| Clark F Morris 2008-01-26, 6:56 pm |
| On Wed, 10 Oct 2007 14:02:46 +1300, "Pete Dashwood"
<dashwood@removethis.enternet.co.nz> wrote:
>
>
>"William M. Klein" <wmklein@nospam.netcom.com> wrote in message
>news:egUOi.87746$zh6.26538@fe10.news.easynews.com...
>
>Didn't work for me.
>
>That was fine, thanks.
>
>I've always had a soft spot for IMS :-) Used it for years before DB2 became
>available.
>
>The main things I got from the document are as follows:
>
>1. IBM is being HUGELY influenced by what is happening in the real world,
>and have realised they need to provide bridges to the OO environment. I
>think what they are doing is good.
>
>2. Like all sales literature there were statements in the document that made
>me smile and laugh :-) The justification for hierarchic access as being best
>for "Mission Critical" and where the "query is known in advance" (hard
>coded) just made me chuckle. If IBM had abandoned IMS years ago there would
>be no such writing. I remember the pain in the arse traversing hierarchical
>DBs was and how we used Command codes to "remember" our positioning across
>dequeue boundaries. (Command Code 'C' stored the concatenated key of where
>you were in the "tree" so you didn't have to re-traverse it on re-entry.)
>The fact is that the Relational model can implement a hierarchical
>structure, but the hierarchical model cannot easily implement a relational
>structure. This is marketing justification for an existing product, not real
>data processing theory.
>
>It is even more amusing because it was IBMers who formulated the Relational
>theory and showed it to be mathematically pure... Funny how Marketing can
>trumpet something when promoting one product, then ignore it when promoting
>another... :-)
>
>You could substitute "VSAM" for IMS in the arguments described, and it
>wouldn't change the meaning (more efficient when queries are known in
>advance, good for saving object structures, etc.)
In both cases it may be that for the functions being implemented with
the response time requirements for those functions both IMS and VSAM
may be better suited than a relational data base. In the various
mainframe worlds, other database organizations and indexed file access
were developed to a higher degree than on Unix and Winows systems.
>
>Nevertheless, they have obviously poured investment into IMS and the results
>are impressive.
>
>3. IBM are demonstrating commitment to a web based world and the support
>for SOA and Web Services is good. As a co-owner of the SOAP copyright they
>obviously realise that they can leverage much with platform independent XML.
>Good to see.
>
>Thanks for posting this, Bill. It was interesting and quite nostalgic for
>me.
>
>Pete.
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