Modular Development

[Superfly1611]

Hey all,

I've been charged with finding out how you write an application that is modular.

Lets say for example that I need to write an application that takes information from data sources such as an XML file or a HTML form etc and then outputs the in a new format.
How would I make the application modular in terms of someone else being able to write and install there own module/assembly for the system that enables the same system to then make use of another data source such as a database or an RSS feed without having to make any changes to the original application?

I realise that this will involve object orientation and I believe that i'd be able to use interfaces to write the kind of code needed for this... the bit i'm not so clear on is how to go about writing my application in such a way that i can install another assmebly and initate communication between the different assemblies without editing my original code.

I hope my questions make sense... cause my brain aches and i'm not sure i could re-word it if I tried

Many Thanks for any and all help you can give me

 

[PlausiblyDamp]

http://www.xtremedotnettalk.com/showthread.php?t=49597 is probably a good starting point for you.

You are correct about interfaces being the way to go though Also the loading mechanism in the linked article is only one way of doing this - you could also provide a more config file based approach to discovering and loading the dlls.

 

[Superfly1611]

That is a truely great article
I think I would probably use a mix of both config files and directory based discovery, but thats the easy bit. That article explained the hard bit... implicity instatiating an object.

 

[samsmithnz]

Look on Microsoft.com for Multi-tiered applications. The basic idea is that each level of your application is seperate and can be replaced with another part with minimal rework. For example you might have two layers, a User Interface and a Dataaccess class. If you need to change from SQL to Oracle, you'd only have to change the dataaccess class - the UI doesn't need any rework. Well in theory anyway.