3270 Access

Host Integration Server 2004 provides 3270 connectivity through 3270 logical units (LUs). A 3270 LU is known as a dependent LU because it requires a mainframe to function. Each 3270 LU defined within Host Integration Server 2004 is configured to use an existing connection to the mainframe system. Each 3270 LU corresponds to a matching LU resource allocated on the host computer, usually specified within VTAM. The 3270 LU definition in Host Integration Server 2004 is identified by a number that matches the number of the corresponding LU resource on the mainframe, and by a user-specified name.

The 3270 LU is further classified by the type of service provided over the connection. Like physical units (PUs) physical units, LU types are designated by numbers. For example, 3270 display data streams are known as LU 2 streams. Within Host Integration Server 2004, a 3270 LU can be configured as one of the following types:

  • Display (LU 2)
  • Printer (LU 1 or LU 3)
  • Application (LUA)
  • Downstream

Once configured, these LUs are accessed from an end-user applications using Host Integration Server 2004 client software that is installed on the client workstation. The client software manages communications between a 3270 application (like a terminal emulator) and the Host Integration Server 2004 computer. Applications designed for the Host Integration Server 2004 client API use the LUs defined within Host Integration Server 2004 to establish a communications link from the client personal computer to the mainframe via Host Integration Server 2004.

The link between the LU definition in Host Integration Server 2004 and the host LU resource is called a session. Sessions can be permanent and automatically started during initialization, or established on an as-needed basis. Concurrent sessions can share the same physical devices and communications links.

See Also

Using LU Pools

Assigning LUs to Workstations

Providing Hot Backup and Load Balancing

To download updated Host Integration Server 2004 Help from www.microsoft.com, go to http://go.microsoft.com/fwlink/?linkid=29507.

Copyright © 2004 Microsoft Corporation.
All rights reserved.
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