Transport Bridge

A transport bridge is an FTL service that efficiently forwards messages among sets of transport buses.

Functionality

You can configure a bridge with two or more terminals, called transport sets (or more briefly, sets). You can configure each set with one or more transports.

A transport bridge forwards all messages in all directions. Whenever a message arrives on any one of its transports, it immediately republishes that message on all of the transports in all of the other sets. However, it does not forward the message on other transports within the same set.

The transports can be of the same type, or they can be of different transport protocols. For example, you can bridge between shared memory and TCP transports.

A transport bridge operates completely within a single realm. It forwards messages among transports defined within the realm, but it cannot forward messages between two different realms.

Transport bridges can forward one-to-many messages and one-to-one messages.

Transport bridges support one-to-one messages on transports that support inbox abilities.

You can arrange two or more bridge processes for fault-tolerant operation. Although this feature ensures automatic and quick recovery, failover might leave some messages unforwarded.

Design Features

Low latency is a key feature of the transport bridge. The transport bridge implementation is extremely fast and efficient. It forwards packets immediately, even before all the packets of a message have arrived.

Transport bridges are transparent to your application programs. Clients do not need to do anything different to communicate across a bridge, nor can they detect whether a bridge mediates between them.

Latency

Although the transport bridge is efficient, it still adds an extra layer between sending and receiving processes, which necessarily increases message latency.

In some situations, sending on several transports could result in less additional latency than a bridge, at the cost of limiting maximum throughput. To optimize results for your specific application needs and resources, test empirically. For more information, see Multiple Transports and Serial Communications.

  • Transport Bridge Use Cases
  • Transport Bridge Topologies
    Transport bridges support only the three topologies presented in the topics that follow.
  • Transport Bridge Restrictions
    Although transport bridges are flexible, these restrictions apply.
  • Transport Bridge Configuration
    You can arrange several bridges within a realm. Each bridge requires a separate bridge definition with a distinct bridge name, at least two transport sets, and at least one transport in each set.
  • Bridge Service
    Bridge services implement the transport bridges that you define in the realm definition. Any FTL server can provide and manage a bridge service.
  • Arranging Fault-Tolerant Bridge Services
    You can configure two or more bridge services for fault-tolerant operation. Although this feature ensures automatic and quick recovery, failover might leave some messages unforwarded.
  • Bridges among Dynamic TCP Meshes
    You can use transport bridges to link the disjoint mesh topologies that a dynamic TCP mesh transport establishes in satellite locations.
  • Bridges Status Table
    The Bridges status table reports the state of bridge objects. Bridge objects are clients of the FTL server.