Here is a question for WCF hosting environment:
You are developing an application that performs file backups in the
background. The background application will host a Windows
Communication Foundation (WCF) service and must be active as soon as
the machine is running. The background application will not have a
user interface. A front-end application will consume the WCF service
and will provide the user interface.
You need to choose a host environment for the WCF service. Which
hosting environment should you choose?
A. Microsoft Internet Information Services (IIS) 6.0
B. Windows Process Activation Services (WAS)
C. A Windows Forms application
D. A Windows Service
The answer is D, but a lot documents of WCF MSDN and books all favor IIS/WAS over Windows Service, as they are more robust and resilient etc. I don't really see why it has to be D here. What is the reasoning behind D then?
The answer is D, because one of the requirements is:
must be active as soon as the machine is running.
When you use Windows Service you can start it even before user has authorized in system.
IIS gives on-demand loading. When a request comes in, the ServiceHost is constructed, then the service class being hosted is instantiated, and the request is handled. Nothing needs to be running around the clock. This setup requires more time and effort every time a message comes in.
Related
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.
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.
Does anyone recognise this error?
The SecurityContextSecurityToken with context-id=urn:uuid:xxx (key generation-id=) is not registered
It has suddenly appeared in the service trace log of my WCF service.
We had a Windows service successfully transmitting data into the WCF service for a day until it broke. The error manifests when the Windows service tries to connect to the WCF service.
It's highly unlikely that the environments changed. The two services exist on separate machines (an application server and a web server). Both are Windows Server 2003 SP1 machines, and the web server is running IIS 6.
Unfortunately, we have scarce access to the servers to help us debug, so any guesses on what might be wrong would be highly appreciated.
Indi
We had this problem with Web Service Extension 3.0, which was used before WCF. I have not experianced this with WCF, but I think that it is worth checking.
The scenario works like this:
The service starts and the user that is the identity of the service gets logged on.
When the service makes a call it is done in the security context of this user
After a while the logon token becomes so old (a day?) that the service will no longer accept it.
The easy way to test this is to restart the windows service.