Abstract:
A method, system, computer program product, and data structure for processing requests for services in a networked data processing system is provided. In one embodiment a request is received by a service provider. The request includes defined allowable actions and request definition compositions. The request also includes a plurality of actions wherein the relationships between the plurality of actions are defined. The service provider processes the plurality of actions according to the defined relationships and generates a response.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The present invention relates generally to computer software and more specifically to methods for facilitating business to business interactions in electronic commerce. 
         [0003]    2. Description of Related Art 
         [0004]    Automating business to business interactions is an important problem in electronic commerce. With the increase in the automation of internal business processes of organizations, there is a demand for building systems to address the issues of seamlessly automating long running business to business interactions. Several approaches have been adopted to address this problem. 
         [0005]    Currently, there are peer business applications that interact through simple request/response interactions. The communications between the businesses are guided by well defined protocols for exchanging the requests and responses. The request/response interactions may be either synchronous or asynchronous. An example of a synchronous interaction could be a HTTP request by one business, which triggers a business process inside the peer business system and finally gets a response when the processing of the request is completed. Alternatively, asynchronous requests and responses are sent as separate messages, i.e., the server processes a request asynchronously, and sends a response back to the requester. 
         [0006]    For example, referring to  FIG. 1 , a block diagram of a typical prior art business-to-business interaction is depicted. In the prior art, a business A  102 , implemented as a data processor, sent a request  106  to business B  104 , also implemented as a data processor. Business B  104  then sent an acknowledgment  108  back to business A  102  and then a response  110 . The second request  112  is then sent from business A  102  to business B  104 . This second request  112  may depend on the results of the response  110  to the first request  106 . Business B  104  then sends an acknowledgment  114  back to business A  102  and then a response  116  after the request  112  has been processed. 
         [0007]    Electronic service contracts help simplify the setting up of long standing business relationships. Electronic service contracts may define either synchronous or asynchronous processes. Synchronous refers to events that are synchronized, or coordinated, in time, whereas, in contrast, asynchronous refers to events that are not synchronized, or coordinated, in time. An example of asynchronous interaction could be requests made using the Coyote Business Process Framework as described in U.S. Pat. No. 6,148,290 which is hereby incorporated herein by reference for all purposes. Contracts explicitly specify the messages that are exchanged for requests and responses. The Coyote business process framework provides a base for setting up and conducting long running asynchronous transactions. 
         [0008]    All of the approaches described above require the exchange of several messages back and forth for each process (each process may include multiple requests) before a desired result could be achieved. Typically an alternative action or a successive action is requested only after the results of the preceding action are known to the requesting business. This results in long delays and longer connectivity between the partners. 
         [0009]    Thus, for example, business A  102  may be an agent purchasing airline tickets and hotel accommodations for a traveler. However, suppose the traveler is unwilling to travel unless airline tickets are obtained for less than a specified amount. Business A  102  must then await the response related to the request for airline tickets before submitting the request for hotel accommodations. However, such a wait is time consuming and also may result in hotel accommodations at a preferred location becoming unavailable during periods of high demand. 
         [0010]    Among the other models that address the business to business interactions are mobile agents that are dispatched from one business to another. The mobile agents are software defined by a programming language or a scripting language which can be executed or interpreted by the node at which the agent is deployed. The peer business system then executes the logic packaged into the mobile agent and then responds with the results of the actions. 
         [0011]    Prior art approaches to solve this problem have tried to use mobile agent technology as shown in  FIG. 2 . In this case, mobile agents  206  and  208 , which are arbitrary programs written in high-level programming languages, contain the logic for generating multiple requests  210  to be performed by business B  204 , the decision logic to be adopted after the outcome of each action, as well as generating the final responses  212 . There are many problems however with this scenario as illustrated by Stefan Pleisch in IBM Research Report RZ 3152 State of the Art of Mobile Agent Computing—Security, Fault Tolerance, and Transaction Support, IBM Zurich Research Lab, 1999. 
         [0012]    First, there is the problem of persistence and fault-tolerance. The mobile agent depends on the mobile agent execution system to provide persistent storage and tolerance to faults. This is especially essential in an ecommerce setting since ecommerce interactions are typically long-running and may take days or even weeks. However, the state to be made persistent in mobile agents is not explicitly defined and it is difficult for a server business to give any kind of guarantees. 
         [0013]    Second, there is the problem of transaction support. Ecommerce interactions often require ACID transaction guarantees or possibly weaker transaction guarantees across multiple requests (may use compensating transactions). Again, the mobile agent execution system would have to provide these support to the mobile agent. This is difficult to do since the server system does not have an explicit understanding of the mobile agent code. 
         [0014]    Third, there is the problem of resource control. An arbitrary piece of Java code may invoke any actions in an uncontrolled manner leaving the mobile agent execution system responsible for determining the access control policies. Again, this is difficult to achieve in a mobile agent setting because of the lack of well-defined, mutually-agreed-on policies (contracts) between the server and client. 
         [0015]    Fourth, there is the problem of complexity. Writing a mobile agent is a non-trivial task requiring programming in a programming language. It is also procedural rather than declarative in style (for mobile agents written in imperative languages). The business logic may not require this full complexity and it does not make the composition semantics explicit as in a declarative style. 
         [0016]    Therefore, it would be desirable to have a system and data structure for processing service requests such that recovery of previous steps is possible after failure and, additionally, in a manner that does not compromise the security of the computer receiving the requests. 
       SUMMARY OF THE INVENTION 
       [0017]    The present invention provides a method, system, computer program product, and data structure for processing requests for services in a networked data processing system. The present invention addresses the issue of achieving the execution of a complex composite requests without suffering from the drawbacks (i.e., lack of support for persistence, transactional execution and security) mentioned earlier. The transactor model provides a framework for composing complex business requests and presenting it to the peer business and achieving the desired execution without having to exchange several messages back and forth. A composite request is expressed as a composition of multiple requests or actions, that captures the data &amp; execution dependency across actions as well as integrity constraints to be followed during execution. It also expresses the response format of a composite request. The composite request adheres to the composition constructs, any additional constraints on composition as well as allowable request set specified via a service contract. The compositional construct describes how the service provider is to select an action to be executed from a set of actions and how a set of requests are to be executed. The compositional construct can also be applied recursively to make a more complex request. The integrity rules associated with each grouping of actions may provide a priority order in which the actions should be executed, whether the actions should be executed as an “all or nothing” arrangement, and whether the actions should be executed for as long as a constraint is not violated (i.e., constraint on any variable, e.g., total dollar amount, etc.). The data flow relationships specify whether the output from one action should be used as the input for another action. Each group in the compositional construct can be defined such that any one action from the group is selected for execution or that all actions are executed. 
         [0018]    The transactor framework overcomes the drawbacks of general agent codes written in a programming language. First, the service contract explicitly specifies allowable requests, and composition rules, and hence, there is no security exposure. Second, transaction or any other integrity requirements are expressed declaratively and hence, can be supported by the peer business system. This also simplifies business logic (since it is expressed via declarative specification) while supporting asynchronous and disconnected operations. Finally, the composite request reduces latency since the client needs to make only one invocation instead of many. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
           [0020]      FIG. 1  depicts a block diagram of a typical prior art business-to-business interaction is depicted; 
           [0021]      FIG. 2  depicts a block diagram of mobile agent technology illustrating the problems with prior methods of implementing mobile agents; 
           [0022]      FIG. 3  depicts a pictorial representation of a network of data processing systems in which the present invention may be implemented; 
           [0023]      FIG. 4  depicts a block diagram of a data processing system that may be implemented as a server in accordance with a preferred embodiment of the present invention; 
           [0024]      FIG. 5  depicts a block diagram illustrating a data processing system in which the present invention may be implemented; 
           [0025]      FIG. 6  depicts a block diagram of a composite business-to-business interaction in accordance with the present invention; 
           [0026]      FIGS. 7A-7B  depict diagrams illustrating a transactor input and output message data structures in accordance with the present invention; 
           [0027]      FIGS. 8A-8B  depict diagrams illustrating an exemplary transactor data structure input message and output message in accordance with the present invention; 
           [0028]      FIGS. 9A-9B  depict diagrams illustrating exemplary portions of a transactor data structure in accordance with the present invention; 
           [0029]      FIGS. 10A-10B  depict diagrams illustrating exemplary portions of a transactors data structure in  FIGS. 9A-9B  with additional criteria in accordance with the present invention; 
           [0030]      FIG. 11  depicts a diagram illustrating another example of conditions that may be placed in a transactor data structure in accordance with the present invention; 
           [0031]      FIG. 12  depicts a diagram illustrating a portion of a transactor data structure illustrating hierarchical groups in accordance with the present invention; 
           [0032]      FIG. 13  depicts a diagram illustrating an exemplary portion of a transactor data structure illustrating integrity rules in accordance with the present invention; 
           [0033]      FIG. 14  depicts a diagram illustrating an exemplary portion of a transactor data structure in accordance with the present invention; and 
           [0034]      FIG. 15  depicts a block diagram illustrating an exemplary transactor implementation in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0035]    With reference now to the figures,  FIG. 3  depicts a pictorial representation of a network of data processing systems in which the present invention may be implemented. Network data processing system  300  is a network of computers in which the present invention may be implemented. Network data processing system  300  contains a network  302 , which is the medium used to provide communications links between various devices and computers connected together within network data processing system  300 . Network  302  may include connections, such as wire, wireless communication links, or fiber optic cables. 
         [0036]    In the depicted example, service provider  304  is connected to network  302  along with storage unit  306 . In addition, requesting partners  308 ,  310 , and  312  are connected to network  302 . These requesting partners  308 ,  310 , and  312  maybe, for example, personal computers or network computers. In the depicted example, server  304  provides data, such as boot files, operating system images, and applications to clients  308 - 312 . Requesting partners  308 ,  310 , and  312  are requesting partners to service provider  304 . Network data processing system  300  may include additional servers, clients, and other devices not shown. In the depicted example, network data processing system  300  is the Internet with network  302  representing a worldwide collection of networks and gateways that use the TCP/IP suite of protocols to communicate with one another. At the heart of the Internet is a backbone of high-speed data communication lines between major nodes or host computers, consisting of thousands of commercial, government, educational and other computer systems that route data and messages. Of course, network data processing system  300  also may be implemented as a number of different types of networks, such as for example, an intranet, a local area network (LAN), or a wide area network (WAN).  FIG. 3  is intended as an example, and not as an architectural limitation for the present invention. 
         [0037]    Referring to  FIG. 4 , a block diagram of a data processing system that may be implemented as a server, such as service provider  304  in  FIG. 3 , is depicted in accordance with a preferred embodiment of the present invention. Data processing system  400  may be a symmetric multiprocessor (SMP) system including a plurality of processors  402  and  404  connected to system bus  406 . Alternatively, a single processor system may be employed. Also connected to system bus  406  is memory controller/cache  408 , which provides an interface to local memory  409 . I/O bus bridge  410  is connected to system bus  406  and provides an interface to I/O bus  412 . Memory controller/cache  408  and I/O bus bridge  410  may be integrated as depicted. 
         [0038]    Peripheral component interconnect (PCI) bus bridge  414  connected to I/O bus  412  provides an interface to PCI local bus  416 . A number of modems may be connected to PCI local bus  416 . Typical PCI bus implementations will support four PCI expansion slots or add-in connectors. Communications links to clients  308 - 312  in  FIG. 3  may be provided through modem  418  and network adapter  420  connected to PCI local bus  416  through add-in boards. 
         [0039]    Additional PCI bus bridges  422  and  424  provide interfaces for additional PCI local buses  426  and  428 , from which additional modems or network adapters may be supported. In this manner, data processing system  400  allows connections to multiple network computers. A memory-mapped graphics adapter  430  and hard disk  432  may also be connected to I/O bus  412  as depicted, either directly or indirectly. 
         [0040]    Those of ordinary skill in the art will appreciate that the hardware depicted in  FIG. 4  may vary. For example, other peripheral devices, such as optical disk drives and the like, also may be used in addition to or in place of the hardware depicted. The depicted example is not meant to imply architectural limitations with respect to the present invention. 
         [0041]    The data processing system depicted in  FIG. 4  may be, for example, an IBM e-Server pSeries system, a product of International Business Machines Corporation in Armonk, N.Y., running the Advanced Interactive Executive (AIX) operating system or LINUX operating system. 
         [0042]    With reference now to  FIG. 5 , a block diagram illustrating a data processing system is depicted in which the present invention may be implemented. Data processing system  500  is an example of a requesting partner computer. Data processing system  500  employs a peripheral component interconnect (PCI) local bus architecture. Although the depicted example employs a PCI bus, other bus architectures such as Accelerated Graphics Port (AGP) and Industry Standard Architecture (ISA) may be used. Processor  502  and main memory  504  are connected to PCI local bus  506  through PCI bridge  508 . PCI bridge  508  also may include an integrated memory controller and cache memory for processor  502 . Additional connections to PCI local bus  506  may be made through direct component interconnection or through add-in boards. In the depicted example, local area network (LAN) adapter  510 , SCSI host bus adapter  512 , and expansion bus interface  514  are connected to PCI local bus  506  by direct component connection. In contrast, audio adapter  516 , graphics adapter  518 , and audio/video adapter  519  are connected to PCI local bus  506  by add-in boards inserted into expansion slots. Expansion bus interface  514  provides a connection for a keyboard and mouse adapter  520 , modem  522 , and additional memory  524 . Small computer system interface (SCSI) host bus adapter  512  provides a connection for hard disk drive  526 , tape drive  528 , and CD-ROM drive  530 . Typical PCI local bus implementations will support three or four PCI expansion slots or add-in connectors. 
         [0043]    An operating system runs on processor  502  and is used to coordinate and provide control of various components within data processing system  500  in  FIG. 5 . The operating system may be a commercially available operating system, such as Windows 2000, which is available from Microsoft Corporation. An object oriented programming system such as Java may run in conjunction with the operating system and provide calls to the operating system from Java programs or applications executing on data processing system  500 . “Java” is a trademark of Sun Microsystems, Inc. Instructions for the operating system, the object-oriented operating system, and applications or programs are located on storage devices, such as hard disk drive  526 , and may be loaded into main memory  504  for execution by processor  502 . 
         [0044]    Those of ordinary skill in the art will appreciate that the hardware in  FIG. 5  may vary depending on the implementation. Other internal hardware or peripheral devices, such as flash ROM (or equivalent nonvolatile memory) or optical disk drives and the like, may be used in addition to or in place of the hardware depicted in  FIG. 5 . Also, the processes of the present invention may be applied to a multiprocessor data processing system. 
         [0045]    As another example, data processing system  500  may be a stand-alone system configured to be bootable without relying on some type of network communication interface, whether or not data processing system  500  comprises some type of network communication interface. As a further example, data processing system  500  may be a personal digital assistant (PDA) device, which is configured with ROM and/or flash ROM in order to provide non-volatile memory for storing operating system files and/or user-generated data. 
         [0046]    The depicted example in  FIG. 5  and above-described examples are not meant to imply architectural limitations. For example, data processing system  500  also may be a notebook computer or hand held computer in addition to taking the form of a PDA. Data processing system  500  also may be a kiosk or a Web appliance. 
         [0047]    The present invention of composite business interactions, referred to herein as transactors, addresses these problems of mobile agents while providing a simple (quick and easy-to-use) framework. 
         [0048]    Composite interactions, as shown in  FIG. 6 , combine multiple request/response interactions allowed by the provider. This reduces latency since the client need only make one invocation instead of many. Further, it simplifies business logic while supporting disconnected operation. The composite asynchronous request is processed at the server business including logic that in the simple interaction scenario was at the client end. Thus, business A  602  submits both the request  1  and  2  in a request packet  606  that is sent to business B  604 . The request packet  606  includes code or information, as described more fully below, to specify how the requests are to be processed, such as in what order and conditions that are to be applied. Business B  604  then sends back a single acknowledgment packet  608  acknowledging both request  1  and  2 . Once business B  604  has finished processing the request, a single response packet  610  containing the results for both requests  1  and  2  is sent back to business A  602 . 
         [0049]    In a preferred embodiment, with reference now to  FIGS. 7A-7B , diagrams illustrating a transactor input and output message data structures are depicted in accordance with the present invention. A transactor input message  700  data structure sent by the requesting data processing machine to the recipient contains three parts: a message header  702 , and a payload consisting of a transactor  704 , and an input message set  706 . The specification of transactor follows the allowable composition rule and allowable request as specified in a service contract. 
         [0050]    The service contract formally specifies and describes the rules for interacting with a service. This formal description extends the service contract specification introduced in U.S. Pat. No. 6,148,290 issued Nov. 14, 2000 which is incorporated herein by reference and includes supported composition construct, specification of composite request and response format, and supported integrity rules constructs, e.g., transaction, and any additional constraints on request composition. The service contract also defines [as describes] allowable actions, request response relationship for each action and constraints on invocation of an action. 
         [0051]    The message header  702  includes such information as an identification and name of the sender (or requestor). The transactor  704  contains the actions to be performed by the recipient business data processing system and the relationships between the actions. Examples of actions are reservations and purchases. Examples of relationships include the order in which to process requested actions, whether to perform all or none of the requests in cases in which one request may fail, and branching dependencies in which one of two or more branches of actions is selected based on the result of another action. The input message set  706  includes input messages and identifications. For example, in the case of a request to reserve a hotel room, the input message may contain text or other information indicating that the hotel reserved should be a 5 star hotel or that the hotel should be close to the airport. 
         [0052]    The transactor output message  708  data structure sent by the recipient of the request to the requestor after the request has been processed includes a message header  710 , transactor  712 , and output message set  714 . The message header  710  includes, for example, an identification and name of the sender of the request. The transactor  712  includes the actions and relationships as received from the transactor input message  700 , thus allowing the sender to verify that the results received correspond to the actions and relationships specified in the request. The output message set  714  includes output messages and identifications which indicate the result of the requests as processed by the recipient. 
         [0053]    With reference now to  FIGS. 8A-8B , diagrams illustrating an exemplary transactor data structure input message and output message are depicted in accordance with the present invention. The message components of a transactor input message set  800 ,  820 ,  822 ,  824 , may be written in, for example, a markup language such as, extensible markup language (XML), hypertext markup language (HTML), or other language, such as, for example, electronic data interchange (EDI). The input message ID  802  is “Air-reserve” and the message is reserve an airline. Input message ID&#39;s  803  and  806  are “Hotel 1-reserver” and “Hotel2-reserver” respectively with corresponding messages instructing recipient business to reserve a hotel. 
         [0054]    Transactor output message  810  includes output message action ID&#39;s  812 - 816  that correspond to input message ID&#39;s  802 - 806  thus informing the sender as to which input message  820 - 824  each output message  830 - 834  corresponds. Each output message  830 - 834  provides the result or response to the corresponding input messages  820 - 824 . 
         [0055]    With reference now to  FIGS. 9A-9B , diagrams illustrating exemplary portions of a transactor data structure are depicted in accordance with the present invention. As discussed above, the transactor  704  includes a definition of relationships between actions. In  FIG. 9A , actions  904  and  906  are grouped as a combination which indicates that the recipient data processing system should perform both actions. In  FIG. 9B , the group type is labeled “selection” which indicates that the recipient of the request should do one or the other of actions  908  and  910 , but not both. Thus, in the depicted example, the recipient data processing system would reserve either hotel  1  or hotel  2  but not both. 
         [0056]    With reference now to  FIGS. 10A-10B , diagrams illustrating exemplary portions of a transactors data structure in  FIGS. 9A-9B  with additional criteria are depicted in accordance with the present invention. In  FIGS. 10A-10B , actions  1002 - 1008  are grouped as depicted. However, in addition to grouping the actions  1002 - 1008  as in  FIGS. 9A-9B , the actions are also ordered  1010 - 1012 . Thus by including the ordered  101 - 1012  instruction, the recipient of the request is instructed to perform the actions in the order listed. Thus, in  FIG. 10A , the action of “reserve airline” is performed before the action “reserve hotel  1 .” Thus, in  FIG. 10A , the recipient of the request performs both actions  1002 - 1004  but the actions  1002 - 1004  are performed in the order listed. In  FIG. 10B , the recipient first attempts to reserve hotel  1  and then, if unsuccessful, attempts to reserve hotel  2 . Therefore, a business, person or other entity can specify a preferred hotel as well as alternative hotels if the preferred hotel is unavailable. 
         [0057]    With reference now to  FIG. 11 , a diagram illustrating another example of conditions that may be placed in a transactor data structure is depicted in accordance with the present invention. In this example, the transactor includes actions  1108  and  1110 , a group type  1102 , an indication  1104  of whether the actions  1108  and  1110  are ordered and an indication if the actions are atomic  1106 . The group type  1102  is “combination” which specifies that the actions  1108  and  1110  should be performed as a combination and that if either action  1108  and  1110  fails, the entire action fails. The ordered  1104  criteria in the depicted example is “yes” indicating that action  1108 , reserve airline, should be performed before action  1110 , reserve hotel  1 . The atomic  1106  criteria in the depicted example is “yes” indicating that the actions  1108  and  1110  cannot be broken up into any smaller subgroups. 
         [0058]    With reference now to  FIG. 12 , a diagram illustrating a portion of a transactor data structure illustrating hierarchical groups is depicted in accordance with the present invention. In this example, the recipient of the request is instructed to perform action  1202  first and then perform one of either action  1204  or action  1206 . This is because action  1202  is grouped in “combination” with actions  1204  and  1206 , but actions  1204  and  1206  are grouped with group type “selection” indicating that only one of actions  1204  and  1206  is to be performed. Furthermore, because actions  1204  and  1206  are ordered, the recipient attempts to perform action  1204  first and then, if that fails, to perform action  1206 . With hierarchical grouping a complex request can be easily composed. 
         [0059]    With reference now to  FIG. 13 , a diagram illustrating an exemplary portion of a transactor data structure illustrating integrity rules is depicted in accordance with the present invention. Integrity rule specifies a constraint that must be satisfied during the execution of a request group. In addition to other rules as discussed above, the actions  1302 - 1308  may be grouped by integrity rule. In the depicted example action groups  1310  and  1312  are grouped with group type “selection” indicating that only one of the actions groups  1310  and  1312  will be performed. Thus, in the depicted example, the actions  1302 - 1304  are grouped together as a combination with an integrity rule of all-or-fail. Thus, both actions  1302 - 1304  are performed, however, if one of the actions fails, both actions fail. If action group  1310  fails as a result of either action  1302  or action  1304  failing, then action group  1312  is performed. Action group  1312  is also grouped by integrity rule indicating that both actions  1306  and  1308  should be performed or none performed. The “all-or-fail” integrity rule is just one of many types of integrity rule. Other types of integrity rules may include a rule that at least one of the actions is performed. 
         [0060]    With reference now to  FIG. 14 , a diagram illustrating an exemplary portion of a transactor data structure is depicted in accordance with the present invention. In this example, the concept of input/output (IO) redirection is illustrated with two actions  1408  and  1410 . Each action  1408  and  1410  includes an action ID  1402  and  1404  and an input ID  1412  and  1406 . The input to action  1410 , pay for reservation, is the action ID  1402  for action  1408 , reserve hotel  1 . Thus, this ensures that the step of paying for the reservation credits the appropriate entity. 
         [0061]    With respect to  FIG. 15 , a block diagram illustrating an exemplary transactor implementation in accordance with the present invention. In the depicted example, a transactor  1502  (i.e., the recipient of the action request, such as business B in  FIG. 5 ), receives a transactor consisting of two requests tid- 1  and tid- 2  each with a unique identifier. The initiator  1506  of the transaction requests tid- 1  and tid- 2  contains persistent storage  1508  to store the parameters related to the requested actions. Transactor  1502  stores the request in persistent storage  1504  and executes the various requests which may involve sending requests to other data processing systems. The action responses  1510  from other data processing systems may be stored in persistent storage  1512  in each of the other data processing systems. Furthermore, the action responses  1510  received by transactor  1502  may be stored in persistent storage  1504 . 
         [0062]    In addition to storing the transactor requests received by transactor  1502 , persistent storage  1504  stores the results of intermediate stages of the process as well as an indication of which step needs to be performed next. Furthermore, if a system failure occurs or one of the steps fails, the entire set of actions responses previously processed is not lost. Each action to be performed by transactor  1502  need not be synchronized if there is no order specified. 
         [0063]    By grouping multiple requests into a single request packet with definitions defining the relationships between request actions, such as which action to perform first and dependencies upon other actions, a user may save significant time in not needing to await a response from one request before sending another request or choosing a course of action. Furthermore, by structuring the requests as described above, the security of the system processing the requests is not compromised since arbitrary code is not executed on the responding system, but rather only a limited number of well defined actions are performed. Furthermore, the requests received by the data processing system comprise high level actions that need to be executed such as, for example, purchasing airline tickets, and do not constitute code that is executed on the target machine. Rather, the target machine interprets the request and executes the requests using its own code that is independent from the representation of the requests. Thus, two different computing systems could be configured to read the same set of requests, but would execute the requests with different code and in different manners. 
         [0064]    Although the present invention has been described primarily in the context of processing requests sent between data processing systems via a network, the transactors utilized in sending these requests could also be utilized locally within an individual data processing system for ease of expression of higher level business logic. Thus, a user may simply express business objectives or goals in the higher logic of the transactor, and the local system then interprets the transactor in order to perform actions necessary in implementing the business objective or goals. This eliminates the need for the user to be familiar with the particular coding required on a machine for implementing the business objectives, and allows the user to focus his or her efforts on the larger picture. Note in this scenario, there may not be any explicit contract with local system. 
         [0065]    It is important to note that while the present invention has been described in the context of a fully functioning data processing system, those of ordinary skill in the art will appreciate that the processes of the present invention are capable of being distributed in the form of a computer readable medium of instructions and a variety of forms and that the present invention applies equally regardless of the particular type of signal bearing media actually used to carry out the distribution. Examples of computer readable media include recordable-type media, such as a floppy disk, a hard disk drive, a RAM, CD-ROMs, DVD-ROMs, and transmission-type media, such as digital and analog communications links, wired or wireless communications links using transmission forms, such as, for example, radio frequency and light wave transmissions. The computer readable media may take the form of coded formats that are decoded for actual use in a particular data processing system. 
         [0066]    The description of the present invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiment was chosen and described in order to best explain the principles of the invention, the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.