Editing Pipeline (software) (section)

==VM/CMS and z/OS==
[[CMS Pipelines]] is a port of the pipeline idea to [[VM/CMS]] and [[z/OS]] systems. It supports much more complex pipeline structures than Unix shells, with steps taking multiple input streams and producing multiple output streams. (Such functionality is supported by the Unix kernel, but few programs use it as it makes for complicated syntax and blocking modes, although some shells do support it via arbitrary [[file descriptor]] assignment).

Traditional application programs on IBM mainframe operating systems have no standard input and output streams to allow redirection or piping. Instead of spawning processes with external programs, CMS Pipelines features a lightweight dispatcher to concurrently execute instances of more than 200 built-in programs that implement typical UNIX utilities and interface to devices and operating system services. In addition to the built-in programs, CMS Pipelines defines a framework to allow user-written [[REXX]] programs with input and output streams that can be used in the pipeline.

Data on IBM mainframes typically resides in a [[record-oriented filesystem]] and connected I/O devices operate in record mode rather than stream mode. As a consequence, data in CMS Pipelines is handled in record mode. For text files, a record holds one line of text. In general, CMS Pipelines does not buffer the data but passes records of data in a lock-step fashion from one program to the next. This ensures a deterministic flow of data through a network of interconnected pipelines.