External System Integration
This page provides a high-level overview of the External System sub-system. There are multiple project management systems (Apache Maven, Gradle, sbt, etc.) and IntelliJ Platform provides a mechanism to support them in IDEs.
Most of the project management systems provide a similar set of facilities from the integration point of view:
build a project from external system config (pom.xml, build.gradle.kts, etc.)
provide a list of available tasks
allow to execute a particular task
That means that we can separate external system-specific logic and general IDE processing. The External System sub-system provides a simple API for wrapping external system elements and extensible IDE-specific processing logic.
Project Data Domain
The external system wrapper is required to be able to build project info on the basis of the given external system config. That information is built with the following base classes:
DataNode class is just a holder for the target data (a data type is defined by the
DataNode objects might be organized in directed graph where every edge identifies parent-child relation.
For example, a simple one-module project might look as below:
The IDE provides a set of built-in
ExternalEntityData classes but any external system integration or third-party plugin developer might enhance project data by defining custom
ExternalEntityData and store them at a child of appropriate
Managing Project Data
Processing project data built on an external system config basis can be performed with
ProjectDataService. It is a strategy which knows how to manage particular
ExternalEntityData. For example, when we want to import a project from an external model, we can start with the top level
DataNode which references project info and then import its data using corresponding service.
Custom services can be registered via
com.intellij.externalProjectDataService extension point.
The good thing is that we can separate project parsing and management here. That means that a set of
ProjectDataServices can be introduced for particular technology and then every external system integration can build corresponding data if necessary using it.
Importing from External Model
The IntelliJ Platform provides an API for importing projects from external models:
There are two classes built on the template method pattern which simplify implementation:
AbstractExternalProjectImportBuilder is built on top of the 'external system settings' controls.
Example of the project import provider and builder for Gradle:
It's possible to configure external system integration to automatically refresh project structure when external project's config files are modified.
Auto-Import for ExternalSystemManager Implementation
Auto-Import for Standalone External Systems
Some external systems don't have
ExternalSystemManager (e.g., Maven), but they also can use auto-import core to track changes in settings files. For this, implement
ExternalSystemProjectAware interface that describes settings files for tracking and an action to reload the project model. Then register the instance with
ExternalSystemProjectTracker to start tracking.
Icon for Reload Notification
From 2020.1, the icon for reload notification can be specified per external system. Implement
ExternalSystemIconProvider and register via com.intellij.externalIconProvider extension point in plugin.xml. Alternatively, set
reloadIcon field external system implements
The general idea is that all external system settings controls are represented by implementations of
ExternalSystemSettingsControl interface. There are also external system project-local settings and global external system settings. So, basically particular external system settings UI looks as below:
It's recommended to extend from
AbstractExternalProjectSettingsControl for implementing project-level settings control as it already handles some of them.
Similar approach is used for providing Import from External System UI - implementation is expected to extend
AbstractImportFromExternalSystemControl and it has not linked external projects list, but target external project path control:
com.jetbrains.intellij.platform:external-system-test-framework from IntelliJ Platform Artifacts Repositories.
Relevant base classes: