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 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 Apache Commons Math versions. Maven knows how to download the pre-built binary for released Apache Commons Math versions. The previous command may not work for development Orekit versions as they may depend on unreleased Apache Commons Math versions. Maven cannot download pre-built binaries for unreleased Apache Commons Math 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:7.1-SNAPSHOT: Could not find artifact org.apache.commons:commons-math3:jar:3.6-SNAPSHOT
In this case, you should build the missing Apache Commons Math artifact and install it in your local maven repository beforehand. This is done by cloning the Apache Commons Math source (using the MATH_3_X branch) from Apache git repository in some temporary folder and install it with maven. This is done by running the commands below (using Linux command syntax):
git clone --branch MATH_3_X https://git-wip-us.apache.org/repos/asf/commons-math.git cd commons-math mvn install
Once the Apache Commons Math 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, findbugs 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:
unpack the distribution inside your Eclipse workspace
create a new java project from existing sources and direct Eclipse to the directory where you unpacked Orekit
set the source folders to
in the source tab of the Configure Build Path dialog
set the external libraries to JRE system library (provided by Eclipse), Junit 4.x (provided by Eclipse) and Apache Commons Math (available at Apache Software Foundation Commons Math downloads page) in the libraries tab of the Configure Build Path dialog