CODEWITHSUNDEEP
javatomcataopaspectj
drgn
drgn

Reputation: 1140

Intercepting method of an tomcat application with aop

I have a problem which is hard to explain so lets get started:

Context: I have a application running on a tomcat server Lets call it "admin". The admin have an import/export function. Our own application is an extension to that and we need to gather some information when the "admin apps" use the import/export function.

Problem: The third party jar that contain the class ImportController is located there: ~/someFolder/admin/WEB-INF/lib/admin.jar. The goal is to gather the Old project ID and the new Project ID so that our extension can link our class to the right project. Since i know the method signature i though i could use AOP to do so.

Idea: The idea i came with is to put something like idHiJacker.jar that would contain a single pointcut and advice into the ~/someFolder/admin/WEB-INF/lib/ and enable load-time weaving. That advice would simply put the information into an xml file so our extension would be able to read it when we want to put the link back after a project import.

Also i must say I'm a pure newbie with AOP and web stuff. But i do not wish to import a monster for just doing this small operation with AOP. At the moment im reading on aspectJ and AspectWerkz

Question:

Edit: Also if you have good tutorial to link with answer, it would be awesome

Thanks for your time and answer

Upvotes: 0

Views: 664

Answers (2)

Miserable Variable
Miserable Variable

Reputation: 28752

Question:

1) Am I in the right direction? Do you see anything that would make this idea not work at all?

I can't see any reason why this will not work. Aspect Oriented Programming and cross-cutting concerns apart, the notion of advice is to execute some before or after some other pointcut and often to influence the behavior of that advised function. You are doing exactly that here.

2) If this is possible what would be the good practice to do it in a very clean manner?

There is some inherent chaos with aspects/advices -- since the control flow is hijacked more then a simple sequential reading of code is needed to understand whats going on. 

3) Should i do it with AspectJ? AspectWerkz? Or Something else?

I have never used AspectWerkz but I have very good experience with AspectJ; especially in terms of the support here on stackoverflow and perhaps even more on its mailing list. 

4) Am i doing this for nothing? Is there an easier way to do that operation?

Unless you can change the code of import controller or change the clients to make extra calls to do the linking thing this interception based approach seems best IMHO.

Upvotes: 1

Biju Kunjummen
Biju Kunjummen

Reputation: 49915

I have suggestion for a simpler solution - use a decorator pattern to wrap around the third party ImportController, put your functionality before the third party library is called. You should be able to do this since you seem to have access to the admin application.

This is essentially doing what AOP is doing, but using code. Your approach using load time weaver should also work, but is in my opinion complicated - if you absolutely plan to go this way, do use AspectJ.

Upvotes: 0

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