Accessing CICS Applications with Alternate Screen Sizes via HostBridge
From Russ
December 5, 2008
Friends,
Here’s an issue recently raised by one of our customers. I put together an answer for them and then thought it might be of value to others as well.
Some CICS applications have been designed to exploit alternate screen sizes of IBM 3270 terminals. For example, a CICS application that displays printed reports might be capable of driving a 3270 Model 5 terminal in its 132 column mode. HostBridge does support CICS applications that exploit a terminal’s alternate screen size. So how do you enable this?
Whenever HostBridge creates a bridge facility/session within CICS, it does so based on the characteristics of a specific type of terminal. By default, HostBridge/CICS reference a TERMINAL definition named CBRF to acquire general characteristics:
CEDA View TErminal( CBRF )
TErminal : CBRF
Group : DFHTERM
Description : Default 3270 Bridge template
AUTINSTModel : No No | Yes | Only
AUTINSTName :
TERMINAL IDENTIFIERS
TYpeterm : DFHLU2
NEtname : CBRF
CONSOle : No No | 0-127 | 129-250
CONSName :
REMOTESYSTem : CBR
REMOTEName : CBRF
REMOTESYSNet :
Modename :
...
Note that CBRF references a TYPETERM definition named DFHLU2 to obtain more specific device characteristics. The TYPETERM definition indicates the terminal model, as well as the primary and alternate screen size (actually, in two places):
CEDA View TYpeterm( DFHLU2 )
TYpeterm : DFHLU2
Group : DFHTYPE
DEScription :
RESOURCE TYPE
DEVice : LUTYPE2
TERmmodel : 2
SESsiontype :
LDclist :
SHippable : Yes No | Yes
MAPPING PROPERTIES
PAGesize : 024 , 080 0-255
ALTPage : 000 , 000 0-255
ALTSUffix :
FMhparm : No No | Yes
OBOperid : No No | Yes
PAGING PROPERTIES
AUTOPage : No No | Yes
DEVICE PROPERTIES
DEFscreen : 024 , 080 0-255
ALTSCreen : , 0-255
...
APPLICATION FEATURES
BUildchain : Yes No | Yes
USerarealen : 000 0-255
Ioarealen : 00256 , 04000 0-32767
UCtran : Yes No | Yes | Tranid
...
DFHLU2 specifies a primary screen size of 24x80, but no alternate screen size. Furthermore, CBRF and DFHLU2 are IBM-provided definitions and can’t be modified. Thus, to cause HostBridge and the target CICS application to use an alternate screen size, you must define/use alternate TERMINAL and TERMTYPE resources.
As part of the HostBridge installation, alternate TERMINAL and TERMTYPE definitions are installed: HBRF and HBRLU2. These definitions are identical to CBRF/DFHLU2 except that:
• HBRF references TYPETERM HBRLU2
• HBRLU2 defines the USERAREALEN parameter as 255 bytes (this parameter defines the length of the TCTUA and is the most common reason why customers use these alternate definitions).
As provided, TYPETERM HBRLU2 does not define an alternate screen size. Thus, the first step is to change the definition of HBRLU2 such that an alternate screen size is specified. Alternatively, you could copy HBRLU2 and create a new TYPETERM definition (as well as a new TERMINAL definition which references it). For example:
CEDA View TYpeterm( HBRLU2 )
TYpeterm : HBRLU2
Group : DFHTYPE
DEScription :
RESOURCE TYPE
DEVice : LUTYPE2
TERmmodel : 5
SESsiontype :
LDclist :
SHippable : Yes No | Yes
MAPPING PROPERTIES
PAGesize : 024 , 080 0-255
ALTPage : 027 , 132 0-255
ALTSUffix :
FMhparm : No No | Yes
OBOperid : No No | Yes
PAGING PROPERTIES
AUTOPage : No No | Yes
DEVICE PROPERTIES
DEFscreen : 024 , 080 0-255
ALTSCreen : 027 , 132 0-255
...
APPLICATION FEATURES
BUildchain : Yes No | Yes
USerarealen : 255 0-255
Ioarealen : 00256 , 04000 0-32767
UCtran : Yes No | Yes | Tranid
...
Assuming you changed TYPETERM HBRLU2, and that TERMINAL HBRF references HBRLU2, then all you need to do is tell HostBridge to create the bridge facility based on TERMINAL HBRF. To do this, you specify the directive hb_facility_like=HBRF with the HostBridge request (hb_terminal is a synonym for hb_facility_like).
HostBridge directives can be specified in a number of different ways. Since hb_facility_like controls fundamental attributes of the bridge facility, it can be specified two ways:
• On the first request sent to HostBridge to create the session (via an individual HTTP request or via a HostBridge script);
• In the HBR@SESS command file (which is processed with the first request of the session).
Provided these steps are followed, a CICS application that supports should adapt accordingly and send output in that mode. HostBridge will also adapt accordingly and include the contents of the entire page/screen in the XML response (or make the entire page/screen available within the script).
* * *
There you have it.
More later.
Russ