| Communications Access Methods for SAS/CONNECT and SAS/SHARE Software |
There are two types of
communications access methods: program-to-program
and terminal-based.
Program-to-program communications access methods use
networking
protocols to allow two processes to interact over a network. They have these
advantages over terminal-based communications access methods:
- much larger packet sizes
- data transmitted in binary form (therefore, not requiring the
application to perform any character set encoding)
- message notification often performed asynchronously.
Program-to-program
communications access methods may require additional
system software to achieve support on all of the necessary platforms. Here is a list of program-to-program
methods of communication
that are supported by SAS/CONNECT and SAS/SHARE.
- APPC
- is an abbreviation for Advanced Program-to-Program Communication.
This type of connection uses the LU 6.2 protocol for distributed processing
within an IBM SNA network. APPC and LU 6.2 are often used interchangeably.
- CPIC
- is an acronym for Common Programming Interface for Communications.
This interface supports the IBM SAA (System Application Architecture) solution
by providing a method for developing portable distributed applications. CPIC
functions as a layer that resides on top of the APPC protocol.
- DECnet
- is an acronym for the Digital Equipment Corporation Networking
architecture. In SAS documentation, this term describes the task-to-task communication
interface over a DECnet network.
- NetBIOS
- is an acronym for the IBM Network Basic Input/Output System.
This is an operating system interface for application programs that are running
on nodes in a local area network.
- SPX
- is an abbreviation for the Novell Sequenced Packet Exchange.
This is a communications protocol that provides guaranteed delivery of Internetwork
Packet Exchange (IPX) packets. IPX enables NetWare workstations to communicate
with NetWare servers, and SPX adds the connection-oriented features required
for reliable client/server communication.
- TCP/IP
- is an abbreviation for Transmission Control Protocol/Internet
Protocol. This is a program-to-program interface that is supported by multiple
vendors over multiple vendors' hardware.
The following program-to-program-based
connection types are supported by SAS/SHARE only:
- IUCV
- is an abbreviation for Inter-User Communications Vehicle.
This interface is a part of the VM/CMS operating system and is used by programs
that run under VM/CMS.
- VTAM LU 0
- is an acronym for Virtual Telecommunications Access Method.
This type of connection uses LU 0 protocol for program-to-program communications
with an IBM SNA network under the OS/390 operating system.
- XMS
- is an abbreviation for Cross-Memory Services. This interface
is part of the OS/390 operating system and is used by programs that run within
a single OS/390 environment.
Terminal-based communications access methods let two processes
interact over a network by using a terminal interface. They have these characteristics:
- limited transmission packet size (because of the size of the terminal
screen)
- limited efficiency (because they force the application to perform
character-set encoding to write data to the screen even though users are not
expected to read from the screen)
- message notification generally accomplished through polling.
Because of the limitations of
terminal-based communication methods,
these methods cannot support Remote Library Services. Terminal-based interfaces,
however, are relatively inexpensive and generally available.
The following terminal-based
connection types are supported by SAS/CONNECT only:
- EHLLAPI
- is an acronym for Extended High-Level Language Applications
Programming Interface. EHLLAPI is a standard 3270 programming interface that
uses the SNA LU2 protocol and is provided by many third-party vendors for
OS/2, DOS, and Windows workstations. SAS/CONNECT
first moved to this standard interface with Release 6.06 of SAS Software under
OS/2. EHLLAPI, HLLAPI, and WinHLLAPI are sometimes used interchangeably.
Support for Windows HLLAPI (WinHLLAPI) was added with Release 6.11 of SAS
software under Windows. Release 6.11 defines a standard and consistent IBM
EHLLAPI-style implementation with the addition of Windows specific extensions.
- TELNET
- is a terminal application interface written to use the TELNET
protocol. TELNET is less efficient than TCP/IP because it is layered on top
of the TCP/IP protocol. Because TELNET can communicate with an asynchronous
interface in the remote environment, and it can run over an existing TCP/IP
network, it is useful with SAS/CONNECT when
the remote host does not have a supported TCP/IP product.
Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.
