[Meinds-developers] Aspects and state

[Rickard <ri...@xp...>]

Hey

Following Dim's queries I tested how easy it would be to implement state 
management for the ACL. It was very very easy :-)

First of all I did an ACLState interceptor. I added this to the 
ACLBuilder factory, so that all ACLImpl's had it "on top" of them. In 
invoke, before delegating the call the ACLState interceptor reads an XML 
file with ACL info corresponding to the resource it is attached to (e.g. 
"urn:user:john" will cause the file "urn/user/john/acl.xml" to be 
loaded). The ACLImpl was then fed these entries. The interceptor then 
delegated to the ACLImpl which could then perform its tasks. When the 
method returned the ACLState interceptor can check whether the method 
was a modifying one (i.e. "add") and then store the state back into the 
acl.xml file.

All of this without having to change ACLImpl *at all*. Pretty neat. AOP 
rocks :-) Since I didn't have to change ACLImpl at all, I can now 
replace the ACLState interceptor with one that uses a database or 
heuristics or whatever instead, which is great.

/Rickard

-- 
Rickard Öberg