Orekit can be built from source using several different tools.
All these tools are Java based and can run on many different operating systems, including Unix, GNU/Linux, Windows and Mac OS X. Some GNU/Linux distributions provide these tools in their packages repositories.
Maven is a build tool that goes far beyond simply compiling and packaging a product. It is also able to resolve dependencies (including downloading the appropriate versions from the public repositories), to run automated tests, to launch various checking tools and to create a web site for a project. It runs on any platform supporting Java.
For systems not providing maven as a package, maven can be downloaded from its site at the Apache Software Foundation. This site also explains the installation procedure.
As with all maven enabled projects, building official released versions of Orekit is straightforward (see below for the special case of development versions), simply run:
mvn package assembly:single
The preceding command will perform all dependencies retrieval, compilation, tests and packaging for you. At the end, it will create several files named target/orekit-x.y.jar where x.y is the version number.
This command should always work for released Orekit versions as they always depend only on released Hipparchus versions. Maven knows how to download the pre-built binary for released Hipparchus versions. The previous command may not work for development Orekit versions as they may depend on unreleased Hipparchus versions. Maven cannot download pre-built binaries for unreleased Hipparchus versions as none are publicly available. In this case the command above will end with an error message like:
[ERROR] Failed to execute goal on project orekit: Could not resolve dependencies for project org.orekit:orekit:jar:8.0-SNAPSHOT: Could not find artifact org.hipparchus:hipparchus-core:jar:1.0-SNAPSHOT
In this case, you should build the missing Hipparchus artifact and install it in your local maven repository beforehand. This is done by cloning the Hipparchus source from Hipparchus git repository at GitHub in some temporary folder and install it with maven. This is done by running the commands below (using Linux command syntax):
git clone https://github.com/Hipparchus-Math/hipparchus.git cd hipparchus mvn install
Once the Hipparchus development version has been installed locally using the previous commands, you can delete the cloned folder if you want. You can then attempt again the mvn command at Orekit level, this time it should succeed as the necessary artifact is now locally available.
If you need to configure a proxy server for dependencies retrieval, see the Guide to using proxies page at the maven site.
If you already use maven for your own projects (or simply eclipse, see below), you may want to install Orekit in your local maven repository. This is done with the following command:
mvn install
For other commands like generating the site, or generating the checkstyle, spotbugs or jacoco reports, see the maven plugins documentation at maven site.
Eclipse is a very rich Integrated Development Environment (IDE). It is a huge product and not a simple build tool.
For systems not providing eclipse as a package, it can be downloaded from its site at the Eclipse Foundation.
The simplest way to use Orekit with Eclipse is to follow these steps:
using your operating system tools, unpack the source distribution directly inside your Eclipse workspace. The source distribution file name has a name of the form orekit-x.y-src.zip where x.y is the version number. Unpacking this zip file should create a folder of the form orekit-x.y in your workspace.
using Eclipse, import the project by selecting in the top level “File” menu the entry “Import…”
in the wizard that should appear, select “Maven -> Existing Maven Projects”
select the folder you just created in your workspace by unpacking the source distribution. The “pom.xml” file describing the project will be automatically selected. Click finish
The Orekit library should be configured automatically, including the dependency to the underlying mathematical library. Note however that the tutorials that are present in the source distribution are not automatically added by this process (because the tutorials correspond to extra code and as such they are not referenced in the pom.xml file).
Now you have an orekit-x.y project in you workspace, and you can create your own application projects that will depend on the Orekit project.
You can also check everything works correctly by running the junit tests.
If you want to go further and run the tutorials, you should update the project configuration to add them. In the Eclipse Package Explorer tab, right-click on the orekit-x.y project and select from the conext menu the entry “Build Path -> Configure Build Path…”. Then in the wizard that should appear, select the “Source” tab in the right pane, click the button “Add Folder…”, open the “tutorials” folder, select the two sub-folders “java” and “resource” and click “OK”. Now the projects should display the tutorials. Note that since 9.0, you need to have an “orekit-data” folder in your home directory in order to run the tutorials.