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! 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.
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.
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.