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PF4J - Update

Travis CI Build Status Maven Central

The goal of this project is to supply an update mechanism for PF4J. It's an open source (Apache license) lightweight (around 15KB) extension for PF4J, with minimal dependencies (only pf4j and gson).


  • UpdateManager allows you to inspect the repositories (local, remote) for updates, available (new) plugins. Also this class allows you to install available plugins, update or uninstall existing plugins.
  • UpdateRepository defines a local/remote repository (pluggable)
  • PluginInfo defines the plugin information for each repository's plugin
  • PluginRelease defines a plugin release
  • FileDownloader defines a pluggable way of downloading from a repository
  • FileVerifier defines a pluggable way of verifying downloaded files, e.g. checksum verification

Using Maven

In your pom.xml you must define the dependencies to PF4J artifacts with:


where ${pf4j-update.version} is the last pf4j-update version.

You may want to check for the latest released version using Maven Search

How to use

It's very simple to add pf4j-update in your application. The whole code of below snippet is available on Github.

public static void main(String[] args) {
    // create plugin manager
    PluginManager pluginManager = new DefaultPluginManager();

    // create update manager
    UpdateManager updateManager = new UpdateManager(pluginManager);

    // >> keep system up-to-date <<
    boolean systemUpToDate = true;

    // check for updates
    if (updateManager.hasUpdates()) {
        List<PluginInfo> updates = updateManager.getUpdates();
        log.debug("Found {} updates", updates.size());
        for (PluginInfo plugin : updates) {
            log.debug("Found update for plugin '{}'",;
            PluginInfo.PluginRelease lastRelease = updateManager.getLastPluginRelease(;
            String lastVersion = lastRelease.version;
            String installedVersion = pluginManager.getPlugin(;
            log.debug("Update plugin '{}' from version {} to version {}",, installedVersion, lastVersion);
            boolean updated = updateManager.updatePlugin(, lastVersion);
            if (updated) {
                log.debug("Updated plugin '{}'",;
            } else {
                log.error("Cannot update plugin '{}'",;
                systemUpToDate = false;
    } else {
        log.debug("No updates found");

    // check for available (new) plugins
    if (updateManager.hasAvailablePlugins()) {
        List<PluginInfo> availablePlugins = updateManager.getAvailablePlugins();
        log.debug("Found {} available plugins", availablePlugins.size());
        for (PluginInfo plugin : availablePlugins) {
            log.debug("Found available plugin '{}'",;
            PluginInfo.PluginRelease lastRelease = updateManager.getLastPluginRelease(;
            String lastVersion = lastRelease.version;
            log.debug("Install plugin '{}' with version {}",, lastVersion);
            boolean installed = updateManager.installPlugin(, lastVersion);
            if (installed) {
                log.debug("Installed plugin '{}'",;
            } else {
                log.error("Cannot install plugin '{}'",;
                systemUpToDate = false;
    } else {
        log.debug("No available plugins found");

    if (systemUpToDate) {
        log.debug("System up-to-date");


The library has very few components. The main component is the UpdateManager.
This class contains methods for repositories inspection

public List<UpdateRepository.PluginInfo> getAvailablePlugins();
public boolean hasAvailablePlugins();
public List<UpdateRepository.PluginInfo> getUpdates();
public boolean hasUpdates();
public List<UpdateRepository.PluginInfo> getPlugins();
public List<UpdateRepository> getRepositories();

and methods for plugin handling

public boolean installPlugin(String url);
public boolean updatePlugin(String id, String url);
public boolean uninstallPlugin(String id);

UpdateManager can work with multiple repositories (local and remote). All repositories are either defined in a repositories.json file or provided in UpdateManager's constructor.

Below I defined two repository: localhost and folder.

    "id": "localhost",
    "url": "http://localhost:8081/"
    "id": "folder",
    "url": "file:/home/decebal/work/pf4j-update/downloads/"

Each repository has a unique id and a URL.

In the root of this project you have a repositories.json file used by the test applications.

For more information please see the test sources (UpdateTest, ...). It's a good idea to run these tests and to see the results.


The project is made for customization and extension to your own needs. Here are some examples:

Tailor repository loading

First you can supply to UpdateManager your custom location and name of repositories.json if you want it to live somewhere else.

If you need even more control, UpdateManager accepts repositories in constructor and through setters. Implement your own UpdateRepository, FileDownloader and FileVerifiers to handle your own custom repsitory structures, authentication, checksum verifications etc.

Subclass UpdateManager

For full control, subclass UpdateManager and override relevant methods.

Repository structure

Each repository exposes multiple plugins using a plugins.json file.
Below I registered two plugins: welcome-plugin and hello-plugin.

    "id": "welcome-plugin",
    "description": "Welcome plugin",
    "releases": [
        "version": "0.8.0",
        "date": "Jun 5, 2014 9:00:35 PM",
        "url": "pf4j-demo-plugin1/0.8.0/"
        "version": "0.9.0",
        "date": "Jun 25, 2014 9:58:35 PM",
        "url": "pf4j-demo-plugin1/0.9.0/"
    "id": "hello-plugin",
    "description": "Hello plugin",
    "releases": [
        "version": "0.8.0",
        "date": "Jun 5, 2014 9:12:35 PM",
        "url": "pf4j-demo-plugin2/0.8.0/"
        "version": "0.9.0",
        "date": "Jun 25, 2014 9:58:35 PM",
        "url": "pf4j-demo-plugin2/0.9.0/"


Fields per plugin

Property Format Description
id string Unique id, mandatory
name string Display name (short)
description string Describe your plugin
provider string Name of plugin provider
releases List List of releases (minimum one)

Fields per release

Property Format Description
version X.Y.Z Version of release (SemVer format)
date date Release date, ISO8601 or yyyy-MM-dd format
requires Expression SemVer expression, e.g. ">=2.0.0"
url URL-string Link to zip, either absolute or relative URL
sha512sum <sha512-digest>
or <hash-file URL>
or ".sha512"
String with SHA-512 HEX digest of file content
URL to file with SHA-512 string
Fetch SHA-512 file next to plugin, with .sha512 file suffix

New properties may appear in the future.

The last (current) release of the plugin is calculated taking into account by the version property. In our example, the last release for each plugin is the release with version 0.9.0.

We encourage using yyyy-MM-dd format for release date. Localized US format as in the examples above will also work. If the date is not parsable, it will be set to epoch (1970-01-01) and print a warning in logs.

NOTE: The requires property was a simple X.Y.Z string in versions up to 0.3.0, interpreted as >=X.Y.Z. You may want to update your old plugins.json files to the new syntax.

Example for 'hello-plugin' (plugin2):

URL from repositories.json: http://localhost:8081/ Relative URL in plugins.json: pf4j-demo-plugin2/0.8.0/ Resulting UpdateRepository.PluginRelease.url: http://localhost:8081/pf4j-demo-plugin2/0.8.0/

In the downloads folder of the project you have a repository (plugins.json and artifacts - plugins archives) used by the test applications. The structure of the repository is:

  • plugin1
    • 0.8.0
    • 0.9.0
  • plugin2
    • 0.8.0
    • 0.9.0
  • plugins.json

For each plugin you have a folder (plugin1, plugin2) that contains subfolder for each version (0.8.0, 0.9.0). In each version folder you have the plugin archive (.zip) according to PF4J specification.

Mailing list

Much of the conversation between developers and users is managed through mailing list.


This project will be maintained under the Semantic Versioning guidelines as much as possible.

Releases will be numbered with the follow format:


And constructed with the following guidelines:

  • Breaking backward compatibility bumps the major
  • New additions without breaking backward compatibility bumps the minor
  • Bug fixes and misc changes bump the patch

For more information on SemVer, please visit