The format of the cache is completely changed and should never be
assumed. Any existing code using the previous cache format for Java
Web Start or Java Plug-in will no longer work. Existing applications
in the Java Web Start cache will be upgraded and converted to the new
cache format the first time you run a Java Web Start application, or
if you launch the cache viewer using javaws -viewer.
The system cache will be upgraded and converted to the new format
the first time you launch Java Web Start in system mode, or if you
just launch javaws -system.
The caching mechanism and download engine are redesigned and consolidated between Java Web Start and Java Plug-in. This brings several new features to Java Web Start, previously available only in Java Plug-in and vice versa. They are :
Caching can be disabled using the Java Control Panel.
Java Web Start honors the maximum cache size set using Java Control Panel.
Java Web Start can start a cleanup thread to remove Least Recently Used(LRU) items from the cache when approaching the maximum cache size.
The “cache-control:
no-cache" HTTP header is now supported. "no-cache"
means cached contents cannot be used without re-validation. When the
no-cache directive is used , an update check is always made to make
sure the cached content is the same as the server copy pointed to by
the resource URL. If so, cached copy can be used. If not, server
copy will be downloaded.
Expiration field is ignored, which
means that even if the cached resource is not expired yet, update
check will still be performed.
The "cache-control: no-store" HTTP header is now supported. Resource will not be stored into the cache if this http header is included.
The "expires" HTTP header is now supported. The Expires HTTP header field gives the date/time after which the response is considered stale. A stale cache entry may not be returned by a cache unless it is first validated with the origin server. No update check will be made if the cache entry is accessed before the expiration time.
The expiration-date is supported. If a downloaded resource contains an expiration date, it will not be used after that date.
In Java SE 6 unsigned Java Web Start applications that specify a version other than the latest one will trigger a security warning, requiring explicit user permission before the application will run. Signed Java Web Start applications are not affected.
Java Web Start and Java Plug-in now support CRL (Certificate Revocation Lists) and OCSP (Online Certificate Status Protocol) for verifying the certificates.
Java Control Panel provides an option to select the default SSL handshaking protocol. The default is set to SSLv3 and SSLv2. You can also change it to TSL.
The Java Console is excluded from modality. By using the new modality features of AWT in Java 6, you can interact with Java Console even when your application is displaying a modal dialog.
All dialogs and screens of Java Web Start and Java Plug-in are redesigned to be more user friendly, intuitive, and accessible.