JMSReader

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Short Summary

JMSReader converts JMS messages into CloudConnect data records.

Component	Data source	Input ports	Output ports	Each to all outputs¹⁾	Different to different outputs²⁾	Transformation	Transf. req.	Java	CTL
JMSReader	jms messages	0	1	yes	no	yes	no	yes	no

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1) Component sends each data record to all connected output ports.

2) Component sends different data records to different output ports using return values of the transformation. See Return Values of Transformations for more information.

Abstract

JMSReader receives JMS messages, converts them into CloudConnect data records and sends these records to the connected output port. Component uses a processor transformation which implements a JmsMsg2DataRecord interface or inherits from a JmsMsg2DataRecordBase superclass. Methods of JmsMsg2DataRecord interface are described below.

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Ports

Port type	Number	Required	Description	Metadata
Output	0	yes	For correct data records	Any¹⁾

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1): Metadata on the output port may contain a field specified in the Message body field attribute. Metadata can also use Autofilling Functions.

JMSReader Attributes

Attribute	Req	Description	Possible values
Basic
JMS connection	yes	ID of the JMS connection to be used.
Processor code	1)	Transformation of JMS messages to records written in the graph in Java.
Processor URL	1)	Name of external file, including path, containing the transformation of JMS messages to records written in Java.
Processor class	1)	Name of external class defining the transformation of JMS messages to records. The default processor value is sufficient for most cases. It can process both `javax.jms.TextMessage` and `javax.jms.BytesMessage`.	JmsMsg2DataRecordProperties (default) \| other class
JMS message selector		Standard JMX "query" used to filter the JMS messages that should be processed. In effect, it is a string query using message properties and syntax that is a subset of SQL expressions. See http://java.sun.com/j2ee/1.4/docs/api/javax/jms/Message.html for more information.
Processor source charset		Encoding of external file containing the transformation in Java.	ISO-8859-1 (default) \| other encoding
Message charset		Encoding of JMS messages contents. This attribute is also used by the default processor implementation (`JmsMsg2DataRecordProperties`). And it is used for `javax.jms.BytesMessage` only.	ISO-8859-1 (default) \| other encoding
Advanced
Max msg count		Maximum number of messages to be received. 0 means without limitation. See Limit of Run for more information.	0 (default) \| 1-N
Timeout		Maximum time to receive messages in milliseconds. 0 means without limitation. See Limit of Run for more information.	0 (default) \| 1-N
Message body field		Name of the field to which message body should be written. This attribute is used by the default processor implementation (`JmsMsg2DataRecordProperties`). If no Message body field is specified, the field whose name is `bodyField` will be filled with the body of the message. If no field for the body of the message is contained in metadata, the body will not be written to any field.	bodyField (default) \| other name

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1) One of these may be set. Any of these transformation attributes implements a JmsMsg2DataRecord interface.

See Java Interfaces for JMSReader for more information.

See also Defining Transformations for detailed information about transformations.

Advanced Description

Limit of Run

It is also important to decide whether you want to limit the number of received messages and/or time of processing. This can be done by using the following setting:

Limited Run

If you specify the maximum number of messages (Max msg count), the timeout (Timeout) or both, the processing will be limited by number of messages, or time of processing, or both of these attributes. They need to be set to positive values.

When the specified number of messages is received, or when the process lasts some defined time, the process stops. Whichever of them will be achieved first, such attribute will be applied.

	Note
	Remember that you can also limit the graph run by using the `endOfInput()` method of `JmsMsg2DataReader` interface. It returns a boolean value and can also limit the run of the graph. Whenever it returns `false`, the processing stops.

Unlimited Run
On the other hand, if you do not specify either of these two attributes, the processing will never stop. Each of them is set to 0 by default. Thus, the processing is limited by neither the number of messages nor the elapsed time. This is the default setting of JMSReader.

Java Interfaces for JMSReader

The transformation implements methods of the JmsMsg2DataRecord interface and inherits other common methods from the Transform interface. See Common Java Interfaces.

Following are the methods of JmsMsg2DataRecord interface:

void init(DataRecordMetadata metadata, Properties props)
Initializes the processor.
boolean endOfInput()
May be used to end processing of input JMS messages when it returns false. See Limit of Run for more information.
DataRecord extractRecord(Message msg)
Transforms JMS message to data record. null indicates that the message is not accepted by the processor.
String getErrorMsg()
Returns error message.

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