Re: [Webmacro-devel] WM WebApp design draft

[Lane S. <la...@op...>]

Marc Palmer wrote:

>>> Am I on the nail now?
>>
>>
>> Yeah. You let the template author control the expert action flow. Not 
>> the servlet writer. In this case, the action control flow is 
>> delegated to a template writer's expert knowledge of the action flow, 
>> rule base. The programmer writes the ugly stuff like transaction 
>> commits, etc.
>
>
> OK, the only thing I don't like about this is using WM as a general 
> purpose language. We don't have all the syntax and capabilities of a 
> "full" language as well as the WM philosophy consideration that it's 
> just for presentation. 

Expert rule processing is business processing rule stuff like

#if ($customerInGoldClub) {#setDisccount(.10, $customer) }

it is this kind of stuff that you want to expose to the web app team.

>
>
> Is this really necessary anyway? I mean, a template will expose links 
> to a bunch of actions so the user clicks on them / submits forms. 
> These will execute the appropriate action, and return the appropriate 
> response. 

the actions must have a way to evaluate user rules, settings. this can 
be as simple as providing a WebMacro instance by itself for rule processing.

>
>
> Actions will be able to support some kind of "nextAction" parameter 
> that indicates what should happen next after the Action executes. 

I do not think you want to go there. I think you leave this protocol to 
the user to define as required or not required.

>
>
> i.e. an InsertIntoDatabaseAction might look for the nextAction 
> parameter and use some supplied mechanism to execute that action after 
> the insert. If the nextAction parameter is not present, it could just 
> return a results template with the new database contents. (for example)

Again, you are making predictions about the recipe. Let's build the 
kitchen with a lot of clean and powerful, process-neutrality. The cooks 
are the web-app builders. Let them come in with their own recipes.

>
>
> I can't see how the business rules of an application can be cleanly 
> coded into a WM template (or main template plus included parts). 
> Wouldn't it be really ugly? 

see above.

>
>
> One thing I am planning to add to the idea is a default helper for 
> generating URIs to execute actions, so the template need not know the 
> details of "hidden" parameter names and so on. This concept could be 
> extended to support creating a single URI that will result in the 
> execution of several actions i.e:
>
> <FORM METHOD=POST ACTION="$WebMacro.executeActions( ["insertIntoDB", 
> "commitToDB", "queryDB"])">
> ...hidden fields containing parameters such as table name and fields....
> ...visible data fields...
> </FORM> 

I think this is a good tool.

>
>
> This function would make a pretty complex long URI, or put the info 
> into the session and return a short URI that identifies the info in 
> the session so the servlet can retrieve it and work out what actions 
> to execute. 

I do this now but use a #macro do the formatting. Could easily be done 
by a java helper tho.

>
>
> This would make things quite modular and allow actions to be stacked - 
> writing to a DB and then emailing the data for example - with the 
> proviso that all the info necessary to perform all actions must be 
> available in the first request. We could allow per-action parameters 
> to be supplied too:
>
> <FORM METHOD=POST ACTION="$WebMacro.executeActions( 
> ["insertIntoDB:table=testdata", "commitToDB", 
> "queryDB:sqlselect='SELECT * FROM 
> testdata',template='dataresults.wmt'"])">
>
> As every, thoughts welcome... but I really don't believe this webapp 
> will be the cure for all web application needs... just enough for 90% 
> of websites, and at the very least a much better replacement for 
> server side includes and related technologies. 

agreed.

>
>
> Marc
>
>
>
>
>
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Lane Sharman
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