jsr-56 - Java Community Process Program

An unmodified Web server can be used with the basic protocol and can often be used to download
extensions that do not have a version-id 15 . It will never return the 10 Could not locate resource error code,
and always instead return the 404 HTTP status code.
6.2 BASIC DOWNLOAD PROTOCOL
JAR and image resources without version information (i.e., the version attribute is not specified), and
JNLP files are downloaded with an HTTP GET request to the Web server. For example, given the
following jar element:
then the JNLP Client must issue the following HTTP GET request:
http://www.mysite.com/c.jar
to retrieve the JAR file.
The JNLP Client must examine the HTTP response status code and MIME type to determine if the result
was successful. The valid responses are described in Section 6.1.2
6.3 VERSION-BASED DOWNLOAD PROTOCOL
The basis of the version-based download protocol is that all resources are uniquely identified by a
URL/version-id pair. Thus, a JNLP Client can at any given time request a specific version of a resource
located at a specific URL.
The JNLP Client issues an HTTP GET request that includes the specific version of the resource that it
needs. The request includes the field version-id, which specifies the requested version. For example,
given the following jar element:
then the JNLP Client must issue the following HTTP GET request 16 :
http://www.mysite.com/c.jar?version-id=2.3%2B
The JNLP Client must examine the HTTP response status code and MIME type to determine if the result
was successful. The valid responses are described in Section 6.1.2. For the above jar element, the
application/x-java-archive-diff MIME type cannot be returned. It can only be returned for incremental
requests.
The version string used in the request is not necessarily exact, e.g., 2.3+. The Web server must specify the
exact version-id of the resource that is returned in the response by setting the HTTP header field: xjava-jnlp-version-id.
The exact version returned must be one that matches the requested version
string.
15 This works since most Web servers will simply ignore the extra arguments and just return the file that the URL is pointing to.
16 The plus sign (+) in the version string is converted into the %2B given the standard encoding for arguments in URLs
JSR-56 - Proposed Final Draft 40 of 74