What Is Meant by Naming


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Introducing the BEA Tuxedo System

The BEA Tuxedo system uses three naming devices: service names, message queue names, and event names. Names can be any words or alphanumeric strings, as long as they do not begin with a period ("."). Because administrative servers use the BEA Tuxedo system infrastructure, system and application resources must be clearly distinguished.

Naming Services

When services are named, an application component can locate another component through a name. Names can be simple words (such as "deposit") or alphanumeric strings (such as "deposit2"). Names should be selected on the basis of the scope of the application and a map that contains the global picture of the relationships among application components. These maps or services are like the pages in a telephone book for application components.

When a BEA Tuxedo system server is activated, the bulletin board (the dynamic part of the MIB) advertises the names of its services. Service names are associated with a server's physical address so that requests can be routed to that server. Names that programmers use in their applications are completely location transparent. When a client program asks for a service by name, the BEA Tuxedo system consults its name registry in the bulletin board. The name registry provides the information necessary to convert the string name (for example, TICKET) to a machine name and the physical address of a server that advertises that service. The BEA Tuxedo system then sends the request to the appropriate server.

Locating a Service by Name

Advertising Services

The BEA Tuxedo system uses two administrative servers to coordinate the distribution of information on the bulletin board to all active machines in the application:

DBBL-The Distinguished Bulletin Board Liaison server propagates global changes to the MIB and maintains the static part of the MIB. The DBBL coordinates the state of different machines involved in an application. Only one DBBL exists for an entire application. It can be migrated to other machines for fault resiliency.
BBL-The Bulletin Board Liaison server maintains the bulletin board. A BBL resides on every active machine in an application. The BBL coordinates changes to the local MIB and verifies the integrity of application programs active on its machine.

Naming Events

The BEA Tuxedo system offers a publish-and-subscribe mechanism: clients and servers can dynamically register or unregister a standing request to receive alerts (or messages) when a particular event occurs. Other clients and servers post user-defined or system events as they occur in the application. When a client or server no longer needs to be notified about a particular event, the relevant subscription can be cancelled.