JXTA Message Elements are used to add data to a Message. Message Elements are
immutable objects. A Message Element may be shared amongst as many messages
as is desired. A Message Element is composed of four components:
An optional name. This may be any String . Unnamed
elements are assumed to have the name "" (the empty string).
An optional MimeMediaType . If not specified
the Mime Media Type is assumed to be "Application/Octet-Stream".
Data. Sub-classes of MessageElement allow you to create elements based
on a variety of data formats.
An optional signature. This is a Message Element that is associated to
this element and may contain a cryptographic signature/hash of this message
element.
The data contained with in a MessageElement is accessible in four ways:
