PTERMs NODEs LTERMs

mymf doubts · New User Joined: 12 Jul 2012 Posts: 29 Location: India

Hi,

I have just started working on a new client environment and many of their activities are new to me. One of the regular activity they perform is 'dequeuing of output message Qs'. IMS systems side is new to me and there are many many things which are not clear to me yet!

Can you please help me understand the exact relation between physical/logical terminals and nodes. I have tried to read manuals and here is what I have understood so far!

1) Physical and Logical terminals are pre-defined in IMS SYSGEN. Even if not pre-defined, a product like ETO will enable you to define and use them dynamically.

2) Many logical terminals can be assigned to a physical terminal, and these are defined in SYSGEN. Assignment can be dynamically changed using /ASSIGN command. IMS applications always refer to LTERM names. The output to many LTERMs can be sent to a single PTERM, but a msg received by a LTERM cannot be mapped to multiple PTERMs.

3) Nodes and PTERMs basically represent same thing. I am little confused here. The way I have understood, Nodes are VTAM resources defined at VTAM end matching with the PTERM names defined at IMS end. IMS can address PTERMs as NODES thru IMS commands.

4) When I want to connect to IMS, I logon with the IMS APPLID defined in IMS SYSGEN as well as in VTAM as type APPL under a APPL NODE .

5) When input is sent to IMS thru terminals, the messages get queued with the txn ID as Q name, they are called input Qs. When responses are sent back by applications to users, they get Qed with target LTERM names as Q names, called output Qs.

6) Input Q count and Output Q count should ideally match and their difference should be zero. Sometimes, when the user is signed out even before input is processed, the output Q will be left with few unprocessed messages and shows up as enqueued. If the messages build up across many output Qs it can affect system performance and has to be dequeued by stopping the NODE and using DEQ command with PURGE.

What is this physical terminal? does it represent a physically a specific terminal at a particular location? or is it just the defined NODE at VTAM end which behaves as physical terminal for IMS, but available anywhere to users thru VTAM. So, anybody from anywhere can connect to this 'physical terminal of IMS', VTAM giving that flexibility, and when users actually login and initiate transactions it forks out LTERMS which is finally what IMS applications see and send the response back to.

Sorry for the long question.....please correct me and help me understand it clearly!

Thanks

mymf doubts · New User Joined: 12 Jul 2012 Posts: 29 Location: India

Any response please?!

Have I asked this in the wrong section of the forum?! OR, is something really wrong with what I am asking?!

Please help!!

enrico-sorichetti · Posted: Tue May 28, 2013 4:11 pm

Anuj Dhawan · Posted: Tue May 28, 2013 6:36 pm

You've got a long question out there...

Users enter TRANSACTIONS from TERMINALS. IMS TERMINALS may be dumb terminals, PCs, or special terminals (e.g. Automated Teller Machines). All terminals to be used by the online IMS system must be defined in the "IMSGEN". Every terminal is assigned both a physical terminal name and a logical terminal name. The application programs refer to logical terminals (so the program doesn't need to know if it's talking to a dumb terminal or a PC, for example).

As stated earlier, an application program deals with logical terminal. Terminal independence is associated with device type and address which are transperent to the program. In case of hardware failure, logical terminal can be assigened to a differnt physical terminal.

dick scherrer · Posted: Tue May 28, 2013 10:25 pm

Hello,

mymf doubts · New User Joined: 12 Jul 2012 Posts: 29 Location: India

Sorry Enrico

Was just concerned if I have asked a completely wrong question!

Thank you, Anuj and Dick.

I have read manuals and have understood it to an extent...but not sure! Just wanted to cross check if what I have understood is correct!

Let me go back to manuals few more times !

Thank you all.

Anuj Dhawan · Posted: Wed May 29, 2013 5:24 pm

You're welcome - hope we had been helpful.

dick scherrer · Posted: Wed May 29, 2013 6:48 pm

Hello,

I suspect that much of what your are looking for is site-specific. Site-specific "things" are not in the manual.

Is there some reason you do not want to talk with your IMS support?

mymf doubts · New User Joined: 12 Jul 2012 Posts: 29 Location: India

Hi Dick,

We are going thru bit of a KT crisis! Got into a huge deal who are big on Mainframes, they had in-house techs all these days and they have worked all their life on those machines! 30 years...40 years....same person, in a way whatever suits them and absolutely no documentation !

We are not getting much help from those techs, but we are trying to document the system! Good thing is we have hired those techs on our company for now and no immediate threat to project

But we need to document the setup for future referrence!

Usual outsourcing issues!

dick scherrer · Posted: Tue Jun 04, 2013 9:36 pm

Yup, that Can be challenging

Suggest you make short lists of "Things" you'e identified that need clarification. A few times a week work with one of these long-term assets and do the documentation with their guidance. If you do the write-ups you will learn much more. Suggest you run tests as part of the learning so it will more quickly become familiar to you.

d

mymf doubts · New User Joined: 12 Jul 2012 Posts: 29 Location: India

Thank You, Dick.

We are trying to do exaclty what you have suggested

Running tests is something we still cant do .... no access even for some of the DISPLAY commands!

Anyway, we will get there one day...as you said, early days are always challenging....and we all understand that we would do the same if we worked on something for 30 or 40 years...it then becomes a major part of our life!

Thank you...