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From "Jesse Glick (JIRA)" <j...@codehaus.org>
Subject [jira] (MNG-4752) <scope>endorsed</scope>
Date Fri, 02 Mar 2012 15:21:02 GMT

    [ https://jira.codehaus.org/browse/MNG-4752?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=293222#comment-293222
] 

Jesse Glick commented on MNG-4752:
----------------------------------

Some of the Mojo archetypes for Java EE use a similar idiom, copying dependencies to {{target/endorsed}}
(though not using a special profile to do so); see https://svn.codehaus.org/mojo/trunk/mojo/mojo-archetypes/webapp-javaee6/src/main/resources/archetype-resources/pom.xml
for example.

The NetBeans IDE will check for a directory of this name, and if encountered, prepend any
JARs found there to the Java editor's notion of the "boot" classpath. That enables the editor
to understand APIs added or overridden by endorsed JARs, such as {{javax.annotation.Resource.lookup}}
available in EE 6 but not SE 6; otherwise compilation of projects using such APIs would succeed
but the editor would display them as erroneous.

Obviously a standardized means of marking endorsed libraries would be much better since it
would both simplify POMs, and make IDE integration more predictable (e.g. not requiring the
project to have been built to at least the {{validate}} phase).
                
> <scope>endorsed</scope>
> -----------------------
>
>                 Key: MNG-4752
>                 URL: https://jira.codehaus.org/browse/MNG-4752
>             Project: Maven 2 & 3
>          Issue Type: New Feature
>          Components: Dependencies
>    Affects Versions: 2.2.1
>         Environment: An issue in 2.2.1 but I think the same issue applies also to 3.0.
>            Reporter: Jesse Glick
>             Fix For: Issues to be reviewed for 3.x
>
>
> There appears to be no official way to request usage of a particular Java library (such
as a new release of JAXB) using the Java "endorsed" mechanism. The semantics would be very
similar to provided scope except that the library is expected to override the JRE's boot classpath,
both at compile time (main or test) and runtime ({{exec:exec}} and Surefire).
> As investigated in https://netbeans.org/bugzilla/show_bug.cgi?id=185139#c8 there are
various ways you can get this functionality to work in current Maven releases if you Google
long enough, but all seem hackish. Prepending arguments to the bootclasspath directly is generally
discouraged.
> Manually configuring {{-endorseddirs}} (for {{javac}}) or {{-Djava.endorsed.dirs}} (for
{{java}} incl. Surefire) seems to work, but you have to first download the endorsed libraries
into some subdirectory of target, where they could consume considerable disk space.
> You could fix the disk space issue by passing dirs in the local repository, but this
requires hardcoding details of the {{~/.m2/repository/}} structure in the POM which is very
ugly, and also means duplicating information about {{groupId}}, {{artifactId}}, and {{version}}
(you still need to have artifacts declared elsewhere so they will get downloaded if not initially
present).
> Anyway all these tricks obscure the relatively simple intent of the developer, which
is to use a given artifact in the project in preference to any equivalent in the current JRE.
It is important to have a standardized way of declaring such dependencies, not just to make
it easy to write and maintain {{pom.xml}}, but so that IDEs and other tools know what you
intend to do and can (for example) offer appropriate code completion without reverse engineering
various idioms.
> Much preferable would be to simply declare these dependencies in the normal POM section,
but with {{<scope>endorsed</scope>}}. Then {{maven-compiler-plugin}}, {{maven-exec-plugin}},
{{maven-surefire-plugin}}, etc. would need to be modified to understand these dependencies
and use them appropriately when calling JDK tools. Plugin code could be smart enough to work
optimally in the available environment; for example, if an artifact has only a single JAR
in the local repository (no extra classifiers), the containing directory could be passed directly
to JDK tools as an endorsed dir, but in other cases a {{target/endorsed}} dir could be generated
and used instead.
> One concern is that the notion of an endorsed library is quite specific to the JVM; Maven
projects targeted at other platforms would presumably have no use for this scope. Perhaps
this is not an issue.

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