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Trail: Deployment
Lesson: Java Web Start
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Answers to Questions and Exercises: Java Web Start

### Questions

> 1. Question: In a link that is to run a Java Web Start application, which file is specified as the `a` tag's `href` attribute?

>    Answer: You use the application's `JNLP` file name as the value of the `href` attribute. When a user clicks the link to the `JNLP` file, Java Web Start loads the application specified by that `JNLP` file.

> 2. Question: Which MIME type must a Web server recognize in order for it to host Java Web Start applications?

>    Answer: You must configure the Web server so that files with the .jnlp extension are set to the `application/x-java-jnlp-file` MIME type.

> 3. Question: In an application's `JNLP` file, which two elements must be specified within the `resources` element?

>    Answer: The `resources` element must contain:

>    - The `j2se` element, which specifies the Java platform on which to run the application.
>    - The `jar` element, which specifies the JAR file for the application.

> 4. Question: Which interface provides the ability to an application to control how its own resources are cached?

>    1. `BasicService`
>    2. `DownloadService`
>    3. `PersistenceService`
>    4. `ExtendedService`

>    Answer: B. The `DownloadService` interface provides the ability to an application to control how its own resources are cached.

> 5. Question: True or False: Java Web Start applications run in a secure sandbox by default.

>    Answer: True.

> 6. Question: True or False: If a Java Web Start application is running in a secure sandbox, JAR files for the application can reside on different servers.

>    Answer: False. All JAR files for the application must reside on the same server.

> 7. Question: For a Java Web Start application to support operations outside of the secure sandbox, what must you do with its JAR files?

>    Answer: You must sign JAR files to enable your application can work outside of the sandbox.

### Exercises

> 1. Exercise: Write the XML code you would add to a `JNLP` file in order to request that the application have complete access to the client system.

>    Answer:

>    >     <security>
>    >        <all-permissions/>
>    >     </security>

> 2. Exercise: For a Java Web Start application, you have two icons, `one.gif` and `two.gif`, in the `images` directory in a JAR file. Write the application code you would use to access these images.

>    Answer:

>    >     // Get current classloader
>    >     ClassLoader cl = this.getClass().getClassLoader();
>    >     // Create icons
>    >     Icon firstIcon  = new ImageIcon(cl.getResource("images/one.gif"));
>    >     Icon secondIcon   = new ImageIcon(cl.getResource("images/two.gif"));

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