Abstract:
A method for handling a web service call by clients in a communication network is disclosed. The method comprises issuing client requests to call a web service from a client requester. The method also comprises registering the client request to a callback web service within a callback web service, and invoking the called web service. A response web service is coupled to the callback web service for receiving a response to the at least one client request to call a web service and is also coupled to the client requester for delivering the response when a client request to obtain the response is issued from the client requester.

Description:
TECHNICAL FIELD 
     The present invention relates generally to the Internet and web services, and more particularly to a system and method of handling a web service call in an asynchronous manner. 
     BACKGROUND OF THE INVENTION 
     Web services are one of the latest innovations available to users on the World Wide Web. This new web model allows any client user (a program for example, not necessarily a web browser) to initiate a transaction automatically. 
     By definition, web services comprise software components that can be described, published, discovered and invoked dynamically in a distributed computing environment, generally the World Wide Web. 
     Web services have already proved their usefulness in real-world applications. However, the current standard web service model is a synchronous one, based on a request/response architecture. 
     The following patents illustrate some solutions for performing operations associated with browser requests on the World Wide Web. 
     U.S. Pat. No. 6,317,786 to Yamane discloses a method and system for managing web servers, and more particularly, to a web service system operator for managing multiple web servers. The system can manage traffic by directing web page requests to available web servers and balancing the web page request service load among the multiple servers. The system can collect data on web page requests and web server responses to those web page requests and provide reporting of the data as well as automatic and manual analysis tools. 
     U.S. Pat. No. 6,247,056 to Chou discloses a system and method relating to server architectures in networked computer systems, and more specifically to a distributed architecture for enabling servicing to user requests across different machines. 
     However, supporting real-world enterprise business processes inherently involves asynchronous operations, as the processes are typically long in duration. Activities of each process need to be de-coupled from an initial request in order to optimize the use of system resources and to break the processing into a recoverable set of transactions. 
     Such asynchronous behavior is common for services that require complex processing that may take minutes or even days to complete when, for example, the web service implementation is dependent on batch processing or manual steps requiring human intervention. Therefore, there is a need for a web service system that avoids any lost data; the present invention offers such a solution. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing and other problems of conventional systems and methods, it is an object of the invention to provide a system and method to handle asynchronous web service in a fully transparent manner for the end user. 
     It is another object to provide a system and method that takes advantage of existing protocols and that does not need creation or usage of any specific transport layer or usage of any framework. 
     These and other objects of the present invention are achieved by a system for handling a web service call by clients in a communication network. The system comprises a client requester for issuing client requests. The client requests may comprise at least one client request to call a web service. The system also comprises a callback web service that is coupled to the client requester for registering the at least one client request to call a web service and for invoking the called web service. A response web service is coupled to the callback web service for receiving a response to the at least one client request to call a web service and is also coupled to the client requester for delivering the response when a client request to obtain the response is issued from the client requester. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the invention will be better understood by reading the following more particular description of the invention in conjunction with the accompanying drawings wherein: 
         FIG. 1  is a conceptual view of the system of the present invention. 
         FIG. 2  is a data flow diagram illustrating the main steps for handling a client request according to an embodiment of the present invention. 
         FIG. 3  is a data flow diagram illustrating from the client side the main steps for subscribing to an already registered web service. 
         FIG. 4  is a data flow diagram illustrating the callback web service for requesting the generic callback web service for the completion of the web service. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring first to  FIG. 1 , there is depicted a pictorial representation of an Internet communication system  100 , which may be utilized to implement the present invention. 
     Generally speaking, system  100  operates through the Internet  102  and includes a client requester (e.g., a program)  104 , a callback web service  106 , a web service  108  and a response web service  110 . In an embodiment of the present invention, communication over the Internet is accomplished in accordance with the HTTP protocol, as shown by arrows  112 ,  114 ,  118 ,  120  and  122 . It will be appreciated that only the main characteristics of the web environment useful for the understanding of the invention are discussed herein, and that a more complete description may be found, for example, in the “TCP/IP Tutorial and Technical Overview” IBM Redbooks GG24-3376-06. 
     In system  100 , client requester  104  communicates with callback web service  106  to send a client request (arrow  114 ). 
     The callback web service  106  invokes the web service  108  (arrow  118 ) to wait for a response to the user request (arrow  120 ). 
     The callback web service  106  is also coupled to the response web service  110  to deliver the response (arrow  122 ). 
     Client requester  104  is coupled to the response web service  110  to receive the response (arrow  112 ). 
     System  100  allows a centralized web service to handle web service calls in an asynchronous manner. The callback web service  106  allows users to register their request or to subscribe to existing requests previously submitted. The callback web service  106  further provides the user with an asynchronous answer through the response web service  110 . The callback web service  106  manages when and how the requested web service is called and when and how the answer is sent back to the client requester  104 . 
     One advantage of system  100  is that there is no need of a special framework to be used or to be implemented to offer such facility. Standard web service protocols may be used at the client requester side, such as SOAP (Simple Object Access Protocol). 
     Referring now to  FIG. 2 , the main steps to operate the callback web service  106  are described. 
     Client requester  104  performs an initial request to a web service ‘A’  108  by submitting a web service call (arrow  114 ) to the callback web service  106 . The web service call includes at least the address of the requested web service, generally in the form of an Internet address ‘@ Web Service A’, and a set of parameters ‘paramA’. This set may include the following parameters:
         a ‘WSTC’ parameter to identify the Internet address of the web service to call;   ‘WSTCP’ parameters to specify the parameters associated with the web service to call;   ‘PT’ ProtocoleType parameter to indicate which protocol to be used for the communication;   a ‘RCBI’ parameter to allow the user to configure binding information for sending the web service response to the client.       

     The ‘PT’ input parameter used to indicate to the web service callback the protocol used for the asynchronous response to the query may be for example:
         the Simple Object Access Protocol (SOAP) protocol, in order that a client web service receives the response to the submitted request; or   the Simple Mail Transfer Protocol (SMTP) protocol, in order that the web service response being sent to an e-mail address.       

     The binding information depends on the content of the ‘PT’ input parameter. It is in fact the address needed to connect to the callback web service using the protocol defined by ‘PT’. For example, if the ‘PT’ parameter is set to ‘SOAP’, this RCBI parameter will be the Internet address of the callback web service. If the ‘PT’ parameter is set to ‘SMTP’, then the RCBI parameter will be the e-mail address of the callback service to send the response. The list of such communication types is not exhaustive and can be extended to any communication protocol. 
     After receiving the request, the callback web service  106  examines a local repository  132  that contains pending requests with associated requesters. If a similar request having the same parameters is present in the repository  132 , then the new requester is added to the list of clients to be answered, otherwise if no similar request already exists, the new request is stored in the local repository  132  along with the requester identity. 
     As an answer to this request (arrow  114 ), the callback web service  106  sends back to the client requester  104  an acknowledgment (arrow  122 ) and the session between the client requester  104  and the callback web service  106  is closed. 
     Simultaneously, the callback web service  106  acting for the client requester  104  forwards the initial request to the requested web service ‘A’  108  in the form of a second web service call (arrow  118 ) formatted in a second request having the same format as the initial request (arrow  114 ) issued from the client requester  104 . 
     In response to the callback web service request, the web service ‘A’  108  provides the callback web service  106  with a response according to the HTTP protocol, as shown by arrow  120 . 
     The callback web service  106  then retrieves from the local repository  132  the list of all the requesters corresponding to that web service ‘A’  108 , and transfers to the response web service  100  the response message ‘Response A’ ( 130 ) (as shown by arrow  116 ) with corresponding requester parameters. 
     Then, the requester may obtain the response message at any time on request from the response web service  110 . 
     It is to be appreciated that the callback web service  106  further provides a set of functions to allow a client requester  104  to request from the local repository  132  the list of all current pending requests in order to directly add its own requester address to one or more requests of the list without the need of issuing an initial request  114 . This process is detailed with reference to  FIG. 3 . 
       FIG. 3  details the steps for a client requester  104  to subscribe to an already submitted web service call. First, the client requester  104  submits a ‘get pending’ request (arrow  301 ) in the form of a web service call to the callback web service  106  to obtain a list of all the pending web services already registered. Preferably, the format of the response (arrow  303 ) contains at least a unique identifier for identifying each pending web service, and the address and the input parameters associated with each pending web service. The list of the pending web services is provided by the callback web service  106  by scanning through its local repository  132 . Then, the client requester  104  may subscribe to one or more web services listed in the response (arrow  303 ). A subscribe request (arrow  304 ) is then initiated by the client requester  104 , having as input parameters the unique identifier of the web service as listed in the previously received response (arrow  303 ), and the address of the response web service  110 . The callback web service  106  sends back an acknowledgment (arrow  305 ) to the client requester  104  and the process to obtain the response message ‘Response A’ ( 130 ) is identical to the one previously described with reference to  FIG. 2 . 
     Another additional function may allow a client requester  104  to perform an unregistration for a web service. After receiving a response to a ‘get pending’ request, the client requester  104  submits an ‘unsubscribe’ message to the callback web service  106  and having as an input parameter the unique identifier of the web service. The callback web service sends back an acknowledgment to the client requester  104 , which is then unsubsribed. 
     It is to be appreciated by those skilled in the art that while the invention has been particularly shown and described with reference to a preferred embodiment thereof, various changes in form and details may be made without departing from the spirit and scope of the invention. 
     Particularly, a polling method may be implemented to ask the callback web service  106  for the completion of the web service instead of having a temporary web service. This alternate workflow is described in  FIG. 4 . 
       FIG. 4  details the steps for a client requester  104  to ask the callback web service  106  for the completion of the web service. Client requester  104  performs an initial request to a web service ‘A’  108  by submitting a request  114  to the callback web service  106 . 
     As an answer to this request, the callback web service  106  sends back to the client requester  104  the request ID (arrow  401 ) and the session between the client requester  104  and the callback web service  106  is closed. Simultaneously, the callback web service  106  acting for the client requester  104  forwards the initial request to the requested web service ‘A’  108  in the form of a second web service call  118  formatted in a second request having the same format as the initial request issued from the client requester  104 . 
     Then, at any time, the client requester  104  may send a ‘Get Status’ message (arrow  402 ) to ask the callback web service  106  for the completion of the web service. 
     If the response message ‘Response A’  130  is available in the callback web service  106 , it is transferred as an answer (arrow  404 ) to the client requester  104 , otherwise if it is not available, a ‘Not Completed’ message (arrow  406 ) is sent.