Mef 12 step program

Getting Addicted to MEF A 12 Step Program To Become Addicted to Awesomeness

Step 1: Admitting
James Eggers
From Kansas City
Addicted for about a Year
Talk about it on Twitter and my blog.
Find Odd Situations to Use It More.

MEF?
Managed Extensibility Framework
A framework to simplify building internally and externally compose-able applications
Could possibly become the “LINQ” of .Net 4

Current Issues in Extensibility
Limited Documentation
Complex APIs
Reflection
Large Inheritance Chains
Difficult to Estimate

Step 2: Giving In
Easy To Use
Easy To Learn
Auto-Composition
Metadata
Custom Contracts
Open Source
Auto-Discovery
Extensible

Step 3: Where to Find MEF
Codeplex http://mef.codeplex.com
.Net Framework 4

Step 4: Identifying Items

Step 5: Observing the Addition

Step 6: Understanding - Exports
Extensions To Be Consumed
Export & InheritedExport Attributes
PartNotDiscoverable Attr.
Different Objects:
Properties
Methods
Classes

Step 6: Understanding - Imports
Consumers
Extensibility Points
Import Attribute
ImportMany Attribute
Different Objects:
Properties
Fields
Constructor Params

Step 6: Understanding - Catalogs
Discovers and Instantiates Exports
Used by Containers
Multiple Types
TypeCatalog
AssemblyCatalog
DirectoryCatalog
AggregateCatalog

Step 7: Observing Further

Step 8: Sharing Information
Metadata
Used to provide extra information
Lazy Instantiation
ExportMetadata Attr.
Demo

Step 9: Sharing Experiences
Lessons Learned
InheritedExport can cause hide metadata
ImportMany to IList<T> has to be instantiated before composition
PartNotDiscoverable Attribute doesn't work with TypeCatalogs

Step 9: Sharing Experiences
Lessons Learned(cont)
Stable Composition Can Lead to a lot of Drinking Debugging.
Directory Catalog can load multiples if 2 assemblies are found with the same type in said directory.
Directory Catalog does not look at child directories.
GetCallingAssembly() is great for unit testing part imports.

Step 10: Identifying Opportunities
IoC Container
MVC Controller Factory
“ Flashcard” style programs
Rules Engines
App Themes
Workflow Steps
Many More

Step 11: Practical Observation

Step 12: Continuing Education
Codeplex - http://mef.codeplex.com
MSDN - http://msdn.microsoft.com
My Blog - http://RandomActsOfCoding.Blogspot.Com
MEF Contrib - http://mefcontrib.codeplex.com

My Information
James Eggers
Email - [email_address]
Blog - http://RandomActsOfCoding.Blogspot.Com
Twitter - @JamesEggers

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Mef 12 step program

by JamesEggers on Apr 30, 2010

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Mef 12 step program — Presentation Transcript