Obtaining a Collaboration Kit Instance in a Servlet

When a VaadinService instance isn’t available, it’s impossible to get a CollaborationEngine instance with the getInstance() method. In a servlet, you can get the instance with the getAttribute() method, as long as it has been configured. See the Other Applications in production configuration documentation for details on how to configure Collaboration Kit.

Source code

MyServlet.javapackage com.vaadin.demo.collaboration;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.vaadin.collaborationengine.CollaborationEngine;
import com.vaadin.collaborationengine.MessageManager;
import com.vaadin.collaborationengine.SystemConnectionContext;
import com.vaadin.collaborationengine.UserInfo;

public class MyServlet extends HttpServlet {
    private final UserInfo systemUser = new UserInfo("system");
    private final String topicId = "topic";

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        CollaborationEngine ce = (CollaborationEngine) getServletContext()
                .getAttribute(CollaborationEngine.class.getName());
        if (ce == null) {
            resp.sendError(500,
                    "Collaboration Kit has not yet been initialized");
            return;
        }
        // Retrieve message that was sent in this POST request
        String userMessage = req.getParameter("message");
        String message = "An anonymous user posted the following message: "
                + userMessage;
        sendMessageToTopic(ce, message);
        resp.setStatus(202);
    }

    public void sendMessageToTopic(CollaborationEngine ce, String message) {
        // Get SystemConnectionContext from Collaboration Kit
        SystemConnectionContext systemConnectionContext = ce.getSystemContext();

        MessageManager messageManager = new MessageManager(
                systemConnectionContext, systemUser, topicId, ce);

        messageManager.submit(message) // Send message to topic
                .whenComplete((a, t) -> {
                    // Close the message manager when done
                    messageManager.close();
                });
    }
}

In the following example, a message posted through a form is added to a topic as a system message:

Source code

MyServlet.javapackage com.vaadin.demo.collaboration;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.vaadin.collaborationengine.CollaborationEngine;
import com.vaadin.collaborationengine.MessageManager;
import com.vaadin.collaborationengine.SystemConnectionContext;
import com.vaadin.collaborationengine.UserInfo;

public class MyServlet extends HttpServlet {
    private final UserInfo systemUser = new UserInfo("system");
    private final String topicId = "topic";

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        CollaborationEngine ce = (CollaborationEngine) getServletContext()
                .getAttribute(CollaborationEngine.class.getName());
        if (ce == null) {
            resp.sendError(500,
                    "Collaboration Kit has not yet been initialized");
            return;
        }
        // Retrieve message that was sent in this POST request
        String userMessage = req.getParameter("message");
        String message = "An anonymous user posted the following message: "
                + userMessage;
        sendMessageToTopic(ce, message);
        resp.setStatus(202);
    }

    public void sendMessageToTopic(CollaborationEngine ce, String message) {
        // Get SystemConnectionContext from Collaboration Kit
        SystemConnectionContext systemConnectionContext = ce.getSystemContext();

        MessageManager messageManager = new MessageManager(
                systemConnectionContext, systemUser, topicId, ce);

        messageManager.submit(message) // Send message to topic
                .whenComplete((a, t) -> {
                    // Close the message manager when done
                    messageManager.close();
                });
    }
}

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Documentation

Documentation

Obtaining a Collaboration Kit Instance in a Servlet