XProc: An XML Pipeline Language
An XML Pipeline specifies a sequence of operations to be performed on a collection of XML input documents. Pipelines take zero or more XML documents as their input and produce zero or more XML documents as their output.
A pipeline consists of steps. Like pipelines, steps take zero or more XML documents as their input and produce zero or more XML documents as their output. The inputs to a step come from the web, from the pipeline document, from the inputs to the pipeline itself, or from the outputs of other steps in the pipeline. The outputs from a step are consumed by other steps, are outputs of the pipeline as a whole, or are discarded.
There are two kinds of steps: atomic steps and compound steps.
Atomic steps carry out single operations and have no substructure as far as the pipeline is concerned.
Compound steps include a subpipeline of steps within themselves.
Definition: A pipeline is a set of connected steps, outputs flowing into inputs, without any loops (no step can read its own output, directly or indirectly). A pipeline is itself a step and must satisfy the constraints on steps.
Definition: A step is the basic computational unit of a pipeline. Steps are either atomic or compound.
Definition: An atomic step is a step that performs a unit of XML processing, such as XInclude or transformation, and has no internal subpipeline. Atomic steps carry out fundamental XML operations and can perform arbitrary amounts of computation, but they are indivisible.
Definition: A compound step is a step that contains additional steps. That is, a compound step differs from an atomic step in that its semantics are at least partially determined by the steps that it contains.
An XML Pipeline specifies a sequence of operations to be performed on a collection of XML input documents. Pipelines take zero or more XML documents as their input and produce zero or more XML documents as their output. A pipeline consists of steps. Like pipelines, steps take zero or more XML documents as their input…