EXIficient
EXIficient - open source implementation of the W3C Efficient XML Interchange (EXI) format specification.
The EXI format is a very compact representation for the Extensible Markup Language (XML) Information Set that is intended to simultaneously optimize performance and the utilization of computational resources.
API support
- SAX 1
- SAX 2
- DOM
- StAX
- XmlPull
Apache Maven Dependency
<dependency>
<groupId>com.siemens.ct.exi</groupId>
<artifactId>exificient</artifactId>
<version>1.0.4</version>
</dependency>
Requirements
- Java 1.5 or higher
- Xerces2 Java Parser
Library - Code Sample
/*
* Setup EXIFactory as required
*/
EXIFactory exiFactory = DefaultEXIFactory.newInstance();
// e.g., add additional settings beyond the default values
// exiFactory.setGrammars(GrammarFactory.newInstance().createGrammars("foo.xsd")); // use XML schema
// exiFactory.setCodingMode(CodingMode.COMPRESSION); // use deflate compression for larger XML files
/*
* encode XML to EXI
*/
String fileEXI = "foo.xml.exi"; // EXI output
OutputStream osEXI = new FileOutputStream(fileEXI);
EXIResult exiResult = new EXIResult(exiFactory);
exiResult.setOutputStream(osEXI);
XMLReader xmlReader = XMLReaderFactory.createXMLReader();
xmlReader.setContentHandler( exiResult.getHandler() );
xmlReader.parse("foo.xml"); // parse XML input
osEXI.close();
/*
* decode EXI to XML
*/
String fileXML = "foo.xml.exi.xml"; // XML output again
Result result = new StreamResult(fileXML);
InputSource is = new InputSource(fileEXI);
SAXSource exiSource = new EXISource(exiFactory);
exiSource.setInputSource(is);
TransformerFactory tf = TransformerFactory.newInstance();
Transformer transformer = tf.newTransformer();
transformer.transform(exiSource, result);Command-line Interface
EXIficient also provides a command-line interface.
/* Class: com.siemens.ct.exi.cmd.EXIficientCMD */
#########################################################################
### EXIficient ###
### Command-Shell Options ###
#########################################################################
-h /* shows help */
-encode
-decode
-i
-o
-schema
-xsdSchema /* XML schema datatypes only */
-noSchema /* default */
-strict
-preservePrefixes
-preserveComments
-preserveLexicalValues
-preservePIs /* processing instructions */
-preserveDTDs /* DTDs & entity references */
-bytePacked
-preCompression
-compression
-blockSize
-valueMaxLength
-valuePartitionCapacity
-noLocalValuePartitions /* EXI Profile parameters */
-maximumNumberOfBuiltInProductions
-maximumNumberOfBuiltInElementGrammars
-includeOptions
-includeCookie
-includeSchemaId
-includeSchemaLocation
-includeInsignificantXsiNil
-includeProfileValues
-retainEntityReference
-fragment
-selfContained <{urn:foo}elWithNS,elDefNS>
-datatypeRepresentationMap
# Examples
-encode -schema notebook.xsd -i notebook.xml
-decode -schema notebook.xsd -i notebook.xml.exi -o notebookDec.xmlEXIFactory Settings
Note: in general all options are set in a way that a small EXI stream is produced. However for larger XML files (e.g., COMPRESSION) or desired fidelity options (e.g., preserver comments) different settings might be chosen.
| General | Information | Default | Hint |
|---|---|---|---|
| blockSize | Specifies the block size used for EXI compression | 1,000,000 | The default blockSize is intentionally large but can be reduced |
| valueMaxLength | Specifies the total capacity of value partitions in a string table | unbounded | Reducing the number reduces the possible required memory usage |
| valuePartitionCapacity | Specifies the total capacity of value partitions in a string table | unbounded | Often larger strings (> 16 characters) are unlikely to be a string table hit. Hence setting a lower value may reduce memory usage and speed up processing for no string table hits |
| com.siemens.ct.exi.core.FidelityOptions | ||
|---|---|---|
| Option | Information | Default |
| FEATURE_COMMENT | Comments are preserved | false |
| FEATURE_PI | Processing Instructions are preserved | false |
| FEATURE_DTD | DTDs and Entity References are preserved | false |
| FEATURE_PREFIX | Namespace Prefixes are preserved | false |
| FEATURE_LEXICAL_VALUE | Lexical form of values is be preserved (e.g., float 1.00 vs 1) | false |
| com.siemens.ct.exi.core.CodingMode | Information (default is BIT_PACKED) | Hint |
|---|---|---|
| BIT_PACKED | Alignment option value bit-packed indicates that the the event codes and associated content are packed in bits without any paddings in-between | Small files |
| BYTE_PACKED | Alignment option value byte-alignment indicates that the event codes and associated content are aligned on byte boundaries | Small files |
| PRE_COMPRESSION | Alignment option value pre-compression alignment indicates that all steps involved in compression are to be done with the exception of the final step of applying the DEFLATE algorithm | Large Files (e.g., compression built-in in transport) |
| COMPRESSION | The compression option is used to increase compactness using additional computational resources (DEFLATE algorithm) | Large Files |
| com.siemens.ct.exi.core.EncodingOptions | Information | Default | Hint |
|---|---|---|---|
| INCLUDE_COOKIE | EXI Cookie, which is a four byte field that serves to indicate an EXI stream | false | Useful if stream can be of any other type than EXI |
| INCLUDE_OPTIONS | EXI Options, which provides a way to specify the options used to encode the body of the EXI stream. | false | Useful if options may vary or are unknown to recipient |
| INCLUDE_SCHEMA_ID | Identify the schema information, if any, used to encode the body | false | Useful if schema information are unknwon to recipient |