The Present AOP Frameworks in .Net

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3. The Present AOP Frameworks in .Net

(This chapter is based on my old article - “.Net AOP Frameworks Research Report v1.1”, for integration of this series of articles, I integrate it here.)

3.1 Aspect#

Version: 2.1.1.0 beta

Link: http://aspectsharp.sourceforge.net/

Dependency: antlr, Castle.DynamicProxy

Description:
Aspect# is an AOP (Aspect Oriented Programming) framework for the CLI (.Net and Mono). It relies on DynamicProxy and offers a built-in language to declare and configure aspects, and is compliant to AopAlliance. It became part of the Castle Project in June 2005.

Main Features:
- Custom mini configuration language, not xml.
- Mix/Intercept classes and methods through dynamic proxy approach. 

Restrictions:
- Classes to be created dynamic proxy for shouldn’t be sealed and only virtual methods can be intercepted.
- Using intercepted classes is not completely transparent to users that users should explicit create the dynamically proxied class through the AspectEngine.
- No static weaving support. 

3.2 AspectDNG

Version: 0.7 beta 

Link: http://sourceforge.net/projects/aspectdng

Dependency: mono.petoolkit, rail 

Description:
AspectDNG is a .NET aspect weaver, that's to say a tool that can "transplant" code into an existing assembly. This transplant is made after the standard .NET compilation, which means that both aspect and the so called "base" code (the one the transplant will be operated on) can be developed in any programming language that is compatible with .NET CLS. Another way to say that: AspectDNG works on assemblies (EXE or DLL) that may have been created out of C#, VB.NET, Eiffel.NET, Managed C++...  

Main Features:
- Xml, XPath based configuration file format.
- IL level static Weaving.
- Custom xml based disassembled language ILML which can be used to convert assemblies to and be modified/combined and then converted to assemblies. 

Restrictions:
- Static weaving only.
- Not very stable. 

3.3 Eos

Version: 0.3.3 beta 

Link: http://www.cs.virginia.edu/~eos

Dependency: none 

Description:
Eos is an aspect-oriented extension for C# on Microsoft® .NET Framework™. Eos aims to improve upon the current aspect-oriented language model in three dimensions. First, it generalizes aspect instantiation & advice weaving model to eliminate the need for the work-arounds that are unavoidable today when aspects are used to express certain crosscutting concerns. Second it generalizes the join point model. Third it aims to eliminate the distinction between class and aspect constructs in favor of a single conceptual building block that combines the expressive capabilities of current classes and aspects, significantly improving conceptual integrity and uniformity in language design. The language is very similar to AspectJ except for constructs which are not implemented in Eos and constructs which AspectJ does not provides. 

Main Features:
- AspectJ like extended C# language and custom compiler.

Restrictions:
- Static weaving only.
- It seems no source code provided.
- Not very stable. 

3.4 Encase

Version: 0.7 beta 

Link: http://theagiledeveloper.com/category/15.aspx

Dependency: none 

Description:
Encase is an aspect oriented programming framework for the .NET Platform written in C#. Encase is unique in that it provides aspects to be applied during runtime in managed code rather then being configuration file based that other AOP frameworks rely upon. The advantage of applying aspects in this way is that it promotes productivity to developers new and/or unfamiliar with AOP. 

Restrictions:
- Encase cannot mixin multiple classes that implement a shared interface? For instance, if class A implements IAlphabet, and class B implements IAlphabet, classes A and B can not both be mixed in as an aspect.
- Encase can only provide interception and aspect weaving to virtual (overridable) methods and properties.
- Encase is unable to apply aspects to sealed (Not Inheritable) classes.
- Like Aspect#, but more unstable. 

3.5 Loom.Net

Version: 1.5 Beta2 

Link: http://www.dcl.hpi.uni-potsdam.de/research/loom/

Dependency: none 

Description:
The LOOM .NET project aims to investigate and promote the usage of AOP in the context of the Microsoft .NET framework. We have been developing two AOP tools (so called weavers) that all implement different approaches to weaving: A runtime weaver crating weaved objects on the fly and a static weaver. 

Main Features:
- Support under .Net Framework 2.0 beta
- Include both dynamic proxy based dynamic interception and il level rail like static weaving support. 

Restrictions:
- The static weaver seems not very stable. 

3.6 Other Frameworks 

AspectC# (AspectJ like C# extended compiler)
Link: http://www.dsg.cs.tcd.ie/index.php?category_id=169

Weave.NET (provide a load-time il level weaving implementing)
Link: http://www.dsg.cs.tcd.ie/index.php?category_id=194