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Addresses (JavaGroups.JavaStack.Address) are used to represent
group member locations, they are mainly used in the destination and
source fields of messages (see 3.1.3). An address at the Channel level is simply an opaque Object, however, channel
implementations will typically use subclasses to represent
implementation-specific addresses. The JChannel implementation uses
the combination of an IP address and a port for its addresses. An Address contains a method for comparing them to other Addresses;
this will be used to establish a deterministic ordering between sets of
addresses (used by Membership below).
The JChannel implementation knows about Addresses: the UDP layer
for example creates a local address when started (in the form of an Address). However, when passed up to the application, it would be passed
as an Object. JChannel protocol layers would cast the Object
to an Address, but addresses would not be allowed to be interpreted
as any subclass when crossing the channel boundary: applications treat
addresses as opaque handles which can be used to send
messages. This allows to port JavaGroups onto different group transports,
with different address schemes, without affecting applications.
1999-08-19