NXML (an XML parser written in nML)

Hyun-Goo Kang and Eun-Sun Cho
ROPAS
Computer Science
Korea Advanced Institute of Science and Technology

Introduction

XML describes a class of data objects called XML documents and partially describes the behavior of computer programs which process them. XML is an application profile or restricted form of SGML, the Standard Generalized Markup Language [ISO 8879]. By construction, XML documents are conforming SGML documents. XML documents are made up of storage units called entities, which contain either parsed or unparsed data. Parsed data is made up of characters, some of which form character data, and some of which form markup. Markup encodes a description of the document's storage layout and logical structure. XML provides a mechanism to impose constraints on the storage layout and logical structure.

A software module called an XML processor is used to read XML documents and provide access (e.g. http, ftp, ...) to their content and structure. It is assumed that an XML processor is doing its work on behalf of another module, called the application.

Implemenation

XML 1.0 specification is describing the required behavior of an XML processor in terms of how it must read XML data and the information it must provide to the application. An XML processor's job is summarized as following.

• browsing/parsing an XML document : check whether it's well-formed
• validating : check whether it's complies with the constracts expressed in associated document type definition
• producing a internal data object which XML processor's users can process easily

Our goal is implementing a non-validating XML processor in nML. The result of parsing is an internal data structure which represents XML document itself.

Restriction

• parsing
  • encoding : assumed as ISO-8859/1 (support only 1 byte char set)
  • document browsing method : assumed as "file" or "http"
  • it doesn't support public literal resolving (meaningless)
• validation : not supported
• DOM style API
  • NXML module just return a tree style data structure which represents XML documnet. To be more general XML processor, it should support DOM style API generation. This will be interesting because nML is not a object oriented language : How can we express it similarly or make it better using functional programming/module (eg. functor) style?

Download

• nxml0.9.tar.gz