Getting the sources

For developing JNode you first need to get the sources. There are basically 3 possible ways to get them with different advantages and disadvantages. These possibilities contain:

  • Getting the sources from our nightly build server. You can find a tar.bzip2 file from here. This is the fastest way to get the sources, but you should not use it for development as it makes it hard to update your local sources once modified.
  • The second possibility is to use SVN, which is our main repository. SVN is easy to use but is a bit slow on the one hand and on the other hand you need access permissions to commit. For getting access permission one has to proove he's able to follow the JNode guidelines.
  • For new developers the recommended way is to use git. We have a git repository that is kept in sync and makes it easy to create patches against trunk.

Have a look at the subpages for a more detailed description of the commands.

SVN Usage (Deprecated : we have moved to GitHub)

This page is deprecated since we have moved to GitHub

This is a slight overview of SVN and how to use it. First of all there are three ways to access SVN: svn, svn+ssh and via https. Sourceforge uses WebDAV, that means you can also browse the repository online with your favorite browser, just click on this link.

Subversion uses three toplevel directories named trunk, branches and tags. Trunk can be compared to CVS Head, branches and tags are self-explanatory, I think Smiling

To checkout the source simply type:
svn co https://jnode.svn.sourceforge.net/svnroot/jnode/trunk/ jnode
which creates a new directory called jnode (Mind the space between "trunk/" and "jnode"!) . In this directory all stuff of the repository in /jnode/trunk will be copied to jnode/ on your local computer.

svn up|add|commit as expected.

New to subversion is copy, move and delete. If you copy or move a file, the history is also copied or moved, if you e.g. delete a directory it will not show up anymore if you do a new checkout.

If you want to make a branch from a version currently in trunk you can simply copy the content from trunk/ to branches/, e.g. by:
svn copy https://jnode.svn.sourceforge.net/svnroot/jnode/trunk/ https://jnode.svn.sourceforge.net/svnroot/jnode/branches/my-big-change-branch/

I think that's the most important for the moment, for more information have a look at the SVN Handbook located here.

Btw, for using SVN within eclipse you have to install subclipse located here.

Using Git (at GitHub)

The URLs for official git repository at GitHub are listed below :

Site: https://github.com/jnode/jnode
Https: https://github.com/jnode/jnode.git
SSH: [email protected]:jnode/jnode.git

For those who know what they are doing already and simply want push access, refer to the page on setting up push access. For those that are unfamiliar with git, there are a few git pages below that explain some of the common tasks of setting up and using git. This of course is not meant to be a replacement for the git manual.

Git Manual: http://www.kernel.org/pub/software/scm/git/docs/user-manual.html
Git Crash Course for SVN users: http://git.or.cz/course/svn.html

Setting up push access

In order to gain push access to the repository you will have to create a username on the hosting site and upload a public ssh key. Have the key ready as it will as for it when you sign up. If you have a key already you can register your username here and give your username, email and public key. There's no password involved with the account, the only password is the one you put on your ssh key when you create it, if you choose to do so. Its not like there is sensitive material involved, so dont feel compelled to use a password.

In order to generate an ssh key will require ssh be installed. Most linux distributions will have this already. Simply type in:

ssh-keygen

and your key will be generated. Your public key will be in ~/.ssh/ in a file with a .pub suffix, likely id_rsa.pub or id_dsa.pub. Open the file in a text editor (turn off line wrapping if its enabled), and copy/paste the key into your browser. Its important that the line not be broken over multiple lines.

Once your account has been created, send an email to the address found by the Owner tag on the jnode repo website, which is here. Once you are added you will need to configure your git configuration to use the new push url with your username.

When you originally cloned the repository the configuration setup a remote named origin that referenced the public repo using the anonymous pull url. We'll now change that using git-config.

git config remote.origin.url [email protected]:[user]/jnode.git

Of course replacing [user] with your username, which is case sensitive.

Now you should be setup. Please see the page on push rules and etiquette before continuing.

Setting up your local git repo

The first thing you want to do, obviously, is install git if its not already. Once git is intalled we need to clone the public repository to your local system. At this time of this writing this requires about a 130MB download.

First, position your current directory in the location where you want your working directory to be created. Don't create the working directory as git will refuse to init inside an existing directory. For this example we will clone to a jnode directory in ~/git/.

cd ~/git
git clone [email protected]:jnode/jnode.git jnode

Once this has finished you will have a freshly created working directory in ~/git/jnode and the git repository itself will be located in ~/git/jnode/.git For more info see Git Manual Chapter 1: Repositories and Branches

This process has also setup what git refers to as a remote. The default remote after cloning is labeled as origin and it refers to the public repository. In order to keep your repository up to date with origin, you will have to fetch them. See Updating with git-fetch for more info.

When fetch pulls in new objects, you may want to update any branches you have locally that are tracking branches on origin. This will almost always be true of the master branch, as it is highly recommended that you keep your master branch 'clean' and in sync with origin/master. It's not necessary, but it may make life easier until you understand git more fully. To update your master branch to that of origin/master simply

git rebase origin master

Then if you wish to rebase your local topic branches you can

git rebase master [branch]

The reason we're using git rebase instead of git merge is because we do not generally want merge commits to be created. This is partly to do with the svn repo that commits will eventually be pulled into. svn does not handle git merges properly, as a git merge object has multiple parent commits, and svn has no concept of parents. Where git employs a tree structure for its commits, svn is more like a linked list, and is therefore strictly linear. This is why its also important to fetch and rebase often, as it will make the transition of moving branches over to the svn repo much easier.

To learn more about branches refer to the git manual. It is highly recommended that new users to git read through chapters 1-4, as this explains alot of how git operates, and you will likely want to keep it bookmarked for quick referencing until you get a handle on things.

For those users that find the git command line a bit much, there is also `git gui` that is a very nice tool. It allows you to do alot of the tasks you would do on the command line via gui. There is also an eclipse plugin that is under development called egit, part of the jgit project implementing a pure java git implementation.

Git Etiquette

Once you have push access to the public git repo, there are a few simple rules i'd like everyone to observe.

1) Do not push to origin/master
This branch is to be kept in sync with the svn repo. This branch is updated hourly. When it is updated, any changes made to it will be lost anyway as the udpate script is setup in overwrite mode. Even with this, if someone goes to fetch changes from origin/master before the update script has had a chance to bring it back in sync, then those people will have an out of sync master, which is a pain for them. To be on the safe side, when pulling from origin master, it doesnt hurt to do a quick 'git log origin/master' before fetching to see if the commit messages have a git-svn-id: in the message. This is embedded by git for commits from svn. If the top commits do not have this tag, then someone has pushed into origin/master.

2) Do not push into branches unless you know whats going on with it.
If you have a branch created on your local repo and you would like to have your changes pulled upstream then push your branch to the repo and ask for it to be pulled. You can push your branch to the public repo by

git push origin [branch]

so long as a branch by that name does not already exist. Once the changes have been pulled the branch will be removed from the public repo. That is unless the branch is part of some further development. You will still have your branch on your local repo to keep around or delete at your leisure.

3) Sign-off on your work.
Although git preserves the author on its commits, svn overwrites this information when it is commited. Also it is your waying of saying that this code is yours, or that you have been given permission to submit it to the project under the license of the project. Commits will not be pulled upstream without a sign-off. The easiest way to set this up is to configure git with two variables.

git config user.name [name]
git config user.email [email]

Then when you go to make your commit, add an -s flag to git commit and it will automatically append a Signed-off-by: line to the commit message. This is not currently being enforced project wide, although it should be. Also if someone sends you a patch, you can add a Created-by: tag for that person, along with your own sign-off tag.