webmention4j

Webmention implementation in Java.

Usage

Client

The client module contains an implementation of a Webmention client which can be used to notify a Webmention endpoint server.

import dev.rilling.webmention4j.client.WebmentionClient;
import dev.rilling.webmention4j.common.Webmention;

import java.io.IOException;
import java.net.URI;

public final class WebmentionClientExample {
	public static void main(String[] args) {
		URI source = URI.create("https://example.com/blog-item");
		URI target = URI.create("https://example.org/something-else");

		WebmentionClient webmentionClient = new WebmentionClient();
		try {
			if (!webmentionClient.supportsWebmention(target)) {
				System.out.println("No endpoint found for target URL.");
				return;
			}

			webmentionClient.sendWebmention(new Webmention(source, target));
			System.out.println("Success!");
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

Server

The server module contains an implementation of a Webmention endpoint servlet which can be used to listen to Webmentions and process them.

import dev.rilling.webmention4j.common.Webmention;
import dev.rilling.webmention4j.server.AbstractWebmentionEndpointServlet;

public static class LoggingWebmentionEndpointServlet extends AbstractWebmentionEndpointServlet {

	@Override
	protected void handleWebmention(Webmention webmention) {
		System.out.println("Received Webmention '" + webmention + "'.");
	}
}

Examples

The example module contains example CLI applications that can be executed.

Client CLI Example

Webmention client CLI sending Webmention for http://localhost:8080/somethingelse being mentioned on http://localhost:8080/blogpost:

java -cp webmention4j-example-*.jar dev.rilling.webmention4j.example.WebmentionClientExample --source https://example.com/somethingelse --target https://example.org/blogpost

Instead of --target, the --crawl flag may be used to send Webmentions for all pages linked in the source page.

java -cp webmention4j-example-*.jar dev.rilling.webmention4j.example.WebmentionClientExample --source https://example.com/somethingelse --crawl

For all options, see the --help flag.

Server CLI Example

Webmention endpoint server CLI that logs incoming Webmentions:

java -cp webmention4j-example-*.jar dev.rilling.webmention4j.example.WebmentionEndpointServletExample

For all options, see the --help flag.