How can I configure the service router to enable transactions, because the backend service uses them and this feature doesnt work since I introduced the ServiceRouter in the middle of the Client & Server dialog.
Thanks in advance
If you haven't figured it out, have a look at the IDuplexSessionRouter contract.
More information here.
Routing service is only intermediary. It doesn't participate in transaction. It is just something that should be as much transparent to client and service as possible.
Transactions in WCF are provided as additional messages send over wire. So my understanding is that if you are using router you must correctly route these messages as well. I have to say I have no idea how to do it without reading and fully understanding WS-AT protocol specification.
But maybe I'm wrong. In such case start with configuring routing service with transactional binding same as your client and service.
Related
I want to achieve the following:
Expose WCF endpoint to client from which they request a long-running operation.
Map the inbound request to a NServiceBus Message.
Publish the message to the bus for processing.
Send a reply to the client acking that their request has been received and we will begin processing it.
Bus works the message through a handler.
Can you help me with some examples here please?
Thanks in advance
You can check out the WcfIntegration sample that comes with NSB to see how to expose an endpoint via WCF. To hand off the message, you can simply call Bus.Send() to another endpoint to do processing, then use the Bus.Return() that is in the sample. From there, the other endpoint can look just like the Server part of the FullDuplex sample without the Bus.Reply() logic.
Awhile ago I created some example code that is similar to this, although it used a traditional ASMX web service and not a WCF one, but that is really just an implementation detail.
Check out NServiceBus External WebService Example on GitHub.
So I'm looking into implementing NServiceBus in our current setup and just trying to get a better understanding of how things should be setup.
Our current setup consists of multiple clients (websites, scheduled tasks, etc..) calling a WCF service we have set up for handling the sending of emails. Of course, if the service goes down then our clients start getting errors and all of those messages are then lost (one of the reasons we want an ESB).
I've seen how you can configure your WCF service to handle nservicebus messages in a pub/sub setup. What I'm not sure on is what is the best way to set it up.
Setup 1:
Client (Publisher) -> NServiceBus handler (Subscriber) -> WCF Service
In this case, to scale you'd increase the number of handlers (hosted nservicebus services?), keeping just the one WCF service.
Setup 2:
Client (Publisher) -> WCF Service (Subscriber)
This one you just increase the number of WCF services to scale (updates would be a nightmare).
I just started looking into the ESB architecture in general so if I'm completely off let me know. I'm essentially just wanting to know what is working for you, and what the "best practice" tends to be.
Thanks!
I'm not completely clear on what you need WCF for anymore if you implement this via NServiceBus. Is the WCF component required for anything besides receiving messages (to send an email) from the multiple clients? If not, you could remove WCF from the equation.
From the sound of it, you will also want the Service to act as a single logical endpoint that handle requests to send emails. If that's the case, you will want to use Send (a command) instead of Publish (an event). Publish is used to broadcast an event, which means that something happened already; Send is used to instruct another component to do something. It sounds like you want the latter.
Scaling of an endpoint can be done via the Distributor. This may or may not be useful depending on where you expect the bottleneck to be.
Edit: Based on your comment, I would simply go with the second setup, and just add the handler to the WCF service. If you are hosting WCF in IIS, make sure you have something that wakes the process up if the app pool recycles (the incoming message won't wake it up the same way an incoming request to WCF will).
We do something similar internally where one NSB endpoint handles all the sending of email. The clients can either use NSB directly to Bus.Send() the command to send a message to the email endpoint or you can expose that endpoint via WCF as well (only to get the commands over to the endpoint). Once the endpoint has the commands, they would just call your existing service to maintain compatibility with your existing clients.
I'm a WCF newbie, and I need some help to begin with a project:
I will have a managed application (server) that needs to communicate (messaging system) with several clients over the internet and vice versa.
What is the best approach to achieve this?
using wsDualBinding?
UPDATE
I decided to use the NetTcpBinding mode instead.
It depends on what capabilities your service needs to expose, and what type of clients you need to support. Any of the HTTP-based bindings will work over the internet, its simply a question of the way the data is encoded.
A summary of the built-in bindings and what they support can be found here: http://msdn.microsoft.com/en-us/library/ms731092.aspx
But the most common are:
BasicHttpBinding - This is a basic web service-style binding, usable by any SOAP client.
WebHttpBinding - This allows your service to be used by non-SOAP HTTP clients
WsHttpBinding - This allows your service to use extended service features like transactions and sessions.
WsDualHttpBinding - This is required if your service needs a duplex channel, meaning your service needs to make callbacks up to the client.
Since you specifically asked about the dual binding:
If you are writing an application that needs to be able to make a callback from server into the client, then a dual binding is really your only option. Since you specifically mentioned chat, however, I don't think a dual-channel service is going to work very well.
The way the callbacks work in WCF is that your client makes a call to the service, using a dual channel, and must provide an implementation of the callback interface. The server can use this to make calls to the client for the duration of the service method call; the callback context is per-service-call, so once that call returns, it is no longer valid. In other words, your server cannot just asynchronously "call into" your client, it has to wait for the client to "poll" the server. And if you're going to do that, you don't really need the callback anymore.
Honestly, I don't think I would use WCF for an interactive bi-directional chat application, but I can think of two possible options to do so:
Do the polling client option, using a simple BasicHttpBinding on the server and continuously ask for new messages.
Set your client applications up to self-host a local WCF service, and provide the endpoint information to the server when you log in. This requires your clients to accept incoming connections, which gets messy (but if you can pull it off, I'd go for a NetTcpBinding here.)
WSDualHttpBinding is not a good choice for internet. Callback works great only in local network (intranet) that has no Firewall and NAS restrictions.
See this post for more details:
Connecting over internet to WCF service using wsDualHttpBinding times out
Use WsHttpBinding if you want to set up server to server communications (that should work for WPF).
Use WebHttpBinding if you are planning to use data from Javascript.
I'm trying to build a WCF self hosted service (eventually in a windows service) that will receive binary and text base messages from remote thick clients that have no accounts on my hosted machine. I'm trying to figure out both my binding options and security options, and in reading the patterns and practices guides, my head has completely spun around at least once.
The clients would be authenticated against a custom SQL based method, so I'd like to be able to pass that info in the initial login request and then set an authorization token of some kind. (This part of the problem is probably outside the scope of the question, but I included it in case it might make a difference.)
Any thoughts at all would be very helpfull.
Ryan
The choice of binding and security option depends on the usage of your WCF service. Is it just for your rich client or are you planning to expose it to the world as API? If it's just for your rich app, does it run on LAN or over untrusted, unreliable Internet?
With WCF you can configure the service to expose multiple endpoints with different bindings, for example both SOAP and REST. In general, I'd start with something stateless and lightweight like basicHttpBinding and webHttpBinding, passing user and password on every request. Once you have that up and running you can optimize cache authentication, provide binary endpoint etc.. only if it actually helps.
There's no need to have just one binding. Having said that if it's self hosted you're "on your own" here. I've never looked at what's involved.
I have been tasked to implement a WCF service that makes use of NetMsmqBinding. I wrote the service and it works fine. The problem is that in the last minute they told me that there will be no Active Directory integration. So I don't know how to configure the security of the service. There is a VPN tunnel between the service's and the client's machines but they do not use the same active directory. Please advice. Any kind of help or tutorials would be appreciated.
The problem is that the service is not always online. That is why using WCF over MSMQ is preferred for this scenario. So I am sending one way messages through MSMQ - which works fine. My only problem is that I am new to WCF and am not familiar with WCF security. I would like to be able to sign and encrypt the messages since the information to be sent to the service is confidential. I would like to make sure that only authorized clients call the service. Any suggestions?
I'm not sure I understand your question so correct me, if I'm wrong. I have recently been woring on a WCF service that was hosted on a computer with no Active Directory available. We secured it using certificates. Is it an option for you? It's pretty painless (if you get past the 'put the certificate in the store and give the correct user access to it' part).
You should be able to take advantage of network transparency.
Use webservices to communicate from one system to the other. You might have to deal with extra latency, but it should still be usable.
Well first, you can use WCF's security, the WS-* stuff. Some info here:
http://blogs.msdn.com/motleyqueue/archive/2007/10/06/complementing-msmq-security-with-wcf.aspx
Second, you might find this blog to be helpful:
http://blogs.msdn.com/johnbreakwell/default.aspx
One of the articles there about cross-domain sending mentions this article (Cross-Enterprise Support):
http://msdn.microsoft.com/en-us/library/ms705127(VS.85).aspx
Which might help you configure it in general.
Thank you, Michael, but this information wasn't helpful...
I found this: http://www.codeplex.com/WCFSecurityGuide/Release/ProjectReleases.aspx?ReleaseId=14070 - a book from "Microsoft Pattern & Practices" which describes in detail the security in WCF - a must-read for every WCF developer.