[forge-dev] Forge Scaffold x-Project { Aerogear, Arquillian, Errai, Java EE, RichFaces, Spring } - inputs and meetings

Thomas Frühbeck fruehbeck at aon.at
Sun Mar 10 19:54:47 EDT 2013

Hi Vineet,

I thought about how to summarize the most important issues and hope to 
have found the most important ones:

1) very detailed knowledge of the properties, relationships of the 
entity model
         (EmbeddedID, owning side of OneToOne/ManyToMany, Version field, 
generic type, array properties (e.g. char[]), lob)

2) a concise and inuitive naming convention for variables of templates
         it is tedious and error prone to create and maintain a naming 
convention like: entity, entityRef, refType, entityType, inverseField, 
field etc.
         a common understanding of such variable names would foster 
readability and maintainability across plugins

3) a templating system allowing complex decisions based on the roles of 
properties/relationships and their related entites
That's the hardest point, let me try to explain using an analogy: the UI 
artifact like a play (theater)
When designing a UI generator for entities I assigned kind of roles to 
each property, like a director directing actors in a play.
During the course of the play different groups of actors show up at 
different times in different dresses and say some lines of text. They 
interact with each other to give a complete picture. Some talk a lot 
when present, some say only one line. According the roles of the actors 
they change the groups they belong to.

MetaWidget isolates properties, so I had to pass quite a lot of 
information as context to each builder. Finally I had to prerecord many 
of the different "scenes" to be able to finally put it all together and 
generate a complete flow of the "piece".

Perhaps it makes sense to generate a kind of meta database describing 
the entities and relationships, which can then be passed to a template 
like FreeMarker.
This way the analysis would be separatable from the rendering, a naming 
convention could be well established.
And by storing the metadata between executions it could be possible to 
identify "dirty" properties which were changed and provide the user with 
precise information about necessary rebuilds.
I am sure this has been "invented" hundreds of times already :-)



Am 07.03.2013 11:09, schrieb Vineet Reynolds Pereira:
> Hi Thomas,
>     Thanks for raising all of this in a single mail. I've more or less faced the same problems. My response is inline.
> Best regards,
> Vineet
> ----- Original Message -----
>> From: "Thomas Frühbeck" <fruehbeck at aon.at>
>> To: "forge-dev List" <forge-dev at lists.jboss.org>
>> Sent: Wednesday, March 6, 2013 9:38:07 PM
>> Subject: Re: [forge-dev] Forge Scaffold x-Project { Aerogear, Arquillian, Errai, Java EE, RichFaces, Spring } -
>> inputs and meetings
>> Can you please point out the locations of the respective scaffold
>> plugins you refer to, and give some introduction to the direction of
>> planned development.
> We have two scaffold plugins now whose learnings are being used to create this new plugin:
> 1) https://github.com/forge/scaffold-html5
> This is the AngularJS plugin I've been working on
> 2) https://github.com/sebastienblanc/scaffold-html5/tree/scaffold-aerogear
> This is a prototype Aerogear+AmgularJS plugin (not to be confused with https://github.com/forge/scaffold-aerogear/).
> Sebastian worked on this, and it is based on an older version of the AngularJS plugin.
> The differences between the two, are mostly in -
>      a) the templates used to create the scaffold,
>      b) the static AG libraries and Angular services that are to be created in the generated scaffold.
> If you notice carefully, we've decoupled the inspection of entities (using Metawidget inspectors) and the generation of the scaffold (using Freemarker templates) based on the inspection results.
> This has been basis for the design of the new scaffold plugin. We've put down some notes and event diagram for now:
> a. Notes: https://docs.google.com/document/d/16gi5xQbh1Yk9K0sHUTpWZUhxcDedYFBqzBtUagrN-ZI/edit?usp=sharing
> b. Event diagram: https://docs.google.com/drawings/d/1sCgEUHtqiItIsLH40SEW0KOZefuq9bzLzE6FggaMbaA/edit?usp=sharing
> I dont have your GMail address at hand, so if you can provide it, Sebastian can give you access.
> These are very early days, so nothing is set in stone, and this is bound to change as we cater to more usecases.
>> I read from the meeting transcript:
>>       - extendable templates to prevent scaffold duplication
>>       - conventions must be established
>>       - scaffold generate tests
>> Knowing Faces, Aerogear plugins and my proposed Errai plugin quite
>> well
>> I find it somewhat amusing to see them all be based on frameworks and
>> provide some extendability, yet each in a very distinct and not very
>> congruent way - perhaps my bad?
>> During building my Errai plugin I found it e.g. difficult to
>> implement
>> thorough type safety and entity relationships when the calls of the
>> scaffold are either per single file/entity ("generateFromEntity") or
>> for
>> all files/entities ("generateIndex"), both not so well suited for
>> handling of _relationships_.
> I concur with you on this. I'm facing a similar problem involving relationships across classes, but perhaps on a much smaller scale.
> I need to access the classes on the other side of the relationship, to choose one among a set of properties, to be used for display in the views.
> For example, if I have a model having a Customer -> StoreOrder relation of type 1:M, then I need to know what property of StoreOrder should I display in the Customer views.
> If you're interested, you can see the relevant code in lines 66-83 in the IntrospectorClient class, of the AngularJS plugin:
> https://github.com/forge/scaffold-html5/blob/master/src/main/java/org/jboss/forge/scaffold/html5/IntrospectorClient.java#L66
> Right now, this need hasn't been considered in the new plugin, since this looked more like an edge case that didn't need "standardization" across scaffold providers.
> But we can move towards incorporating this into the design, since there are atleast two plugins now that would need something similar.
> Personally, I need access to the Metawidget inspection results (or something similar) of the related entity, but I don't want to incorporate this as is into the design.
> That's mostly because we'd like to see your usecases as well, and how they could be incorporated into the event model.
>> Furthermore the development models are interestingly far apart:
>>       - Faces: unsafe JSP + converters/handlers/_named_ beans + server
>>       side
>>       - Errai: compile time type safety, intensive integrity
>>       validation,
>> client side optimizations
>> e.g.
>>       - the Errai compilation would fail, if a "Form"Composite
>>       declared a
>> widget that is not found in its HTML template, thus enforcing the
>> template be generated _together_ with its "Form"Composite
>>       - by _re_building only _one_ entity (generateFromEntity) in
>>       Errai
>> the generated code would possibly fail miserably w/o rebuilding also
>> its
>> related entities
>> Honestly I found myself frequently in the miserable position to
>> rebuild
>> the complete entity model because of interdependencies. Anyway, while
>> writing these lines I find interesting possibilities to decouple code
>> for more flexibility :-)
>> I am very interesting in evolving my plugin, so I hope you can give
>> some
>> idea about the planned templating etc.
> Well, we're using Freemarker in both the plugins. But, we're leaving the choice of the template engine to the scaffold provider for now, so you could use the Forge parser API if you want to generate new Java classes without relying entirely on text-based templates, or for that matter rely on Seam-Render that you seem to be using, or even use multiple template engines if some of them are better suited than others for emitting certain types of artifacts. There are however some considerations to make though, since the inspection result may not be available in a form that the template engine expects, so an adapter may be necessary. For Freemarker, the inspection result (the input data model for templating) is provided as a Map to the template engine.
> I may not have understood the bit about "rebuilding the complete entity model", and my assumption here is that the generated scaffold needs to be rebuilt from scratch when changes are made to the JPA entities. This is something that we may not fix right away in the scaffold plugin design, but yes, it would be something to consider. Perhaps it would make sense to have an in-memory model of what needs rebuilding, and what parts of the generated scaffold are "dirty" and need to be regenerated.
> My answer here may be incomplete, since I've just briefly looked inside your plugin-errai project, so we could discuss this in depth.
>> If there are not yet clear directions I am ready to scetch out the
>> main
>> issues I encountered for open discussions.
> That would be great. We're also preparing a POC (as a Forge plugin) for the new scaffold plugin design and once we have it ready for discussion, we shall be sending out another mail. We could consider these issues of yours during the construction of the POC.
>> Thomas
>> Am 06.03.2013 14:38, schrieb Vineet Reynolds Pereira:
>>> Hello all,
>>>       This is more of a follow up on Lincoln's mail sent earlier on
>>>       the cross-project scaffold team.
>>>       Sebastian and I have been working on fleshing out the details
>>>       of the new scaffold plugin to handle several requirements, as
>>>       part of the single collaborative scaffold initiative. We're
>>>       going to attempt making this work on Forge 1, and port the
>>>       design over to Forge 2. While our work so far has covered
>>>       fairly decent ground, it is mostly due to the commonalities
>>>       in the scaffolds we work on - AngularJS and Aerogear.
>>>       JSF/RichFaces, Errai are notable exceptions, and I'd like to
>>>       propose a weekly/bi-weekly cross-scaffold team meeting to
>>>       pour over the details of this new scaffold plugin, so that
>>>       design decisions will attempt to accomodate all projects
>>>       (instead of only HTML5 ones). 30 mins should be fine to start
>>>       with, stretching to a maximum of an hour (if there are too
>>>       many topics to discuss).
>>>      I'd like to know what time would be suitable for this
>>>      discussion. If we cannot find a suitable time for everyone to
>>>      join in, or if you schedules are busy, we could have impromptu
>>>      meetings.
>>> Thanks,
>>> Vineet
>>> _______________________________________________
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>>> forge-dev at lists.jboss.org
>>> https://lists.jboss.org/mailman/listinfo/forge-dev
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