[jsr-314-open] Metadata complete jar files

[Andy Schwartz]

All -

This issue turned up again yesterday in an Apache MyFaces thread, 
starting around:

http://myfaces.markmail.org/search/?q=#query:+page:2+mid:te2j33f6gsbtedcb+state:results

Although Mojarra does implement the desired behavior, unfortunately it 
looks like the specification was never updated to match, likely because 
I never logged a spec issue. :-(

Leonardo was kind enough to correct that:

http://java.net/jira/browse/JAVASERVERFACES_SPEC_PUBLIC-952

Can include this small but important spec tweak in 2.2?

Andy


On 9/3/09 4:58 PM, Andy Schwartz wrote:
> Gang -
>
> Section 11.5.1 of the spec defines the following annotation scanning 
> behavior:
>
>> Requirements for scanning of classes for annotations
>> * If the <faces-config> element in the WEB-INF/faces-config.xml file 
>> contains metadata-complete attribute whose value is “true”, the 
>> implementation must not perform annotation scanning on any classes 
>> except for those classes provided by the implementation itself. 
>> Otherwise, continue as follows.
>> * If the runtime discovers a conflict between an entry in the 
>> Application Configuration Resources and an annotation, the entry in 
>> the Application Configuration Resources takes precedence.
>> * All classes in WEB-INF/classes must be scanned.
>> * For every jar in the application's WEB-INF/lib directory, if the 
>> jar contains a “META-INF/faces-config.xml” file or a file that 
>> matches the regular expression “.*\.faces-config.xml” (even an empty 
>> one), all classes in that jar must be scanned.
>
>
> Since application developers have the ability to disable annotation 
> scanning at a global level, this means that any component set that 
> wants to support this mode would need to provide a metadata complete 
> faces-config.xml file. I don't think this is a hardship for most 
> component vendors, since presumably component vendors are going to 
> want to provide design-time metadata (eg. JSR-276 metadata), which, 
> for the moment, requires a faces-config.xml file anyway.
>
> A question that came up here is whether we can tweak section 11.5.1 to 
> accommodate metadata complete jar files. That is, can we specify that 
> any jar that contains a faces-config.xml with a 
> metadata-complete="true" attribute would not be scanned? This would 
> allow component vendors to indicate that their jar files are metadata 
> complete, and thus avoid the cost of annotation scanning for the 
> contents of the jar.
>
> Note that while the annotation scan is typically a one time hit 
> (during application startup), design-time tools may end up 
> starting/stopping JSF repeatedly during the development process. Thus, 
> avoiding unnecessary scanning should provide for a more efficient 
> development experience.
>
> Any thoughts on whether we could/should make this change? Does anyone 
> know of reasons why we avoided specifying this originally?
>
> Also - if we agree to make this change, is this small enough that we 
> could get this into the the next MR?
>
> Andy