intro

intro

Modeltools, shelltools and clicktools all use XML documents extensively - for model definition and for many related tasks. The majority of model tools have an XML parser and some even have two XML parsers (e.g. the job tools).

The reason for having two XML parsers in a tool is that these parsers are not reentrant and sometimes a second document must be parsed while a first document is being parsed.

Types Of XML Parsers<

There are basically two types of XML parsers.

DOM (for Document Object Model). A DOM parser (also called a tree-based parser) parses an entire document into a tree before document analysis is initiated. This means that parsing can be undertaken without prior knowledge of the schema used to create the document. All that is required is valid XML grammar. DOM parsers can be slow and memory intensive.

SAX (for Simple API for XML). A SAX parser (also called an event-based parser) parses a document one tag at a time (with specific tags triggering parser events). The parser must know the schema that was used to create the document. SAX parsers are fast and memory frugal.