Before you start, take a look at an out of the box demo built using the Java client library: the Java applet that is part of the KAAZING Gateway bundle. To see this Java applet in action, perform the following steps:

2. In a browser, navigate to the out of the box demos at `http://localhost:8001/demo/`.

3. Click **Java** and follow the instructions.

Taking a Look at the Java Client Demo Using Eclipse

1. Open Eclipse. If you do have Eclipse, you can [download it](http://www.eclipse.org/downloads/ "Eclipse Downloads") and install it.

2. In Eclipse, in the **File** menu, click **New**, and then click **Java Project**.

`GATEWAY_HOME/demo/java/src/gateway/com/kaazing/net/ws/demo`.

10. Copy the files named **LoginDialog.java** and **WebSocketFrame.java**.

11. In Eclipse, right-click the **org.kaazing.net.ws.demo** package under the **src** folder in your new project, and click **Paste**. The demo source files are added to the package.

13. In Eclipse, from the **Run** menu, click **Run As** and then **Java Application**. (By default, Eclipse should be configured to build the project automatically. If you receive a build error, from the **Project** menu, click **Build Project**.)

The Java client launches in a new window titled **WebSocket Echo Demo**.

This procedure describes how you can use the `EventSource` API--provided by the Kaazing Java client library--in Java. This API allows you to take advantage of the server-sent events standard as described in the [HTML5 specification](http://www.w3.org/html/wg/html5/#server-sent-events). For example, you can create a Java applet or stand-alone Java application that uses the Java HTML5 Communications client library to receive streaming data from a news feed or streaming financial data. The support for server-sent events is provided by the `EventSource` class and its supporting classes.

Before You Begin

- In Windows, in the Java Control Panel, on the **Advanced** tab, choose **Java console**, then select **Show console**.

- On Mac OS X, for Java 7 (required), access the **Java** system preference in **System Preferences**, click **Advanced**, and under **Debugging**, click **Enable logging**. Then, under **Java console**, select **Show console**.

7. Restart the browser and use the out of the box Java Echo Demo.

8. In a browser, navigate to the out of the box demos at `http://localhost:8001/demo/`, click **Java** and follow the instructions. The Java Console will open and display all logs from the Java Client.

A challenge handler is a constructor used in an application to respond to authentication challenges from the Gateway when the application attempts to access a protected resource. Each of the resources protected by the Gateway is configured with a different authentication scheme (for example, Basic, Application Basic, Application Negotiate, or Application Token), and your application requires a challenge handler for each of the schemes that it will encounter or a single challenge handler that will respond to all challenges. Also, you can add a dispatch challenge handler to route challenges to specific challenge handlers according to the URI of the requested resource.

To Secure Your Java and Android Clients

2. The authentication request and the header are converted into a ChallengeRequest (as defined in RFC 2617) and sent to a challenge handler registered in the client application for authentication challenge responses.

3. The ChallengeResponse credentials generated by a registered challenge handler are included in a replay of the original request to the Gateway, which allows access to the resource (assuming the credentials are sufficient).

Challenge Handler Class Imports

- `canHandle(ChallengeRequest challengeRequest)` determines if the challenge handler can handle the authentication scheme required by the Gateway (for example, Basic, Application Basic, Negotiate, Application Negotiate, or Application Token). The method takes a ChallengeRequest object containing a challenge and returns true if the challenge handler has the potential to respond meaningfully to the challenge. If this method determines that the challenge handler can handle the authentication scheme, it returns true and the `handle()` method is used. If this method returns false, the ChallengeHandler class (that contains all of the registered individual ChallengeHandler objects) continues looking for a ChallengeHandler to handle the request.

- `handle(ChallengeRequest challengeRequest)` handles the authentication challenge by returning a challenge response. Typically, the challenge response invokes a login handler to collect user credentials and transforms that information into a ChallengeResponse object. The ChallengeResponse sends the credentials to the Gateway in an Authorization header and notifies the Gateway on what challenge handler to use for future requests. If `handle()` cannot create a challenge response, it returns `null`.

### Overriding Default Challenge Handler Implementations

Kerberos challenge handler not working

- The client cannot connect to the Kerberos Domain Controller (KDC).

- Service name is in the incorrect format in the Kerberos challenge handler code.

- The pop-up dialog in the client used to obtain user credentials does not ensure that the username format is correct.

- [To Use the WebSocket API in Java](#to-use-the-websocket-api-in-java): The first example is a brief, general example of how your client can invoke the interfaces sequentially. The relevant interface will block the next interface until it has been successful or it will throw an exception.

- [Build the Java API Client Demo](#build-the-java-api-client-demo): The second example provides the steps to create a standalone Java client, including the steps needed to compile and run the interface in Eclipse.

Before You Begin

- A specified protocol name, host name, port number, and file name.

</p>

Setting and Overriding Defaults on the WebSocketFactory

-------------------------------------------------------

import org.kaazing.net.ws.WebSocketMessageWriter;

```

6. Change the default class statement that was generated by Eclipse to:

Eclipse has real-time error checking to inform you of any missing syntax elements.

23. Save the client in Eclipse.

25. Test your new client. In Eclipse, in the **Run** menu, click **Run**. The Java client launches. The **Location** field contains a URI for the Echo service running on the Gateway using the WebSocket scheme, ws://: `ws://localhost:8001/echo`.

26. Click **Connect**. The Log displays: