This topic applies only to the IBM Business Automation Workflow Advanced
configuration.

Calling data handlers from bindings

Draft comment:
This topic only applies to BAW, and is located in the BAW repository. Last updated on 2025-03-13 12:15

As mentioned earlier, data handlers in IBM® Workflow Server are not callable from exports or imports directly. This section illustrates how to call data handlers from JMS, MQ and HTTP bindings. It assumes you are familiar with data bindings for JMS, MQ JMS, generic JMS, MQ, and HTTP bindings.

The following sections show how the delimited data handler created previously is invoked from these data bindings.

JMS, MQ JMS and Generic JMS data bindings
MQ data binding
HTTP data binding
Configuring a data binding to call a data handler
Using data handler instances from multiple threads

JMS, MQ JMS and Generic JMS data bindings

The code snippets that follow show how the delimited data handler whose configuration was created previously is invoked from the JMS data bindings. The JMS data binding implementation uses the configuration QName of the data handler to obtain and create the data handler instance from the binding registry.

Converting native data to data object

The String or bytes data is extracted from the JMS Message and a corresponding reader or inputstream is created and passed to the data handler. The data handler converts the input native data to a business object and returns it to the data binding.

1	public void read(Message jmsMessage)
2	        throws JMSException
3	{
4	    QName configurationName = new QName("http://ProcessCustomerWPS", "DelimitedDataHandlerConfiguration");
5	    DataHandler dataHandler = (DataHandler)bindingRegistry.locateBinding(configurationName, bindingContext);
6	
7	    if (jmsMessage instanceof TextMessage) {
8	        String textMessage = ((TextMessage) jmsMessage).getText();
9	        Reader reader = new StringReader(textMessage);
10	        this.dataObject = (DataObject)datahandler.transform(reader,DataObject.class, null);                
11	        return;
12	    }
13	
14	    if (jmsMessage instanceof BytesMessage) {
15	        BytesMessage bytesMessage = (BytesMessage) jmsMessage;
16	        byte[] sourceBytes = new byte[(int) bytesMessage.getBodyLength()];
17	        bytesMessage.readBytes(sourceBytes);
18	        ByteArrayInputStream InputStream = new ByteArrayInputStream(sourceBytes);
19	        this.dataObject = (DataObject)datahandler.transform(inputStream, DataObject.class, null);
20	        return;
21	    }
22	}

Converting data object to native data

In case of TextMessage, a Writer is created and passed to the data handler transformInto method. For BytesMessage, an OutputStream is created and passed into the transformInto method.

24	public void write(Message jmsMessage)
25	        throws JMSException
26	{
27	    QName configurationName = new QName("http://ProcessCustomerWPS", "DelimitedDataHandlerConfiguration");
28	    BindingRegistry bindingRegistry = BindingRegistryFactory.getInstance();
29	    DataHandler dataHandler = (DataHandler)bindingRegistry.locateBinding(configurationName, bindingContext);

30	    if((jmsMessage instanceof TextMessage){
31	         Writer writer = new StringWriter();    
32	     datahandler.transformInto(dataObject, Writer, null);                
33	     String messageString = writer.toString();
34	    ((TextMessage) message).setText(messageString);
35	    return;
36	}
       if((jmsMessage instanceof BytesMessage)
37	    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
38	    datahandler.transformInto(dataObject, outputStream, null);                
39	    byte[] messageBytes = outputStream.toByteArray();
40	    ((BytesMessage) message).setBytes(messageBytes);
41	    return;
42	}

MQ data binding

The following code snippet shows how the delimited data handler is invoked from the MQ data binding. The MQ data binding implementation uses the configuration QName of the data handler to obtain and create the data handler instance from the binding registry.

Converting native data to data object

If the format is null, the InputStream is directly passed to the data handler. If the format is MQSTR, then a reader is constructed from the characters and passed to the data handler. The data handler converts the input native data to a business object and returns it to the data binding.

1	public void read(MQMD md,
2	                 List headers,
3	                 MQDataInputStream inputStream)
4	        throws IOException
5	        // Create the configuration information for the child DataHandler
6	        QName configurationName = new QName("http://ProcessCustomerWPS", "DelimitedDataHandlerConfiguration");
7	        BindingRegistry registry = BindingRegistryFactory.getInstance();
8	        DataHandler dataHandler = (DataHandler) bindingRegistry.locateBinding(configurationName, context);
9	        
10	        if(format != null && (format.equals("MQSTR") || format.equals(""))
11	        {
12	            String textMessage = inputStream.readMQChar(InputStream.available());
13	            Reader reader = new StringReader(textMessage);
14	            this.dataObject = (DataObject)datahandler.transform(reader,DataObject.class, null);                
15	
16	        }
17	        else
18	        {
19	             this.dataObject = (DataObject)dataHandler.transform(inputStream, DataObject.class, null);
20	        }
21	        //deal with business exception
22	   }

Converting data object to native data

If the format is MQSTR, a Writer is created and passed to the data handler transformInto method otherwise the OutputStream is directly passed into the transformInto method of data handler.

1	    public void write(MQMD md,
2	                      List headers,
3	                      MQDataOutputStream output)
4	        throws IOException
5	    {
6	        // Create the configuration information for the child DataHandler
7	        QName configurationName = new QName("http://ProcessCustomerWPS", "DelimitedDataHandlerConfiguration");
8	
9	        BindingRegistry registry = BindingRegistryFactory.getInstance();
10	        DataHandler dataHandler = (DataHandler) bindingRegistry.locateBinding(configurationName, context);
11	
12	        if(format != null && (format.equals("MQSTR") || format.equals(""))
13	        {
14	            Writer writer = new StringWriter();
15	            datahandler.transformInto(dataObject, writer, null);                
16	            String messageString = writer.toString();
17	             output.writeMQChar(messageString);
18	        }
19	        else
20	        {
21	
22	            dataHandler.transformInto(dataObject, output, null);
23	        }
24	    }

HTTP data binding

The following code snippet shows how the delimited data handler is invoked from the HTTP data binding. The HTTP data binding implementation uses the configuration QName of the data handler to obtain and create the data handler instance from the binding registry.

Converting native data to data object

The bytes are read from the HTTPInputStream and an input stream is created from those bytes. The input stream is then passed to the data handler.

25	public void convertFromNativeData(HTTPInputStream inputStream)
26	        throws DataBindingException, IOException
27	{
28	    // Create the configuration information for the child DataHandler
1	    QName configurationName = new QName("http://ProcessCustomerWPS", "DelimitedDataHandlerConfiguration");
2	    BindingRegistry registry = BindingRegistryFactory.getInstance();
3	    DataHandler dataHandler = (DataHandler) registry.locateBinding(configurationName, context);
4	    byte[] bytes = httpInputStream.getBytes();
5	    ByteArrayInputStream InputStream = new ByteArrayInputStream(bytes);
6	
7	    this.dataObject = dataHandler.transform(inputStream, DataObject.class, null);
8	    //...
9	}

Converting data object to native data

An OutputStream is created and passed into the transformInto method. The result of the transformation is then extracted from the outputstream and set on the HTTPOutputStream.

10	public void write(HTTPOutputStream output)
11	        throws IOException
12	{
13	    // Create the configuration information for the child DataHandler
14	    QName configurationName = new QName("http://ProcessCustomerWPS", "DelimitedDataHandlerConfiguration");
15	    BindingRegistry registry = BindingRegistryFactory.getInstance();
16	    DataHandler dataHandler = (DataHandler) registry.locateBinding(configurationName, context);
17	    
18	    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
19	    dataHandler.transformInto(dataObject, outputStream, null);
20	    byte[] messageBytes = outputStream.toByteArray();
21	
22	    httpControl.setContentLength(bytes.length);
23	    output.write(messageBytes);
24	    
25	    // ...
26	}

Configuring a data binding to call a data handler

We have shown how to call a data handler from a data binding with example code. You can also configure a data binding to call a data handler using the binding resource configuration wizard, where the data handler is configured as a property (see Creating a data format transformation resource configuration).

Using data handler instances from multiple threads

The data handler instance created as described is not thread safe so a data handler instance should not be called from more than one thread. Create a new instance each time you need to apply the data handler.