Description
Parser is a program part which represents the physical form of a data and converts it into storage form for the program. The one which reads XML Data in a XML file is referred to as XML Parser. Until unless the code is copied as a unit block blindly, every XML program should call the XML Parser. There are two kinds of XML Parsers:
- Object Based Parsers : In object based parsers, a tree of objects are built which will have XML Document elements. (Eg: DOM Parser)
- Event Based Parsers : Event based parses reads the file and generates the events when it checks if any elements, text or attributes are present in the file. (Eg: SAX, StAX Parsers)
Description
If the XML file data has to be read then developer has to write their own code to parse the XML file which is complicated procedure. To avoid this, Java/programming language has given parsers like DOM and SAX to read the XML file. XML Parser consumes lot of time and it is complicated. Whereas DOM/SAX parser is used to parse the XML file. Using this, the code can be developed fast and accurate.
As shown in the above figure, DOM reads the XML file and stores in tree format. Whereas the SAX Parser will have stream of events and will call the methods like startDocument, startElement, characters, endElement, endDocument
| DOM Parsers | SAX Parsers |
|---|---|
| DOM stands for Document Object Model | SAX stands for Simple API for XML |
| DOM reads the entire document | SAX reads node by node |
| DOM is useful when reading small to medium size XML files | SAX is used when big XML files to be parsed |
| DOM is tree based parser | SAX is event based parser |
| DOM is little slow as compared to SAX | SAX is faster than DOM |
| DOM can insert and delete nodes | SAX cannot insert and delete nodes |
Description
Advantages
- DOM parsers works fine when document is divided into parts and accessed randomly.
- Operations like read and write on a document will be performed using DOM Parsers.
- Memory supported by DOM parsers is inefficient.
- DOM Parsers are complicated.
- Memory supported by SAX Parsers is efficient.
- In stream applications, the functionality of SAX parsers is good.
- The information is divided into pieces and clients will not have all the dat auntil the users create own data structure.
Key Points
- The one which reads XML Data in a XML file is referred to as XML Parser.
- DOM/SAX parser is used to parse the XML file.