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From Joe Germuska <>
Subject Re: Spring and XWork in Ti
Date Thu, 01 Sep 2005 16:23:55 GMT
>Just as we discovered Chain commands were difficult to use for 
>Struts users (all the casting for one), Ti users will generally 
>write interceptors and not chain commands.  Interceptors are more 
>natural, support around operations better due to easier use local 
>variables, and provider easier access to the Action they are 
>intercepting with no casting.

I'm just wondering when this discovery was made.  I don't recall 
seeing a lot of discussion about it.  I don't know enough about 
WebWork interceptors to argue whether they are easier or not, 
although it seems like if you really want to implement "around" style 
programming, they would fit better, since the model with which Struts 
executes per-mapping commands doesn't really give you anything to 
wrap around.  I guess you can always make a chain with filters; I 
can't think of a time I ever wanted to apply a solution like that, so 
it's pretty abstract to me.  I just don't remember there being much 
discussion about whether commands were easy or hard.

>In Ti, while we do use chain for general request processing, where I 
>think it really shines is decision points, something the CoR is 
>built to solve.  A good example is the chain that creates a form 
>bean.  A chain is called, and the first command that sees it can 
>create it, does, then returns "true" as the responsibility has been 
>assumed.  So in summary, Ti developers will work with chains and 
>some interceptors, while the average Ti application will only need 
>to know interceptors.

Ti depends on commons-chain 1.0.  The LookupCommand in that version 
of commons-chain treats a "true" return value from any called chain 
as a signal to abort the entire chain processing.  Did Ti reimplement 
the idea that some commands would ignore the return value from a 
looked-up-chain, as has since been added to the unreleased SVN head 
of commons-chain?  Or has that just not been noticed yet?


Joe Germuska       
"Narrow minds are weapons made for mass destruction"  -The Ex

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