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From "Michael Jasnowski" <mjasn...@bea.com>
Subject RE: Struts Web Services Enablement Project
Date Fri, 04 Jun 2004 19:36:04 GMT
>Gotcha.  This is clear in my mind now.  The only concern I might have, and 
>believe me I know how weird this going to sound, is that this might make it 
>TOO flexible!

In most cases, you would only be transforming against incoming documents you expected
from different clients, as opposed to an open ended set of formats. It's just the flexibility
to be *able* to transform that I think is key.  You might have rules that sniff the incoming
document for it's type, and the invoke a registered transformation against it to an internal
format you understood, or perhaps just let it pass if you recognize the format.

-----Original Message-----
From: Frank Zammetti [mailto:fzammett@hotmail.com]
Sent: Friday, June 04, 2004 3:31 PM
To: dev@struts.apache.org
Subject: Re: Struts Web Services Enablement Project


>Yes, as already confirmed.  One area where web services are used is 
>standardizing how multiple applications can retrieve the same type of data 
>from different servers.  For example, if you have multiple servers that 
>produce gridded weather data, all the data producers could get together and 
>define a common XML schema for requesting data from their servers that they 
>all implement.  This way, clients can use different data providers 
>interchangably.  This XML schema standardization is a very fluid process 
>that can be subject to many changes.  It is easiest if your application is 
>as isolated as possible from the actual XML schema.

Gotcha.  This is clear in my mind now.  The only concern I might have, and 
believe me I know how weird this going to sound, is that this might make it 
TOO flexible!

What I mean is, I think there are products already out there better suited 
to deal with more complex service requests, and with regard to other 
discussion points in this thread, if your to a point where you are exposing 
more complex things, as in your weather example, I'd be willing to bet you 
probably wouldn't consider doing it with this anyway, regardless of whether 
I added the transofmration capabilities or not.  You would probably be 
talking directly to your real business objects and not wanting to go through 
the Actions, and then there are far better ways to do things than this.

I'm certainly not ruling out what your saying, your've definitely convinced 
me of the benefit it would bring, but I do see it as something for down the 
road because I get the feeling it really morphs what I'm doing into a much 
grander plan.  I certainly dion't mind grand plans, and don't mind working 
to make those plans a reality, but I'm not as convinced that it fits in with 
the simple model I started with, and so it might be an addition after the 
more basic model is solidified.

>The problem with just using a JSP is you need to write a JSP for each 
>action.  If you use auto-generated XML, you can define a smaller number of 
>XSL stylesheets to match common XML elements for transformation.  
>Furthermore, the pipeline approach allows you to break up the 
>transformation process to support transformation stages that may involve 
>more complex processing.

Actually, as it stands now you would only have to write a JSP for any 
responses that can't be described by the default JSP.  It's hard to say how 
many situations would really require a custom JSP, but my gut tells me that 
it's probably no better than 50/50 in favor of creating a new JSP.  My bet 
is that half the time, and maybe even more, the default template will 
suffice, probably with the member list attribute in use more times than not. 
  Granted, if your response has to work within the confines of a defined 
schema as in your weather example, then your talking a new JSP, and then 
that becomes a burden most likely.  But again, it your doing something like 
that, I suspect you'd have decided against my little package already!

Again I think this is somethng that I can see where the benefit comes in, 
but probably baloons the complexity again.  I can concieve of this project 
expanding as time goes on to more "compete" with the more developed packages 
out there now, but I feel like that's a much more long-term goal than what 
I'm trying to accomplish now.

>While struts-chain won't be incorporated into Struts until probably 1.3 
>(but could be somewhere in 1.2), it is still available to be used with 
>Struts 1.1.  Since you are requiring a custom request processor anyways, 
>just use the struts-chain request processor and refactor your capabilities 
>into multiple commands instead of extended RequestProcessor methods.  The 
>burden on your users will be about the same and the transition to future 
>Struts will simply require you to discontinue the specific use of the 
>chain's legacy RequestProcessor.  Your function code will already be in 
>commands that are already compliant.

That sounds good, I will definitely look into doing it this weekend.  Your 
comments above alay whatever fears I might have had, it sounds like the 
right thing to do overall, and not a massive change either.

>Good job with what you've put together so far.  I think this extension is a 
>great addition to the toolbox available to Struts developers.

Thank you, I'm very glad to hear the positive feedback I've gotten, and just 
as happy that people are interested enough to at least make suggestions and 
question what I'm doing.  Any comments, regardless of what side of the fence 
they are on or if/when I act on things is valuable.  I was concerned that I 
was the only one that thought this might be something useful, but it sounds 
like I'm not alone, and that certainly motivates me to develop it further.

>Don
>
>>
>>Thanks!
>>
>>Frank
>>
>>>From: Don Brown <mrdon@twdata.org>
>>>Reply-To: "Struts Developers List" <dev@struts.apache.org>
>>>To: Struts Developers List <dev@struts.apache.org>
>>>Subject: Re: Struts Web Services Enablement Project
>>>Date: Fri, 04 Jun 2004 12:14:16 -0400
>>>
>>>I think there can be considerable benefit from exposing Struts Actions.  
>>>For one, how Struts is currently architected, all the validation happens 
>>>in the Struts layer so putting the web service interface in front of that 
>>>makes sense.  Two, many times user authorization occurs in the Actions 
>>>and so if this code hooked into the Servlets API, authorization is 
>>>automatically taken care of.
>>>
>>>I'd recommend two feature additions to make this useable for document 
>>>style SOAP messaging:
>>>
>>>1) Put a configurable XML transformation pipeline before the SOAP message 
>>>gets interpreted for parameters, and after the response is created.  The 
>>>pipeline for the response should start with auto-generated request XML 
>>>(via something like XStream).
>>>
>>>2) Improve the request parameter schema for the incoming XML document to 
>>>include XPath paths as parameter names.  This way, using something like 
>>>JXPath, a complex XML element could be automatically created, to be then 
>>>transformed by the pipeline.  Send the resulting XML to the action via a 
>>>wrapper action form or even just put it in the request.  Better yet, have 
>>>the resulting XML be processed by an XML binding framework like XStream 
>>>to create arbitrary Java objects to be passed to the action.
>>>
>>>The key is to enable any XML schema to be used as input and output.  The 
>>>XML pipeline further isolates you from schema changes.
>>>
>>>Finally, I'd also recommend looking at using struts-chain rather than a 
>>>RequestProcessor.  If the above functionality was decomposed into 
>>>different Commands, one could easily plug in, say, a different XML 
>>>binding framework or get rid of the XPath processor altogether.
>>>
>>>Don
>>>
>>>Duncan Mills wrote:
>>>
>>>>Didn't mean to be harsh - I was just presenting the alternative 
>>>>viewpoint that has to be answered.  Personally I can see the benefit 
>>>>that this project could offer, but the counter stance is a one to raise 
>>>>is it not?
>>>>
>>>>Regards
>>>>
>>>>Duncan Mills
>>>>Senior Principal Product Manager
>>>>Oracle Application Development Tools
>>>>
>>>>
>>>>Jung, Eric wrote:
>>>>
>>>>>Wow, that's kind of harsh, Duncan.
>>>>>
>>>>>-----Original Message-----
>>>>>From: Duncan Mills [mailto:duncan.mills@oracle.com]
>>>>>Sent: Friday, June 04, 2004 3:38 AM
>>>>>To: Struts Developers List
>>>>>Subject: Re: Struts Web Services Enablement Project
>>>>>
>>>>>
>>>>>Frank forgive me here, but playing Devils Advocate, if you have clean

>>>>>MVC separation then surely the last thing you want to do is to expose

>>>>>Actions as Web Services.
>>>>>It is reasonable to want to expose Business Service Providers such as

>>>>>EJB, or TopLink beans as Web Services but that's up in the model layer,

>>>>>what's the point in pushing the access point down into the Controller

>>>>>code?
>>>>>
>>>>>Or do you see here a solution for all those folks who've not followed

>>>>>best practice and have intermingled Controller functionality with 
>>>>>Business logic..?
>>>>>
>>>>>Regards
>>>>>
>>>>>Duncan Mills
>>>>>Senior Principal Product Manager
>>>>>Oracle Application Development Tools
>>>>>
>>>>>
>>>>>
>>>>>Frank Zammetti wrote:
>>>>>
>>>>>
>>>>>
>>>>>>Hello devs!  This is my first time posting here, and my first attempt

>>>>>>at contributing to an Apache project.  I hope I'm going about it 
>>>>>>properly! :)
>>>>>>
>>>>>>In short, I have a little project going with the stated goal of 
>>>>>>allowing a Struts developer to expose any existing business logic,
as 
>>>>>>implemented in Struts Actions and their subordinate helper classes,
as 
>>>>>>Web Services, and do this with NO changes required to any existing

>>>>>>application code, and as little change to Struts itself as possible.
 
>>>>>>Simplicity is the key to this!
>>>>>>
>>>>>>Today I released a second version of this project to the user's 
>>>>>>mailing list, and after some feedback I think it's at a point where

>>>>>>I'd like to make you all aware of it, and get some higher-level 
>>>>>>feedback.  It's certainly far from complete at this point, but I think

>>>>>>even now it's in a useful form.
>>>>>>
>>>>>>My hope is that eventually it will be good enough to be included in

>>>>>>the base Struts distro, but that's obviously a long way off, if ever.
>>>>>>
>>>>>>With all that in mind, please at your convenience visit 
>>>>>>http://www.omnytex.com/strutsws
>>>>>>
>>>>>>There you will find some more detailed technical information and a

>>>>>>download which contains everything you need, including a simple sample

>>>>>>webapp demonstrating the whole mess.
>>>>>>
>>>>>>I thank you in advance for any time you spend on this!
>>>>>>
>>>>>>Frank W. Zammetti
>>>>>>
>>>>>>_________________________________________________________________
>>>>>>Looking to buy a house? Get informed with the Home Buying Guide from

>>>>>>MSN House & Home. http://coldwellbanker.msn.com/
>>>>>>
>>>>>>
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>>>>>>
>>>>>
>>>>>
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>>>>>
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>>>>>
>>>>>
>>>>>
>>>>
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>>>>
>>>
>>>
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>>
>>_________________________________________________________________
>>Check out the coupons and bargains on MSN Offers! 
>>http://youroffers.msn.com
>>
>>
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>
>
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