In software, an XML pipeline is formed when XML (Extensible Markup Language) processes, especially XML transformations and XML validations, are connected. For instance, given two transformations T1 and T2, the two can be connected so that an input XML document is transformed by T1 and then the output of T1 is fed as input document to T2. Simple pipelines like the one described above are called linear; a single input document always goes through the same sequence of transformations to produce a single output document.

Linear operations

Linear operations can be divided in at least two parts

Micro-operations

They operate at the inner document level

Document operations

They take the input document as a whole

Sequence operations

They are mainly introduced in XProc and help to handle the sequence of document as a whole

Non-linear

Non-linear operations on pipelines may include: Some standards also categorize transformation as macro (changes impacting an entire file) or micro (impacting only an element or attribute)

XML pipeline languages

XML pipeline languages are used to define pipelines. A program written with an XML pipeline language is implemented by software known as an XML pipeline engine, which creates processes, connects them together and finally executes the pipeline. Existing XML pipeline languages include:

Standards

Product-specific

Pipe granularity

Different XML Pipeline implementations support different granularity of flow.

Standardization

Until May 2010, there was no widely used standard for XML pipeline languages. However, with the introduction of the W3C XProc standard as a W3C Recommendation as of May 2010, widespread adoption can be expected.

History

Standards

Recommendations

Working drafts

Product specific