Chapter 14. The JXTA Advertisement Specification

Advertisements are metadata documents used by JXTA protocols to describe resources. Advertisements are used to describe peers, peergroups, pipes, content, services, and many other types of resources. JXTA advertisements are presented in XML. Many of the JXTA protocols depend on advertisements to provide key information or are used to pass advertisements between peers. Services can define new advertisement types by subtyping existing advertisement types or by defining completely new advertisements. Advertisement subtypes allow for additional information to be provided as well as richer metadata.

Advertisements are composed of a series of hierarchic elements. The elements may appear in any order within the advertisement. Each element can contain its data or additional elements. An element can also have attributes, which are name/value string pairs. An attribute is used to store metadata, which helps to describe the data within the element.

The JXTA protocols rely on the following advertisements:

  • Peer advertisement

  • Peergroup advertisement

  • Pipe advertisement

  • Module class advertisement

  • Module specification advertisement

  • Module implementation advertisement

  • Rendezvous advertisement

XML and JXTA Advertisements

All JXTA advertisements are represented in XML. XML provides a powerful means of representing data and metadata throughout a distributed system and provides a universal (software platform-neutral) representation: ...

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