ОмниМарк: Төртінші буын бағдарламалау тілі және дерек өңдеу құралы

OmniMark is a fourth generation programming language used mostly in the publishing industry. It is currently a proprietary software product of Stilo International. As of July 2022, the most recent release of OmniMark was 11.0.

OmniMark is used to process data, and convert it from one format to another, using a streaming architecture that allows it to handle large volumes of content sequentially without having to keep it all in memory. It has a built in XML parser, and support for XQuery via integration with Sedna native XML database. It also has features to process find rules which implement a similar concept to regular expressions, although the pattern expression syntax is more English like than the regular expression syntax used in Perl and other languages like the Ruby programming language, both of which are more widely used than OmniMark. OmniMark can also be used for schema transformation tasks in the same way as XSLT, but supports switching between procedural and functional code without the need for any additional constructs to support the procedural elements.

OmniMark was originally created in the 1980s by Exoterica, a Canadian software company, as a SGML processing program called XTRAN. XTRAN was later renamed OmniMark, and Exoterica became OmniMark Technologies. The current owners of OmniMark, Stilo International, have their main offices in the UK but also maintain an office in Canada. In 1999, OmniMark president and CEO John McFadden announced that OmniMark 5 would be available free of charge, to better compete with Perl. OmniMark is no longer distributed under such a model.

OmniMark treats input as a flow that can be scanned once, rather than as a static collection of data that supports random access. Much of an OmniMark program is in the form of condition=>action rule where the condition recognizes a length of data to be acted upon and the action specifies what is to be done with the data. There are two kinds of condition:
An element rule, which can only be used with structured documents (well formed XML, valid XML, or SGML), recognizes a complete element: the start tag, the element content, and the end tag. Since the content may hold other elements, element rules can operate in a nested fashion. OmniMark manages the nesting in such a way that the element rules can be defined independently of each other. A pattern, which can be used with both structured and unstructured documents, recognizes a length of text. Patterns are used like regular expressions in other languages (python, Perl, awk, ) but have an English like syntax that facilitates the creation of complex expressions. When parsing a structured document, patterns can be used on text going into the parser or on text coming out of the parser.

OmniMark sees input as a flow; a program does not hold input data in memory unless part of the data has been saved in variables. As the input flows by, OmniMark maintains an element stack containing information that can be used to guide the transformation of text via the OmniMark pattern matching facility. When each start tag is encountered, OmniMark pushes another element description on the stack. The element description includes the element name, the attribute names with the types and values of the attributes, along with other information from the parser (such as whether that element is an EMPTY element). When the corresponding end tag is encountered, the element description is popped from the top of stack. With SGML, some tags may be omitted, but OmniMark acts as if the tags were present and in the right places.

In some applications, much of a document can be handled by a well designed generic action, so that only a fraction of the document needs special handling. This can greatly reduce the size and complexity of a program and, in the case of XML documents, can make a program very tolerant of changes in the structure of the input document.

This program replaces the omitted tags in a simple SGML document and outputs something similar to well formed XML. The program does not translate SGML empty tags correctly to XML empty tags and it does not handle many of the SGML features that can be used in SGML documents.