Provides transport protocol mappings for SNMP.

The `org.snmp4j.transport` classes are capable of sending and receiving byte messages to and from a network using transport mapping specific transport protocol. All SNMP4J transport mappings have to implement the `org.snmp4j.TransportMapping` interface. SNMP4J supports two transport mappings for the transport protocols UDP and TCP:

- The UDP transport mapping is the default SNMP transport mapping. It is implemented by the `DefaultUdpTransportMapping` class.
- The TCP transport mapping is implemented by the `DefaultTcpTransportMapping` using the `java.nio` package.

Additional transport mappings can be easily added. It is sufficient to implement the `org.snmp4j.TransportMapping` interface and add an instance of that class to the `Snmp` (or `MessageDispatcher`) object. To be able to lookup a transport mapping by an `Address` class via the `TransportMappings` (as `Snmp` does for notification listeners), a transport mapping has to be registered in a transport mapping registration file. The default file is `transports.properties` in the `org.snmp4j.transport` package. To use a different file, set the system property `org.snmp4j.transportMappings`.

Connection-oriented transport mappings like TCP should implement the `ConnectionOrientedTransportMapping` interface to support `MessageLengthDecoder` and `TransportStateListener`.

The following UML class diagram shows the classes of the `org.snmp4j.transport` package and their relationships (relationships to other packages are not shown):