Dependencies

While the Phoebus framework tries to minimize unnecessary dependencies, both the framework and the CS-Studio tools built on it naturally have external dependencies. Based on our experience with the previous, Eclipse-RCP-based version of CS-Studio, we set two goals:

• Establish a well-defined, known, reproducible target platform
• Support multiple build tools

Target Platform

The Target Platform is basically a set of *.jar files or Java modules that provides all the necessary external dependencies, including for example a JSON and a MySQL client library.

• The content of the target platform, i.e. the exact set of files, is well known. For example, it would specify "jackson-core-2.9.4.jar" and "mysql-connector-java-5.1.45.jar", i.e. the exact name and version of the JSON and MySQL libraries.
• The target platform is establisted early on in the build process. It may be assembled by the first step in the build process, it may be downloaded as a ZIP file. The point is that the complete target platform is available before the first source file gets compiled.
• The target platform allows offline development. Given the target platform and the CS-Studio source files, no network access is needed because all sources and their external dependencies are available.
• The target platform is in a format that allows using different build tools

Our current way of defining and creating the target platform is Maven-centric, but with slight adjustments and conventions over a Maven-only approach to meet all goals. Instead of depending on Maven for the complete build process, using Maven to only build the dependencies will assemble all external dependencies in dependencies/phoebus-target/target/lib.

From then on, any build tool can be used; no additional network access is required to download more dependencies.

As an alternative to using Maven, the target/lib files could also be copied from another build setup, including the snapshotData from a nightly build server. It could even be collected manually based on the information in the dependencies/**/pom.xml files.

Build Tools

In principle, once the target platform has been assembled, any of the build tools can be used to develop, built and run CS-Studio. It is also possible to switch between built tools.

Building the target platform, however, is easiest using Maven.

Maven

Each set of Phoebus framework, CS-Studio core, application and service source files comes with a Maven pom.xml that lists its dependencies. Maven can automatically download these dependencies. Without actually listing the complete target platform content, Maven determines it each time the sources are compiled. Such a pure Maven approach is in fact quite convenient while it works, but can become very troublesome in case of build errors, especially when combined with limited network access:

• The dependency information in the pom.xml is specific to Maven.
• If one pom.xml lists "ab5.jar" as a dependency, and another lists "ab9.jar", which version will be used?
• The complete target platform is only known after successfully(!) building everything.

To overcome these issues, we list all external dependencies that can be obtailed from Maven-Central in the file dependencies/phoebus-target/pom.xml. The dependencies/install-jars subtree allows adding dependencies that cannot be downloaded.

One initial maven build of the dependencies collects the target platform into dependencies/phoebus-target/target/lib:

mvn clean verify -f dependencies/pom.xml

To truly use the files from the target platform, all the other pom.xml could now refer to them via 'system' references:

<dependency>
  <groupId>some.group</groupId>
  <artifactId>whatever</artifactId>
  <version>2.0</version>
  <scope>system</scope>
  <systemPath>../../dependencies/phoebus-target/target/lib/whatever2.0.jar</systemPath>
</dependency>

In reality we keep the normal pom file dependency references without systemPath, but we only use references that are also listed in the dependencies/phoebus-target/pom.xml. If a submodule pom.xml needs an added dependency, or one with a new version number, the target platform pom.xml must be updated as well. This way, the initial build of the dependencies module will fetch all dependencies, and subsequent Maven builds of other modules will be able to use cached copies.

Ant

Ant builds use the target platform files from dependencies/phoebus-target/target/lib. The target platform thus needs to be created as decribed for Maven, or you obtain a copy of such a target/lib from a previous build.

Eclipse

Eclipse .project and .classpath files are included which refer to the platform files.

Intellij IDEA; NetBeans

Uses the Maven pom.xml, so once the dependencies have been built, all dependencies should be available.