Class IncrementEJBUpes

java.lang.Object
  |
  +--IncrementEJBUpes

public class IncrementEJBUpes
extends java.lang.Object
implements org.xml.sax.ContentHandler

MQSeries Workflow EJB invocation sample

This sample shows you how to invoke an EJB using an UPES via JMS

This way to invoke EJBs supports transactions, but does not allow you to retrieve the Workflow containers metamodel

This class implements the ContentHandler interface of SAX, which allows it to parse XML files. This implies a lot of unused dummy methods.

This is not a sample on how to parse XML, it only picks out the interesting elements from the incoming XML message and ignores the rest. For a more sophisticated sample on XML parsing in a UPES, please view the "Distributed process sample using XML" available on the MQSeries Workflow product CD. It will be installed in <MQWF_ROOT>\SMP\DPXML. Check there readme.html for details.


Inner Class Summary
private  class IncrementEJBUpes.Data
          Subclass to hold the parsed data
 
Field Summary
private  java.lang.StringBuffer currentElement
          Remembers the content of the currently parsed XML element
private  IncrementEJBUpes.Data data
          Object to hold the parsed data
private static java.lang.String eol
          OS specific end of line
private  com.transarc.jmon.examples.Inc.IncHome incrementHome
          EJB home
private  java.lang.String latestTag
          Remembers the latest parsed XML tag
private  org.xml.sax.Locator locator
          Position indicator for XML parsing
private  javax.jms.QueueConnection qConn
          JMS queue connection
private  javax.jms.QueueReceiver qReader
          JMS queue receiver
private  javax.jms.QueueSession qSess
          JMS queue session
private  javax.jms.QueueSender qWriter
          JMS queue sender
private  org.xml.sax.XMLReader saxParser
          XML parser
private  long startMillis
          For performance measuring
private  long stopMillis
          For performance measuring
 
Constructor Summary
IncrementEJBUpes()
          Constructor Reads the properties from file, gets the initial JNDI context, initializes the JMS interface, sets up the SAX parser and gets the EJB home
 
Method Summary
 void characters(char[] ch, int start, int length)
          Receive notification of character data.
 void endDocument()
          Receive notification of the end of a document.
 void endElement(java.lang.String namespaceURI, java.lang.String localName, java.lang.String name)
          Receive notification of the end of an element.
 void endPrefixMapping(java.lang.String prefix)
          End the scope of a prefix-URI mapping.
private  int executeCommand()
          Dispatcher method that actually invokes the EJB methods
 void ignorableWhitespace(char[] ch, int start, int length)
          Receive notification of ignorable whitespace in element content.
static void main(java.lang.String[] args)
          Main method, no parameter evaluation
 void processingInstruction(java.lang.String target, java.lang.String data)
          Receive notification of a processing instruction.
private  void run()
          Listener method of the UPES Listens in a loop on the queue until a message is received.
 void setDocumentLocator(org.xml.sax.Locator loc)
          Receive an object for locating the origin of SAX document events.
 void shutdown()
          Shutdown method for the UPES.
 void skippedEntity(java.lang.String name)
          Receive notification of a skipped entity.
 void startDocument()
          Receive notification of the beginning of a document.
 void startElement(java.lang.String namespaceURI, java.lang.String localName, java.lang.String name, org.xml.sax.Attributes attrs)
          Receive notification of the beginning of an element.
 void startPrefixMapping(java.lang.String prefix, java.lang.String uri)
          Begin the scope of a prefix-URI Namespace mapping.
 void writeResponse(javax.jms.Message msg)
          Formats the XML response message, sets some message properties and sends the message back to the queue specified in the input paramaters properties.
 
Methods inherited from class java.lang.Object
, clone, equals, finalize, getClass, hashCode, notify, notifyAll, registerNatives, toString, wait, wait, wait
 

Field Detail

data

private IncrementEJBUpes.Data data
Object to hold the parsed data

saxParser

private org.xml.sax.XMLReader saxParser
XML parser

latestTag

private java.lang.String latestTag
Remembers the latest parsed XML tag

currentElement

private java.lang.StringBuffer currentElement
Remembers the content of the currently parsed XML element

locator

private org.xml.sax.Locator locator
Position indicator for XML parsing

qConn

private javax.jms.QueueConnection qConn
JMS queue connection

qSess

private javax.jms.QueueSession qSess
JMS queue session

qReader

private javax.jms.QueueReceiver qReader
JMS queue receiver

qWriter

private javax.jms.QueueSender qWriter
JMS queue sender

eol

private static final java.lang.String eol
OS specific end of line

startMillis

private long startMillis
For performance measuring

stopMillis

private long stopMillis
For performance measuring

incrementHome

private com.transarc.jmon.examples.Inc.IncHome incrementHome
EJB home
Constructor Detail

IncrementEJBUpes

public IncrementEJBUpes()
Constructor Reads the properties from file, gets the initial JNDI context, initializes the JMS interface, sets up the SAX parser and gets the EJB home
Method Detail

characters

public void characters(char[] ch,
                       int start,
                       int length)
                throws org.xml.sax.SAXException
Receive notification of character data.

This method is part of the SAX API.

The Parser will call this method to report each chunk of character data. SAX parsers may return all contiguous character data in a single chunk, or they may split it into several chunks; however, all of the characters in any single event must come from the same external entity so that the Locator provides useful information.

The application must not attempt to read from the array outside of the specified range.

Note that some parsers will report whitespace in element content using the ignorableWhitespace method rather than this one (validating parsers must do so).

Specified by:
characters in interface org.xml.sax.ContentHandler
Parameters:
ch - The characters from the XML document.
start - The start position in the array.
length - The number of characters to read from the array.
Throws:
org.xml.sax.SAXException - Any SAX exception, possibly wrapping another exception.
See Also:
ignorableWhitespace(char[], int, int), Locator

endDocument

public void endDocument()
                 throws org.xml.sax.SAXException
Receive notification of the end of a document.

This method is part of the SAX API and is here just a dummy implementation.

The SAX parser will invoke this method only once, and it will be the last method invoked during the parse. The parser shall not invoke this method until it has either abandoned parsing (because of an unrecoverable error) or reached the end of input.

Specified by:
endDocument in interface org.xml.sax.ContentHandler
Throws:
org.xml.sax.SAXException - Any SAX exception, possibly wrapping another exception.
See Also:
startDocument()

endElement

public void endElement(java.lang.String namespaceURI,
                       java.lang.String localName,
                       java.lang.String name)
                throws org.xml.sax.SAXException
Receive notification of the end of an element.

This method is part of the SAX API.

The SAX parser will invoke this method at the end of every element in the XML document; there will be a corresponding startElement event for every endElement event (even when the element is empty).

For information on the names, see startElement.

Specified by:
endElement in interface org.xml.sax.ContentHandler
Parameters:
uri - The Namespace URI, or the empty string if the element has no Namespace URI or if Namespace processing is not being performed.
localName - The local name (without prefix), or the empty string if Namespace processing is not being performed.
qName - The qualified XML 1.0 name (with prefix), or the empty string if qualified names are not available.
Throws:
org.xml.sax.SAXException - Any SAX exception, possibly wrapping another exception.

endPrefixMapping

public void endPrefixMapping(java.lang.String prefix)
                      throws org.xml.sax.SAXException
End the scope of a prefix-URI mapping.

This method is part of the SAX API and is here just a dummy implementation.

See startPrefixMapping for details. This event will always occur after the corresponding endElement event, but the order of endPrefixMapping events is not otherwise guaranteed.

Specified by:
endPrefixMapping in interface org.xml.sax.ContentHandler
Parameters:
prefix - The prefix that was being mapping.
Throws:
org.xml.sax.SAXException - The client may throw an exception during processing.
See Also:
startPrefixMapping(java.lang.String, java.lang.String), endElement(java.lang.String, java.lang.String, java.lang.String)

executeCommand

private int executeCommand()
                    throws java.lang.Exception
Dispatcher method that actually invokes the EJB methods
Returns:
The value of the increment counter in the EJB
Throws:
java.lang.Exception - Any occurred exception will be rethrown unfiltered

ignorableWhitespace

public void ignorableWhitespace(char[] ch,
                                int start,
                                int length)
Receive notification of ignorable whitespace in element content.

This method is part of the SAX API and is here just a dummy implementation.

Validating Parsers must use this method to report each chunk of whitespace in element content (see the W3C XML 1.0 recommendation, section 2.10): non-validating parsers may also use this method if they are capable of parsing and using content models.

SAX parsers may return all contiguous whitespace in a single chunk, or they may split it into several chunks; however, all of the characters in any single event must come from the same external entity, so that the Locator provides useful information.

The application must not attempt to read from the array outside of the specified range.

Specified by:
ignorableWhitespace in interface org.xml.sax.ContentHandler
Parameters:
ch - The characters from the XML document.
start - The start position in the array.
length - The number of characters to read from the array.
See Also:
characters(char[], int, int)

main

public static void main(java.lang.String[] args)
Main method, no parameter evaluation

processingInstruction

public void processingInstruction(java.lang.String target,
                                  java.lang.String data)
                           throws org.xml.sax.SAXException
Receive notification of a processing instruction.

This method is part of the SAX API and is here just a dummy implementation.

The Parser will invoke this method once for each processing instruction found: note that processing instructions may occur before or after the main document element.

A SAX parser must never report an XML declaration (XML 1.0, section 2.8) or a text declaration (XML 1.0, section 4.3.1) using this method.

Specified by:
processingInstruction in interface org.xml.sax.ContentHandler
Parameters:
target - The processing instruction target.
data - The processing instruction data, or null if none was supplied. The data does not include any whitespace separating it from the target.
Throws:
org.xml.sax.SAXException - Any SAX exception, possibly wrapping another exception.

run

private void run()

Listener method of the UPES

Listens in a loop on the queue until a message is received.

Then the message is parsed and evaluated. If a shutdown command is received, the loop is left after an empty response is sent back.

The other commands are processed and the result is sent back.


setDocumentLocator

public void setDocumentLocator(org.xml.sax.Locator loc)
Receive an object for locating the origin of SAX document events.

This method is part of the SAX API.

SAX parsers are strongly encouraged (though not absolutely required) to supply a locator: if it does so, it must supply the locator to the application by invoking this method before invoking any of the other methods in the ContentHandler interface.

The locator allows the application to determine the end position of any document-related event, even if the parser is not reporting an error. Typically, the application will use this information for reporting its own errors (such as character content that does not match an application's business rules). The information returned by the locator is probably not sufficient for use with a search engine.

Note that the locator will return correct information only during the invocation of the events in this interface. The application should not attempt to use it at any other time.

Specified by:
setDocumentLocator in interface org.xml.sax.ContentHandler
Parameters:
locator - An object that can return the location of any SAX document event.
See Also:
Locator

shutdown

public void shutdown()

Shutdown method for the UPES.

Terminates queue listening and cleans up the JMS resources.


skippedEntity

public void skippedEntity(java.lang.String name)
                   throws org.xml.sax.SAXException
Receive notification of a skipped entity.

This method is part of the SAX API and is here just a dummy implementation.

The Parser will invoke this method once for each entity skipped. Non-validating processors may skip entities if they have not seen the declarations (because, for example, the entity was declared in an external DTD subset). All processors may skip external entities, depending on the values of the http://xml.org/sax/features/external-general-entities and the http://xml.org/sax/features/external-parameter-entities properties.

Specified by:
skippedEntity in interface org.xml.sax.ContentHandler
Parameters:
name - The name of the skipped entity. If it is a parameter entity, the name will begin with '%', and if it is the external DTD subset, it will be the string "[dtd]".
Throws:
org.xml.sax.SAXException - Any SAX exception, possibly wrapping another exception.

startDocument

public void startDocument()
                   throws org.xml.sax.SAXException
Receive notification of the beginning of a document.

This method is part of the SAX API and is here just a dummy implementation.

The SAX parser will invoke this method only once, before any other methods in this interface or in org.xml.sax.DTDHandler DTDHandler (except for setDocumentLocator).

Specified by:
startDocument in interface org.xml.sax.ContentHandler
Throws:
org.xml.sax.SAXException - Any SAX exception, possibly wrapping another exception.
See Also:
endDocument()

startElement

public void startElement(java.lang.String namespaceURI,
                         java.lang.String localName,
                         java.lang.String name,
                         org.xml.sax.Attributes attrs)
                  throws org.xml.sax.SAXException
Receive notification of the beginning of an element.

This method is part of the SAX API.

The Parser will invoke this method at the beginning of every element in the XML document; there will be a corresponding endElement event for every startElement event (even when the element is empty). All of the element's content will be reported, in order, before the corresponding endElement event.

This event allows up to three name components for each element:

  1. the Namespace URI;
  2. the local name; and
  3. the qualified (prefixed) name.

Any or all of these may be provided, depending on the values of the http://xml.org/sax/features/namespaces and the http://xml.org/sax/features/namespace-prefixes properties:

Note that the attribute list provided will contain only attributes with explicit values (specified or defaulted): #IMPLIED attributes will be omitted. The attribute list will contain attributes used for Namespace declarations (xmlns* attributes) only if the http://xml.org/sax/features/namespace-prefixes property is true (it is false by default, and support for a true value is optional).

Specified by:
startElement in interface org.xml.sax.ContentHandler
Parameters:
uri - The Namespace URI, or the empty string if the element has no Namespace URI or if Namespace processing is not being performed.
localName - The local name (without prefix), or the empty string if Namespace processing is not being performed.
qName - The qualified name (with prefix), or the empty string if qualified names are not available.
atts - The attributes attached to the element. If there are no attributes, it shall be an empty Attributes object.
Throws:
org.xml.sax.SAXException - Any SAX exception, possibly wrapping another exception.
See Also:
endElement(java.lang.String, java.lang.String, java.lang.String), Attributes

startPrefixMapping

public void startPrefixMapping(java.lang.String prefix,
                               java.lang.String uri)
                        throws org.xml.sax.SAXException
Begin the scope of a prefix-URI Namespace mapping.

This method is part of the SAX API and is here just a dummy implementation.

The information from this event is not necessary for normal Namespace processing: the SAX XML reader will automatically replace prefixes for element and attribute names when the http://xml.org/sax/features/namespaces feature is true (the default).

There are cases, however, when applications need to use prefixes in character data or in attribute values, where they cannot safely be expanded automatically; the start/endPrefixMapping event supplies the information to the application to expand prefixes in those contexts itself, if necessary.

Note that start/endPrefixMapping events are not guaranteed to be properly nested relative to each-other: all startPrefixMapping events will occur before the corresponding startElement event, and all endPrefixMapping events will occur after the corresponding endElement event, but their order is not otherwise guaranteed.

There should never be start/endPrefixMapping events for the "xml" prefix, since it is predeclared and immutable.

Specified by:
startPrefixMapping in interface org.xml.sax.ContentHandler
Parameters:
prefix - The Namespace prefix being declared.
uri - The Namespace URI the prefix is mapped to.
Throws:
org.xml.sax.SAXException - The client may throw an exception during processing.
See Also:
endPrefixMapping(java.lang.String), startElement(java.lang.String, java.lang.String, java.lang.String, org.xml.sax.Attributes)

writeResponse

public void writeResponse(javax.jms.Message msg)
Formats the XML response message, sets some message properties and sends the message back to the queue specified in the input paramaters properties.
Parameters:
msg - The XML message object to which the response corresponds.