Generic Http Module
- by MartinF
The problem
I am trying to make a generic http module in asp.net C# for handling roles defined by an enum which i want to be able to change by a generic parameter. This will make it possible to use the generic module with any kind of enum defined for each project.
The module hooks into the Authenticate event of the FormsAuthenticationModule, and is called on each request to the website. The module exposes public events which could be defined in the global.asax.
But i cant seem to figure out how to make the generic http module work like a non generic module.
There is 3 main problems.
I cant register the generic http module in the web.config like any other module as i cant specify the generic parameter, or is possible somehow ?
The way to solve that as far as i can figure out is to create a non-generic http module that intializes the generic HttpModule (the generic parameter is defined in a custom section for the module in the web.config).
But that introduces the next problem.
I cant find out how to make the public events exposed by the generic module available to hook into through the global.asax as you would normally do with a non-generic module by just making a public method with the name like ModuleClassName_PublicEventName.
The init() method on the http module gets an reference to the HttpApplication object created in the global.asax. I dont know if it somehow could be possible with reflection to search for the methods and if they are defined in the global.asax (HttpApplication super class) hook them up with the correct event handler ? or if any methods on the HttpApplication object can be used?
How would i store and later get a reference to the generic module created in the non-generic module ?
I can get the non-generic module with HttpContext.Current.ApplicationInstance.Modules.Get("TheModule"); but is there any way i can store a reference to the generic module in the non-generic module (cant figure out how it should be possible), or store it somewhere else so i can always get it? If I can get a reference to the generic module from the global.asax etc. the events mentioned in nr. 2 can be manually wired to the methods.
Thoughts and other possible solutions
Instead of registering the module in the web.config it can be manually initialized by overridding the Init method of the HttpApplication and calling the Init method on the module.
But that will introduce some new problems.
The module will no longer be added to the the ModulesCollection. So I will need to store a reference somewhere else.
This could be done with a property in the global.asax, and by implementing an interface, or by creating an generic abstract base type inheriting from HttpApplication, that the global.asax could inherit from. In the generic abstract base type i could also override the init method.
It will still not automatically hook up methods in the global.asax with events in the generic module. If it is possible with reflection to search for defined methods in the super type of the HttpApplication it could be automatically done that way.
But i can wire the methods in the global.asax with the events in the generic module manually either in the Init method or anywhere else by getting reference to the generic module.
It doesnst really need to implement the IHttpModule interface if i choose to manually initalize the generic module. I could just aswell move all the code to the abstract base type inheriting from the HttpApplication.
I would prefer to register the module simply by defining it in the web.config as it will be the easiest and most natural / logical solution. Also it would be great if it could be kept as a HttpModule instead of having to define a an abstract base type inheriting from HttpApplication, else it will be more thighed up and not as loose and plugable as i wanted it to be (but maybe it is not possible).
Another alternative would be to make it all static.
As far as i can figure out i would have to somehow make sure that only one method can be added to the public static events, so it wont add a reference each time a new instance of the global.asax is created.
I simply cant find out what is the best solution. I have been messing around with this and thinking about it for days now.
Maybe there is an option that i havent thought of ?
Hope anyone out there can help me.
