HP SNA 3270 Data Stream Programming Interface for OpenVMS

HP SNA 3270 Data Stream Programming SPD 26.87.11
Interface for OpenVMS, Version 1.8
This product is a set of subroutines used to perform
such functions as establishing sessions, sending data,
receiving data, and disconnecting sessions. In addition,
the 3270 DS interface may be used to interpret the 3270
data stream and build a screen image. The OpenVMS
application is then free to interact with the screen image.
The 3270 DS product allows two modes of connection:
Data Stream Mode and Field Mode.
Data Stream Mode
Data Stream Mode provides a means to send and re-
ceive uninterpreted 3270 data streams as defined by
IBM. In this mode, the interface performs all SNA-
specific functions. For example, the OpenVMS applica-
tion is not required to handle chaining, brackets, RUs, or
RHs. At the same time, this mode allows the interface
to provide the OpenVMS application with the complete
3270 data stream. It is the OpenVMS user’s respon-
sibility to interpret the outbound data stream for 3270
orders and commands, and to build and manipulate a
screen image (if desired). Similarly, it is the OpenVMS
user’s responsibility to build the inbound data stream
from the user’s own screen image or from some other
data structure.
An OpenVMS application that needs to use extended
attributes must use a Data Stream Mode connection.
Extended attributes are extensions to the basic field at-
tributes, namely:
• Extended highlighting (blink, reverse video, under-
score)
• Color
• Programmed symbols (selectable symbol set)
• Screen partitions and windows
Field Mode
Field Mode performs a presentation service to provide
a screen image interface. The screen image may be
read field by field, or accessed directly. The interface
interprets 3270 commands and orders in an outbound
data stream to build the screen. In addition, it produces
an inbound 3270 data stream from the updated screen
image.
As with the Data Stream Mode, Field Mode insulates
the OpenVMS user from the SNA protocol. Extended
attributes are not supported by the Field Mode connec-
tion.
Asynchronous Event Notification
The 3270 DS product provides a mechanism for an
OpenVMS user application to receive control when an
asynchronous "network event" occurs, such as discon-
nection of a DECnet logical link, an SNA circuit failure,
or the receipt of an Unbind Type 2 from IBM. The Open-
VMS application is called at a notification entry point de-
fined by the application at connection time; an indication
of the event that occurred is reported.
User Interface
Users of the 3270 DS product should be experienced
OpenVMS application programmers. They can use any
of the OpenVMS programming languages that conform
to the OpenVMS Calling Standard to create application
programs that interact with application programs on an
IBM system. The user documentation provides example
segments written in the following languages:
• MACRO-32
• BLISS-32 Implementation Language
•C
• COBOL
• FORTRAN
• PASCAL
• PL/I
Users of the 3270 DS product are not required to have
extensive knowledge of SNA.
INSTALLATION
Installation services from HP are recommended for
a customer’s first purchase of this software product.
These services provide for installation of the software
product by an experienced software specialist.
HARDWARE REQUIREMENTS
Processors Supported
Itanium, Alpha and VAX configurations as specified in
the OpenVMS Operating System for I64, Alpha and
VAX Software Product Description (SPD 82.35.xx and
25.01.xx).
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