SAX (Simple API for XML)

SAX (Simple API for XML) is a popular, event-driven, stream-based [[APIs|API]] for processing [[Extensible Markup Language|XML]] documents in [[Java]]. Unlike the [[Document Object Model]] (DOM), SAX does not load the entire XML document into memory. Instead, it reads the document sequentially and triggers events (such as the start and end of elements) that can be handled by the application. This approach makes SAX highly efficient for parsing large XML files.

SAX is based on an event-driven model where it triggers different events as it reads through the XML document. These events include the start and end of elements, character data, and processing instructions.

Since SAX does not keep the entire XML document in memory, it is more memory-efficient than DOM, especially for large XML files. This makes it suitable for applications with memory constraints or for processing very large XML documents.

SAX reads XML documents sequentially from start to end. It does not allow random access to elements in the XML document, which can be a limitation for certain use cases. A SAX parser invokes callback methods corresponding to the XML document events. Developers implement these methods in a handler class to process the XML data.

SAX is generally faster than DOM for reading XML documents because it doesn’t incur the overhead of building an in-memory tree representation of the XML document. Unlike DOM, SAX does not provide the capability to create or modify XML documents. It is a read-only API.

SAX allows for robust error handling during parsing. The parser can report warnings, errors, and fatal errors encountered in the XML document. SAX is ideal for scenarios where you need to read and process large XML documents or streams without modifying them, such as data extraction and XML validation.

Implementing a SAX parser can be more complex than using DOM because the developer must manage the application state and handle the parsing events appropriately. SAX is widely used in [[Java]] applications and is part of the standard Java API (in the javax.xml.parsers package).