1 / 36

Asynchronous Programming with C# v.Next

Asynchronous Programming with C# v.Next. Pavel Yosifovich Hi-Tech College pavely@hi-tech.co.il http://blogs.microsoft.co.il/blogs/pavely. Agenda. C# Evolution Trends Synchronous vs. Asynchronous Asynchrony the “old way” The New Way Odds and Ends Summary. C# Evolution. C# 4.0.

bozica
Download Presentation

Asynchronous Programming with C# v.Next

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Asynchronous Programming with C# v.Next Pavel Yosifovich Hi-Tech College pavely@hi-tech.co.il http://blogs.microsoft.co.il/blogs/pavely

  2. Agenda • C# Evolution • Trends • Synchronous vs. Asynchronous • Asynchrony the “old way” • The New Way • Odds and Ends • Summary

  3. C# Evolution C# 4.0 Dynamic Typing C# 3.0 Language Integrated Query C# 2.0 Generics C# 1.0 Managed Code

  4. Trends

  5. Trends • Increasingly connected applications • More latency • More UI responsiveness problems • More scalability issues • Asynchronous programming • Becoming the norm in responsive, scalable apps • Async-only APIs, e.g. JavaScript and Silverlight

  6. C# Evolution C# v.Next Asynchronous Programming C# 4.0 Dynamic Typing C# 3.0 Language Integrated Query C# 2.0 Generics C# 1.0 Managed Code

  7. Responsive UI demo

  8. Asynchrony in a Nutshell • Synchronous  Wait for result before returning • string DownloadString(...); • Asynchronous  Return now, call back with result • void DownloadStringAsync(..., Action<string> callback); • Asynchronous work != Threads

  9. Synchronous vs. Asynchronous var data = DownloadData(...); ProcessData(data); STOP Thread DownloadData ProcessData DownloadDataAsync(... , data => { ProcessData(data); }); Thread DownloadDataAsync ProcessData

  10. Synchronous vs. Asynchronous var data = DownloadData(...); ProcessData(data); STOP STOP Thread DownloadData ProcessData DownloadDataAsync(... , data => { ProcessData(data); }); Thread DownloadDataAsync ProcessData

  11. Asynchronous Methods • Goal: Just like synchronous programming • Framework: Use Task<T> for all asynchrony • Add Task<T> support to existing .NET and Silverlight APIs • Developers can do the same • Languages: Asynchronous Methods • “async” modifier marks method or lambda as asynchronous • “await” operator yields control until awaited task completes

  12. Task<T> • Represents “ongoing operation” • Could be async I/O, background worker, anything... • Single object for status, result and exceptions • Composable callback model • var task2 = task1.ContinueWith(t => … t.Result …); • The “await” operator rewrites to continuations • Combinators • WhenAll, WhenAny, Delay, etc.

  13. Asynchronous Control Flow async voidDoWorkAsync() { var t1 = ProcessFeedAsync("www.acme.com/rss"); var t2 = ProcessFeedAsync("www.xyznews.com/rss"); awaitTask.WhenAll(t1, t2); DisplayMessage("Done"); } asyncTaskProcessFeedAsync(stringurl) { var text = awaitDownloadFeedAsync(url); var doc = ParseFeedIntoDoc(text); awaitSaveDocAsync(doc); ProcessLog.WriteEntry(url); } Message Pump UI Thread

  14. Asynchronous Control Flow async voidDoWorkAsync() { var t1 = ProcessFeedAsync("www.acme.com/rss"); var t2 = ProcessFeedAsync("www.xyznews.com/rss"); awaitTask.WhenAll(t1, t2); DisplayMessage("Done"); } asyncTaskProcessFeedAsync(stringurl) { var text = awaitDownloadFeedAsync(url); var doc = ParseFeedIntoDoc(text); awaitSaveDocAsync(doc); ProcessLog.WriteEntry(url); }

  15. Asynchronous Control Flow async voidDoWorkAsync() { var t1 = ProcessFeedAsync("www.acme.com/rss"); var t2 = ProcessFeedAsync("www.xyznews.com/rss"); awaitTask.WhenAll(t1, t2); DisplayMessage("Done"); } asyncTaskProcessFeedAsync(stringurl) { var text = awaitDownloadFeedAsync(url); var doc = ParseFeedIntoDoc(text); awaitSaveDocAsync(doc); ProcessLog.WriteEntry(url); }

  16. Asynchronous Control Flow async voidDoWorkAsync() { var t1 = ProcessFeedAsync("www.acme.com/rss"); var t2 = ProcessFeedAsync("www.xyznews.com/rss"); awaitTask.WhenAll(t1, t2); DisplayMessage("Done"); } asyncTaskProcessFeedAsync(stringurl) { var text = awaitDownloadFeedAsync(url); var doc = ParseFeedIntoDoc(text); awaitSaveDocAsync(doc); ProcessLog.WriteEntry(url); }

  17. Asynchronous Control Flow async voidDoWorkAsync() { var t1 = ProcessFeedAsync("www.acme.com/rss"); var t2 = ProcessFeedAsync("www.xyznews.com/rss"); awaitTask.WhenAll(t1, t2); DisplayMessage("Done"); } asyncTaskProcessFeedAsync(stringurl) { var text = awaitDownloadFeedAsync(url); var doc = ParseFeedIntoDoc(text); awaitSaveDocAsync(doc); ProcessLog.WriteEntry(url); } t1

  18. Asynchronous Control Flow async voidDoWorkAsync() { var t1 = ProcessFeedAsync("www.acme.com/rss"); var t2 = ProcessFeedAsync("www.xyznews.com/rss"); awaitTask.WhenAll(t1, t2); DisplayMessage("Done"); } asyncTaskProcessFeedAsync(stringurl) { var text = awaitDownloadFeedAsync(url); var doc = ParseFeedIntoDoc(text); awaitSaveDocAsync(doc); ProcessLog.WriteEntry(url); } t1 t2

  19. Asynchronous Control Flow async voidDoWorkAsync() { var t1 = ProcessFeedAsync("www.acme.com/rss"); var t2 = ProcessFeedAsync("www.xyznews.com/rss"); awaitTask.WhenAll(t1, t2); DisplayMessage("Done"); } asyncTaskProcessFeedAsync(stringurl) { var text = awaitDownloadFeedAsync(url); var doc = ParseFeedIntoDoc(text); awaitSaveDocAsync(doc); ProcessLog.WriteEntry(url); } t1 t2

  20. Asynchronous Control Flow async voidDoWorkAsync() { var t1 = ProcessFeedAsync("www.acme.com/rss"); var t2 = ProcessFeedAsync("www.xyznews.com/rss"); awaitTask.WhenAll(t1, t2); DisplayMessage("Done"); } asyncTaskProcessFeedAsync(stringurl) { var text = awaitDownloadFeedAsync(url); var doc = ParseFeedIntoDoc(text); awaitSaveDocAsync(doc); ProcessLog.WriteEntry(url); } t1 t2 

  21. Asynchronous Control Flow async voidDoWorkAsync() { var t1 = ProcessFeedAsync("www.acme.com/rss"); var t2 = ProcessFeedAsync("www.xyznews.com/rss"); awaitTask.WhenAll(t1, t2); DisplayMessage("Done"); } asyncTaskProcessFeedAsync(stringurl) { var text = awaitDownloadFeedAsync(url); var doc = ParseFeedIntoDoc(text); awaitSaveDocAsync(doc); ProcessLog.WriteEntry(url); } t1 t2 

  22. Asynchronous Control Flow async voidDoWorkAsync() { var t1 = ProcessFeedAsync("www.acme.com/rss"); var t2 = ProcessFeedAsync("www.xyznews.com/rss"); awaitTask.WhenAll(t1, t2); DisplayMessage("Done"); } asyncTaskProcessFeedAsync(stringurl) { var text = awaitDownloadFeedAsync(url); var doc = ParseFeedIntoDoc(text); awaitSaveDocAsync(doc); ProcessLog.WriteEntry(url); } t1 t2  

  23. Asynchronous Control Flow async voidDoWorkAsync() { var t1 = ProcessFeedAsync("www.acme.com/rss"); var t2 = ProcessFeedAsync("www.xyznews.com/rss"); awaitTask.WhenAll(t1, t2); DisplayMessage("Done"); } asyncTaskProcessFeedAsync(stringurl) { var text = awaitDownloadFeedAsync(url); var doc = ParseFeedIntoDoc(text); awaitSaveDocAsync(doc); ProcessLog.WriteEntry(url); } t1 t2  

  24. Asynchronous Control Flow async voidDoWorkAsync() { var t1 = ProcessFeedAsync("www.acme.com/rss"); var t2 = ProcessFeedAsync("www.xyznews.com/rss"); awaitTask.WhenAll(t1, t2); DisplayMessage("Done"); } asyncTaskProcessFeedAsync(stringurl) { var text = awaitDownloadFeedAsync(url); var doc = ParseFeedIntoDoc(text); awaitSaveDocAsync(doc); ProcessLog.WriteEntry(url); } t1 t2   

  25. Asynchronous Control Flow async voidDoWorkAsync() { var t1 = ProcessFeedAsync("www.acme.com/rss"); var t2 = ProcessFeedAsync("www.xyznews.com/rss"); awaitTask.WhenAll(t1, t2); DisplayMessage("Done"); } asyncTaskProcessFeedAsync(stringurl) { var text = awaitDownloadFeedAsync(url); var doc = ParseFeedIntoDoc(text); awaitSaveDocAsync(doc); ProcessLog.WriteEntry(url); } t1 t2    

  26. Asynchronous Control Flow async voidDoWorkAsync() { var t1 = ProcessFeedAsync("www.acme.com/rss"); var t2 = ProcessFeedAsync("www.xyznews.com/rss"); awaitTask.WhenAll(t1, t2); DisplayMessage("Done"); } asyncTaskProcessFeedAsync(stringurl) { var text = awaitDownloadFeedAsync(url); var doc = ParseFeedIntoDoc(text); awaitSaveDocAsync(doc); ProcessLog.WriteEntry(url); } t1 t2     

  27. Asynchronous Control Flow async voidDoWorkAsync() { var t1 = ProcessFeedAsync("www.acme.com/rss"); var t2 = ProcessFeedAsync("www.xyznews.com/rss"); awaitTask.WhenAll(t1, t2); DisplayMessage("Done"); } asyncTaskProcessFeedAsync(stringurl) { var text = awaitDownloadFeedAsync(url); var doc = ParseFeedIntoDoc(text); awaitSaveDocAsync(doc); ProcessLog.WriteEntry(url); } t1 t2      

  28. Asynchronous Control Flow async voidDoWorkAsync() { var t1 = ProcessFeedAsync("www.acme.com/rss"); var t2 = ProcessFeedAsync("www.xyznews.com/rss"); awaitTask.WhenAll(t1, t2); DisplayMessage("Done"); } asyncTaskProcessFeedAsync(stringurl) { var text = awaitDownloadFeedAsync(url); var doc = ParseFeedIntoDoc(text); awaitSaveDocAsync(doc); ProcessLog.WriteEntry(url); } t1 t2       

  29. Asynchronous Control Flow async voidDoWorkAsync() { var t1 = ProcessFeedAsync("www.acme.com/rss"); var t2 = ProcessFeedAsync("www.xyznews.com/rss"); awaitTask.WhenAll(t1, t2); DisplayMessage("Done"); } asyncTaskProcessFeedAsync(stringurl) { var text = awaitDownloadFeedAsync(url); var doc = ParseFeedIntoDoc(text); awaitSaveDocAsync(doc); ProcessLog.WriteEntry(url); } t1 t2       

  30. What About Exceptions? • Should be as simple as the synchronous case varwc = newWebClient(); try { stringtxt = awaitwc.DownloadStringTaskAsync(url); dataTextBox.Text = txt; } catch(WebExceptionx) { // Handle as usual }

  31. How Does it Work? async Task<XElement> GetRssAsync(stringurl) { var client = newWebClient(); var task = client.DownloadStringTaskAsync(url); var text = await task; var xml = XElement.Parse(text); return xml; }

  32. How Does it Work? Task<XElement> GetRssAsync(stringurl) { var $builder = AsyncMethodBuilder<XElement>.Create(); var $state = 0; TaskAwaiter<string> $a1; Action $resume = delegate { try { if ($state == 1) goto L1; var client = newWebClient(); var task = client.DownloadStringTaskAsync(url); $state = 1; $a1 = task.GetAwaiter(); if ($a1.BeginAwait($resume)) return; L1: var text = $a1.EndAwait(); var xml = XElement.Parse(text); $builder.SetResult(xml); } catch (Exception $ex) { $builder.SetException($ex); } }; $resume(); return $builder.Task; } async Task<XElement> GetRssAsync(string url) { var client = new WebClient(); var task = client.DownloadStringTaskAsync(url); var text = await task; var xml = XElement.Parse(text); return xml; }

  33. Asynchronous Methods • As simple as synchronous code • Unifies computational, network and I/O asynchrony • More scalable servers • More responsive UI

  34. C# Evolution C# v.Next Asynchronous Programming C# 4.0 Dynamic Typing C# 3.0 Language Integrated Query C# 2.0 Generics C# 1.0 Managed Code

  35. Compiler as a Service Meta-programming Read-Eval-Print Loop Class public Foo Language Object Model Field DSL Embedding private X string Compiler Compiler SourceFile .NET Assembly Source code Source code Source code Source code

  36. Resources • Visual Studio Async CTP • http://msdn.com/vstudio/async • Eric Lippert’s Blog • http://blogs.msdn.com/b/ericlippert/ • The Async CTP does not currently work if SP1 is installed • Need to install on top of the RTM version • A new CTP will probably be released soon that will work with SP1

More Related