As briefly described in earlier sections, the HEC is the component of the MyRT protocol suite that interfaces to the distributed applications residing on the hosts. Each daemon consists of a Dispatcher, a set of State Machines, an External Queue, an Internal Queue, a Routing Service, a Registry Service and Connection Tables. This is illustrated in Figure 3. The HEC provides the interface between the applications running on the host and the MyRT protocol. It communicates with the SEC of the switch the host is connected to. In each HEC, there are two State Machines, a Sender state machine and a Receiver state machine. This is to enable a host to simultaneously act as a sender and receiver for different connections under establishment. The tables at the HEC maintain the list of currently active connections, their route information, QoS specifications and other parameters necessary for the implementation of the distributed algorithm. If a message from either the host or the SEC is sent to the HEC, it is queued at the External Queue. The Dispatcher of the HEC repeatedly reads and processes messages from the External Queue. If the Dispatcher reads a message which cannot be processed immediately (the appropriate state machine may be locked), it temporarily stores it in the Internal Queue. The Dispatcher first accesses messages from the internal queue and only then from the external queue. The Registry Service provides a routine for receiver applications to register endpoints for connections for TCPUDP, similar to a bind operation. When applications register their endpoint, they provide the parameters to act as destination for prospective connection requests.