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Re: [wtp-dev] Mixing spec levels in EAR. Opinions?


Hi Kaloyan,

Thank you for raising this issue. I agree we are inconsistent in parts, and although we don't necessarily need to resolve all of the issues immediately we should at least have a common definition of what is 'correct' and may eventually be supported by WTP.

Among the IBM committers we generally agree with #2, but have made an interesting distinction: the schema used by a DD is only a bottom boundary on the spec level of the EAR or module. As an example, a '1.4' EAR that contains an EJB 3.0 module is really just an EE 5 EAR (or EE 6.0 or ...) with an older DD. Likewise, EJB 3.0 annotations within an EJB module is an indication that the EJB is at least EE 5/EJB 3.0, even if the DD still points to the EJB 2.0 schema.

If DD schemas and spec API usage are just a bottom boundary, it means that there is nothing within the contents of an EAR or module that can precisely determine its level. So how do we tell if it is valid for a user to add an EJB 3.0 module to what currently looks like a 1.4 EAR? Was it really an EE 5 EAR all along, do they want to uplevel the EAR, or is the user simply making a mistake?

The solution we came to is using facets. Facet versions allow the user to tell us which spec level they expect an EAR/module to be at, and gives us something to tool for and validate against. The versions are set on project creation or on import based on what we initially find in the modules. From there, the facet version of an EAR determines the maximum spec level of modules that can be added or which servers it can be run on, and validation can show errors for invalid modules or if the DD points to a schema above the level of the facet.

If you agree with the original distinction (that true EAR 1.4s can't hold EJB 3 modules, but the schema used by the DD is only a bottom boundary on the spec level), then I think you'll eventually come to the same conclusion we have. Please feel free to let me know what you think and others can chime in, or we can discuss on one of the WTP calls.

Thanks,
Tim deBoer
deboer@xxxxxxxxxx



From: "Raev, Kaloyan" <kaloyan.raev@xxxxxxx>
To: "General discussion of project-wide or architectural issues." <wtp-dev@xxxxxxxxxxx>
Date: 06/26/2008 09:04 AM
Subject: [wtp-dev] Mixing spec levels in EAR. Opinions?





Hello,

I want to bring up again an issue that was discussed some time ago in
Bugzilla. It is about mixing of spec levels of EAR and included modules.
There are two bugs related:
https://bugs.eclipse.org/bugs/show_bug.cgi?id=220929
https://bugs.eclipse.org/bugs/show_bug.cgi?id=229893

Everybody agree that EAR with spec level X could include modules with
spec level X or lower. Example: EAR 5 can include EJB 2.1.
But there is no consensus of opinion on EAR with spec level X to include
modules with spec level higher than X. Example: EAR 1.4 to include EJB
3.0. There are two contrary opinions:
 1. EAR 1.4 can include EJB 3.0
 2. EAR 1.4 cannot include EJB 3.0.

The supporters of opinion 1 says that it is not forbidden by the Java EE
spec.
The supporters of opinion 2 says that it is (at least indirectly)
forbidden by the spec. This is because the contract of the Java EE spec
says that a deployment module compliant with spec level X must always be
able to deploy on an application server compliant with spec level X. Now
let's look again at our example of EAR 1.4 including EJB 3.0. EAR 1.4 is
a J2EE 1.4 deployment module and it is guaranteed by the spec that it
will deploy on all J2EE 1.4 compliant servers. But if we try to deploy
it on an J2EE 1.4 compliant app server, that is not at the same time
Java EE 5 compliant, then our deployment will fail, because of the
included EJB 3.0 module (which is Java EE 5 spec level).

At the moment there is an inconsistency in several dialogs in WTP
regarding this issue. For example the Java EE Module Dependencies
property page of an EAR 1.4 project filters Java EE 5 modules for
selection, while at the same time the project creation wizard allows a
EJB 3.0 project to be added to an existing EAR 1.4 project.

I suggest that we discuss this problem and hope we will have an
agreement for WTP 3.0.1. I invite all application server vendors
represented in this mailing list to express their support for either
opinion 1 or opinion 2.

Greetings,
Kaloyan Raev
Eclipse WTP Committer
<
http://www.eclipse.org/webtools/people/person.php?name=raev>
Senior Developer
NW C JS TOOLS JEE (BG)
SAP Labs Bulgaria
T +359/2/9157-416
mailto:kaloyan.raev@xxxxxxx
www.sap.com
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