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>1.0.7</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.xml

EXIFactory 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