Sunday, May 1, 2011

WCF Configuration Nightmare, MSBuild, IIS AppCmd

In this post I am going discuss about some of the deployment nightmare that you might have when you design SOA, where you segregate logic into several decoupled services. the post would not really deal with production deployment , but about internal developer releases.

The problem here is that when you have multiple services, and you want to deploy your code in one of the test environments for testing before you release it to the testing team, you have a huge amount of configurations that you need to change.
This typically includes...

1) Changing service addresses, this might include WCF services that your service has referenced. Sometimes it might be the case that one of this service refer not just one service. All the service might not be deployed in one machine, hence, referring localhost will not work.

2) Changing database connections, this might be a cumbersome task, you might have to go into each and every configuration file and change the database serve , database user or database name.

3) Application settings, these might include paths to share folders, etc...

4) Any other configuration sections that might be different from when you are developing in your local machine, for an example, you might not want to give access to meta data after deployment, or you want to change the a few WCF settings like MaxConcurrentConnections.

After deploying all these WCF services you would have to go through these numerous configuration files and change these places to point to the correct changes according to the new environment.

This is cumbersome, and is error prone, you would have to waste a few hours trouble shooting in order to find out which configuration piece was configured wrongly.

A very primitive way of deploying WCF services would be to build your application from Visual Studio and then manually add these services into IIS and if your exposing your services through non HTTP endpoints in IIS7, the you would have to configure binding for the protocol used.
Once this is done, now you would configure service addresses and DB connections. you might have to create a .SVC file for HTTP activation manually or you could use the publish option in Visual Studio to create this automatically.

Next I will outline some of the ways to improve this process.


One this is you can create a MSBuild script that would build your solution and then copy the out put into another location.
MSBuild is powerful enough to do this, this script would be a very small script, you can just instruct MSBuild to build your application pointing to your solution.
If your trying to deploy your web application, then you just need to write a target that would copy the output to a folder called bin and then copy the whole source of the web application without the .cs or ascx files.
You can learn more about MSBuild here

IIS7 AppCmd

Now once this is done , you can use IIS 7 AppCmd that ships with IIS tools to create the web application and WCF application, the app cmd tool is a command line tool that gives administrator the same power that they get with IIS7 GUI, so its just a matter of creating a .BET file to do the task of deploying it in IIS & and call the .Bat file in your MSBuild script as a target.
You can learn more about App Cmd here

MSBuild Extension Pack

MSBuild does not come with any target to change configuration values, however there is a community task library that you use to do this, one such task library is the MSBuild Extension Pack.
This component gives you a set of task to manipulate XML files, like reading, writing and updating.
This is exactly what we want to use to change our configuration files to point to the correct server and change the DB connections.
You can learn more about MSBuild Extension pack here

Automating deployment nightly

Now all you have to do is instruct cruse control or hudsion to execute your build script and you have you your latest build deployed in your environment nightly or weekly.

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