基于插件的WCF Web服务

Question

I am implementing a IIS Hosted WCF web service to accept leads from third parties. There are plenty of operations that may happen pre/post saving the information. I am thinking of implementing this as plug-in based architecture.

Example of pre-save operations are

• duplicate checking before saving
• making sure the information is valid (not mickey mouse)

Post-save operations are

• zipcode based routing to correct warehouse
• lead assignment.

I have been reading about MEF, but i have been unable to decide if this is actually worth implementing MEF where loading and unloading of plugins for every call will likely increase the overhead? Is there a way to just load all your plugins in some magic application_start ?

Answer 1

I agree with Steven that you don't need a plugin architecture for this. You are good to go with just properly designed services. There are some very good hints about this in Steven's blog post - Writing Highly Maintainable WCF Services .

Nonetheless, to answer the second part of the question, there is nothing stopping you from initializing the MEF composition container in your Application_Start and store it statically (other than that it introduces a global state, which is often a bad design decision). Then it would be shared across the requests and you could use it to compose parts as needed without the overhead of repeated exports discovery.