Editing Tuxedo (software) (section)

===Clustering===
The heart of the Tuxedo system is the Bulletin Board (BB).  This is a shared memory segment that contains the configuration and state of a Tuxedo domain.  Servers, services, transactions, and clients are all registered in the BB providing a global view of their state across the machines within a domain.  To coordinate updates to the BB a process called the Bulletin Board Liaison (BBL) runs on each machine to keep the local copy of the BB up-to-date.  A master machine runs a process called the "Distinguished Bulletin Board Liaison" that coordinates the updates to the BB.  This allows each machine to have a view of what servers, services, transactions, and clients are on each machine within the domain.

Another process on each machine called the Bridge is responsible for passing requests from one machine to another.  This allows Tuxedo to spread load across the various machines within a domain and allows servers and services to be running on multiple machines.  In addition, the BBL and Bridge monitor each other and restart the other should one fail.  In the advent of a failure of the master machine, another machine designated as a backup master can take over the function of master machine.  Also, since machines within a single domain can be of different architectures (x86, IA32, SPARC, P-Series, etc.), the Bridge is also responsible for handling differences in things like [[endianness]].

On [[Oracle Exalogic]] Tuxedo leverages the [[Remote direct memory access|RDMA]] capabilities of [[InfiniBand]] to bypass the bridge.  This allows the client of a service on one machine to directly make a request of a server on another machine.