Kindly help me in architecting a solution which is required for my ongoing project.
I have developed some WCF Services hosted as windows services which I did and working fine so far. Now I am asked to develop a master WCF type of service which should be intelligent enough to manage all other WCF service for possible corruption/errors and can repair them and restart.
Thanks in advance.
As we have written a custom host and took us years to make it a real application server, I will share some of the challenges that we had. Creating a custom host that manages WCF services as an NT service is a very challenging task if you want to manage all of the details and treat the NT service as a real service host. The challenges start from managing multiple Appdomains ( one for each Service ), managing the statuses of the services, startup times, deployments from the IDE and the worst of all is activation. Have you considered how to implement that? If you do not have this feature, it means that all of your services will be active and in memory at all times. IIS and Appfabric do that very well and trust me , it is noty easy to implement. The other part that was challenging was a UI to manage this host and offcourse a UI that can manage multiple hosts ( NT services running on different boxes ). Do you need a discovery proxy implementation? And at last how about if you want to manage services running in your custom host , IIS and App fabric the same way?
Think about before doing such an implementation because the scope may crypt on you as you do it.
I do something similar here.
Create a Dictionary<key, ApplicationDomain> collection into your main program
Key: something unique for each application domain, like a Guid or a System.Type.
That ApplicationDomain class exposes a internal property to access your AppDomain proxy (that which inherits a MarshallByRef class)
Load your WCF host into main program, so you'll get access to that collection
Every time your service get some access, you just need to take that key, access your proxy and do anything you want within your service hoster.
Keypoint: Your service must have access to all your service hosts.
Related
I am in the middle of an internal debate about IIS hosting. For a given enterprise application we have N WCF services.
One option is to host each WCF service in its own IIS application. This implies each service has its own web.config and [possibly] its own Application Pool.
Another option is to hose all WCF services in one IIS application. This implies one web.config for all those services and one Application Pool.
The individual option gives the flexibility to have different configuration (IIS and web.config) for each service. Individual Application Pools would enable more granular control of resetting the processes.
The shared option is more simple and is possible because the IIS and application configuration (web.config) should be the same for each service.
I am looking for advice\best practice between these two options.
Working in the same type of enterprise environment as the one you describe we find the best practise is as follows:
Group similar functions into "Applications" which are then hosted under one WCF service. This gives us e.g. CustomerService, AccountsService etc.
Each service has its own App. Domain to give it process separation and security separation from the other services. That is, each service runs under the context of an ActiveDiretory (AD) account and doing this allows us secure downstream resources such as SQL server databases.
E.g. CustomerService runs under DOMAIN\CustomerServiceUser user. We can then secure for example stored procedures related to customer functions so they can only be executed by the CustomerServiceUser user. We can then use integrated security for our connection to the SQL server. This allows enterprise permissions to be managed at the Active Directory level.
We deploy using scripting for both the IIS configuration and our web.config files. This has the advantage that the IIS configuration can also be kept in source control as can the transform files for our web.config files. We then have full version history or our configuration and additionally can use this to quickly roll out additional machines if we decide to duplicate & load balance the services.
This is what we find to be the best practise although the requirements of your organisation may be different.
i am new in wcf and started learning. i got one confusion like that i create a small wcf service and just do not host it in IIS,console apps or win service but from another apps i can add the service reference of svc file and found it is working. if wcf can work without hosting in any place like "IIS,console apps or win service " then why people would alway host wcf service in IIS,console apps or win service. can anyone tell me the reason.
people use IIS and windows services in general because they are simpler to setup and run more consistently. they can also be hosted more easily on servers where the services can be configured to start automatically, and as usually wcf is used as a server communication method it is usually this that you want to do.
hosting in console applications is generally easier to setup for simple examples for testing purposes, when you want to test your services locally.
Whilst hosting in applications as possible it's a less common scenario to use wcf to communicate between 2 applications on the same machine.
EDIT:
Your original question asked why people always talk about IIS, services etc. The point I was making was that usually wcf is used for web services, and is usually run on a server other than the local machine. Even though it can be used for inter process communication on the same machine this is not the most common use case. This is why you see a lot of examples using IIS and not too many hosting it in a Windows forms app.
My head hurts so much I think I need a bottle of aspirin...
I've created a WCF service and, with help of others from this site and the department I work in, the WCF service is running as a service on my development machine. Tested it with a console app and it works.
But, it's not supposed to be on my development machine. It needs to be on a different server.
This is difficult because the server it is supposed to reside on DOES NOT have Visual Studio installed on it.
So I cannot run the VS 2008 Command Prompt with installutil to run the WCF service as a service on that server.
Broadly speaking, you've got three options, all of which are described on MSDN:
Host the service under IIS
Self-host the service in any managed .NET application
Host the WCF service under a Windows Service
Which one is right for you depends on what your service is for, how it'll be consumed, how scalable and secure you need the set-up to be, and a dozen other things besides. Without knowing a bit more about what your service does and how it'll be used in your organisation, it's difficult to make a recommendation.
IIS hosting is easy to set up and is the way to go if you want to leverage all of the industrial-strength hosting functionality that a full-blown web server offers.
Self-hosting is quick and easy - you can knock out a WCF-hosting console app in two minutes flat - but is the clunky solution. You of course have to run the host application as a particular Windows user. Perhaps not ideal?
Hosting under a Windows service is the middle ground. It gives you that always-available functionality without having to be logged in as a specific user, but doesn't offer the configurability and scalability of the IIS solution. It takes a bit more effort than belting out a quick console app, but not much.
The server that the windows service will reside on will have the .NET Framework. INSTALLUTIL is located in the Microsoft.NET\Framework(version number) folder in the Windows directory.
For example, C:\Windows\Microsoft.NET\Framework\v2.0.50727.
No need to write a console app to host your service now (unless you want to).
You can also host your WCF service under IIS, check this out: MSDN - How to: Host a WCF Service in IIS. It really is just a five minute job :)
I need to remotely spawn WCF services on a remote machine from a client. I cannot use IIS (no HTTP) or WAS (no Windows Server 2008).
Was wondering if there's a way to do it apart from these hosting environments without having to create a service on the remote machine responsible for the spawning of other WCF services.
If a Windows Service host is the only way, can someone point me to a good article or book for an efficient architecture for doing this (including lifecycle management of spawned WCF services).
Thanks
Riko
If you cannot use IIS/WAS, then you're only option left is self-hosting.
You can host your WCF service in either a Windows (NT) Service, or a console app, or any other app you like to have.
The point though is: other than IIS/WAS which will load your service class as needed, when a request comes in and needs to be processed, in a self-hosting environment, you have to have your host app up and running - that's why a NT Service seems like the best choice at least for production environments, a service that can be run even if no one is logged on to the machine. Console or other apps require a user being logged on, and the app must be running.
Hope this helps a bit.
Marc
There is one additional option you can use on Server 2003 - hosting WCF services in COM+:
http://msdn.microsoft.com/en-us/library/bb735856.aspx
This is not as easy as hosting non-HTTP services in WAS on Server 2008, but provides a better supported monitoring and deployment model than hosting as an NT Service. Generally in my experience, though, most people I know have used NT services since is fairly straightforward to generate one in .NET, and then they perf counters or something similar to monitor them in production.
I've got a WCF service on a server on one side of a firewall. I need to access the service from many workstations on the other side of the firewall. The network guys insist that all holes through the firewall are one-to-one so at the mo, I'll have to set up every workstation one by one. There could be loads and it'll get tedious and be prone to errors.
Is it possible to set up a WCF server on this side of the firewall that can in some clever way just act as a proxy to the 'real' WCF service on the other side of the firewall? If so, could you point me to some reference material?
There is a new concept of a WCF Relay service being developed for the Windows Azure "cloud" computing space. That would allow you to create your scenario fairly easily - just host some bits of your service out in the cloud.
See these links for more information:
WCF services hosted on Windows Azure
Software in the cloud: the Relay service
.NET ServiceBus: Hands-On with Relays
or search Google for "WCF Relay Service". There are also a number of new bindings specifically for these WCF scenarios.
Hope this helps.
Marc
UPDATE:
WCF v4 - to be released with .NET 4.0 later this year (2009) will include a RoutingService class which can be used in scenarios like this.
See more info about the WCF4 routing service here:
Content based routing in WCF 4
Routing messages in WCF 4.0
A developer's introduction to WCF .NET 4 Beta 1
I have a few suggestions, maybe one would work in your case:
Place the WCF service outside the firewall. If the WCF service needs to talk to the database, open the database port for the IP address of the machine running the WCF service.
Program or use code generation to create a WCF service that is simply a pass through layer
There may be some functionality in your firewall that allows you to publish an end point