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wcfazurecloud
Phillip Scott Givens
Phillip Scott Givens

Reputation: 5464

Notifying WCF Subscribers in Cloud Computing

I have been reading a lot about WCF lately and whenever the subject of implementing a subscriber-broadcast mechanism comes up (as in an instant messaging system), the solution invariably is to use a static dictionary to hold your subscriber channels.

An example can be found in the answer to the following question, but it is a common practice. Making a list of subscribers available across calls to a service

This seems like a very good solution for "traditional" web programming, but how is this handled in the cloud? Specifically, how do we get around the fact that every computer in the grid has different "static" variables?

I know very little about the different Cloud platforms. Are there different solutions for Azure, Amazon Web Services and VMWare?

Upvotes: 1

Views: 297

Answers (3)

Bart Czernicki
Bart Czernicki

Reputation: 3693

For broadcasting/push-type notifications, please look at SignalR (http://signalr.net/). Microsoft is making that part of the ASP.NET platform: http://channel9.msdn.com/Events/Build/2012/3-034

It has some real nice functionality like gracefully, falling back on multiple mechanisms if advanced things like WebSockets are not supported by the server/client. While it is do-able, you would have to code all of that in WCF.

There are pretty big differences between the cloud vendor platforms. I could post you multiple links but the cloud vendors you mention are changing VERY rapidly with what they offer. Your commitment to a particular cloud vendor is for the long term...don't think of it as well Vendor A has something Vendor B doesn't. There are differences BTW like that...Amazon for example, has specialized VMs: high I/O, high memory, high CPU. While, Azure for example has a much better designed VM layer.

I think of it this way (mu opinion)...Microsoft is a company that owns: .NET, ASP.NET, server platforms: SQL Server, Windows Server, SharePoint, Office Services etc. They are very well positioned against someone like Amazon or VMWare which do not have rich product portfolios like this. Plus Microsoft can price those servers into the cloud, Amazon/RackSpace/VMWare have to pay Microsoft a premium for it. You seem like you are talking about WCF/.NET, which would favor the Microsoft Azure platform.

On Azure you can run Linux VMs; code in python, Java etc. but it favors the Microsoft stack. Conversely, for AWS you can run .NET/Microsoft etc, but it favors the Linux/open source stack. Think of it in long term...because in 2 years both major cloud vendors will be making commitments in those areas. For example, RackSpace is going all-in with their OpenStack platform...they have no choice.

Upvotes: 1

Neil Thompson
Neil Thompson

Reputation: 6425

It might be worth you looking into something like RabbitMQ on AppHarbor. It's something I keep meaning to look at but can't find the time. I only mention it because nobody else has ;)

Upvotes: 0

Alan Smith
Alan Smith

Reputation: 716

The Windows Azure Service Bus has a a couple of options that you can use for broadcasting WCF events.

The Realy service has a netEventRelayBinding, which will allow subscribing service instances to reeive a one-way service call when a client calls an endpoint. If the clients are discinnected, they will not receive any messages.

http://msdn.microsoft.com/en-us/wazplatformtrainingcourse_eventingonservicebusvs2010_topic2.aspx

Brokered Messaging has tipics and subscriptions where a message can be broeadasct to up to 2,000 subscribers. The messages are stored durably, so if a client is disconnedted they wil receive all the messages when they reconnect.

http://www.cloudcasts.net/devguide/Default.aspx?id=12044

Regards,

Alan

Upvotes: 0

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