Releasing a new version of Hipparchus is not an easy process. Here are some steps that have been used in the past. They can be used as guidelines to avoid forgetting something.

You can also use the shell script to perform some of the commands depicted here.


In order to sign the binary releases, one has to create (once) a GPG signing key. This can be done on Linux-type using the command:

gpg --full-generate-key

Once the key has been generated, it should be registered on the Hipparchus server so users would be able to download it from Ask on the Hipparchus forum or on the GitHub discussion so the project team can add it.

Prepare Git branch for release

Release will be performed on a dedicated branch, not directly on master. So a new branch must be created as follows and used for everything else:

git branch release-X.Y
git checkout release-X.Y

Change library version number

The pom.xml files (both the top level one in the aggregator and the lower level ones for the various modules) contain the version number of the library. During development, this version number has the form X.Y-SNAPSHOT. For release, the -SNAPSHOT part must be removed. On a system with Unix utilities, you can do it with the single following line:

for pom in pom.xml hipparchus-*/pom.xml ; do mv $pom $pom.old ; sed 's,-SNAPSHOT,,' < $pom.old > $pom ; rm $pom.old ; done

Commit the change:

git add pom.xml hipparchus-*/pom.xml
git commit -m "Dropped -SNAPSHOT in version number for official release."

This step is performed by the shell script.

Update maven plugins versions

Release is a good opportunity to update the maven plugin versions. They are all gathered at one place, in a set of properties in hipparchus-parent/pom.xml, in a set of properties:

<!-- Project specific plugin versions -->


You can find the latest version of the plugins using the search feature at The properties name all follow the pattern hipparchus.some-plugin-name.version, the plugin name should be used in the web form to check for available versions.

Beware that in some cases, the latest version cannot be used due to incompatibilities.

Beware also that some plugins use configuration files that may need update too. This is typically the case with maven-checkstyle-plugin and maven-pmd-plugin. The src/conf/checkstyle.xml and src/conf/pmd-ruleset files may need to be checked.

Before committing these changes, you have to check that everything works. So run the following command:

LANG=C mvn -Prelease site site:stage

If something goes wrong, either fix it by changing the plugin configuration or roll back to an earlier version of the plugin.

Browse the generated site starting at page target/staging/index.html. Beware not to use target/site/index.html because it only contains the top level part of the site, not the modules. The target/staging directory which was generated by the site:stage part of the command gathers everything in one place.

When everything runs fine and the generated site is OK, then you can commit the changes:

git add hipparchus-parent/pom.xml src/conf/checkstyle.xml src/conf/pmd-ruleset.xml
git commit -m "Updated maven plugins versions."

Creating release notes

The release notes are created automatically using the maven-changes-plugin.

Some preparation is needed as Hipparchus is a multi-module product and this is not managed directly by the plugin.

The first step is to finalize the modules hipparchus-x/src/changes/changes.xml files. The release date and description, which are often only set to TBD during development, must be set to appropriate values. The release date at this step is only a guess three or four days in the future, in order to take into account the 72 hours release vote delay. If some modules had no changes at all, it is still worth adding a new <release> entry for the version, if the hipparchus-core module itself changed, as all other modules depend on it. It also simplifies management for users, as for any X.Y version released, all modules will have such a version number.

The second step to perform is to gather the entries from the modules hipparchus-x/src/changes/changes.xml files into the aggregator file src/changes/changes.xml. Forgetting this step would imply the release notes are incomplete as only this file is parsed during release notes generation.

The third step to perform is to run the following commands (don't forget to replace X.Y by the correct version number):

mkdir -p hipparchus-parent/src/changes
cp src/changes/* hipparchus-parent/src/changes/
mvn -Dversion=X.Y changes:announcement-generate -pl hipparchus-parent
cp hipparchus-parent/target/announcement/release-notes.vm RELEASE-NOTES.txt
rm -rf hipparchus-parent/src

After these commands have been run, the RELEASE-NOTES.txt file has been updated automatically. It should be reviewed and edited manually to improve readability (mainly whitespaces, indentation and lines wrapping) and then committed:

git add RELEASE-NOTES.txt src/changes/changes.xml hipparchus-*/src/changes/changes.xml
git commit -m "Updated release notes."

This third step is performed by the shell script (but the first two steps must be performed manually).

Updating documentation

Several files must be updated to take into account the new version:

file name usage required update
hipparchus-*/src/site/site.xml site structure and menus Add an entry in the menu for X.Y API docs (don't remove the existing entries for previous versions!)
src/site/site.xml site structure and menus Add an entry in the menu for X.Y API docs (don't remove the existing entries for previous versions!)
src/site/markdown/ site home page Update the text about the latest available version, including important changes from RELEASE-NOTES.txt
src/site/markdown/ downloads links Add a table with the links for files of the new versions, don't forget the date in the table caption introduction for new users Use the latest version number in the example property myprojectname.hipparchus.version

Documentation files to update

Once the files have been updated, commit the changes:

git add hipparchus-*/src/site/site.xml src/site/site.xml src/site/markdown/*.md
git commit -m "Updated documentation for the release."

Tag and sign the git repository

When all previous steps have been performed, the local git repository holds the final state of the sources and build files for the release. It must be tagged and the tag must be signed. Note that before the vote is finished, the tag can only signed with a -RCx suffix to denote Release Candidate. The final tag without the -RCx suffix will be put once the vote succeeds, on the same commit (which will therefore have two tags). Tagging and signing is done using the following command, with -RCn replaced with the Release Candidate number:

git tag X.Y-RCn -s -u key-ID -m "Release Candidate n for version X.Y."

The key ID is the 16 hexadecimal digits representing the manager keyID. This key ID should be available in the file.

The tag should be verified using command:

git tag -v X.Y-RCn

Pushing the branch and the tag

When the tag is ready, the branch and the tag must be pushed to GitHub so everyone can review it:

git push --tags origin release-X.Y

Generating signed artifacts

In order to upload the generated artifacts to SonaType OSS site, an account must have been set up and the corresponding credentials must be set in the servers section of the $HOME/.m2/settings.xml file, using an id of ossrh:

    <username>the user name to connect to the OSS site</username>
    <password>the encrypted password</password>

In order to sign the generated artifacts, the gpg key ID must be configured properly for maven to pick it. This can be done by adding a property that will be triggered automatically as follows in the profiles section of the $HOME/.m2/settings.xml file:

       <gpg.keyname>the 16 hexadecimal digits representing the manager keyID</gpg.keyname>

When these settings have been set up, generating the artifacts is done by running the following commands:

mvn clean
mvn deploy -DskipStagingRepositoryClose=true -Prelease

During the generation, maven will trigger gpg which will ask the user for the pass phrase to access the signing key.

A huge number of files will be uploaded to SonaType server, some of which we do not really release. So once the commands ends, you will have to log into SonaType OSS site, check the staging repository and remove all the artifacts related to hipparchus-aggregator and hipparchus-coverage modules by right-clicking and selecting “delete”. When the artifacts are considered OK, the repository must be closed so it is ready for the upcoming vote for the release.

This step is performed by the shell script, except the closing of the OSS repository, removing the spurious artifacts.

Uploading non-maven artifacts

The non-maven artifacts are the web site and the source and binary archives.

In addition to generate the maven artifacts and upload them, the command from the previous step also generated the source and binary release files we provide directly at the Hipparchus site in the downloads pages. Archives in both .zip and .tar.bz2 formats are created for sources and binaries, as well as their signatures but missing the checksums. The checksums must be generated manually using the command:

for f in target/hipparchus-*.zip target/hipparchus-*.tar.bz2 ; do md5sum < $f > $f.md5 ; done

The 12 files (,,, hipparchus-X.Y-bin.tar.bz2, hipparchus-X.Y-bin.tar.bz2.asc, hipparchus-X.Y-bin.tar.bz2.md5,,,, hipparchus-X.Y-src.tar.bz2, hipparchus-X.Y-src.tar.bz2.asc, hipparchus-X.Y-src.tar.bz2.md5) must be uploaded manually to the Hipparchus site (in a new staging/downloads directory) so people can review them.

The site is generated locally using:

LANG=C mvn site site:stage

Once generated, the site can be archived and uploaded to the Hipparchus site:

cd target/staging
tar cjf ../ .

This archive content must be extracted in the staging directory that already contains the downloads directory with the 12 files uploaded just before.

Prepare the site for the release

When the staging directory is ready, the Apache server configuration must be updated to allow this directory to be served (it is not served when no vote is going on). This server configuration file is located in the /etc/apache2/sites-enabled folder. The # comment marker in front of the line that references the staging directory must be removed, the file must be saved and the apache2ctl restart command must be run to relaunch the Apache server.

Calling for the vote

Everything is now ready so the developers and PMC can vote for the release. Create a new topic in the developers category of the forum with a subject line of the form:

[VOTE] Releasing hipparchus X.Y from release candidate n

and a content of the form:

This is a VOTE in order to release version X.Y of the Hipparchus library.
Version X.Y is a maintenance release.

Highlights in the X.Y release are:
  - feature 1 description
  - feature n description

The release candidate n can be found on the GitHub repository as
tag X.Y-RCn in the release-X.Y branch.

Source and binary archives are available using the staged web
site downloads page at

Note that the index page at /downloads does not show the X.Y release,
as it has not been voted yet.

The release notes can be read here:

Maven artifacts are available at

The votes will be tallied in 72 hours for now, on 20yy-mm-ddThh:mm:00Z (this is UTC time).

After the vote

If the vote fails, the maven artifacts must be removed from OSS site by dropping the repository and non-maven artifacts must be removed from the staging directory in the Hipparchus site. Then a new release candidate must be created, with a new number, a new tag and new artifacts. Another vote is needed for this new release candidate.

Tagging the released version

As the vote passed, a final signed tag must be added to the succeeding release candidate, verified and pushed:

git tag X.Y -s -u key-ID -m "Version X.Y."
git tag -v X.Y
git push --tags

Merging the release version into master

After the release branch has been completed, it should be merged back to the master branch:

git checkout master
git merge --no-ff release-X.Y
git push

Releasing maven artifacts on SonaType

In order to publish the maven artifacts, one should log into SonaType OSS site, select the staging repository and press the “Release” button in the top menu.

Releasing source artifacts on GitHub

In order to publish the source artifacts, one should log to GitHub, go to the page and declare the new release.

Finalize the site after the successful vote

The non-maven artifacts must also be published on the Hipparchus server by moving them from the staging repository to the general repository. Beware to create a new directory for the site and link the latest version to it. This allows older versions to be kept available if needed. A dedicated apidocs-X.Y folder must also be set up with a copy of the directory. Here again, it allows older versions to still be available online.

The Apache server configuration must be updated to forbid serving the now unused staging directory, and to add an alias for the new apidocs-X.Y folder. Once again, this is done by editing the Apache configuration file in the /etc/apache2/sites-enabled folder, saving it and running apache2ctl restart.

Announcing the release

The last step is to announce the release by creating a new topic in the announcements category of the forum.

Preparing next version

After the release branch has been completed, it should be merged back to the master branch and the pom.xml must be updated with the -SNAPSHOTflag for the next release number. On a system with Unix utilities, you can do it with the single following line:

for pom in pom.xml hipparchus-*/pom.xml ; do mv $pom $pom.old ; sed 's,<version>X.Y</version>,<version>X.Z-SNAPSHOT</version>,' < $pom.old > $pom ; rm $pom.old ; done

Commit the change:

git add pom.xml hipparchus-*/pom.xml
git commit -m "Preparing development of next version."

Back to top

Reflow Maven skin maintained by Olivier Lamy.