The OPSHMC OPS/REXX program uses the TCP/IP Simple Network Management Protocol (SNMP) trap method and the "Address HWS" host command environment uses
Hardware Interface Service (HiS) to interact with IBM's Base Control Program internal interface (BCPii) to reach out the Hardware Management Console (HMC).
Why there are two methods?
There was a rumor that IBM was not going to support the SNMP trap method of communications with the HMC the OPSHMC OPS/REXX program is still using.
CA Technologies reacted to this information and developed HIS and that was the whole reason behind why it was created.
HIS is packaged in a separate ESD PAX file to be installed under Common Services r14.1 release.
The OPSHMC is a simpler interface, but doesn't provide as much as using HIS and BCPii does. The OPSHMC can simply issue queries, set commands to the HMC and get responses back via IBM's provided API (DLL's you download and use during the installation of CA OPS/MVS). The HIS and BCPii components provides the same functions via "Address HWS".
You have to create your own OPS/REXX programs and provides API events when HMC activity occurs, which you can write CA OPS/MVS API rules to respond to.
The BCPii/HIS also provides more built-in security and it could be harder to install and setup as there are multiple ASIDs to setup and maintain that shares information.