PollingDuplex using MultipleMessagesPerPoll issue in latest SL4 GDRs

Some customers are reporting on the Silverlight forums that they are unable to have a functional PollingDuplexHttpBinding setup, or their current polling duplex client have faulted channels. This behavior is a regression introduced in SL4 GDR1 and is visible when the following conditions are put together: -Use of PollingDuplex-DuplexMode is set to MultipleMessagesPerPoll -Http stack…


PollingDuplex multiple mode timeouts demystified

The new MultipleMessagesPerPoll mode added to PollingDuplex in Silverlight 4, comes with some new timeouts , so I thought it would be useful to post a detailed description of how those work. Unfortunately this is not currently covered by our documentation, which is something we are looking to address in upcoming documentation refreshes. This is…


HTTP duplex messaging improvements in Silverlight 4

One of the new features in the WCF stack in Silverlight 4 is an improvement of our PollingDuplex binding, which allows duplex communication over HTTP. HTTP is a request/reply communication medium, so some tricks are needed to make it look like a duplex transport, where both the client and the server can send messages to…


Fiddler inspector for WCF Silverlight Polling Duplex and WCF RIA

  Fiddler is a wild popular tool for web development debugging. It enables user to look at the http traffic and diagnoses issues. Natively it provides Raw, Hex, Xml and some other views that understand specific formats. For the format it doesn’t understand, it provides an Inspector plugin model that user can easily implement and hook…


The case of null httpcontext.current.session

Because of un-addressable client in SL, we introduced Polling Duplex channel to support callback in WCF Silverlight. It started as a channel in Silverlight2. We added service model support in Silverlight3 and MultipeMode, aka chunking in Silverlight4. See MSDN for more information about how to use it. Recently some customer reported that session state object…


Tracing PollingDuplex in Silverlight 4

Did you know it is now easier to debug the server side PollingDuplex in Silverlight 4? With the addition of tracing, you can now get a peek at what is happening internally within your service. Traces from PollingDuplex will include information about what failed in communicating with your clients and how it was handled. Enabling…


Some known WCF issues in Silverlight 4

When shipping a product, there are always a handful of painful issues that we unfortunately cannot fix due to schedule pressure. One thing we can do is blog about these issues early and provide workarounds, so customers don’t have to spend countless hours debugging. Here is the list of known issues in the WCF stack….


Two samples from today’s MIX talk

Thanks to the folks who attended my talk at MIX 2010 today. As promised, I’m posting the two samples I showed. I’ll post an update when the video from my talk is available, so folks who couldn’t attend can see it. Local Search I built a Silverlight application that runs on Windows Phone 7. It’s…