Client-Server Support

Features

Client-Server Support allows the SNAP-IX function to be distributed across multiple systems on an IP network, with the SNA protocol layer located on SNA servers and the SNA applications located on SNA clients.

  • The core SNA components run on UNIX servers, with UNIX and Windows clients running user applications.
  • 3270, 5250, and RJE emulation programs are provided on UNIX clients.
  • Support is included for other vendors' 3270 and 5250 emulation programs on Windows clients, including Attachmate's Extra!, NetManage's Rumba, and IBM Personal Communications emulators.
  • API libraries provide support for SNA applications (LU type 0, 1, 2, 3 or 6.2) on both UNIX and Windows clients. The interfaces on Windows clients implement the standards defined by the WOSA SNA specifications.
  • The administration programs and diagnostics facilities are integrated into the client-server model, and allow LAN-wide administration from a single point of control.
  • Multiple servers can be configured to work in coordination to provide a pool of resources to clients.

Key Benefits

  • The occupancy and performance overhead on client machines is reduced by offloading the core communications stack onto the server.
  • A single data link can be shared by multiple users on different machines, eliminating the need for a physical network connection from each machine.
  • A multiple server system can provide duplicate connectivity, such as connection to a particular host; this allows load balancing between the servers, and provides hot back-up if one of the servers or links develops a fault.
  • The dynamic allocation of resource is distributed around the LAN and is not dependent on a single "service broker" machine.
  • The use of LU pooling across multiple servers makes it easy to configure and add servers and users.
  • The size of the host VTAM definition is reduced because fewer PUs and links need to be defined.

Example Configurations

The SNAP-IX client-server system uses TCP/IP for communication between each server and its clients, and can be integrated into a TCP/IP network in different ways. Two possible scenarios are illustrated below.


branch configuration


In the example above, SNAP-IX client-server is implemented as a branch configuration, in which a SNAP-IX server is situated at each branch of an enterprise. Each branch server supports users who are attached to the server over a LAN with the TCP/IP protocol. The branch servers and mainframes are linked to the main corporate network backbone using SNA.



centralized configuration


In the example above, SNAP-IX client-server is implemented as a centralized configuration, in which SNAP-IX servers in the data center support users connected across an enterprise TCP/IP network.