Establishing Connections Between BEA Tuxedo and BEA TOP END Systems

BEA TOP END nodes advertise available services to adjacent nodes at connection time. New services are advertised dynamically. Services are unadvertised if they are no longer available. Thus, at any time a BEA TOP END node can determine the status of all services on nodes to which it is connected.

The BEA Tuxedo system takes a different approach. Within a multi-node BEA Tuxedo domain, the connection architecture is quite similar to that of a BEA TOP END system. However, interdomain connectivity is different.

The BEA Tuxedo system offers three possible connection policies that can be assigned to a TEDG:

By default, the connection to another domain is not made until a service request that requires such a connection is made (CONNECTION_POLICY=ON_DEMAND). This type of connection is called a lazy connection. The gateway, however, advertises remote services to the local domain before any connections are made. If a connection cannot be made, the gateway returns an error to the caller, but the relevant services remain advertised.

Optionally, a TEDG can be configured to connect, automatically, with other BEA TOP END systems at the start of each day (CONNECTION_POLICY=ON_STARTUP). If a connection is established, all associated services are assumed to be available and are advertised. If a connection cannot be established, or if a connection is established but subsequently fails, related services are suspended (CONNECTION_POLICY=INCOMING_ONLY and CONNECTION_POLICY=ON_STARTUP). Thus, remote services can be configured such that they are continually advertised (CONNECTION_POLICY=ON_DEMAND), or advertised only when a connection to the remote domain is open (CONNECTION_POLICY=ON_STARTUP and CONNECTION_POLICY=INCOMING_ONLY).

For local services, regardless of the connection policy, the TEDG advertises (exports) its local services to the BEA TOP END system when a connection is established with a BEA TOP END node. The TEDG determines which services to advertise using the rules in the DMCONFIG file for the local domain. The TEDG advertises each SERVICE entry in the DM_LOCAL_SERVICES section that is associated with the local domain. For each of these services the TEDG advertises the associated parameters (TE_PRODUCT, TE_FUNCTION, and TE_TARGET) to the BEA TOP END system. The status of individual service availability is not tracked by the BEA TOP END system; only the status of the network connection is tracked.

Connecting at Boot Time (ON_STARTUP)

The BEA Tuxedo ON_STARTUP policy most closely resembles the BEA TOP END connection policy. When this policy has been selected, the TEDG attempts to connect to each of its configured BEA TOP END nodes. If multiple network addresses are configured they are tried serially. Connection retries apply if configured. If a connection attempt succeeds, the TEDG advertises the associated remote services to the local domain. If a connection attempt fails (or is lost), the associated imported services are suspended until the connection is reestablished. The status of individual service availability on the BEA TOP END node is not tracked.

Connecting When a Client Program Requests a Remote Service (ON_DEMAND)

The ON_DEMAND or "lazy connection" policy is the default connection policy on the BEA Tuxedo system. Connections are attempted as needed to fulfill client requests for remote services. If multiple network addresses are configured they are tried serially. Connection retries do not apply. The TEDG advertises remote services to the BEA Tuxedo system on startup but does not actually connect to any BEA TOP END nodes. Remote services are always advertised, regardless of the connection status. The status of individual service availability on the BEA TOP END node is not tracked.

Accepting Incoming Connections Only (INCOMING_ONLY)

The INCOMING_ONLY policy specifies that the TEDG does not attempt to connect to remote domains and does not advertise associated remote services. Connections must be initiated by the BEA TOP END system connecting to the TEDG or by a manual connection attempt by the BEA Tuxedo administrator. Multiple network addresses can be handled only by an administrator establishing a connection manually. Connection retries do not apply. When a connection is successfully established, the associated remote services are advertised. If a connection fails, the associated imported services are suspended until the connection is reestablished. The status of individual service availability on the BEA TOP END node is not tracked.