There seems to be a number of ways of writing "TOP
END". You can also see it as all one word, TopEnd, in various cases
and fonts to emphasize the word `open' in the middle, as in
`T-open-D'. I guess you can put that down to the NCR marketing folk,
but I've been assured that the official spelling was all-uppercase and
as two words.
TOP END was developed by NCR as a distributed Transaction Processing Monitor (TPM) and first released in 1991 on their UNIX platforms. About the same time NCR was acquired by AT&T. AT&T, who up until then had being using Tuxedo as its primary TPM started to use TOP END and Tuxedo was sold as part of the UNIX and Unix Laboratory bundle to Novell. After renaming NCR as AT&T Global Information Systems (GIS), NCR was once again floated as a public company, with the NCR name. In that time TOP END gained, with the Massively Parallel NCR3600 and TERADATA, an important and large niche in data warehousing, where it reigned supreme. NCR where less successful in their ports of TOP END to other platforms, it was and is still closely associated with NCR hardware.
In the middle of 1998 NCR took the decision (surprising to many) to
sell TOP END to the owners of the rival Tuxedo TPM, (by now BEA Systems) in a
deal which valued TOP END at around $55 million. BEA made
assuring noises about support for TOP END, but did not seem to be
actively selling it. At about the same time, BEA also took over
Entersoft, who were responsible for the majority of TOP END's non-NCR
ports. Entersoft has now been completely assimilated by BEA and their
domain name appears to be that of an Internet Service Provider (ISP).
By the end of 1999, BEA released a gateway transition product for
Tuxedo to migrate users from TOP END to Tuxedo and to all intents and
purposes TOP END was dead, no longer appearing on BEA's redesigned web
site in anything but an historical context.
Top End is a client/server system, with clients making requests of servers. In TOP END Application Servers are individual operating system processes running under the control of Node Manager. They advertise at least one and commonly a number of Functions which are grouped into Products. Each Function encapsulates a piece of business logic, is analogous to a CICS Transaction program and can be conversational (in this respect it is very like Tuxedo although in TOP END they are known as Dialogs). There can be a number of instances of Application Servers running at the same time and in-bound requests are queued and then distributed to them. These Servers can be automatically started and stopped in response to a changing load pattern. Since there can be a number of identical Servers all working at the same time they are frequently referred to as Server Replicas. When a server is occupied with a Function it cannot process further requests for any of the Functions that it advertises. TOP END has a single threaded model.
TOP END's Transactions are managed by a separate specialized Server which is permanently connected to the Resource that it is using (such as a database). In this it differs from Encina whose equivalent to the Application Server, the Process Agent, maintains a separate thread of control within the same operating system process to manage its Transactions.
TOP END uses a specialized process called the Node Manager
to distribute work to the individual Application Servers. These Node
Managers also communicate with each other and clients via Network Interface
Programming in TOP END
Like other TPM TOP END has its own Application Programming
Interface (API) for communication, the so called Client Server
Interface API (CSI). This API is primarily concerned with
communications and is not used to control Transactions. The CSI
consists of a series of send and receive function calls
END, when using this API relies upon a separate set of functions, TX
(which is the standard X/Open for Transaction Control) for Transaction
demarcation (for example
tx_commit, defines the
successful end of a Transaction).
After the purchase of TOP END by BEA Systems information on TOP END (and much of the material was in the form of a product brochure) dwelled on the now defunct Entersoft web site and then on BEA's. This has now all gone and TOP END no longer appears to have an official Web presence. BEA should be contacted directly for support and information.