org.qbroker.jms

Class HTTPMessenger

java.lang.Object

org.qbroker.jms.HTTPMessenger

public class HTTPMessenger
extends java.lang.Object

HTTPMessenger connects to a web server and initializes one of the operations, such as retrieve, download and store, or other commands.

There are four methods, retrieve(), download(), fulfill() and store(). The first method, retrieve(), is used to retrieve content from a web server. The method of download() is used for synchronous requests. The method of fulfill() is for asynchronous requests with the initial request and multiple subsequent checks on the status. The method of store() is used for putting or posting content to a web server. Except for retrieve(), the rest of methods treat the return code of 2xx as a success. If IgnoreHTTP412 is set to be true, the methods of download(), fulfill() and store() will not treat the return code of 412 as a failure.

ResponseProperty is a map for retrieving the header properties from an HTTP response. It contains multiple key-value pairs with key for an HTTP header and value for a property name of messages. Once the response is back, the values of the selected headers will be copied into the message. On the other hand, RequestProperty is a map for setting header properties on an HTTP request. Before sending the request to an HTTP service, those selected headers will be set via copying the properties from the message.

This is NOT MT-Safe. Therefore, you need to use multiple instances to achieve your MT goal.

Author:

yannanlu@yahoo.com

Constructor Summary

Constructors

Constructor and Description
HTTPMessenger(java.util.Map props) Creates new HTTPMessenger

Method Summary

Modifier and Type	Method and Description
void	close()
void	download(XQueue xq) It gets a JMS message from xq that contains a URL to be downloaded and downloads the web page via http.
void	fulfill(XQueue xq) It gets a JMS message from xq that contains a static URL for the initial asynchronous request and a dynamic URL template for a subsequent checking on the status of the fulfillment via http.
java.lang.String	getOperation()
java.lang.String	getURI()
boolean	isConnected()
java.lang.String	reconnect()
void	retrieve(XQueue xq) retrieve a page from web server and put it to an XQ
void	store(XQueue xq) It gets a JMS Message from the XQueue and stores its content into a URL via http POST continuously.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

HTTPMessenger

public HTTPMessenger(java.util.Map props)

Creates new HTTPMessenger

Method Detail

retrieve

public void retrieve(XQueue xq)
              throws java.io.IOException,
                     javax.jms.JMSException

retrieve a page from web server and put it to an XQ

Throws:

java.io.IOException

javax.jms.JMSException

download

public void download(XQueue xq)
              throws java.io.IOException,
                     TimeoutException,
                     javax.jms.JMSException

It gets a JMS message from xq that contains a URL to be downloaded and downloads the web page via http. It puts the content of the page into the message body and sends it back. The requester at the other end of the XQueue can easily read the content out of the message.

Since the download operation relies on a request, this method will intercept the request and process it. The incoming message is required to be writeable. The method will set a String property of the message specified by the RCField with the return code, indicating the status of the process to fulfill the request. The requester is required to check the value of the property once it gets the message back. If the return code is 0, the download is successful. Otherwise, the message body will not contain the content out of download operation.

It supports GET, POST and PUT. For POST, IsPost must be set to true. For PUT, UsePut has to be set to true. The Template or message body must contain the query content for POST or PUT. If it is GET, Template will be used to set the dynamic path for REST.

Throws:

java.io.IOException

TimeoutException

javax.jms.JMSException

fulfill

public void fulfill(XQueue xq)
             throws java.io.IOException,
                    TimeoutException,
                    javax.jms.JMSException

It gets a JMS message from xq that contains a static URL for the initial asynchronous request and a dynamic URL template for a subsequent checking on the status of the fulfillment via http. After the initial request, it waits and keeps checking on the status of the fulfillment. Once the request is fulfilled, it puts the fulfilled response into the message body and sends it back. The requester at the other end of the XQueue can easily read the content out of the message.

Since the fulfill operation relies on an initial request and multiple subsequent checks, this method will intercept the JMS request and process it. The incoming message is required to be writeable. The method will set a String property of the message specified by the RCField with the return code, indicating the status of the fulfillment process. The requester is required to check the value of the property once it gets the message back. If the return code is 0, the fulfillment is successful. Otherwise, the message body will not contain the result.

For the initial request, it supports both GET and POST. If it is POST, IsPost must be set to true. The Template or message body must contains the fulfillment content for POST. If it is GET, Template will be used to set the dynamic path for the REST calls.

The incoming message is also supposed to have a substitution statement to rewrite the URL for the subsequent rest calls to check the response. It should be stored in SubField if it is defined. For the subsequent rest calls, it only supports GET. The URL substitution only formats the content from the initial response. For each subsequent rest call, the method evaluates the response status. It it is OK, the content of the response will be set to the message body. Otherwise, it will sleep for a while defined by SleepTime and retries up to Retry times.

Throws:

java.io.IOException

TimeoutException

javax.jms.JMSException

store

public void store(XQueue xq)
           throws java.io.IOException,
                  TimeoutException,
                  javax.jms.JMSException

It gets a JMS Message from the XQueue and stores its content into a URL via http POST continuously.

It will always try to retrieve the URL from the field specified by FieldName property. If the message does not contain the URL, the method will use the default URL defined by URI property.

The store operation also supports the requests. If the XAMode has enabled the XA_CLIENT bit, it will treat the message as a request from the uplink. In this case, the incoming message is required to be writeable. The method will set a String property of the message specified by the RCField with the return code, indicating the status of the process to fulfill the request. The requester is supposed to check the value of the property once it gets the message back. If the return code is 0, the operation is successful. Otherwise, the request will be dropped due to failures. On the other hand, if the XA_CLIENT bit has been disabled by XAMode, the incoming message will not be modified.

If the XQueue has enabled the EXTERNAL_XA bit, it will also acknowledge the messages. This method is MT-Safe.

Throws:

java.io.IOException

TimeoutException

javax.jms.JMSException

close

public void close()

reconnect

public java.lang.String reconnect()

getOperation

public java.lang.String getOperation()

getURI

public java.lang.String getURI()

isConnected

public boolean isConnected()