Thought this could be useful for anyone not on the Silverlight mailing list
"Do you know, does "Silverlight 4: Duplex WCF over TCP" have any issues with server affinity in a web farm / load balancing configuration?" >scalable solution to the cloud >http://blogs.msdn.com/ales/archive/2009/09/22/scalable-duplex-messaging-with-silverlight-3-and-windows-azure.aspx -David Burela From: ozsilverlight-boun...@ozsilverlight.com [mailto:ozsilverlight-boun...@ozsilverlight.com] On Behalf Of Peter Gfader Sent: Wednesday, 31 March 2010 2:47 PM To: ozSilverlight Subject: Re: "Real" time updates to and from clients Hi >> Do you know, does "Silverlight 4: Duplex WCF over TCP" have any issues with >> server affinity in a web farm / load balancing configuration? Yes this issue is there from http://tomasz.janczuk.org/2009/08/performance-of-http-polling-duplex.html Current implementation of polling duplex protocol in Silverlight 3 requires client affinity to a particular physical server machine for the lifetime of the WCF channel (WCF proxy). Moreover, the server maintains in-memory state for the duration of the session with the client. If you are using a load balancer that cannot guarantee client affinity to a particular backend, or if your hosting infrastructure cannot guarantee that the service will keep running on the same machine, the protocol will fail. In the practice of load balanced web farms, the Silverlight polling duplex protocol in the current form does not scale out well. Scale out solution to this problem here ... http://tomasz.janczuk.org/2009/09/scale-out-of-silverlight-http-polling.html And porting that scalable solution to the cloud http://blogs.msdn.com/ales/archive/2009/09/22/scalable-duplex-messaging-with-silverlight-3-and-windows-azure.aspx .peter.gfader. http://peitor.blogspot.com/ http://twitter.com/peitor On Tue, Mar 30, 2010 at 5:44 PM, ross <r...@perenni.com.au<mailto:r...@perenni.com.au>> wrote: Interesting. Do you know, does "Silverlight 4: Duplex WCF over TCP" have any issues with server affinity in a web farm / load balancing configuration? I believe that might be an issue with Duplex WCF over http. On Tue, Mar 30, 2010 at 4:08 PM, Peter Gfader <peter.gfa...@gmail.com<mailto:peter.gfa...@gmail.com>> wrote: > Hi list > I just give you a quick update on this.. >>>PeterG: WCF net.tcp protocol in Silverlight 4 (Polling over TCP Sockets) > I have to correct my self here. > This is not the case, WCF is not polling over TCP sockets, but keeping a > socket open and using that to send and receive messages... awesome > performance... > > Initially I started typing up an email, then I was thinking: Hey put this on > your blog and get some traffic on it... > So here is the blog post > http://peitor.blogspot.com/2010/03/time-communication-clientserver.html > > Content here > -------- > > We are building something similar and have the following requirements > > People on the web should be able to use it > No download of an application > Broadcasting messages to all user (server to clients) > Everyone should be able to use it > > People behind firewalls, proxies, NATs, ... > People with 1 of the current browsers > > Lightweight solution needed > > > > We tested and verified different technology options like: > > HTML+ Reverse AJAX > Silverlight 2: Duplex WCF over HTTP (Long polling HTTP connection under the > hood or Comet-style) > Silverlight 4: Duplex WCF over TCP (is using net.tcp, socket connection > under the hood) > Silverlight raw Sockets (maybe even using SocketsLight) > Silverlight UDP > HTML 5 web sockets > > The signs for HTML 5 web sockets are not so good, even though the promise > for the socket implementation sounds interesting! > But it seems that HTML 5 is not going to be ready before ~201X, X > 2 and > not sure what that X is... > More here > http://blogs.techrepublic.com.com/programming-and-development/?p=718 > http://www.webmonkey.com/blog/HTML_5_Won_t_Be_Ready_Until_2022DOT_Yes__2022DOT > > > > We finally are using "Silverlight with Duplex WCF over TCP" > And falling back to "Silverlight with Duplex WCF over HTTP" when we have a > firewall or proxy in the middle that causes connection problems. > > The main reason for going in that direction was: > > Ease of development and productivity in coding with Silverlight and WCF > Developing against one API (WCF) and doing an easy fallback behind the > scenes (10 lines of code!) > Performance is awesome by using TCP (see Tomasz post about that) > Testing Silverlight means testing 1 environment against testing different > browsers, operating systems, JavaScript versions, OS versions, browser > versions,.... > > > > PS > There is a new HTTP polling duplex mode added in Silverlight 4 RC, called > "MultipleMessagesPerPoll", makes this technology even more interesting > > > .peter.gfader. > http://peitor.blogspot.com/ > http://twitter.com/peitor > On Thu, Jan 28, 2010 at 7:10 PM, Peter Gfader > <peter.gfa...@gmail.com<mailto:peter.gfa...@gmail.com>> > wrote: >> >> >>In Silverlight 3 didn't they introduce a duplex WCF service? >> >> Yes they introduced duplex WCF services, but it is doing "long" polling >> under the hood... >> >> Messages from the server to the client within a particular session are >> sent using an HTTP response to a long lasting HTTP request the client makes >> to the server (the "long poll"). >> The client side implementation of the polling duplex protocol ensures that >> the server always has such pending HTTP request available; as soon as the >> server sends a message to the client using the response to the long poll, >> the client issues a new long poll. >> From >> >> >> http://tomasz.janczuk.org/2009/09/scale-out-of-silverlight-http-polling.html >> >> .peter.gfader. >> http://peitor.blogspot.com/ >> >> On Thu, Jan 28, 2010 at 4:17 PM, John OBrien >> <j...@soulsolutions.com.au<mailto:j...@soulsolutions.com.au>> >> wrote: >>> >>> Peter, >>> >>> We used sockets in Silverlight2 to prototype a spatial collaboration >>> concept. The main issues we faced were: >>> >>> 1. Needed to run a windows application (testing=console app, >>> production=windows service) for both server side processing and also as a >>> policy service. Made it hard to deploy. >>> >>> 2. Very raw technology, we had to deal with packets of data and >>> worried about robustness of the server solution under heavy load. >>> >>> >>> >>> In the end we didn't move beyond the prototype but decided we need to >>> evaluate the purchase of a socket based communication server (often used for >>> online games). >>> >>> >>> >>> In Silverlight 3 didn't they introduce a duplex WCF service? >>> >>> >>> >>> John. >>> >>> >>> >>> From: >>> ozsilverlight-boun...@ozsilverlight.com<mailto:ozsilverlight-boun...@ozsilverlight.com> >>> [mailto:ozsilverlight-boun...@ozsilverlight.com<mailto:ozsilverlight-boun...@ozsilverlight.com>] >>> On Behalf Of Peter Gfader >>> Sent: Thursday, 28 January 2010 1:33 PM >>> To: ozsilverli...@ozsilverlight.com<mailto:ozsilverli...@ozsilverlight.com> >>> Subject: "Real" time updates to and from clients >>> >>> >>> >>> Hi All, >>> >>> >>> >>> I play around with "real time" updates to and from SL clients, and have >>> figured out a couple of possibilities with Silverlight. >>> >>> Sockets >>> Polling over WCF in SL2 or SL3 (HTTP) >>> WCF net.tcp protocol in Silverlight 4 (Polling over TCP Sockets) >>> >>> Anyone has some good or bad experience with them? >>> >>> >>> >>> Regarding >>> >>> Performance >>> Ease of development >>> Security (Firewalls are not a problem) >>> >>> >>> >>> My opinion so far: >>> >>> Sockets >>> >>> Harder to write than calling a WCF service >>> Best option regarding performance >>> >>> Polling over WCF (HTTP) >>> >>> Not a nice solution regarding performance >>> >>> WCF net.tcp protocol in Silverlight 4 (Polling over TCP Sockets) >>> >>> Under the hood sockets, but I don't have to worry about sockets >>> Good performance >>> >>> Port restrictions to all of those I have seen... >>> >>> >>> >>> Your opinions? >>> >>> >>> >>> PS >>> >>> This guy has a nice Socket implementation for getting updates from a >>> server >>> >>> http://petermcg.wordpress.com/2008/06/05/stock-list-demo-part-3/ >>> >>> >>> >>> This guy is writing about WCF net.tcp in SL 4 >>> >>> >>> http://tomasz.janczuk.org/2009/11/wcf-nettcp-protocol-in-silverlight-4.html >>> >>> >>> >>> PS2 >>> >>> What can I do against port restrictions? >>> >>> >>> >>> .peter.gfader. >>> >>> http://peitor.blogspot.com/ >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> _______________________________________________ >>> ozsilverlight mailing list >>> ozsilverli...@ozsilverlight.com<mailto:ozsilverli...@ozsilverlight.com> >>> http://prdlxvm0001.codify.net/mailman/listinfo/ozsilverlight >>> >> > > > _______________________________________________ > ozsilverlight mailing list > ozsilverli...@ozsilverlight.com<mailto:ozsilverli...@ozsilverlight.com> > http://prdlxvm0001.codify.net/mailman/listinfo/ozsilverlight > > _______________________________________________ ozsilverlight mailing list ozsilverli...@ozsilverlight.com<mailto:ozsilverli...@ozsilverlight.com> http://prdlxvm0001.codify.net/mailman/listinfo/ozsilverlight
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