As we've already seen, the eclipse.ini file controls the Eclipse startup. It is an extra component that makes the Eclipse platform very configurable. You can find the list of command-line arguments that can be used in their documentation at

http://help.eclipse.org/luna/topic/org.eclipse.platform.doc.isv/reference/misc/runtime-options.html

It is important to acknowledge the following warnings that this documentation mentions:

Setting the -vm option allows us to be sure of the JVM implementation on which Eclipse runs as a program. You might have noticed that we've targeted the JVM as a library (*.dll / *.so). It has better performance on startup and also identifies the program process as the Eclipse executable and not just as the Java executable.

If you wonder which JVM Eclipse uses when a –vm option is not set, be aware that Eclipse DOES NOT consult the JAVA_HOME environment variable. (Eclipse wiki).

Instead, Eclipse executes the Java command that parses your path environment variable.

The suggested JVM argument list comes from Piotr Gabryanczyk's work on the Java memory management model. Initially, for JetBRAINS IntelliJ settings, this configuration is also useful for an Eclipse environment. It helps in the following tasks:

The instantiated objects throughout the program's life cycle are stored in the Heap memory. The suggested parameters define a JVM startup Heap space of 128 mb (-Xms) and an overall 512 mb maximum heap space (–Xmx). The heap is divided in two subspaces, which are as follows:

With Hotspot or OpenJDK, the permanent generation space was used to store information related to the classes' definition (structure, fields, methods, and so on.). You may have already encountered a PermGen space OutOfMemoryError exception when the loaded structure becomes too big. In this situation, the solution is to increase the -XX:MaxPermSize argument. It is no longer necessary with JDK8.

For this purpose, the Permanent Generation (PermGen) space has been replaced by a metadata space that is not part of the heap but of the native memory. The default maximum size of this space is unlimited. However, we can still restrict it with -XX:MetaspaceSize or -XX:MaxMetaspaceSize.

Downgrading a compliance level allows us to run a lower version of a Java compiler than the one the JDK is natively identified to. It impacts the Eclipse builds, errors, and warnings and also the JavaDocs. It is obviously not possible to set a higher compilation version than the native version of a compiler.

Inside Eclipse, most of the Maven configuration comes from the m2eclipse plugin (also called Maven integration for Eclipse). This plugin is included, by default, in Eclipse Luna. It is then not necessary to download it manually. After the Maven configuration that we went through, m2eclipse is also very helpful to trigger Maven operations from the IDE context and to provide assistance to create Java Maven projects. You will learn more about m2eclipse in the next section.

We then installed a basic settings.xml file. This file is used to configure Maven without being bound directly to any projects. The most common uses of settings.xml are probably profile definition and credential storage to access the repository manager(s).

With Maven profiles, you have the possibility to run a build for a specific environment and to match a specific configuration (variable values, set of dependencies, and so on.). Maven profiles can be cumulated with each other. They can be activated through a command line, declaratively in the Maven settings or from the environment configuration such as files being present or missing on the filesystem, the used JDK, and so on.

A repository manager is a third-party application that manages all the required binaries and dependencies that a developed application may need. Acting as a buffering proxy between development environments and public repositories, a repository manager provides control of critical parameters such as build time, availability of dependencies, visibility and access restriction, and so on.

Famous solutions include Apache Archiva, Artifactory, Sonatype Nexus. In the context of our application, we won't make use of a repository manager.

Eclipse for JEE developers allows the integration of Tomcat with other application servers within the development environment. This is made possible through the provided Web Tools Platform (WTP) plugins that can manage web artefacts, their compilation, and their deployment into the web server.

In the servers tab (made visible earlier), double-clicking on the created Tomcat v8.0 server, opens a configuration window and enables the possibility of setting up parameters that are normally defined in the server.xml Tomcat file, which is located in the tomcat8\conf directory.

By default, WTP abstracts this configuration and doesn't impact the genuine server.xml file. This behavior can be changed by activating the Publish module contexts to separate XML files option in the Server configuration window.