Hartmann pipeline
From Free net encyclopedia
A Hartmann pipeline is a non-free extension of the Unix pipeline concept, providing for more complex paths, multiple input/output streams, and other features. It is an example and extension of Pipeline programming.
A Hartmann pipe is a non-procedural representation of a solution of a data processing problem as a dataflow. The error-prone step of translating the dataflow to a traditional procedural programming language is eliminated. Hartmann pipelines may thus be considered as an executable specification language.
The concept was developed by John Hartmann, a Danish engineer with IBM. It is available as a software product CMS Pipelines for a number of IBM platforms.
Features
Some of the salient characteristics that distinguish Hartmann Pipeline from ordinary Unix pipes are:
- Filters may have multiple inputs and multiple outputs. For example, a selection filter can send the found records down one output pipe and the not found records down another.
- A linear notation for representing pipeline networks.
- An interface that allows REXX programs to act as filters.
- A pacing strategy in the Pipeline supervisor that allows, for example, a stream to be split, say by a selection filter, and the records on the output legs to be processed by other filters, then merged by a join filter and have the record order preserved in result stream.
- As implied by the previous item, data streams are (generally) not simply buffered and passed along to the next filter. The filters operate in parallel with input and output records handled by the Pipeline supervisor.
Similarity to APL
Programmers familiar with the APL programming language will see some similarities in Hartmann pipelines. It is obvious that the author was influenced by APL; some of the filters have names and functions similar to specific APL primitive functions. An example is the TAKE filter, which passes a specified number of records.
As with APL, programmers adept in the use of pipelines will have their view of data processing problems and how they may be best solved fundamentally and permanently changed.