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Hacking on AS7

modified by jaikiran pai in JBoss AS7 Development - View the full document

1. Create a github account



2. Fork jboss-as into your account



3. Clone your newly forked copy onto your local workspace

$ git clone git@github.com:[your user]/jboss-as.git
Initialized empty Git repository in /devel/jboss-as/.git/
remote: Counting objects: 2444, done.
remote: Compressing objects: 100% (705/705), done.
remote: Total 2444 (delta 938), reused 2444 (delta 938)
Receiving objects: 100% (2444/2444), 1.71 MiB | 205 KiB/s, done.
Resolving deltas: 100% (938/938), done.
$ cd jboss-as


4. Add a remote ref to upstream, for pulling future updates

git remote add upstream git://github.com/jbossas/jboss-as.git 


5. Use maven (via build.sh) (make sure you use maven 3)

$ ./build.sh install
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO] JBoss Application Server: BOM ..................... SUCCESS [1.834s]
[INFO] JBoss Application Server: Parent Aggregator ....... SUCCESS [0.022s]
[INFO] JBoss Application Server: Domain Core ............. SUCCESS [3.051s]
[INFO] JBoss Application Server: Server Manager .......... SUCCESS [0.204s]
[INFO] JBoss Application Server: Server .................. SUCCESS [0.283s]
[INFO] JBoss Application Server: Domain Controller ....... SUCCESS [0.084s]
[INFO] JBoss Application Server: Process Manager ......... SUCCESS [0.314s]
[INFO] JBoss Application Server: Remoting ................ SUCCESS [0.390s]
[INFO] JBoss Application Server: Build ................... SUCCESS [5.696s]
[INFO] ------------------------------------------------------------------------
[INFO] ------------------------------------------------------------------------


6. Pulling later updates from upstream

$ git pull --rebase upstream master
>From git://github.com/jbossas/jboss-as
 * branch            master     -> FETCH_HEAD
Updating 3382570..1fa25df
 {parent => bom}/pom.xml                            |   70 ++++----------
 build/pom.xml                                      |   13 +--
 domain/pom.xml                                     |   10 ++
 .../src/main/resources/examples/host-example.xml   |    2 +-
 .../resources/examples/jboss-domain-example.xml    |   28 +++---
 .../main/resources/schema/jboss-domain-common.xsd  |   12 +--
 .../main/resources/schema/jboss-domain-host.xsd    |    2 +-
 domain/src/main/resources/schema/jboss-domain.xsd  |   17 ++--
 pom.xml                                            |  100 ++++++++++++++++++--
 process-manager/pom.xml                            |    3 +-
 10 files changed, 156 insertions(+), 101 deletions(-)
 rename {parent => bom}/pom.xml (85%)


(--rebase will automatically move your local commits, if you have any, on top of the latest branch you pull from, you can leave it off if you do not). Please note that --rebase is very important if you do have commits. What happens is that when git pull can't fast forward, it does a merge commit, and a merge commit puts the sucked in changes ON TOP of yours whereas a rebase puts them BELOW yours. In other words a merge commit makes the history a graph, and we prefer a cleaner, easier to follow linear history (hence the rebasing). Further once you do a merge commit it will be difficult to rebase the history before that commit (say you want to combine two commits to one later) as described in point 12.


One way to not forget --rebase the rebase option is you may want to create an alias




 $ git config --global alias.up "pull --rebase"


and then just use the new alias instead of pull


 $ git up upstream master


One last option, which some prefer, is to avoid using pull altogether, and just use fetch + rebase (this is of course more typing)



7. Pushing pulled updates (or local commits if you aren't using topic branches) to your private github repo (origin)


$ git push
Counting objects: 192, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (44/44), done.
Writing objects: 100% (100/100), 10.67 KiB, done.
Total 100 (delta 47), reused 100 (delta 47)
To git@github.com:[your user]/jboss-as.git
   3382570..1fa25df  master -> master


You might need to say -f to force the changes. Read the note on 12 though before you do it.

8. Discuss your planned changes (if you want feedback)

9. Make sure there is a JIRA somewhere for the enhancement/fix



10. Create a simple topic branch to isolate that work (just a recommendation)

git checkout -b my_cool_feature
Note: See tips section for how to use a nice git prompt for tracking what branch you are in!

11. Make the changes and commit one or more times (Don't forget to push)

git commit -m 'JBAS-XXXX Frunubucate the Fromungulator'
git commit -m 'JBAS-YYYY Tripple Performance of Fromungulation'
git push my_cool_feature


Note that git push references the branch you are pushing and defaults to master, not your working branch.


12. Rebase your branch against the latest master (applies your patches on top of master)

git fetch upstream
git rebase -i upstream/master
# if you have conflicts fix them and rerun rebase
# The -f, forces the push, alters history, see note below
git push -f origin my_cool_feature



The -i triggers an interactive update which also allows you to combine commits, alter commit messages etc. It's a good idea to make the commit log very nice for external consumption. Note that this alters history, which while great for making a clean patch, is unfriendly to anyone who has forked your branch. Therefore you want to make sure that you either work in a branch that you don't share, or if you do share it, tell them you are about to revise the branch history (and thus, they will then need to rebase on top of your branch once you push it out).

13. Get your changes merged into upstream

  1. Make sure your repo is in sync with other unrelated changes in upstream before requesting your changes be merged into upstream by repeating  step 12.
  2. Email a pull request to jbossas-pull-requests@lists.jboss.org (if I haven't subscribed the list, do it here) with a link to your repo, a description of the changes, and who reviewed (if any)
  3. After review a maintainer will merge your patch, update/resolve issues by request, and reply when complete
  4. Don't forget to switch back to master and pull the updates
    1. git checkout master
      git pull upstream master


Appendix A.  Adding a new external dependency

  1. Edit pom.xml and add a property of the form "version.groupId.artifactId" which contains the Maven version of the dependency.  Add your dependency to the <dependencyManagement> section, and use the property for the version.  If your new dependency has any transitive dependencies, be sure to <exclude> them (or if possible, update the project so that all its dependencies are of provided scope).
  2. Add your dependency to any AS modules that require it, but only with group/artifact.
  3. Edit build/pom.xml and add your dependency with only group/artifact.
  4. Create a directory in build/src/modules corresponding to the module's name (which will differ from the Maven group/artifact name; look at other modules to get a feel for the naming scheme), with a version of "main", like this: "build/src/modules/org/jboss/foo/main".
  5. Create a module.xml file inside the "main" directory.  Use a module.xml from another similar module as a template.
  6. Edit build/build.xml and add a <module-def> element.  The name listed in the <module-def> element corresponds to the module name.  The group/artifact listed in the nested maven-resource element(s) refer to the Maven group/artifact name.
  7. Important: Make sure you did not introduce any transitive dependencies by using "mvn dependency:tree".  If you did, be sure to add <exclusion>s for each of them to your dependency as described above.
  8. Important: Do not introduce a dependecy on the "system" module.  If you need access to JDK classes which are not covered by any other dependency, use the "javax.api" module as a dependency.


Please be sure to preserve the alphabetical ordering of all POMs and the build.xml file.

Appendix B.  Adding a new AS submodule

  1. Create the directory corresponding to the submodule and add it to the root pom.xml file.  The convention is to leave off the "jboss-as-" portion, so "jboss-as-remoting" becomes "remoting".
  2. Create a POM for your submodule (use another submodule as a template).  Make sure all dependencies you specify do not include a version.  The group ID should be "org.jboss.as", and the artifact ID should begin with "jboss-as-" and there should be a proper <name> for the new module.
  3. Add the new submodule to the top section of the <dependencyManagement> of the top-level pom.xml.  The version should be set to "${project.version}".  This section is sorted alphabetically by artifact name so please preserve that ordering.
  4. Add the new submodule to the modules section element of the top-level pom.xml
  5. Add your submodule dependency to any AS modules that require it, but only with group/artifact.
  6. Edit build/pom.xml and add the new submodule with only group/artifact.
  7. Create a directory in build/src/modules corresponding to the submodule, with a version of "main", like this: "build/src/main/resources/modules/org/jboss/as/new-subsystem/main".
  8. Create a module.xml file inside the "main" directory.  Use a module.xml from another subsystem as a template.
  9. Edit build/build.xml and add a <module-def> element for the subsystem.  Use the module name and Maven coordinates from steps 6 and 2 respectively.  Use another submodule as a template.


Please be sure to preserve the alphabetical ordering of all POMs and the build.xml file.


Appendix C.  Profiling with JProfiler

Performance tuning is an important part of AS7 development.  In order to use JProfiler on a standalone AS 7 instance, first you need to add the following to your standalone.conf file:


JAVA_OPTS="$JAVA_OPTS -Djboss.modules.system.pkgs=com.jprofiler -agentlib:jprofilerti -Xbootclasspath/a:/path/to/jprofiler/bin/agent.jar"


The "jboss.modules.system.pkgs" property tells JBoss Modules to allow the "com.profiler" classes to be found from any class loader, which is essential to allow the JProfiler agent to run.


It's easiest to then just set up your JProfiler session as "Remote", and start the server and the profiler in any order.  That's it!


Appendix D. Importing into Eclipse


The directory "ide-configs/eclipse" contains both formatter and code templates.  Use these to pass the CheckStyle enforcer during the build if coding from Eclipse.


Tips & Tricks!

Creating a Git status prompt in your terminal

This makes it easy to not forget what branch you are working in and quickly tell if you have changes. The following will adjust the PS1 on unix (or cygwin on Windows). Note that it assumes a compiled version of git, which is also the case for the OSX packages. If you are using the bundled rpm version, change the completion path to "/etc/bash_completion.d/git"



if [ -f "$GIT_COMPLETION_PATH" ]; then

if [[ ${EUID} == 0 ]] ; then
      PS1="\[\033[01;31m\]\h\[\033[01;34m\] \w\[\033[33m\]$ADD_PS1\[\033[34m\] \$\[\033[00m\] "
      PS1="\[\033[01;32m\]\u@\h\[\033[01;34m\] \w\[\033[33m\]$ADD_PS1\[\033[34m\] \$\[\033[00m\] "


IDE Integration



Follow the steps mentioned here http://community.jboss.org/wiki/HackingAS7usingEclipse

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