Building An App With Plug-in Support

Question

I'm starting a new project which would greatly benefit from program add-ons. The program in its most basic form reads data from a serial port and parses it into database records. Examples of add-ons that could be written would be an auto-archive add-on, an add-on to filter records, etc. I'm writing both the program and the add-ons, but some customers need custom solutions, so instead of branching off and making a completely separate program, add-ons would be great. The simplest add-on would probably be a form who's constructor takes an object reference, manipulates the object in some way, then closes.

Unfortunately, I have absolutely no idea where to start coding, and almost as little idea where to search. Everything I search for turns up browser add-ons. From what I have gathered, I need to look into dynamic loading DLLs. Besides that, I'm clueless. Does anyone have any good resources or examples I that they know of?

I'm happy to provide more details, but this project is in its inception, so I don't have a ton of specific details (specifics kind of defeats the point of add-ons, too.)

Answer 1

You should seriously consider using the Managed Extensibility Framework (MEF) to handle your plugin architecture. It requires thinking about things a little differently, but it is well worth the mind-stretch.

Answer 2

This is a simple example to illustrate the basic technique.

codeproject.com - Plugin Architecture using C#

This article demonstrates to you how to incorporate ... as a plugin for another application or use it as a standalone application.

in .NET 4 you now have the Managed Extensibility Framework (MEF) to do much of the plumbing.

In .NET 3.5 you had the System.AddIn but it was deemed by many to be far too complex.

codeproject.com - AddIn Enabled Applications with System.AddIn

AddIns (sometimes called Plugins) are seperately compiled components that an application can locate, load and make use of at runtime (dynamically). An application that has been designed to use AddIns can be enhanced (by developing more AddIns) without the need for the orginal application to be modified or recompiled and tested