Channels

A channel is an interface with another Sun Internet Mail Server (SIMS) 3.5 component, another mail system, or mail user agent. The actual hardware connection or software transport or both may vary widely from one channel to the next.

Each channel consists of up to two channel programs and an outgoing message queue for storing messages that are destined to be sent to one or more of the interfaces associated with the channel. Channel programs perform two functions:

		They transmit messages to other interfaces, deleting them from their queue after they are sent.
		They accept messages from other interfaces, placing them or enqueueing them into channel queues. Note that while a channel program only removes messages from its own queue, it can enqueue messages in any queue, including its own.

A channel program that initiates a message transfer to another interface on its own is called a master program. A program that accepts transfers initiated by another interface is called a slave program. A channel can be served by a master program or a slave program.

PROFS NJE

The Network Job Entry package (NJE) allows the user to transfer work and data throughout a distributed network of host systems. NJE defines a set of facilities and related protocols to support these capabilities. NJE was originated by IBM.

An NJE network is a collection of peer-coupled systems connected by communication links. A member of an NJE network is called an NJE node. Any number of network types can be available between the various nodes. For implementation, however, the next connected NJE node must be able to communicate via the System Network Architecture (SNA) network.

End user data objects are sent or received as SYSIN/SYSOUT streams or nodal messages. System input (SYSIN) data objects in general are jobs to be executed at the destination node. System output (SYSOUT) are files created by a user job and are processed as either print files or punch files. However, other processing requirements for such SYSOUT objects are possible.

An NJE node can support one or more of the following functions:

		Transmit: Packages SYSIN or SYSOUT jobs in NJE control records and inserts such an NJE file into the network.
		Receive: Recognizes NJE files with embedded control records and processes them.
		Store-and-Forward: Receives NJE files, stores them in a local queue, and forwards them to the next node.
		Command and Message Processing: Allows the transfer of messages and commands through the NJE network.
		Path Management: Enables an NJE node to exchange routing information.