Abstract:
This invention relates to a method and apparatus for controlling multi-node services. There is described a process broker for controlling a process between two or more clients and service registry comprising; a plurality of process templates, each process template representing a process to co-ordinate a service on nodes and comprising one or more steps for coordinating such a service with each node; means for receiving a message from a first node; means for selecting a process template and participating node/s in response to the message; means for envoking the process steps as defined in the selected process template on the selected nodes; and means for responding to the first node with a response of the type defined in the selected process template and based on the response from the participating node/s.

Description:
This invention relates to a method and apparatus for controlling a multi-node process. In particular it relates to a broker system which controls a process between two or more client systems. 
     BACKGROUND 
     Web services describe the set of protocols and technologies that enable applications to communicate with each other over the internet. They are part of the e-business framework that relate to bringing commercial services into the internet world with the same quality of service that one would expect from traditional services. 
     A simple web service involves two parties, a client and a server connected over the internet. The client sends a request over the internet to the server; the server processes the request and sends a response back over the internet to the client; and the client receives the information. Such information could be a weather forecast. 
     A more complex web service involves multiple nodes such as shown in the prior art of  FIG. 1 . A client  12  (seller) sends and receives messages from a client  14  (buyer) in order to receive a payment from the client  14 . A payment service  18  makes payments on behalf of client  14  and payment service  16  receives payments on behalf of client  12 . In this example client  12  requests payment from client  14 ; client  14  passes the request to payment service  18 ; payment service  18  prepares a payment order which is forwarded through client  14  and client  12  to payment service  16 ; payment service  16  sends a message to client  12  if the payment order is excepted. 
     In the above service a process of fixed steps is defined in each node where each node co-ordinates the next step in the process. Knowledge of the process steps is held in each node. Each node only knows how to perform certain steps in the process on its own or with another node. Each step in the process leads to a further step in the process whereby the process is not defined centrally but across the group of nodes. Once a node has finished its own step in the process it will trigger the next node to start the next step. In this example the node has some control but not individual control of the process. 
     Such a distributed process is fixed to that process and those nodes. What is required is a solution where a client can choose a process and choose the nodes to be included in that process. 
     SUMMARY OF INVENTION 
     According to a first aspect of the present invention there is provided a system for controlling a process between two or more nodes as defined in claim  1 . 
     Such a system is called a process broker in the preferred embodiment. A node (called a client in the preferred embodiment) is preferably configured to exclusively interact with the process broker and not with other nodes so that no node can perform processes on that exclusive node without the interaction of the broker. Preferably, such a broker becomes a trusted party. Most preferably, using such a broker system, multiple sub-processes which form part of an overall process are given a single point of focus. 
     Preferably, such a system provides a simple command orientated interface for application developers to enable a client to interact with any predefined service without the knowledge of how actually to interact with that service. Such knowledge is stored within the system. 
     Preferably, the nodes may be one of a number of computer system types. The first node may be a client for envoking a process to buy a product or a service. The second node may be a client with goods or services to dispose of. Another node may be a payment service for the first node and the second node. A further node might be a service registry for locating connection details of the node e.g. the payment service. 
    
    
     
       DESCRIPTION OF DRAWINGS 
       A preferred embodiment of the invention will now be described, by means of example only, with reference to the accompanying figures in which: 
         FIG. 1  is a schematic overview of a multi-node prior art payment process; 
         FIG. 2  is a schematic overview of a multi-node payment process of the present embodiment; 
         FIG. 3  is a schematic diagram of the main components of the process broker of the present embodiment; and 
         FIG. 4  is a multi-node process flow of a payment process template. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The components of the whole system of nodes is described with reference to  FIG. 2 . There is shown client  40  and client  42  connected via a network or networks to process broker  10 . Also connected to process broker  10  are payment service  44 ; payment service  46 ; and service registry  48 . 
     Client  40  stores relevant data in secure store, in this case the relevant data is the name of its payment service  44  and account details held by the payment service  44 . Client  40  and  42  are capable of sending and receiving data to and from the process broker  10 . In this embodiment client  40  is a WAP enabled mobile phone using WAP transport protocol to communicate with the process broker  10 . Client  42  communicates with the process broker  10  via the common network protocol which is HTTP. 
     Service registry  48  contains connection details of the payment service  44  and  46 . Such connections details are acquired by the process broker  10  using a node name supplied by the clients. 
     The network connects all the nodes including the clients, broker and service registry that use the service. The process broker  10  has multiple network transport capability and uses a common HTTP protocol over a network to co-ordinate the web services. 
     Process broker  10  is capable of executing services and is shown in more detail in  FIG. 3 . In this embodiment the process broker is built using IBM® WebSphere® Business Process Beans and runs on an IBM Websphere Web Application Server. However any language or platform may be used if it can run, execute, process and invoke services. The function of the process broker  10  is to store process templates; execute those process templates; maintain state of execution; and handle data between execution steps. Examples of process templates are described. 
     The process broker  10  comprises process engine  30  and process template repository  32 . Process engine  30  comprises the body of the components: message listener  34 ; message sender  35 ; process interpreter  36 ; process execution  37 ; security  38  and protocol converter  39 . Process template repository  32  comprises process template  1  (the payment process template); process template  2  (the payment process template with encryption) and payment process template  3  (the exchange of digital goods for payment). 
     Message listener  34  receives messages from the nodes. This component is capable of receiving messages (whether requests or responses from parties) over whatever transport protocol is used. If the protocol is not the common protocol, but a different protocol, then the protocol convertor  39  is called to convert the different it protocol message. The different protocol is stored so that subsequent messages can be converted different protocol. Message listener  34  distinguishes messages which are part of a current process and those which are requesting execution of a new process by identifying a session id or lack of one in the message. If there is no session id then the message is passed on to the process interpreter  36 . If there is a session id then the message is passed on to the process execution  37 . 
     Message sender  35  transmits messages to the nodes. This component is capable of sending messages (whether requests or responses from parties) over the HTTP transport mechanisms. Normally each message will contain a session id which can be included in the response to show that the message is part of an on going process. If it is known that the receiving node supports a different protocol and does not support the common protocol then the protocol convertor  39  is called to convert to that different protocol before the message is sent. 
     Process interpreter  36  parses a message with no session id to identify if the message is to initiate a session with process execution  37 . It then identifies a process template and parameters from the message (including nodes) for subsequent execution by the process execution  37  and assigns a session number for the processing of the process template. 
     Process execution  37  parses the steps in a selected process template and calls various methods. It also parses responses from nodes if they contain a session id. It counts the steps in the template and executes each one sequentially. Four main methods are described here: internal method; call node method; node address method and role management method. The internal method may be any one of the many internal methods for example mathematical operations, logical operations, string operations, local method calls. The call node method uses message sender  35  to communicate with a node and request a service be performed. This method needs a node address. On returning from a call node method the response is stored and used in the processing of further steps. Node address method acquires a node address by sending a node name to a service directory. This method is invoked when only a node name is given by the initiating or subsequent clients. The role management method to allocate node names to roles and is used when a node name is not directly referenced in a process template. A process template defines a process in terms of roles e.g. source node; target node; payment service of target node. The role management method allocates the roles to specific nodes from the parameters supplied in the first and subsequent messages from the nodes. 
     Security component  38  identifies requests for a secure process. The process broker  10  itself does not use nor need to use any encrypted data except to pass it on to the relevant node. 
     The security component comprises methods for: identifying a request for a secure process template and selecting such a secure process template; identifying a secure process in process template. 
     A process template is the term used here to describe a generic interaction between one of more nodes. Such a description is used by the system to co-ordinate a web process between the nodes. The process template is described in a language suitable for execution by the system, it defines a particular process for achieving a specific goal between multiple nodes, such as a payment process or an exchange of goods process. The process template defines the information that needs to be gathered and exchanged, which roles must be played in the process by a given set of parties, and the steps that need to be taken to achieve the overall goal. Example roles that might be defined in a process template to describe a “Payment” are “Buyer”, “Seller”, “Banker”. In web service terms, a process template comprises one or more sub-processes, each sub-process describing a web service interaction. 
     When a process template is interpreted and executed by the process broker, it becomes a running instance of the process it describes, and the roles defined in it must be bound to actual participating parties, whether these are clients of the processes broker, or services the process broker uses, or is told to use by clients. 
     A process template in the preferred embodiment of the invention is static in the sense that it is stored in a database with other process templates in the system and remain unchanged during execution. 
     Sensitive details are needed in some processes whereby one desires to restrict the access to sensitive details for some parties involved. 
     Protocol converter  39  comprises methods for, when receiving messages from a client, converting the message transport protocol to the common protocol if it is different from the common protocol; and for, when sending a message to a client, converting the message transport protocol to the client&#39;s transport protocol if the client uses a different transport protocol. 
     Encryption techniques can deal with the problem of sensitive details encountered in multiple node systems. Domains of trust exist between like nodes and related nodes, for instance in the embodiment they exist between clients; between a client and their payment service; and between payment services. One situation is when each client has the same level of trust and sees all data for each node. Another situation is when communication between the client and its respective payment service is encrypted with keys known only to the client and that node, no other node is aware. Another situation is when two payment systems are aware of each other and will have exchanged public encryption keys independently or through the broker; therefore data sent through the broker so encrypted will be unknown to the broker. In this third case, the broker is only a semi-trusted third party process co-ordinator because it is allowed to pass on the sensitive data but does not know what it is. 
     In this last case the messages are partially encrypted because only the sensitive data is encrypted and the message is unencrypted. Such a solution has been addressed by the IBM MQe product, where partial encryption of documents and message level encryption is possible so that messages can be routed through nodes without the risk of them being visible to intermediary nodes. However, this product is purely a messaging platform and is the basis for building processes such as the embodiment. IBM MQe operates in a homogeneous environment where MQe is present at each node (in this case the client, payment service and all services to be invoked). 
     A heterogeneous system has a common network transport protocol. The process broker has a substantially common network transport protocol to co-ordinate a process but also comprises means for converting protocols to and from the common protocol if one node does not support the common protocol. Since the process broker is at the centre of the process it is an ideal position to perform such a function and allows the nodes to remain thin and to communicate using their native transport protocol. 
     Two example process templates are described in this embodiment. Each of these process templates are stored in the process template repository  32 . Process templates define services using standard interface definitions. This database of processes templates can be referenced by type and retrieved for interpretation and execution by the Process Engine  30 . 
     The payment process template of  FIG. 4  transfers an electronic payment order directly from a payment service of a client  42  to a payment service of the client  40 . For instance a pair of clients are doing business, and a payment of $1 is required to occur between them. Client  40  (the Seller) wants payment from Client  42  (the Buyer). 
     In Step  401  client  40  sends a request and data to process broker  10 . The request data (C 40  data) contains the name of Client  40 &#39;s Payment Service details (Payment Service  44  where a payment can be made to), the amount to be paid ($1), and a reference to Client  40  that the process broker  10  will understand (e.g. client  40 &#39;s node name or address). No session id is included in the message. 
     In step  402  process broker  10  receives the message via message listener  34 . Message listener  34  identifies that there is no session id and passes it to process interpreter  36 . Process interpreter  36  parses and selects the payment process template as directed by the request. The process interpreter  36  retrieves the process template for a payment process from the process template repository  32  and passes the process template to process execution  37 . Process execution  37  executes that process template using the request data sent as input to the process. The process execution  37  identifies the initiating role in this process template as the Seller, and binds the client  40  to that role using the role management method. The process execution  37  also binds three other roles in the process: Buyer to Client  42 ; BuyerBankingService to Payment service  46  and SellerBankingService to payment service  44 . The SellerBankingService is specified in the request data (C 40 ) and is bound to PaymentService  44  by the process interpreter  36  in this step  402  whereas the BuyerBankingService is bound after step  404 . 
     Step  403  is the first step of the process template as executed by the process execution  37  and this step requests associated data from client  42 . The first process step is defined in terms of a request document for banking service details from the Buyer role. The Buyer role has previously been resolved as client  42  as the input data specifies Client  42 . 
     Client  42  receives the request document and respond by specifying that payment service  46  is the BuyerBankingService based on the seller data (amount=$1). Client  42  adds its own data (C 42  data) to the request document based on client  40 &#39;s data and sends it back to process broker  10 . 
     In step  404  process execution receives a request document from client  42 . In this step process execution calls the role management method and payment service  46  is bound to the BuyerBankingService role after receipt of the client  42  data by the process interpreter  36 . 
     In step  405  process execution calls the service registry  48  if there is a need to acquire node addresses for the payment service  44  and  46 . This process step requests payment service  44  &amp;  46 &#39;s connection details from the service registry  48 , as these are bound to the roles for SellerBankingService and BuyerBankingService respectively. 
     In step  406  process execution  37  sends a request document (buyer details, seller details, amount) to client  42 &#39;s payment service  46  for a payment order to be made out, payable to client  40 . 
     In step  407  process execution  37  receives a payment order from the service registry  48  if all details in order. 
     In step  408  the next flow step in the process template deposits payment order in client  40 &#39;s payment service  44 . 
     In step  409  payment service  44  indicates success or failure and step  410  the last flow step in the process template returns status to client  40 . 
     The second example of a process template is for a more complex process flow involving the exchange of digital goods for payment. No figure is shown for this process as it is the same as  FIG. 2  plus a digital rights management (DRM) node. 
     A pair of clients are doing business. Client  40  (the Seller) wants payment from client  42  (the Buyer) for the amount of $5. In exchange for this, client  40  will transfer ownership of a digital asset, a music file encoded in the MP3 format and protected with a Digital Rights Management (DRM) system run by the music publishing company (DRMService A) that created the music file. 
     Step 1. client  40  sends an “ExchangeGoodsForPayment” request to the Broker specifying its payment service details (PaymentService  44 ), its DRM service name (DRMService A), a reference to the music file known by the DRM service (MP3-A) and Client  42 &#39;s session ID.Step 
     Step 2. The process broker  10  retrieves the ExchangeGoodsForPayment Process Template and binds the supplied data to the appropriate Roles—Buyer, Seller, SellerPaymentService and DRMService. 
     Step 3. The first process step requests banking service details from the Buyer role. The process broker  10  sends a request for this information to client  42 . 
     Step 4. Client  42  receives the request and responds by specifying that payment service  46  is their banking service. Payment service  46  is bound to the BuyerBankingService (the last Role in the Process Template). 
     Step 5. In the next process step, the process broker  10  requests payment service  44  &amp;  46 &#39;s connection details from the service registry  48 , as these are bound to the roles for BankingServices for Seller and Buyer respectively, and the connection details for DRMService A, as this is bound to the DRMService role. 
     Step 6. In the next process step, the process broker  10  sends the composite request to payment service  46  (Buyer details, Seller details, amount) for a payment order to be made out, payable to the Seller. 
     Step 7. The payment service  46  returns a valid payment order to the process broker  10  if all details are in order. 
     Step 8. In the next step, the process broker  10  sends the payment order to payment service  44  to verify that the payment order is valid and acceptable. 
     Step 9. In the next step payment service  44  returns to the broker  10  an indication that the payment order is valid. 
     Step 10. The process broker  10  now sends a request to the DRMService A to change ownership of the virtual asset (MP3-A) from client  40  to client  42 . 
     Step 11. The DRMService A responds to the process broker  10  by confirming that the change of ownership is actioned, but needs committing to complete. 
     Step 12. The next process template step sends the payment order to payment service  44  as a deposit to be fulfilled. 
     Step 13. Payment service  44  indicates success or failure. 
     Step 14. If the result is failure, then the process broker  10  sends a request to the DRMService A to cancel the ownership change, and sends a failure response back to client  40 . However, if the result is success, then the process broker  10  returns a successful status to client  40  (Payment successfully made and asset ownership transferred). 
     The process broker  10  is described in terms of Business Beans but could be implemented in any number of ways suitable for executing process models e.g. a finite state machine, a directed graph interpreter, etc. For instance, Business Process Beans could use an adaptive business service model, whereas a directed graph flow engine such as IBM MQSeries Work Flow (MQWF) would use Flow Definition Modelling Language (FDML).