Comments on Tomek on Software: Performance of HTTP polling duplex server-side cha...

Hi Gone through your article, currently I'm d...

2011-03-12T14:51:57.854-08:00

Hi

Gone through your article, currently I'm developing a Pub/Sub architecture to my system using polling duplex in silverlight with WCF. The error which Kills me in the publish flow is

"The communication object, System.ServiceModel.Channels.ServiceChannel, cannot be used for communication because channel got aborted."

IT will be more helpful if i get a solution for the same

Thanks
Praveen

excuse me if this is a stupid question, what the b...

2010-09-14T11:05:54.339-07:00

excuse me if this is a stupid question, what the bottleneck is it simply hardware, so for instance Broadcast push would is max'd at 1400 users every 2 seconds. To increase that limit significantly would i have to look at a much better server? or load balancing, or reducing the publish frequency?(this option isnt really any good for my application)

Stupid questuion no2, if i had 2 services publishing data out at every 2 seconds would I expect user limit to drop to 700 per service?

QUOTE ==> We are planning to release a sample (...

2010-06-30T15:23:42.685-07:00

QUOTE ==> We are planning to release a sample (in source code form) that demonstrates the consumption of the protocol from .NET 3.5, I will make sure to blog about it once it is available. <== END QUOTE

I think that many people out there would like to have this sample...
Please if you have any news let us now...

Thanks,
Michael

QUOTE ==> We are planning to release a sample (...

2010-06-23T14:01:40.376-07:00

QUOTE ==> We are planning to release a sample (in source code form) that demonstrates the consumption of the protocol from .NET 3.5, I will make sure to blog about it once it is available. <== END QUOTE

Any news about that non-silverlight client sample that would support the "this" long polling duplex protocol? (not the one posted on code.msdn which is completly different)

Thanks!
Eric

Very interesting article! I read it some weeks ago...

2010-02-20T07:40:42.541-08:00

Very interesting article! I read it some weeks ago and the performance you showed here shows that this technique will be enough for our needs. Unfortunately, when we developed a test to see if everything performed good enough we ran into some issues. I would really appreciate if you could give me some hints of what can be wrong.

I've developed a SL3-client that uses pollingduplex to connect to a service. The SL-client is the subscribing client. We also have a publishing client that connects to the service using netTCP binding (over internet). The service is hosted on a VPS with WS2008R2 and IIS7.

The problem is really poor performance! We have tried the service with 30 - 40 clients and it more or less stops responding when trying to connect with more clients. Not stops completely but it's really slow. The task manager on the server shows that the 'IIS worker process' (w3wp.exe) takes up 100% CPU usage.

The strange thing is that this is caused only by connecting the clients to the service. No publishing occurs.

We're running the service configured with 'InstanceContextMode.PerCall' and 'ConcurrencyMode.Single'. We're using throttling as well.

Do you have any idea what might cause this poor performance?

Another question: In your example you've configured the service with 'InstanceContextMode.Single' and 'ConcurrencyMode.Multiple'. Why would it be better from performance point of view to run the service as a singleton instead of as PerCall?

Thanks!

/Kristian

Unfortunately the .NET 3.5 version of the client s...

2010-01-04T20:20:13.746-08:00

Unfortunately the .NET 3.5 version of the client side protocol is currently not available publicly. We are planning to release a sample (in source code form) that demonstrates the consumption of the protocol from .NET 3.5, I will make sure to blog about it once it is available.

Thanks for your response. Is there anyway I can ge...

2010-01-04T11:23:39.105-08:00

Thanks for your response. Is there anyway I can get ahold of this testing code?

Adam

You are right, we did not use Silverlight on the c...

2010-01-01T22:38:15.887-08:00

You are right, we did not use Silverlight on the client to measure server side performance. We have compiled a .NET 3.5 version of the client side of the polling duplex protocol. While doing so, we have turned off the optimization whereby the client will only issue a single poll at a time per scheme/host/port combination at the scope of an AppDomain. (The goal of this optimization in the first place is to reduce the impact of the polling duplex protocol on the connection limit imposed by virtually all common browsers). This allowed us to simulate thousands of Silverlight clients using a single .NET 3.5 process running on a single machine. We then scaled the number of clients to reach saturation point on the server.

I'm curious as to how you obtained these numbe...

2010-01-01T20:05:21.185-08:00

I'm curious as to how you obtained these numbers? How did you write the test client (clearly not silverlight) and get it to use the pollingduplex binding?

I don't recommend enabling WCF binary encoding...

2009-09-04T09:39:19.880-07:00

I don't recommend enabling WCF binary encoding if you already opt into dynamic compression in IIS. The latter is a high-cost high-yield solution. Binary encoding in addition to IIS compression will yield marginal improvements in terms of bandwidth savings. Have you checked your numbers with IIS compression alone and text encoding? You can find some considerations for enabling dynamic IIS compression at http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/25d2170b-09c0-45fd-8da4-898cf9a7d568.mspx?mfr=true.

Regarding compression above, I meant compression +...

2009-09-04T01:30:04.365-07:00

Regarding compression above, I meant compression + binary, as im seeing 5000 row datagrid with binary only, is 5mb and 20 sec to download/render but when i enable binary + compression, the same 5000 row report, is 300k and 3 second to render. Is there any reason we should not enable it for low users but large reports?
slyi

Regarding the limit of the number of clients that ...

2009-09-03T16:28:38.008-07:00

Regarding the limit of the number of clients that could be connected to the pub/sub service from the sample, this is a client side issue, not a server side limitation (assuming you have bumped up the MaxConcurrentSessions correctly). You can validate this by opening additional browser windows from a different client machine, or using a different browser brand from the same machine (e.g. IE and Chrome). Which version of IE are you using?

You should measure the effect of dynamic content c...

2009-09-03T16:26:09.630-07:00

You should measure the effect of dynamic content compression vs. binary encoding in WCF in your particular scenario, but as a rule of thumb dynamic content compression will yield substantially smaller payload sizes than WCF's binary encoding at the cost of substantially higher CPU utilization.

Would you recommend adding compression "enabl...

2009-09-03T07:15:34.068-07:00

Would you recommend adding compression
"enable dynamic content compression" and in ApplicationHost.config adding <add mimeType="application/soap+msbin1" enabled="true" />?

Hi im also check this with create an service objec...

2009-09-03T06:56:33.738-07:00

Hi im also check this with create an service object in a loop. on 11th count the service object failed to create.it give an communication exception.

i have allready set these settings. I m check this...

2009-09-03T06:39:16.530-07:00

i have allready set these settings. I m check this open more than 10 ie windows and on 11th it not work.

It looks like you may be affected by the ServiceTh...

2009-09-02T09:40:24.174-07:00

It looks like you may be affected by the ServiceThrottlingBehavior.MaxConcurrentSessions throttle, default value of which is 10. One of the configuration changes described in this blog suggests to increase the throttle using the respective configuration setting:

<serviceThrottling maxConcurrentSessions="2147483647"/>

Have you applied this change to your service?

Hi Tomas, I have try your application(pubsub) on s...

2009-09-02T01:34:53.734-07:00

Hi Tomas, I have try your application(pubsub) on server 2008, 4gb ram, iis7 with change you describe in your blocg, but it open only 10 clinet. on 11th it not work. please provide me the solution what we do for solve this problem. Thnaks

The broadcast scenario assumes existence of a sing...

2009-08-19T15:43:47.679-07:00

The broadcast scenario assumes existence of a single topic (e.g. stock quote) all clients are subscribed to. The number of subscribers in the broadcast scenario is to be understood as the total number of clients connected to the server simultaneously, which require simultaneus notifications. Please note however that from the perspective of the polling duplex protocol, the content of the notifications sent to clients is less important than number of clients and notification frequency - the messages themselves may be identical or they may differ (assuming they remain within a size ballpark of course). One could model the multiple ticker subscriptions using separate topics (in the pub/sub sense) for every ticker. One also could model this scenario using a single topic per unique combination of stock tickers. The latter approach would most likely perform better with the polling duplex protocol, as it requires fewer notifications to be sent to every client (at most as many as there are clients).

When you calculate the number of clients in the br...

2009-08-19T14:57:57.185-07:00

When you calculate the number of clients in the broadcast scenario, is that per value subscribed to or per user. For the stock price example you give, for example, a user would likely be subscribed to changes in a portfolio of stocks (20 or so) not just 1. So if you have 1,000 users then there would be 20,000 price subscriptions. Is there a way to group all 20 subscriptions into just 1 per client to increase server capacity?

Very good article. Thank you for writing. This p...

2009-08-19T11:15:04.824-07:00

Very good article. Thank you for writing. This provides some good evidence about the suitability of full duplex in several scenarios. This question comes up often when talking about Silverlight client-server models but it is hard to answer well without having the numbers to back it up. Based upon these figured it seems as though a pub/sub architecture would actually be viable for some applications, which was not what I expected. Pessimistically I had assumed that the performance hit would be too great. However, 1000+ simultaneously connected users is a large threshold for most simple web applications.

Thanks!