I want to log every request xml message in my WCF service project to database. Please suggest me which is the best and preferred approach.
1) Using idispatchmessageinspector interface
http://msdn.microsoft.com/en-us/library/system.servicemodel.dispatcher.idispatchmessageinspector(v=VS.90).aspx
OR
2) writing Custom SQL database trace listener?
You would have to write a custom WCF Trace Listener.
Look here for some help: http://www.enusbaum.com/blog/2007/05/19/creating-a-custom-listener-for-your-wcf-application-in-c/ and http://weblogs.thinktecture.com/cweyer/2009/06/custom-tracelistener-writing-trace-messages-to-the-net-services-service-bus.html
The best approach usually depends on various factors, but in your case it seems that using message inspectors would be a preferred approach as this is what it was build for i.e to capture WCF messages and do whatever you want do with them.
SQL trace is to trace SQL messages (communication between SQL server and SQL client applications) and not WCF messages.
I think using idispatchmessageinspector interface and use ThreadPool.QueueUserWorkItem() to read the request and log into database in AfterReceiveRequest event will be better when compared to using Tracing. I feel Tracing may be have some overhead as it is meant for some diagonistic purposes and do not want to enable tracing in prod permanently.
Is there any issues using idispatchmessageinspector and ThreadPool.QueueUserWorkItem() for logging the request message to database?
Thanks!
Bala
Related
Simplified... We are using NServiceBus for updating our storage.
In our sagas we first read data from our storage and updates the data and puts it back again to storage.The NServicebus instance is selfhosted in a windows service. Calls to storage are separated in its own assembly ('assembly1').
Now we will also need synchronous read from our storage through WCF. In some cases there will be the same reads that were needed when updating in sagas.
I have my opinion quite clear but maybe I am wrong and therefore I am asking this question...
Should we set up a separate WCF service that is using a copy of 'assembly1'?
Or, should the WCF instance host nservicebus?
Or, is there even a better way to do it?
It is in a way two endpoints, WCF for the synchronous calls and the windows service that hosts nservicebus (which already exists) right now.
I see no reason to separate into two distinct endpoints in your question or comments. It sounds like you are describing a single logical service, and my default position would be to host each logical service in a single process. This is usually the simplest approach, as it makes deployment and troubleshooting easier.
Edit
Not sure if this is helpful, but my current client runs NSB in an IIS-hosted WCF endpoint. So commands are handled via NSB messages, while queries are still exposed via WCF. To date we have had no problems hosting the two together in a single process.
Generally speaking, a saga should only update its own state (the Data property) and send messages to other endpoints. It should not update other state or make RPC calls (like to WCF).
Before giving more specific recommendations, it would be best to understand more about the specific responsibilities of your saga and the data being updated by 'assembly1'.
I am exposing a WCF service through a basicHttpBinding that executes several operations on a database.
I want to guarantee that if the client does not receive the reply the database operations are rolled back (without any transaction flow through WCF).
E.g. the client calls the "DoX" method which executes on the server but before it is finished the client crashes. The database operations should then be rolled back as soon as the reply can not be send to the client.
Is there any way to do that? Will the [OperationBehavior(TransactionScopeRequired=true)] attribute work in such a manner? Is there a possibility to handle communication errors on the server side?
Update 1:
It seems [OperationBehavior(TransactionScopeRequired=true)] commits the transaction before the reply is send to the client and thus can not be used to perform a rollback if the client does not receive the reply.
Update 2:
To state it clearly again, I do not have the need for the transaction to interact in any way with the client side. The client should neither know of the transaction, have the ability to cancel or commit it, nor should any transaction flow through the binding. The only place I want the transaction to rollback is on the server side if the transport channel can not deliver the message to the receiving client. With the case of TCP/IP this information should be readily available to the server. (No ACK of the TCP packet send back to the client)
So a hypothetical execution flow on the server side (notice the lack of client side) should be:
Receive client request
Start transaction
Execute all logic inside the service operation
Send reply back to client
if (reply.failedToReceive) { transaction.Rollback() } // due to a failing TCP/IP transmission
There is no easy answer to this question. You are asking for a behaviour that is implemented in WS-* but done using basic SOAP. I think your only option if you REALLY can't switch to wsHttpBinding or use duplex as suggested by #Trevor Pilley is to try to mimic the behaviour of WS-Transaction in your own custom protocol based on basic SOAP.
You should be able to get some simplification over the full WS-Transaction specification because
You will probably only need to support transactions over a single service - you will not be doing a distributed transaction over several independent services
You will not need to support both short a transactions (WS-AtomicTransaction) as well as long running transactions (WS-BusinessActivity) probaby atomic transactions would do
You would not need to support any kind of extensibility model (WS-Coordination)
You would not need to implement a discovery/metadata model that describes the protocol (e.g. like WSDL) because you would be coding the protocol behaviour directly into the client and service.
However, you would probably need elements of both WS-Coordination and WS-AtomicTransaction. This is not a simple task by any means and it will be easy to miss something subtle that could cause either rollbacks to not happen or (just as bad) to destroy the performance of your service by having long duration locks all over your database due to crashed clients.
Like I say, this is a complex behaviour and if you cannot use ready-made, standardised protocols, there is no simple answer.
Is there a way to intercept the raw data that's being sent over a TCP WCF endpoint? I have implemented IClientMessageInspector but I am not sure if that's what's actually being sent over the wire.
My goal is to measure the performance of different serializers. I know there is some information out there but I would like to take a closer look at how they behave in my app.
Enable Message Logging in your configuration. To see the raw messag you want to log at Transport level.
You probably want to look into the built-in tracing capabilities of WCF. I don't have a link handy, but search for WCF tracing.
I'm working on shipping in a change for my lab that will hopefully help diagnose some weird channel-faulting weirdness we're seeing. There's a test application that uses DuplexChannelFactory to connect to a couple windows services, and for some reason the channels on this test application seem to be faulting quite a bit. I have plans to implement some retry logic in there, but it would be great to figure out why exactly they're faulting.
I know that channel factories and proxy objects all implement a lot of interfaces, and I've used reflector to crawl through some of them, but I haven't found anything like what I'm looking for. Is there a way to query these objects after they've faulted in order to get some information about what caused the fault?
Edit: The configuration is very basic--the binding is just the default-constructed NetTcpBinding, the service implementation has [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Reentrant)], and no special attributes are on any of the operations in the service contract. However, I'm asking more about general techniques in diagnosing channel faults, not diagnosing this specific case. I wouldn't expect configuration specifics to have too much impact on that; if anything, the configuration details would be something returned by said diagnostics, right?
Ladislav and Shiraz answers are all good and I have gave them +1.
All I can add to them is that normally a faulted channel is the result of unhandled exception on the server. When that happens, WCF thinks that there is somethig fundamentally wrong with the server and faults the channel so that it cannot be used.
The correct approach - which I believe should have been default and come for free - is for the service to catch the exception and create a FaultException and return it (look at this form example http://www.c-sharpcorner.com/UploadFile/ankithakur/ExceptionHandlingWCF12282007072617AM/ExceptionHandlingWCF.aspx)
The reason WCF does not make as default is that it changes the contract and the WSDL so the client has to get the updated WSDL.
So if I were you, I would catch the exceptions, log them and then return a fault exception and this way I would know what the problem is and channels are not faulted.
First thing is it this test application, or are the specific services used by other clients.
Assuming that it is the test client that is causing the problem. There could be 2 problems:
Not closing proxies, therefore hitting max connections to the server.
Not aborting proxies when they are in a failed state.
Diagnostic tool you are looking for is called WCF Tracing. It usually shows why the channel has faulted. You can configure it on both client and server and use SvcTraceViewer.exe to browse collected traces.
Have you hooked on to the ICommunicationObject.OnFauled
I have the standard error handing in place in my service:
I have an IErrorHandler hooked to the service to handle unexpected errors during service execution.
I have try/catch blocks in all my service methods to handle expected cases.
However, there are cases where exceptions are thrown on the server and neither is called.
Here is a case where the server exception is not sent to the IErrorHandler:
Set the receiveTimout on the server binding to 5 seconds.
On the client do this:
.
Service1Client sc = new Service1Client();
ICommunicationObject o = sc as ICommunicationObject;
o.Open(); // open channel
sc.GetData(10); // do a first call
Thread.Sleep(10000); // wait longer than the server receiveTimeout
sc.GetData(10); // Attempt another call: server throws a FaulException
In that case, the error is thrown on the server but I cannot find a way to handle it (and log it). I know an error is raised because if I attach a debugger on the server process and break on all exceptions, the debugger breaks.
I have found other similar cases where low level errors are not passed to my program.
Where can I hook my code to ensure that I can handle ALL exceptions that occur on the server before they are returned to the client app? Should I implement my own IChannel or some other low level interface?
Thanks
UPDATE Sep 21 2009: See this thread on the Microsoft WCF Forum. I'll probably have to implement my own Channel if I want to handle this type of exception. I'll update this post again when I have more info.
After much research and experimentation, the answer is:
At this time (.Net 3.5) there is no mechanism that allows one to handle all possible exceptions that may occur in the context of a WCF call.
Exceptions that happen during the service method execution can easily be handled with:
Try/catch blocks in all service methods to handle expected cases.
IErrorHandler hooked to the services to handle unexpected errors during service execution.
However, for low level WCF infrastructure errors, there is no perfect solution. The best solution that exists seems to be to implement a custom channel to catch more exceptions.
In this Microsoft Connect Bug Report, Microsoft confirms that there is no way to handle all types WCF infrastructure errors.
In this thread on the Microsoft WCF forums, there is a sample on how to implement a custom channel. That solution only works for HTTP, not for HTTPS. Also some WCF infrastructure errors are not caught by the custom channel either (see more details in that specific thread).
Use FaultContracts. Then the fault can be handled at the client end.
http://msdn.microsoft.com/en-us/library/ms732013.aspx
http://www.c-sharpcorner.com/UploadFile/ankithakur/ExceptionHandlingWCF12282007072617AM/ExceptionHandlingWCF.aspx
This is also much better for debugging, since often you will be developing a client and don't want to bring down the server for debugging purposes.
On the client end, use try/catch blocks to catch all exceptions/faults. There are definitely errors that can't be detected on the server end, such as a communication problem, so you need to handle errors on the client end anyways.
If you want centralized error handling, you can create a service that takes messages about all errors, send the error to that server, and have it log that. This can be useful if you want to create a centralized message tracing/performance analysis/logging tool and have a large number of application processors, servers, clients etc.
The point is - if the server is not reachable or can't handle the message, there won't be an error on the server - the error will pop up on the client ("TimeoutException" or others).
So in those cases, having the IErrorHandler on the server really isn't gonna help - since the error really happens on the client (no connection can be made, due to network down, or typo in server's address or sstuff like that).
So on the client side, you definitely also have to use try....catch around all your server calls.
Marc
Set up diagnostic tracing and check the logs with Service Trace Viewer Tool. Link contains information about configuring tracing as well.