How Does Java Web Start Handle URLConnection Caching?

How does Java Web Start handle URLConnection caching?

Java Web Start, a deployment technology for Java applications, utilizes the URLConnection class for network communications. Caching is a critical aspect of improving performance by reducing network traffic and load times for Java applications. Understanding how caching works within Java Web Start can help developers optimize their applications effectively.

// Example of setting cache headers on a server
Cache-Control: no-cache, no-store, must-revalidate
Pragma: no-cache
Expires: 0

Causes

• URLConnection automatically caches resources based on HTTP caching headers such as ETag, Cache-Control, and Expires.
• Java Web Start maintains its own caching mechanism for JAR files and other resources to help manage versioning and updates.

Solutions

• To control caching in Java Web Start, configure your server to send appropriate HTTP headers that dictate caching behavior.
• Utilize the 'jnlp' file to define caching policies effectively, including version numbers and resource URLs.
• Implementing a cache clearing strategy can help manage stale content by utilizing the 'javaws' command line tool.

Mistake: Not including proper caching headers in HTTP responses.

Solution: Always set HTTP headers like Cache-Control and Expires to manage how resources are cached.

Mistake: Failing to check if cached resources are stale.

Solution: Regularly verify resource validity by checking ETag values or implementing versioning.