org.qbroker.jms

Class MessageServlet

java.lang.Object

javax.servlet.GenericServlet

javax.servlet.http.HttpServlet

org.qbroker.jms.MessageServlet

All Implemented Interfaces:

java.io.Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

Direct Known Subclasses:

QServlet

public class MessageServlet
extends javax.servlet.http.HttpServlet

MessageServlet is a servlet for generic message services. It allows a message service running inside the servlet container as a web application. As a web application, the message service can receive JMS messages directly from web clients and sends messages back on HTTP. Therefore, MessageServlet is the frontend and the gateway for message services. It is responsible for transformation between the HTTP requests/responses and JMS messages.

MessageServlet has 6 rulesets referenced by the URL path. The first one is /jms for receiving event postables as the JMS TextEvents. The second is /collectible for receiving event postables from the client and transforming them to the collectible JMS TextEvents. The next is /event for receiving event postables as the non-JMS events. The pre-configured RestURI is for the ruleset to convert simple REST requests to JMS TextEvents. In this ruleset, the path of /json or /xml is for posted JSON or XML data from a client. The path of /stream is for downloading binary content from JDBC datasources, The rest of paths are for ad hoc HTML form requests. When a web request hits one of the URLs, the corresponding ruleset will be invoked to process the incoming request. MessageServlet supports POST, GET and PUT methods. For POST or PUT, those headers matched with HeaderRegex will be copied into the message. One of examples with HeaderRegex is "^[Xx]-.+$" that matches all HTTP headers of starting with "X-". In case of POST, it also supports file upload or raw content such as xml or json.

A collectible TextEvent is a TextEvent with its message body set to the collectible format of the original message. It is meant to be sent to remote destinations. In order to get content of the original message, the remote consumer will have to parse the message body with the EventParser.

For ad hoc form requests, MessageServlet treats them in two different ways. If the attribute of view is defined in the request and it is not empty, the request will be converted into a TextEvent. Otherwise, if the attribute of name is defined and it is not empty, the request will be converted to an Event. If neither view nor name is defined, the ad hoc request will be dropped as a bad request. Further more, if the attribute of URI is defined and it is not empty, the request Event will be packed into collectible.

Once an incoming request is transformed into message, MessageServlet will invoke doRequest() of the assigned service to process the message as the request. After the process is done, the message is supposed to have the response loaded. MessageServlet will convert it back to the HTTP response and sends the response back to the HTTP client.

Author:

yannanlu@yahoo.com

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected org.apache.commons.fileupload.disk.DiskFileItemFactory	factory
protected java.lang.String	headerRegex
protected SimpleCallbackHandler	jaasHandler
protected java.lang.String	jaasLogin
protected java.lang.String	loginURL
protected java.security.MessageDigest	md
protected java.lang.String	name
protected java.lang.String[]	propertyName
protected java.lang.String[]	propertyValue
protected java.lang.String	restURI
protected int	restURILen
protected int	timeout
protected java.lang.String	welcomeURL
protected java.text.SimpleDateFormat	zonedDateFormat

Constructor Summary

Constructors

Constructor and Description
MessageServlet()
MessageServlet(java.util.Map props)

Method Summary

Modifier and Type	Method and Description
void	doDelete(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)
void	doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)
void	doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)
void	doPut(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)
static Event	getEvent(java.util.Map props, boolean isJMS)
protected boolean	login(java.lang.String username, java.lang.String password)
static void	main(java.lang.String[] args)
protected java.lang.String	processRequest(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Event event) With the existing event or the event built from the HTTP request according to the request path, the method sends it to the backend for the response.
void	setService(Service service) sets the service to fulfill requests

Methods inherited from class javax.servlet.http.HttpServlet

doHead, doOptions, doTrace, getLastModified, service, service

Methods inherited from class javax.servlet.GenericServlet

destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, init, log, log

Methods inherited from class java.lang.Object

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

Field Detail

name

protected java.lang.String name

loginURL

protected java.lang.String loginURL

welcomeURL

protected java.lang.String welcomeURL

timeout

protected int timeout

zonedDateFormat

protected java.text.SimpleDateFormat zonedDateFormat

factory

protected org.apache.commons.fileupload.disk.DiskFileItemFactory factory

jaasLogin

protected java.lang.String jaasLogin

restURI

protected java.lang.String restURI

headerRegex

protected java.lang.String headerRegex

jaasHandler

protected SimpleCallbackHandler jaasHandler

propertyName

protected java.lang.String[] propertyName

propertyValue

protected java.lang.String[] propertyValue

md

protected java.security.MessageDigest md

restURILen

protected int restURILen

Constructor Detail

MessageServlet

public MessageServlet()

MessageServlet

public MessageServlet(java.util.Map props)

Method Detail

setService

public void setService(Service service)

sets the service to fulfill requests

doGet

public void doGet(javax.servlet.http.HttpServletRequest request,
                  javax.servlet.http.HttpServletResponse response)
           throws javax.servlet.ServletException,
                  java.io.IOException

Overrides:

doGet in class javax.servlet.http.HttpServlet

Throws:

javax.servlet.ServletException

java.io.IOException

doPost

public void doPost(javax.servlet.http.HttpServletRequest request,
                   javax.servlet.http.HttpServletResponse response)
            throws javax.servlet.ServletException,
                   java.io.IOException

Overrides:

doPost in class javax.servlet.http.HttpServlet

Throws:

javax.servlet.ServletException

java.io.IOException

doPut

public void doPut(javax.servlet.http.HttpServletRequest request,
                  javax.servlet.http.HttpServletResponse response)
           throws javax.servlet.ServletException,
                  java.io.IOException

Overrides:

doPut in class javax.servlet.http.HttpServlet

Throws:

javax.servlet.ServletException

java.io.IOException

doDelete

public void doDelete(javax.servlet.http.HttpServletRequest request,
                     javax.servlet.http.HttpServletResponse response)
              throws javax.servlet.ServletException,
                     java.io.IOException

Overrides:

doDelete in class javax.servlet.http.HttpServlet

Throws:

javax.servlet.ServletException

java.io.IOException

getEvent

public static Event getEvent(java.util.Map props,
                             boolean isJMS)

processRequest

protected java.lang.String processRequest(javax.servlet.http.HttpServletRequest request,
                                          javax.servlet.http.HttpServletResponse response,
                                          Event event)
                                   throws javax.servlet.ServletException,
                                          java.io.IOException

With the existing event or the event built from the HTTP request according to the request path, the method sends it to the backend for the response. Once response is back, it packs the response into a data map and saves the map to the request as the attribute with the key of the context path. Upon success, it returns either the JSP path so that the data will be formatted for output with the given jsp, or the context path for caller to retrieve the data for output. Otherwise, it returns null to indicate failure so that the caller can retrieve the error message.

Throws:

javax.servlet.ServletException

java.io.IOException

login

protected boolean login(java.lang.String username,
                        java.lang.String password)

main

public static void main(java.lang.String[] args)