginTypeId, IOrganizationContext context) at Microsoft.Crm.Caching.PluginTypeCacheLoader.LoadCacheData(Guid key, IOrganizationContext context) at Microsoft.Crm.Caching.CrmMultiOrgCache`2.CreateEntry(TKey key, IOrganizationContext context) at Microsoft.Crm.Caching.CrmSharedMultiOrgCache`2.LookupEntry(TKey key, IOrganizationContext context) at Microsoft.Crm.Caching.PluginTypeCache.LookupEntry(Guid pluginTypeId, IOrganizationContext context) at Microsoft.Crm.Asynchronous.AsyncOperationCommand.GetPluginType(Guid pluginTypeId) at Microsoft.Crm.Asynchronous.EventOperation.InternalExecute(AsyncEvent asyncEvent) at Microsoft.Crm.Asynchronous.AsyncOperationCommand.Execute(AsyncEvent asyncEvent) The only thing I've tried to to update the AsyncSdkRootDomain row in the Deployment table to match the ADSdkRootDomain and the ADApplicationRootDomain values. It was blank. That didn't appear to work. After some more research, I think this might be caused because the Asynch service can't access the SDK web services using SSL. If this is correct, how would one configure a CRM server for secure access, internal and external (IFD) and still allow asynch service to hit web site? Thanks for your help!

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  • asynchrony is viral

    - by Daniel Moth
    It is becoming hard to write code today without introducing some form of asynchrony and, if you are using .NET (e.g. for Windows Phone 8 or Windows Store apps), that means sooner or later you have to await something and mark your method as async. My most recent examples included introducing speech recognition in my Translator By Moth phone app where I had to await mySpeechRecognizerUI.RecognizeWithUIAsync() and when moving that code base to a Windows Store project just to show a MessageBox I had to await myMessageDialog.ShowAsync(). Any time you need to invoke an asynchronous method in your code, you have a choice to make: kick off the operation but don’t wait for it to complete (otherwise known as fire-and-forget), synchronously wait for it to complete (which will entail blocking, which can be bad, especially on a UI thread), or asynchronously wait for it to complete before continuing on with the rest of the method’s work. In most cases, you want the latter, and the await keyword makes that trivial to implement.  When you use the magical await keyword in front of an API call, then you typically have to make additional changes to your code: This await usage is within a method of course, and now you have to annotate that method with async. Furthermore, you have to change the return type of the method you just annotated so it returns a Task (if it previously returned void), or Task<myOldReturnType> (if it previously returned myOldReturnType). Note that if it returns void, in some cases you could cheat and stop there. Furthermore, any method that called this method you just annotated with async will now also be invoking an asynchronous operation, so you have to make that change in the body of the caller method to introduce the await keyword before the call to the method. …you guessed it, you now have to change this caller method to be annotated with async and have its return types tweaked... …and it goes on virally… At some point you reach the root of your user code, e.g. a GUI event handler, and whoever calls that void method can already deal with the fact that you marked it as async and the viral introduction of the keywords stops there… This is all wonderful progress and a very powerful mechanism, and I just wish someone had written a refactoring tool to take care of this… anyone? I mentioned earlier that you have a choice when invoking an asynchronous operation. If the first time you encounter this you wish to localize the impact of all these changes and essentially try to turn the asynchronous behavior into synchronous by blocking - don't! For reasons why you don't want to do that, read Toub's excellent blog post (and check out the rest of his blog with gems on async programming starting with the Async FAQ). Just embrace the pattern knowing that when you use one instance of an await, you'll propagate the change all the way to the root user code method, e.g. typically an event handler. Related aside: I just finished re-writing my MessageBox wrapper class for Phone projects, including making it work in Windows Store projects, and it does expect you to use it with an await :-). I'll share that in an upcoming post for those of you that have the same need… Comments about this post by Daniel Moth welcome at the original blog.

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

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

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  • Creating a Synchronous BPEL composite using File Adapter

    - by [email protected]
    By default, the JDeveloper wizard generates asynchronous WSDLs when you use technology adapters. Typically, a user follows these steps when creating an adapter scenario in 11g: 1) Create a SOA Application with either "Composite with BPEL" or an "Empty Composite". Furthermore, if  the user chooses "Empty Composite", then he or she is required to drop the "BPEL Process" from the "Service Components" pane onto the SOA Composite Editor. Either way, the user comes to the screen below where he/she fills in the process details. Please note that the user is required to choose "Define Service Later" as the template. 2) Creates the inbound service and outbound references and wires them with the BPEL component:     3) And, finally creates the BPEL process with the initiating <receive> activity to retrieve the payload and an <invoke> activity to write the payload.     This is how most BPEL processes that use Adapters are modeled. And, if we scrutinize the generated WSDL, we can clearly see that the generated WSDL is one way and that makes the BPEL process asynchronous (see below)   In other words, the inbound FileAdapter would poll for files in the directory and for every file that it finds there, it would translate the content into XML and publish to BPEL. But, since the BPEL process is asynchronous, the adapter would return immediately after the publish and perform the required post processing e.g. deletion/archival and so on.  The disadvantage with such asynchronous BPEL processes is that it becomes difficult to throttle the inbound adapter. In otherwords, the inbound adapter would keep sending messages to BPEL without waiting for the downstream business processes to complete. This might lead to several issues including higher memory usage, CPU usage and so on. In order to alleviate these problems, we will manually tweak the WSDL and BPEL artifacts into synchronous processes. Once we have synchronous BPEL processes, the inbound adapter would automatically throttle itself since the adapter would be forced to wait for the downstream process to complete with a <reply> before processing the next file or message and so on. Please see the tweaked WSDL below and please note that we have converted the one-way to a two-way WSDL and thereby making the WSDL synchronous: Add a <reply> activity to the inbound adapter partnerlink at the end of your BPEL process e.g.   Finally, your process will look like this:   You are done.   Please remember that such an excercise is NOT required for Mediator since the Mediator routing rules are sequential by default. In other words, the Mediator uses the caller thread (inbound file adapter thread) for processing the routing rules. This is the case even if the WSDL for mediator is one-way.

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  • Asynchrony in C# 5 (Part II)

    - by javarg
    This article is a continuation of the series of asynchronous features included in the new Async CTP preview for next versions of C# and VB. Check out Part I for more information. So, let’s continue with TPL Dataflow: Asynchronous functions TPL Dataflow Task based asynchronous Pattern Part II: TPL Dataflow Definition (by quote of Async CTP doc): “TPL Dataflow (TDF) is a new .NET library for building concurrent applications. It promotes actor/agent-oriented designs through primitives for in-process message passing, dataflow, and pipelining. TDF builds upon the APIs and scheduling infrastructure provided by the Task Parallel Library (TPL) in .NET 4, and integrates with the language support for asynchrony provided by C#, Visual Basic, and F#.” This means: data manipulation processed asynchronously. “TPL Dataflow is focused on providing building blocks for message passing and parallelizing CPU- and I/O-intensive applications”. Data manipulation is another hot area when designing asynchronous and parallel applications: how do you sync data access in a parallel environment? how do you avoid concurrency issues? how do you notify when data is available? how do you control how much data is waiting to be consumed? etc.  Dataflow Blocks TDF provides data and action processing blocks. Imagine having preconfigured data processing pipelines to choose from, depending on the type of behavior you want. The most basic block is the BufferBlock<T>, which provides an storage for some kind of data (instances of <T>). So, let’s review data processing blocks available. Blocks a categorized into three groups: Buffering Blocks Executor Blocks Joining Blocks Think of them as electronic circuitry components :).. 1. BufferBlock<T>: it is a FIFO (First in First Out) queue. You can Post data to it and then Receive it synchronously or asynchronously. It synchronizes data consumption for only one receiver at a time (you can have many receivers but only one will actually process it). 2. BroadcastBlock<T>: same FIFO queue for messages (instances of <T>) but link the receiving event to all consumers (it makes the data available for consumption to N number of consumers). The developer can provide a function to make a copy of the data if necessary. 3. WriteOnceBlock<T>: it stores only one value and once it’s been set, it can never be replaced or overwritten again (immutable after being set). As with BroadcastBlock<T>, all consumers can obtain a copy of the value. 4. ActionBlock<TInput>: this executor block allows us to define an operation to be executed when posting data to the queue. Thus, we must pass in a delegate/lambda when creating the block. Posting data will result in an execution of the delegate for each data in the queue. You could also specify how many parallel executions to allow (degree of parallelism). 5. TransformBlock<TInput, TOutput>: this is an executor block designed to transform each input, that is way it defines an output parameter. It ensures messages are processed and delivered in order. 6. TransformManyBlock<TInput, TOutput>: similar to TransformBlock but produces one or more outputs from each input. 7. BatchBlock<T>: combines N single items into one batch item (it buffers and batches inputs). 8. JoinBlock<T1, T2, …>: it generates tuples from all inputs (it aggregates inputs). Inputs could be of any type you want (T1, T2, etc.). 9. BatchJoinBlock<T1, T2, …>: aggregates tuples of collections. It generates collections for each type of input and then creates a tuple to contain each collection (Tuple<IList<T1>, IList<T2>>). Next time I will show some examples of usage for each TDF block. * Images taken from Microsoft’s Async CTP documentation.

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  • facebook api getting full posts with > 2 comments or > 4 likes

    - by ejang
    when I make the user/feed request on the Facebook Open Graph API, I get a feed object where posts with 2 comments or 4 likes don't reveal the detailed information for those specific comments. I am using https://github.com/Thuzi/facebook-node-sdk to make requests but it is very similar to the 'request' NodeJS library. I can get the full posts individually by making a separate request for that post's Open Graph ID, but this doesn't lend itself to fun code because requests are asynchronous and nesting more asynchronous calls within asynchronous calls doesn't lend itself to fun code. Any way I can obtain the full posts?

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  • Metro: Promises

    - by Stephen.Walther
    The goal of this blog entry is to describe the Promise class in the WinJS library. You can use promises whenever you need to perform an asynchronous operation such as retrieving data from a remote website or a file from the file system. Promises are used extensively in the WinJS library. Asynchronous Programming Some code executes immediately, some code requires time to complete or might never complete at all. For example, retrieving the value of a local variable is an immediate operation. Retrieving data from a remote website takes longer or might not complete at all. When an operation might take a long time to complete, you should write your code so that it executes asynchronously. Instead of waiting for an operation to complete, you should start the operation and then do something else until you receive a signal that the operation is complete. An analogy. Some telephone customer service lines require you to wait on hold – listening to really bad music – until a customer service representative is available. This is synchronous programming and very wasteful of your time. Some newer customer service lines enable you to enter your telephone number so the customer service representative can call you back when a customer representative becomes available. This approach is much less wasteful of your time because you can do useful things while waiting for the callback. There are several patterns that you can use to write code which executes asynchronously. The most popular pattern in JavaScript is the callback pattern. When you call a function which might take a long time to return a result, you pass a callback function to the function. For example, the following code (which uses jQuery) includes a function named getFlickrPhotos which returns photos from the Flickr website which match a set of tags (such as “dog” and “funny”): function getFlickrPhotos(tags, callback) { $.getJSON( "http://api.flickr.com/services/feeds/photos_public.gne?jsoncallback=?", { tags: tags, tagmode: "all", format: "json" }, function (data) { if (callback) { callback(data.items); } } ); } getFlickrPhotos("funny, dogs", function(data) { $.each(data, function(index, item) { console.log(item); }); }); The getFlickr() function includes a callback parameter. When you call the getFlickr() function, you pass a function to the callback parameter which gets executed when the getFlicker() function finishes retrieving the list of photos from the Flickr web service. In the code above, the callback function simply iterates through the results and writes each result to the console. Using callbacks is a natural way to perform asynchronous programming with JavaScript. Instead of waiting for an operation to complete, sitting there and listening to really bad music, you can get a callback when the operation is complete. Using Promises The CommonJS website defines a promise like this (http://wiki.commonjs.org/wiki/Promises): “Promises provide a well-defined interface for interacting with an object that represents the result of an action that is performed asynchronously, and may or may not be finished at any given point in time. By utilizing a standard interface, different components can return promises for asynchronous actions and consumers can utilize the promises in a predictable manner.” A promise provides a standard pattern for specifying callbacks. In the WinJS library, when you create a promise, you can specify three callbacks: a complete callback, a failure callback, and a progress callback. Promises are used extensively in the WinJS library. The methods in the animation library, the control library, and the binding library all use promises. For example, the xhr() method included in the WinJS base library returns a promise. The xhr() method wraps calls to the standard XmlHttpRequest object in a promise. The following code illustrates how you can use the xhr() method to perform an Ajax request which retrieves a file named Photos.txt: var options = { url: "/data/photos.txt" }; WinJS.xhr(options).then( function (xmlHttpRequest) { console.log("success"); var data = JSON.parse(xmlHttpRequest.responseText); console.log(data); }, function(xmlHttpRequest) { console.log("fail"); }, function(xmlHttpRequest) { console.log("progress"); } ) The WinJS.xhr() method returns a promise. The Promise class includes a then() method which accepts three callback functions: a complete callback, an error callback, and a progress callback: Promise.then(completeCallback, errorCallback, progressCallback) In the code above, three anonymous functions are passed to the then() method. The three callbacks simply write a message to the JavaScript Console. The complete callback also dumps all of the data retrieved from the photos.txt file. Creating Promises You can create your own promises by creating a new instance of the Promise class. The constructor for the Promise class requires a function which accepts three parameters: a complete, error, and progress function parameter. For example, the code below illustrates how you can create a method named wait10Seconds() which returns a promise. The progress function is called every second and the complete function is not called until 10 seconds have passed: (function () { "use strict"; var app = WinJS.Application; function wait10Seconds() { return new WinJS.Promise(function (complete, error, progress) { var seconds = 0; var intervalId = window.setInterval(function () { seconds++; progress(seconds); if (seconds > 9) { window.clearInterval(intervalId); complete(); } }, 1000); }); } app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { wait10Seconds().then( function () { console.log("complete") }, function () { console.log("error") }, function (seconds) { console.log("progress:" + seconds) } ); } } app.start(); })(); All of the work happens in the constructor function for the promise. The window.setInterval() method is used to execute code every second. Every second, the progress() callback method is called. If more than 10 seconds have passed then the complete() callback method is called and the clearInterval() method is called. When you execute the code above, you can see the output in the Visual Studio JavaScript Console. Creating a Timeout Promise In the previous section, we created a custom Promise which uses the window.setInterval() method to complete the promise after 10 seconds. We really did not need to create a custom promise because the Promise class already includes a static method for returning promises which complete after a certain interval. The code below illustrates how you can use the timeout() method. The timeout() method returns a promise which completes after a certain number of milliseconds. WinJS.Promise.timeout(3000).then( function(){console.log("complete")}, function(){console.log("error")}, function(){console.log("progress")} ); In the code above, the Promise completes after 3 seconds (3000 milliseconds). The Promise returned by the timeout() method does not support progress events. Therefore, the only message written to the console is the message “complete” after 10 seconds. Canceling Promises Some promises, but not all, support cancellation. When you cancel a promise, the promise’s error callback is executed. For example, the following code uses the WinJS.xhr() method to perform an Ajax request. However, immediately after the Ajax request is made, the request is cancelled. // Specify Ajax request options var options = { url: "/data/photos.txt" }; // Make the Ajax request var request = WinJS.xhr(options).then( function (xmlHttpRequest) { console.log("success"); }, function (xmlHttpRequest) { console.log("fail"); }, function (xmlHttpRequest) { console.log("progress"); } ); // Cancel the Ajax request request.cancel(); When you run the code above, the message “fail” is written to the Visual Studio JavaScript Console. Composing Promises You can build promises out of other promises. In other words, you can compose promises. There are two static methods of the Promise class which you can use to compose promises: the join() method and the any() method. When you join promises, a promise is complete when all of the joined promises are complete. When you use the any() method, a promise is complete when any of the promises complete. The following code illustrates how to use the join() method. A new promise is created out of two timeout promises. The new promise does not complete until both of the timeout promises complete: WinJS.Promise.join([WinJS.Promise.timeout(1000), WinJS.Promise.timeout(5000)]) .then(function () { console.log("complete"); }); The message “complete” will not be written to the JavaScript Console until both promises passed to the join() method completes. The message won’t be written for 5 seconds (5,000 milliseconds). The any() method completes when any promise passed to the any() method completes: WinJS.Promise.any([WinJS.Promise.timeout(1000), WinJS.Promise.timeout(5000)]) .then(function () { console.log("complete"); }); The code above writes the message “complete” to the JavaScript Console after 1 second (1,000 milliseconds). The message is written to the JavaScript console immediately after the first promise completes and before the second promise completes. Summary The goal of this blog entry was to describe WinJS promises. First, we discussed how promises enable you to easily write code which performs asynchronous actions. You learned how to use a promise when performing an Ajax request. Next, we discussed how you can create your own promises. You learned how to create a new promise by creating a constructor function with complete, error, and progress parameters. Finally, you learned about several advanced methods of promises. You learned how to use the timeout() method to create promises which complete after an interval of time. You also learned how to cancel promises and compose promises from other promises.

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  • Parallelism in .NET – Part 17, Think Continuations, not Callbacks

    - by Reed
    In traditional asynchronous programming, we’d often use a callback to handle notification of a background task’s completion.  The Task class in the Task Parallel Library introduces a cleaner alternative to the traditional callback: continuation tasks. Asynchronous programming methods typically required callback functions.  For example, MSDN’s Asynchronous Delegates Programming Sample shows a class that factorizes a number.  The original method in the example has the following signature: public static bool Factorize(int number, ref int primefactor1, ref int primefactor2) { //... .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } However, calling this is quite “tricky”, even if we modernize the sample to use lambda expressions via C# 3.0.  Normally, we could call this method like so: int primeFactor1 = 0; int primeFactor2 = 0; bool answer = Factorize(10298312, ref primeFactor1, ref primeFactor2); Console.WriteLine("{0}/{1} [Succeeded {2}]", primeFactor1, primeFactor2, answer); If we want to make this operation run in the background, and report to the console via a callback, things get tricker.  First, we need a delegate definition: public delegate bool AsyncFactorCaller( int number, ref int primefactor1, ref int primefactor2); Then we need to use BeginInvoke to run this method asynchronously: int primeFactor1 = 0; int primeFactor2 = 0; AsyncFactorCaller caller = new AsyncFactorCaller(Factorize); caller.BeginInvoke(10298312, ref primeFactor1, ref primeFactor2, result => { int factor1 = 0; int factor2 = 0; bool answer = caller.EndInvoke(ref factor1, ref factor2, result); Console.WriteLine("{0}/{1} [Succeeded {2}]", factor1, factor2, answer); }, null); This works, but is quite difficult to understand from a conceptual standpoint.  To combat this, the framework added the Event-based Asynchronous Pattern, but it isn’t much easier to understand or author. Using .NET 4’s new Task<T> class and a continuation, we can dramatically simplify the implementation of the above code, as well as make it much more understandable.  We do this via the Task.ContinueWith method.  This method will schedule a new Task upon completion of the original task, and provide the original Task (including its Result if it’s a Task<T>) as an argument.  Using Task, we can eliminate the delegate, and rewrite this code like so: var background = Task.Factory.StartNew( () => { int primeFactor1 = 0; int primeFactor2 = 0; bool result = Factorize(10298312, ref primeFactor1, ref primeFactor2); return new { Result = result, Factor1 = primeFactor1, Factor2 = primeFactor2 }; }); background.ContinueWith(task => Console.WriteLine("{0}/{1} [Succeeded {2}]", task.Result.Factor1, task.Result.Factor2, task.Result.Result)); This is much simpler to understand, in my opinion.  Here, we’re explicitly asking to start a new task, then continue the task with a resulting task.  In our case, our method used ref parameters (this was from the MSDN Sample), so there is a little bit of extra boiler plate involved, but the code is at least easy to understand. That being said, this isn’t dramatically shorter when compared with our C# 3 port of the MSDN code above.  However, if we were to extend our requirements a bit, we can start to see more advantages to the Task based approach.  For example, supposed we need to report the results in a user interface control instead of reporting it to the Console.  This would be a common operation, but now, we have to think about marshaling our calls back to the user interface.  This is probably going to require calling Control.Invoke or Dispatcher.Invoke within our callback, forcing us to specify a delegate within the delegate.  The maintainability and ease of understanding drops.  However, just as a standard Task can be created with a TaskScheduler that uses the UI synchronization context, so too can we continue a task with a specific context.  There are Task.ContinueWith method overloads which allow you to provide a TaskScheduler.  This means you can schedule the continuation to run on the UI thread, by simply doing: Task.Factory.StartNew( () => { int primeFactor1 = 0; int primeFactor2 = 0; bool result = Factorize(10298312, ref primeFactor1, ref primeFactor2); return new { Result = result, Factor1 = primeFactor1, Factor2 = primeFactor2 }; }).ContinueWith(task => textBox1.Text = string.Format("{0}/{1} [Succeeded {2}]", task.Result.Factor1, task.Result.Factor2, task.Result.Result), TaskScheduler.FromCurrentSynchronizationContext()); This is far more understandable than the alternative.  By using Task.ContinueWith in conjunction with TaskScheduler.FromCurrentSynchronizationContext(), we get a simple way to push any work onto a background thread, and update the user interface on the proper UI thread.  This technique works with Windows Presentation Foundation as well as Windows Forms, with no change in methodology.

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