IMS/DC predated VTAM (which came in 1974). It was BTAM and later also TCAM. IBM MQ started life as a TCAM next generation before being redesigned to be store/forward/transform messaging service. That was more than a decade after IMS/DC message queue. As others have said IMS started as a customer initiative, by Rockwell for the Saturn V moon rocket -- they couldn't keep track of the huge bill of materials needed. The IMS architecture and internal implementation was always performance (instruction path length) and throughput focused. In contrast CICS was application services focused, hence a completely different architecture. For the first 20 years, IMS was an order of magnitude faster than CICS once IMS Fast Path came along (1977). Over time the same technology (things like Data in Memory) was adopted by CICS, so today there is less speed difference. Both exploit the system architecture for z very effectively, something that other transaction manager solutions such as Tuxedo (now Oracle) were never able to do, despite starting 20 years later with a clean slate. Meanwhile there are still IMS application programs running that were written 50+ years ago and are fully supported today!
On Wed, Jul 26, 2023 at 4:27 AM Schmitt, Michael <[email protected]> wrote: > I wasn't working then 😊, but I think that IMS/DB was developed then, as > the bill of materials database. The question I have is when IMS/DC come > along? The online documentation is unclear. > > > The Introduction to IMS says: > > IBM developed an online component to ICS/DL/I to support data > communication access to the databases. The DL/I callable interface was > expanded to the online component of the product to enable data > communication transparency to the application programs. A message queue > function was created to maintain the integrity of data communication > messages and to provide for scheduling of the application programs. > > The online component to ICS/DL/I ultimately became the Data Communications > (DC) function of IMS, which became the IMS Transaction Manager (IMS TM) in > IMS Version 4. > > > So *maybe* the original system just allowed some kind of communication > access to the database, but not a full screen driven transaction server > with a message queue like we know today. > > > > While we're on the subject of IMS/TM... > > Is it true that the MQ Series message queue was based on the IMS/TM > message queue? Or is there no connection other than the function they > provide. > > > -----Original Message----- > From: IBM Mainframe Discussion List <[email protected]> On Behalf > Of rpinion865 > Sent: Tuesday, July 25, 2023 1:09 PM > To: [email protected] > Subject: Re: [EXT] Ars Technica: The IBM mainframe: How it runs and why it > survives > > I'm probably wrong. But I thought IMS was developed for NASA during the > Gemini and Apollo time frame. > > > > > Sent with Proton Mail secure email. > > ------- Original Message ------- > On Tuesday, July 25th, 2023 at 2:05 PM, Schmitt, Michael < > [email protected]> wrote: > > > > No, I don’t know of an IMS/TM + DB2 system. > > > > But then the CICS systems I work with are also not using DB2. They use > VSAM! > > > > And even for IMS/DB, my gut feel is there are a lot more CICS + IMS/DB > installations than IMS/TM + IMS/DB. > > > > > > Also, CICS is from ~1966, IMS/DC (later renamed to IMS/TM in IMS Version > 4) must have been much later than that, but I can't find the date. > > > > Reason I think I it is much later (late 70's? early 80's?) is because, > as I understand it, the reason CICS was designed the way it is was because > at the time, the OS it ran on wasn't so great at multitasking. Or maybe > didn't do multitasking at all. But IMS/DC was designed at a time when the > OS was good at preemptive multitasking between tasks and jobs. Was this MVS? > > > > > > -----Original Message----- > > From: IBM Mainframe Discussion List [email protected] On Behalf > Of David Spiegel > > > > Sent: Tuesday, July 25, 2023 12:38 PM > > To: [email protected] > > Subject: Re: [EXT] Ars Technica: The IBM mainframe: How it runs and why > it survives > > > > Hi Michael, > > I have yet to see a site running IMS/DC and not run IMS/DB. > > Have you actually seen this? > > > > BTW, the article had more than one technical error. For example, a JCL > > Step name with 9 characters. > > > > Regards, > > David > > > > On 2023-07-25 13:16, Schmitt, Michael wrote: > > > > > The Ars Technica article was discussing CICS as an application server. > I was comparing CICS as an application server to IMS/TM as an application > server. The DBMS is a different issue; there's no reason why IMS/TM must be > used with IMS/DB. You can use IMS/TM with DB2. > > > > > > The point I was trying to make was that CICS was designed as a > cooperative multitasking system that reproduces all of the OS functions in > itself. IMS/TM (originally IMS/DC) was designed to use the OS to do OS > things and does none of that in itself, so it is much simpler. > > > > > > -----Original Message----- > > > From: IBM Mainframe Discussion List [email protected] On > Behalf Of David Spiegel > > > Sent: Tuesday, July 25, 2023 11:48 AM > > > To: [email protected] > > > Subject: Re: [EXT] Ars Technica: The IBM mainframe: How it runs and > why it survives > > > > > > Hi Michael, > > > You said: "...CICS is to IMS as Windows 3.1 is to Windows 10. ..." > > > You're comparing apples and oranges. > > > (CICS has no native Database portion.) > > > BTW, a lot of the banks, insurance companies etc. are running CICS+DB2. > > > The majority of IMS users need it to support 40+ year old application > > > systems. > > > Which one is the real dinosaur? (Hint: It's not CICS) > > > > > > Regards, > > > David > > > > > > On 2023-07-25 10:37, Schmitt, Michael wrote: > > > > > > > So CICS is no longer doing cooperative multitasking within each AOR, > and thus requiring CICS versions of OS commands to prevent wait states from > freezing the entire AOR? A CICS program can do direct GETMAINs, LOADS, > abends, rather than use CICS commands? CICS no longer requires special > versions of tools (e.g. debugger, abend dump management) and instead can > use the same tools as batch programs? A CICS programmer no longer needs to > learn a long list of CICS commands and EXEC CICS syntax? A CICS region no > longer contains the storage from all of the transactions currently running > and is now only one transaction in the region at a time? CICS transactions > can no longer stomp on each other's memory? > > > > > > > > Great, I did not know that. > > > > > > > > IMS/TM uses the operating system for multitasking. There are no > IMS/TM specific tools. An IMS/TM programmer only needs to know two > commands, one to get a message and another to send it. IMS transaction > abends look (almost) exactly like a batch abend. IMS programs have no > restrictions on OS facilities. An IMS program can even do an STIMER (WAIT) > without affecting any other transaction processing. Because, it uses the OS > to do preemptive multitasking, like a modern operating system. > > > > > > > > -----Original Message----- > > > > From: IBM Mainframe Discussion List [email protected] On > Behalf Of Crawford Robert C (Contractor) > > > > Sent: Tuesday, July 25, 2023 8:14 AM > > > > To: [email protected] > > > > Subject: Re: [EXT] Ars Technica: The IBM mainframe: How it runs and > why it survives > > > > > > > > Sorry, I worked in a shop that had both and I can tell you CICS is > way more flexible, modern and performed better. > > > > > > > > I will give you this: IMS is a great piece of 90's technology. > > > > > > > > Robert Crawford > > > > Abstract Evolutions LLC > > > > (210) 913-3822 > > > > > > > > -----Original Message----- > > > > From: IBM Mainframe Discussion List [email protected] On > Behalf Of Schmitt, Michael > > > > Sent: Monday, July 24, 2023 11:43 AM > > > > To: [email protected] > > > > Subject: [EXT] Ars Technica: The IBM mainframe: How it runs and why > it survives > > > > > > > > Ars Technica published a deep-dive explainer of modern IBM > mainframes: > > > > > > > > > https://arstechnica.com/information-technology/2023/07/the-ibm-mainframe-how-it-runs-and-why-it-survives/ > > > > > > > > I’d quibble with the application server topic that talks about CICS > with no mention of IMS/TM. CICS is to IMS as Windows 3.1 is to Windows 10. > 😊 > > > > > > > > > ---------------------------------------------------------------------- > > > > For IBM-MAIN subscribe / signoff / archive access instructions, send > email to [email protected] with the message: INFO IBM-MAIN > > > > > > > > > ---------------------------------------------------------------------- > > > > For IBM-MAIN subscribe / signoff / archive access instructions, > > > > send email to [email protected] with the message: INFO > IBM-MAIN > > > > > > > > > ---------------------------------------------------------------------- > > > > For IBM-MAIN subscribe / signoff / archive access instructions, > > > > send email to [email protected] with the message: INFO > IBM-MAIN > > > > > ---------------------------------------------------------------------- > > > > For IBM-MAIN subscribe / signoff / archive access instructions, > > > > send email to [email protected] with the message: INFO > IBM-MAIN > > > > > > ---------------------------------------------------------------------- > > > For IBM-MAIN subscribe / signoff / archive access instructions, > > > send email to [email protected] with the message: INFO IBM-MAIN > > > > > > ---------------------------------------------------------------------- > > For IBM-MAIN subscribe / signoff / archive access instructions, > > send email to [email protected] with the message: INFO IBM-MAIN > > > > > > > > ---------------------------------------------------------------------- > > For IBM-MAIN subscribe / signoff / archive access instructions, > > send email to [email protected] with the message: INFO IBM-MAIN > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN > > > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
