Application Domain and its configuration (Part-1)

In .net all application assembly run under an application domain that is created by default for each application, we don’t need to create it. Common Language Runtime does it for application.

Developers often need to run an external assembly. However, running an external
assembly can lead to inefficient resource usage and security vulnerabilities. The best way to manage these risks is to create an application domain and call the assembly from within the protected environment.

Application domain is logical unit to run different application in a single process. IIS is the very good example of it, in IIS more than one website or application are hosted, still they run independent with out interfering to any other application, hosted on same IIS.

Application domain creates a separate layer for application; .net run time is responsible for the various application runtime, while operating system manage process. In a process, we can run more than one application domain and each application domain has one or more assembly, application running. Each of these application domains can’t access resource or memory used by another application domain.

To create an application domain is as simple as we create an object of a class. The benefit of application domain is that when we don’t require or our work has been completed we can unload resource occupied by application runtime.

System.AppDomain class provides many methods and property to manipulate application domain.

1. Create an application domain

AppDomain ad = new AppDomain(“myAppDomain”);

We can run our assembly under this newly created Application domain.

ad.ExecuteAssembly(“myAssembly.exe”);

We can either call ExecuteAssemblyByName method to run assembly, in that case we need to pass name of assembly.

ad.ExecuteAssembly(“myAssembly.exe”);

There are so many properties and methods provide by AppDomain which gives ability to specify ID to process, friendlyname etc. Methods like Load, ApplyPolicy,CreateIntance etc.

If you notice in above code, we don’t have any constructor to create application domain, we are using static method of AppDomain class.

We can access current domains by ..

AppDomain myCurrentDomain = AppDomain.CurrentDomain;

To unload application domain, call Unload method of AppDomain

AppDomain.Unload(ad);