Yes, I have googled and there are loads of samples out there but each and every one is configured differently or is not quite what I am looking for.
I am trying to find a sample where I have MSMQ set up. I want a WCF Service which gets notified as and when a message arrives in the MSMQ queue.
I also want then a client application which binds to that contract and sends a message, placing it in the MSMQ queue.
Can anyone provide examples or links? I'd greatly appreciate it. I'm just getting confused between different types of messaging, different bindings.... list goes on. I am NOT looking for a System.Messaging implementation.
Thank you.
You can find plethora of examples on MSDN Windows Communication Foundation (WCF) and Windows Workflow Foundation (WF) Samples for .NET Framework 4. When you expand the package look under \WCFWFCardSpace\WCF\Basic\Binding\MsmqIntegration for some basic samples
EDIT:
For transactions it's as simple as:
[OperationBehavior(TransactionScopeRequired = true, TransactionAutoComplete = true)]
public void SubmitPurchaseOrder(MsmqMessage<PurchaseOrder> msg)
{}
You can read more about Poison Message Handling on MSDN More about the MSMQ on MSDN - How to: Exchange Messages with WCF Endpoints and Message Queuing Applications
"When the service reads messages from the target queue under a transaction, the service may fail to process the message for various reasons. The message is then put back into the queue to be read again. To deal with messages that fail repeatedly, a set of poison-message handling properties can be configured in the binding. There are four properties: ReceiveRetryCount, MaxRetryCycles, RetryCycleDelay, and ReceiveErrorHandling. "
EDIT: You would use System.Messaging on the service side.
Related
I'm aware of that there are a couple of posts here on SO that discusses this issue, but I can't figure out a straight answer to my scenario.
Lets say i have:
One queue on Server-A with alot of messages coming in
One WCF service with NetMsmq binding on Server-B reading from Server-A's queue
The very same WCF Service deployed to another Server-C with the same binding reading from Server-A's queue
Am I guaranteed that the services on Server-B and Server-C will never process the same message?
Are there any other problems with this setup that needs to be taken care of?
The purpose of this setup with multiple wcf services reading from the same queue is to increase processing speed, and I do not want to use a hardware loadbalancer.
Thanks for your time!
You will need to make your queue transactional and then set the exactlyOnce property on the binding to true.
Reference:
http://msdn.microsoft.com/en-us/library/system.servicemodel.msmqbindingbase.exactlyonce(v=vs.110).aspx
This should take care of it. You can have multiple readers (WCF Services) reading from the same queue. That's basically a load-levelling concept and is the intent of queue-based messaging. Here is some background documentation on WCF and MSMQ.
http://msdn.microsoft.com/en-us/library/ms789048(v=vs.110).aspx
I have some queries about WCF and multithreading.
My plan is to place items onto the Thread Pool and for it to process messages from the MSMQ queue.
I also will be hosting WCF in WAS.
I am wondering how the threading will work at this point. For example messages will be picked up by the WCF binding to the MSMQ queue and I know that WAS will spin up the service as and when it requires to. But lets say if we have 100 messages to process (100 messages per second for example) - would these be delivered in a threaded way or in a single thread?
If in a threaded manner then how best to commit or abort transactions? Any special considerations?
Sorry for the questions - just need to clarify this.
Its not clear what "placing items onto the Thread Pool" does but on the WCF side, a service using the netMsmqBinding handles "calls" in a similar way as other WCF bindings. The difference is that a "call" is actually an MSMQ message in a queue.
This article on netMsmqBinding gives a very clear explanation of how the binding works. If you configure the WCF service with its default InstanceContext setting (per call or per session depending on the .NET version), the service instances will pick up messages off the queue as-if they were a standard call each. There are setting in MSMQ and WCF that can affect this behavior to make the messages be processed sequentially but that's not the default.
Let WCF handle multi-threading for you by leaving the service set to per call (or per session) and for transactions, look at the code in this sample in MSDN to see how to work with them.
It's a really common pattern and I'm finding it a nightmare to implement!
--
The WcfIntegration sample is almost what I'm looking for in that it receives messages via a WCF endpoint. However, it receives messages back on itself. I want a separate subscriber.
So what I'm trying to do is merge the WcfIntegration and pub/sub samples.
The real need is for a website to call a class library, which then calls the WCF endpoint of the publisher.
A subscriber then picks receives a message that the publisher publishes, and does whatever with it.
--
Rob
You shouldn't need the interface IEventMessageService; NSB handles that for you.
In my local example, I mapped the messages to myself. For you this would be:
<UnicastBusConfig><MessageEndpointMappings>
<add Messages="MyMessages" Endpoint="MyPublisherInputQueue"/>
</MessageEndpointMappings></UnicastBusConfig>
You also need to move your Publish to the actual handler. Right now, it is only happening once (at startup):
public void Handle(EventMessage message)
{
bus.Publish(message);
bus.Return((int)ErrorCodes.None);
}
Make sure your infrastructure is primed, i.e. the queue is transactional, and MSDTC is running.
I'm willing to bet that since there is no mapping, once the service is called, it doesn't know where to put the messages (it calls Bus.Send() internally). I didn't look at the subscribers since that didn't seem to be the issue.
I've finally got it to work here:-
http://code.google.com/p/nservicebus-wcf-pubsub/downloads/list
Anyone is welcome to improve the code.
I have WCF Per-Call service which provides data for clients and at the same time is integrated with NServiceBus.
All stateful objects are stored in UnityContainer which is integrated into custom service host.
NServiceBus is configured in service host and uses same container as service instances.
Every client has its own instance context(described by Juval Lowy in his book in chapter about Durable Services).
If I need to send request over bus I just use some kind of dispatcher and wait response using Thread.Sleep().Since services are per-call this is ok afaik.
But I am confused a bit about messages from bus, that service must handle and provide them to clients. For some data like stock quotes I just update some kind of stateful object and and then, when clients invoke GetQuotesData() just provide data from this object.
But there are numerous service messages like new quote added and etc.
At this moment I have an idea to implement something like "Postman daemon" =)) and store this type of messages in instance context. Then client will invoke "GetMail()", receive those messages and parse them. Problem is that NServiceBus messages are "Interface based" and I cant pass them over WCF, so I need to convert them to types derived from some abstract class.
I Don't know what is best way to handle this situation.
Have you considered a "pure" NServiceBus solution for communicating back to clients? NServiceBus already has that "Postman daemon" capability. NServiceBus messages don't have to be interfaces - you can use regular classes as well.
Hope that helps.
I am shortly starting a project, which requires messages to be held in a queue for a period of 24 hours, this is because the database can't have any updates at certain times of the month. The service also has to be hosted on windows server 2003, which means it will have to be a windows service.
It is also required that the service use WCF so that in 12 months time when we move over to windows server 2008, the service can hosted in iis 7. At present I am wondering if MSMQ is the best way to handle this.
I've been looking into topics like poison message handling & dead letter queues, but nothing that really covers what I am intending to actually do. Could anyone recommend a sample or a tutorial for this ?
Thanks in advance
Yes, it sounds like this is a perfect scenario for WCF and MSMQ. It should be much easier to use MSMQ than to create your own queuing mechanism with the same robustness. You will want to look into the Message.TimeToBeReceived Property for a message expiring timeout.
If the interval specified by the TimeToBeReceived property expires
before the message is removed from the
queue, Message Queuing discards the
message in one of two ways. If the
message's UseDeadLetterQueue property
is true, the message is sent to the
dead-letter queue. If
UseDeadLetterQueue is false, the
message is ignored.
Here are some good starter tutorials on WCF with MSMQ: link1 and link2