Connecting AEM from remote AEM instance (via JCR API)

The best way to allow communication between two AEM instance is by:

Exposing a service from the AEM instance which acts a source of information (say Source-AEM)
Consuming the exported service in the required remote AEM (Consumer-AEM).

In case, you have a use-case where:

A Service cannot be exposed via source AEM
A utility needs to be deployed in Consumer-AEM to access Source-AEM’s information

Then, you can use the following steps to achieve the same.

Please note: AEM does not allow remote connection OOTB. Hence, we would be embedding jcr2dav bundles. No performance testing has been conducted for the shared code.

Step-1: Create a user in Source-AEM Instance.

Create a user in source-AEM Instance with bare minimum access needed by the utility.

Step-2: Add dependencies to your maven project

Add following dependencies to the maven project of the utility.

	<dependency>
	<groupId>org.apache.jackrabbit</groupId>
	<artifactId>jackrabbit-jcr2dav</artifactId>
	<version>2.4.0</version>
	<scope>provided</scope>
	</dependency>
	<dependency>
	<groupId>org.apache.jackrabbit</groupId>
	<artifactId>jackrabbit-jcr2spi</artifactId>
	<version>2.4.0</version>
	<scope>provided</scope>
	</dependency>
	<dependency>
	<groupId>org.apache.jackrabbit</groupId>
	<artifactId>jackrabbit-spi2dav</artifactId>
	<version>2.4.0</version>
	<scope>provided</scope>
	</dependency>

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RemoteConnectionDependency.xml

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Since, the above bundles are not available in AEM, embed dependency for the above bundles in your pom.xml.

	<plugin>
	<groupId>org.apache.felix</groupId>
	<artifactId>maven-bundle-plugin</artifactId>
	<extensions>true</extensions>
	<configuration>
	<instructions>
	<!– <Embed-Dependency> artifactId1, artifactId2;inline=true </Embed-Dependency> –>
	<Export-Package>
	blog.techrevel.service
	</Export-Package>
	<Embed-Dependency>
	jackrabbit-jcr2dav,jackrabbit-jcr2spi,jackrabbit-spi2dav</Embed-Dependency>
	<Embed-Transitive>true</Embed-Transitive>
	<Sling-Model-Packages>
	blog.techrevel
	</Sling-Model-Packages>
	</instructions>
	</configuration>
	</plugin>

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RemoteConnectionEmbedDependency.xml

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Step-3: Access source AEM instance from utlity.

Create an instance of “Jcr2davRepositoryFactory” to access the source AEM Instance.

	package blog.techrevel.servlet;

	import java.io.IOException;
	import java.util.HashMap;
	import java.util.Map;

	import javax.jcr.Node;
	import javax.jcr.NodeIterator;
	import javax.jcr.Repository;
	import javax.jcr.RepositoryException;
	import javax.jcr.Session;
	import javax.jcr.SimpleCredentials;
	import javax.jcr.query.Query;
	import javax.jcr.query.QueryManager;
	import javax.servlet.Servlet;
	import javax.servlet.ServletException;

	import org.apache.jackrabbit.jcr2dav.Jcr2davRepositoryFactory;
	import org.apache.sling.api.SlingHttpServletRequest;
	import org.apache.sling.api.SlingHttpServletResponse;
	import org.apache.sling.api.servlets.SlingSafeMethodsServlet;
	import org.osgi.service.component.annotations.Component;
	import org.slf4j.Logger;
	import org.slf4j.LoggerFactory;

	@Component(service = Servlet.class, property = { "sling.servlet.paths=/bin/testRemoteConnection",
	"sling.servlet.methods=GET" })
	public class RemoteConnectionServlet extends SlingSafeMethodsServlet {

	private static final Logger LOG = LoggerFactory.getLogger(RemoteConnectionServlet.class);

	@Override
	protected void doGet(final SlingHttpServletRequest req, final SlingHttpServletResponse resp)
	throws ServletException, IOException {
	resp.setContentType("text/html");

	try {
	//Connect to repository
	Jcr2davRepositoryFactory repoFactory = new Jcr2davRepositoryFactory();
	Map<String, String> params = new HashMap<String, String>();
	params.put("org.apache.jackrabbit.repository.uri", "http://localhost:4502/crx/server");
	Repository repository = repoFactory.getRepository(params);
	Session session = repository.login(new SimpleCredentials("admin", "admin".toCharArray()), "crx.default");

	//Execute Query
	QueryManager qm = session.getWorkspace().getQueryManager();

	String stmt = "select * from [cq:Component] where isdescendantnode('/apps')";
	Query q = qm.createQuery(stmt, Query.JCR_SQL2);

	NodeIterator results = q.execute().getNodes();

	while (results.hasNext()) {
	Node node = (Node) results.next();
	resp.getWriter().write("<br />" + node.getPath());
	}

	session.logout();
	} catch (RepositoryException e) {
	LOG.error("Exception while connecting to AEM", e);
	}
	}
	}

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RemoteConnectionServlet.java

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For the sample code, access the servlet via URL (http://<Processor-AEM-HOST:Processor-AEM-port>/bin/testRemoteConnection), to get list of all components below “/apps/” folder on Source-AEM Instance.

Step-1: Create a user in Source-AEM Instance.

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