Re: Feedback on Java Code Generator

If you're going to use code generation, consider doing it the way Hibernate,
Spring, etc. do it.

1. You right your code as POJOs, implementing a standard interface.
2. You access those POJOs through the interface.
3. Have your "code generation" kit extend your POJOs at load-time,
implementing the same interface.

That is the opposite of having your classes extend the generated classes.

On 1/7/08, Tim Jowers <[email protected]> wrote:
>
>
> Anyone have input into a Java code generator for quickly putting a
> database on the web?  The design mantra is vanilla Java code and KISS. Right
> now I am using JDBC metadata to produce a Data Access Object, Value Object
> (aka Data Transfer Object), Business Object, and Session Bean (inherits from
> BO). My goal is not to reinvent the wheel in O-R mapping but to make
> something very simple. KISS. I guess the industry trends are toward
> frameworks like AquaLogic or Rails/Grails but this generator simply creates
> vanilla Java code so it may be edited by a skilled programmer.
>
> What are the main issues with code generators? Feedback desired.
> 1. Generated code is unmaintainable. Yes. Seen that many times! Generated
> code cannot be customized. So, for now, I'm created quite simply Java code
> with no special techniques. Even 1.4 compliant (no 1.5 language
> enhancements are being used).
> 2. Does not fit our framework. E.g. one client is using WebLogic 8.1 which
> has source-annotated-comments which pre-dates Java annotations. For them I
> might customize the code to be able to generate webservices and EJB's with
> the old BEA WebLogic way of doing things. They are considering moving to WLS
> 10 or maybe JBoss 4.2. The code is vanilla Java code so the programmer can
> edit the generated code as needed.
> 3. Round-tripping. How to generate the code a second time. The present
> design I'm advocating is to extend the base class (BO) and edit the new
> class. This way the generated code does not conflict with manually changed
> code. Any other ideas?
>
>
> What are the main issues with O-R mapping/mappers? Feedback desired.
> 1. No support for complex relationships. E.g XMLBeans had no capability to
> manage two tables/two object types. I'm using FK and PK metadata to
> generated the VO's. I have methods for "shallow" (just the table to object)
> and "deep" (all related tables  to a hierarchy of objects).
> 2. No support for n-to-m relationships. I saw in the Grails presentation
> they can create tables based on relational keywords in the script class.
> Conversely, I think the n-to-m relationships can be separated into three
> categories such as a lookup table (picklist), an n-to-several, and a true
> n-to-many. I'm working on defining these further as the real interest is how
> they are rendered graphically. I have some db investigation code to make
> estimates on these.
> 3. Does not create a good GUI. I think this is really the main part. A
> smart user could edit a database directly, but a dumb user needs calendar
> and other controls plus a workflow to make them productive. I presently am
> rendering in JSP/HTML and in Flex. I'm  also thinking about how to make a
> workflow builder as the workflow objects seems apparent from the
> relationships.
> 4. No support for ad hoc queries. I'm supporting ad-hoc queries by the
> creation of a new BO. Internally the VO's which correspond to the tables
> used int he query are used.
>
> A few other problems I've run into are:
> 1. Corporate databases are often not normalized. Lots of examples.
> 2. Database constraints are sometimes not defined so not available in
> metadata.
>
> So far the result is I've been able to make JSP/HTML websites very
> quickly. My personal style is I tend to hijack the JSP code and use it in
> custom ways. E.g. http://www.gouno.com/ really is very custom
> HTML/DHTML/JavaScript but uses the basic Java generated code on the back
> end.
>
> My other consideration is what GUI framework to support next. I've added
> support for REST, JSP/HTML, and some for Flex. I'm wondering what is the
> most popular AJAX framework? DOJO? And also for some reason would like to do
> a GTK interface since it it a native framework and runs on the major OS's.
> Thoughts?
>
> Thanks for your feedback,
> Tim Jowers
>
>
>
>
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