Developers wishing to define new message types are invited to discuss them on the mailing list. There is a wiki page for recording message types that have been implemented or agreed.
Messages can carry an arbitrary number of parameters and return a value. All these should be xmlrpc types. The following table shows the correspondance between Java (under rmi) and xml-rpc types (the correspondance between xml-rpc types and other languages will be xml-rpc library dependent).
| xml-rpc type | Java Type |
|---|---|
| boolean (0/1) | Boolean (Boolean.FALSE/Boolean.TRUE) |
| string | String |
| array | List |
| struct | Map |
Many messages rely on the use of URLs, both to locate data and as URIs.
For maximum interoperability developers
should ensure that any URLs conform to RFC1738.
In particular, Java developers should be aware that File.toURL() produces
incorrect URLs.