Network Connection Endpoints

All physical connections are created using TCP/IP. To establish a network connection, both endpoints of the connection must use the same protocol (TCP or TLS), and the same TCP/IP version (TCP4 or TCP6).

In Uniface, the endpoints of physical connections can be:

  • A client application and the Uniface Router.
  • A Uniface Server and either the Uniface Router (if the Server is shared), or a client application (if the Server is exclusive).

The protocol can be specified for each of these connections by the client, the Uniface Server, or the Uniface Router.

Specifying the Protocol in the Client

For a client application attempting to establish a connection to the Uniface Router, the protocol and version are determined by the network connector and host identifier specified in the network connection string. This may be provided by the server path assignment in the assignment file, the $DEFAULT_NET assignment setting, or in the open ProcScript statement.

The network connector and host identifier must match the protocol and version that the Uniface Router used to create the listening port.

Specifying the Protocol in Uniface Server

For a Uniface Server, the protocol and version are determined by /dnp switch used to start the Uniface Server. This specifies the network connector, host and listening port used to connect to the Uniface Router. Normally, the Uniface Router starts Uniface Servers, and in the /dnp switch, it specifies the first listening port of the same network connector used by the Uniface Router. For more information, see Specifying the Protocol in Uniface Router.

An exclusive server may create its own listening port, to which the client then reconnects. In this case, the network connector (TLS or TCP), is determined by the client path. The exclusive server also needs to determine whether it should use the TCP4 or TCP6 protocol version. This decision is based on the format of the host ID. For more information, see Host Identification for TCP/IP and TLS.

You can specify the host name to use in this situation using the $DEFAULT_TCP_HOST setting. For example: 

[SETTINGS]
$DEFAULT_TCP_HOST    MYHOST

Exclusive Servers

A TLS exclusive server always creates its own listening port. For more information, see Connections to an Exclusive Server.

For TCP there are two ways in which connections can be made for an exclusive server.

  • By default the connection from the client in the Uniface Router is inherited by the Uniface Server, so the client and Uniface Router endpoints are re-used.
  • Alternatively, if /gates is specified in the UST definition, the Uniface Server will create its own listening port. In this case, a sequence of connections is made:
    1. First, the client connects to the Uniface Router.
    2. Then a connection is made from the Uniface Server to the Uniface Router.
    3. Finally a connection is made from the client to the Uniface Server’s listening port, and the connection between the client and Uniface Router is terminated.

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