james strachan created TOMEE-794:
------------------------------------
Summary: skinny war support with a standard XML descriptor in the
WEB-INF containing all the maven coordinates of jars to add to the classpath
Key: TOMEE-794
URL: https://issues.apache.org/jira/browse/TOMEE-794
Project: TomEE
Issue Type: New Feature
Reporter: james strachan
Skinny WARs rock. The Resin folks came up with the pomegranate spec a while ago.
http://blog.caucho.com/2009/08/05/pomegranate-draft/
which seems pretty reasonable. The idea is to have an XML file with the maven
coordinates inside the WEB-INF/pom.xml file; then we don't waste disk and time
chucking the same 20Mb of stuff inside WARs only to then unexpand the WAR and
take them out again.
I created something similar in OSGi land
http://fuse.fusesource.org/bundle/overview.html
The main thing folks want to do is reuse their pom.xml for their project; but
then they want to include/exclude some things in the WAR (e.g. excluding
provided scope), or include optional things or not etc.
With FAB I went with the approach of extra manifest headers to help decide when
to hide things / include optional things etc. Then at runtime we'd download the
pom and walk the pom dependencies and whatnot.
I think a much simpler approach though is doing all this choosing & decision
making at build time; then any configuration of these choices is just maven
plugin configuration.
i.e. have a maven plugin which at build time generates the XML file (e.g.
WEB-INF/pom.xml) by walking all the transitive dependencies, excluding things
(e.g. optional / provided stuff) and expanding any maven property values and
whatnot.
So that at runtime, the embedded WEB-INF/pom.xml contains a flat list of
everything required to startup the WAR. i.e. its a 'post processed pom.xml' -
with no transitive dependencies, no property values, no parent poms etc. So
its a massive subset of what kind of pom is allowed. (For this reason its
tempting to use a different XML format to emphasis this subset; I guess worst
case we could use a different XML namespace or XSD?)
This means that at runtime its really fast; since it really is just a list of
maven coordinates to add to the skinny WAR which no maven/aether infrastructure
is required at all - just a little parse of the XML would do to get the maven
coordinates.
In terms of adding the skinny wars to the classpath; it would be good if they
were downloaded and stored locally within the server's directory tree - using a
maven repo style directory tree structure - so that folks could deploy some
apps (they'd download jars on the fly from maven repos). Then they could take a
tarball of a server and know all the required jars are local. Similarly folks
can make a 'tomcat distro generation' maven plugin to pre-populate the
containers's maven repo with stuff it is gonna need.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira
