22.4 Limited Bandwidth Endpoint Discovery

The RTI® Limited Bandwidth Endpoint Discovery (LBED) Plugin reduces discovery time and network traffic by locally defining information about the endpoints that need to be discovered in an XML file. The default dynamic discovery process, on the other hand, sends the information about the endpoints over the network. Therefore, LBED requires all the endpoints to be known ahead of time and each must be declared in an XML file.

Discovery is the behind-the-scenes way in which RTI Connext® objects (DomainParticipants, DataWriters, and DataReaders) find out about each other. Each DomainParticipant maintains a database of information about all the active DataReaders and DataWriters in the same domain. This database is what makes it possible for DataWriters and DataReaders to communicate. To create and refresh the database, each application follows a common discovery process.

The default discovery mechanism in Connext is the one described in the DDS specification and is known as Simple Discovery Protocol, which includes two phases: Simple Participant Discovery and Simple Endpoint Discovery. The goal of these two phases is to build, for each DomainParticipant, a complete picture of all the entities that belong to the remote participants in its peers list, which is a list of nodes with which a participant may communicate.

During the Simple Participant Discovery phase, DomainParticipants learn about each other. The DomainParticipant’s details are communicated to all other DomainParticipants in the same domain by sending participant declaration messages, also known as participant DATA submessages or participant announcements.

During the Simple Endpoint Discovery phase, Connext matches DataWriters and DataReaders. Information about each application’s DataReaders and DataWriters is exchanged by sending publication/subscription declarations in DATA submessages (participant announcements), which we will refer to as publication DATAs and subscription DATAs. The Simple Endpoint Discovery phase uses reliable communication.

With Limited Bandwidth Endpoint Discovery (LBED), the Simple Participant Discovery phase still occurs, but the information normally gathered dynamically by Simple Endpoint Discovery is instead configured statically in an XML file. The static definition of endpoint discovery information is why LBED can also be referred to as Static Endpoint Discovery.

For more details on LBED, including instructions for getting started, see the RTI Limited Bandwidth
Endpoint Discovery Plugin User's Manual.