Patent Publication Number: US-7222165-B1

Title: Service provision support system

Description:
BACKGROUND 
     1. Field of Invention 
     This invention relates to a telecommunications service provision support system, which supports a plurality of different types of services provided in the form of service-specific data processing during a service session. 
     2. Description of Related Art 
     It has been known for service providers to provide different types of services via a retailer party to customers, thereby simplifying the access to services at least from the customers point of view. 
     The price charged to a customer is determined by parameters and pricing schemes set by the service provider. The service provider generates a notification of the price to be charged for the provision of a particular type of service, which may be actually charged by the service retailer. Service providers therefore implement pricing logic within their services. 
     The paper “Operational Support Systems For The Future”, D Freestone and M Owen, BT Technology Journal, Vol. 14, No. 3, July 1996, describes an operational support system (OSS) which provides pricing and billing functions along with other functions such as provisioning, portfolio management and customer help. The paper proposes an approach for delivering flexible, inter-operable business services, and standardised application programming interfaces (APIs) to allow information services from multiple service providers to be packaged together via common interfaces. Notably, the pricing functionality described include the information services generated streams of chargeable “events”. “Events” in this case are only generated by the information services provider if they are considered chargeable, and the choice of such chargeable events is made at the time of construction of the service. The pricing options exemplified include a subscription-type pricing policy, which is known to be a one-off chargeable event. A further policy type is a policy of pricing by content, which requires the number of units of the content to be known from the event parameters. A further policy type exemplified is pricing by duration, which requires the start time and end time to be known from the event parameters. 
     In this regard, chargeable events, other than subscription-type events, have in the past been generated not as a record of an instantaneous event, but as what as may be referred to as a “combined” event, generated when instantaneous events are logically combined. For example, in conventional telephony, a chargeable event is recorded in a call record, which specifies the duration of the call by means of both a start time and an end time. In this sense, the chargeable event recorded in the call record is a “combined” event, consisting of data specifying more than one instantaneous event. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with an aspect of the present invention there is provided a communications service provision support system which supports multiple different types of services during service sessions, 
     said system when in use comprising a session manager which performs functions generic to each of said multiple different types of services during service sessions; 
     wherein for each of said multiple types of services, said session manager is arranged during a service session, in which a plurality of participants participate, to generate event messages indicating discrete changes in the session-related status of individual users of the system and to transmit said event messages to an event handler for processing. 
     By the session manager generating event messages indicating discrete changes in the session-related status of users during a service session, the need for the preselection of chargeable events by the service provider may be alleviated. Instead, by filtering events from a known set of events notified by the session manager, and/or logically combining events generated from that set, pricing and/or costing of usage during a service session may be performed independently of the service provision. 
     Furthermore, the events generated by the session manager may be automatically forwarded for logging and subsequent analysis in a service usage analysis engine. 
     In accordance with a further aspect of the invention there is provided a method of notifying events occurring during a multi-party service session in a communications service provision support system, said method comprising: 
     generating a plurality of event messages during a service session in which a plurality of participants participate, each said event message being generated in response to a discrete change in the session-related status of individual users of the system; and 
     transmitting said event messages to an event handler for processing. 
     In accordance with a yet further aspect of the invention there is provided a method of generating billing records for participation in a service session, in which a plurality of participants participate, provided by a telecommunications system, 
     said method comprising: 
     receiving event messages indicating discrete changes in the status of individual participants in said service session; and 
     generating a plurality of billing records each containing data indicating a charge for a different individual participant&#39;s participation in said service session, wherein a billing record indicating a charge for a particular participant&#39;s participation in said service session includes data derived from discrete changes in the status of other participants in said service session, 
     such that the charge indicated for said particular participant is dependent on a change in status of said other participants during said service session. 
     By allowing the changes in status of other participants to affect a charge to be made for participation by a particular participant, novel and utile tariffing structures may be implemented for multi-party services. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings wherein: 
         FIG. 1  is a schematic block diagram of a telecommunications system in accordance with an embodiment of the present invention; 
         FIG. 2  is a schematic block diagram of system components in the client, retailer and service provider domains of the system illustrated in  FIG. 1 ; 
         FIG. 3  is a schematic block diagram illustrating an embodiment of the arrangement illustrated in  FIGS. 1 and 2 , consisting of interrelated software objects; 
         FIG. 4  is a diagram schematically illustrating a session lifecycle in accordance with an embodiment of the present invention; 
         FIGS. 5 to 13  illustrate interactions between the objects illustrated in  FIG. 3  during various procedures causing a change in the status of a user of the system; 
         FIG. 14  is a schematic block diagram illustrating software objects interactions in an event pricing engine in accordance with an embodiment of the present invention; and 
         FIG. 15  is a schematic block diagram illustrating the handling of events by an event router in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       FIG. 1  is a block diagram illustrating a telecommunications system in accordance with an embodiment of the present invention. The system consists of a retailer server RS and a plurality of third party servers TPS 1 , TPS 2  . . . TPSn. User terminals T 1 , T 2  . . . Tn are connected to the retailer server RS via a data communications network, in this embodiment the Internet. 
     The third party servers TPS 1 , TPS 2  . . . TPSn are either remotely connected to the retailer server RS via communication links  2 , which may be separate physical links and/or logical links, as shown, or are co-located with the retailer server RS. 
     Each third party server has access to a database TPDB 1 , TPDB 2  . . . TPDBn for the storage and retrieval of service-related data. 
     Although the servers RS TPS 1 , TPS 2  . . . TPSn are illustrated in  FIG. 1  as consisting of single servers, each may consist of one or more servers interconnected in a network. The servers may each be implemented on a computing resource, such as a workstation computer. Each of the user terminals T 1 , T 2  . . . Tn may be implemented in the form of a workstation computer, a net computer, a mobile communications terminal, etc. 
       FIG. 2  schematically illustrates further details of the telecommunications system, exemplifying components present in a single user terminal, the retailer server and a single third party server. On the client side, a service browser application program  4  provides access and support to a range of services provided by the various third party servers TPS 1 , TPS 2  . . . TPSn via the retailer server RS. The retailer server RS includes an access control part  5 , whereby a client terminal may initially access the service provision system, an authentication part  6  whereby users of the system may be authenticated such as by means of a password checking procedure, and a subscription part  7  which maintains subscription data for users of the system. 
     During participation in a service the client terminals, the retailer server and the third party server include application program parts, including on the client side, a service-specific application program part  8 , on the retailer side, a session control application program part  9  and on the service provider side, a service control application program part  10 . 
     The retailer server, or server network, also includes an event handler  11  which handles events generated by the session control application part  9  during a service session. 
     It is to be understood that the separation into retailer and service provider domains illustrated in  FIG. 2  is not necessarily a physical division, or a division of ownership or control between different servers. For example, the service provider service control part  10  may be held on a server controlled by the retailer, such as that holding the retailer server RS itself. 
       FIG. 3  illustrates an embodiment of the invention in which the system is implemented as a software object system. A description of object-oriented software concepts may be found in “Design Patterns: Elements of Reusable Object-Oriented Software”, Erich Gamma et al., Addison-Wesley, ISBN 0-201-63361-2, and the bibliography references given therein. 
     In this embodiment, each of the computing elements T 1 , T 2  . . . Tn; RS; TPS 1 , TPS 2  . . . TPSn illustrated in  FIG. 1  is supported by a distributed processing environment (DPE), whereby distributed software objects in different physical parts of the system may interact by the passing of messages, for example using CORBA (Common Object Request Broker Architecture) mechanisms, via data communications links. 
     In the following, reference will be made to the object-oriented language Java (trade mark), which is not intended to be limiting. Other, and indeed heterogeneous mixtures of object-oriented languages may also be used to implement the system. 
     The distributed object system includes service generic code and service specific code, which is distributed between the client side and the server side during a service session. The part of the system including service generic code is referred to herein as the service provision support system. 
     Service specific code in the client domain is referred to herein as a “front” object. The front object in this embodiment is a Java applet which runs on the client machine. The front object  13  communicates with other system objects, to support and control a user&#39;s participation in a session. The front object  13  also provides the service specific front end functionality, such as the service GUI and handling user input relating to the service. 
     Service specific code in the service provider domain is referred to herein as a “back” object. The back object  32  represents the session and its participants within the service provider domain and may interact with other back end systems, such as servers and databases in the service provider domain. It co-ordinates the interaction between participants in a session and stores service specific state while a participant is suspended. The back object  32  can also exert control over a session, for example it can initiate suspend and exit for one or more participants. A possible implementation of the back object  32 , in which objects control the service session and the service provided to individual participants in the service session, is described in our copending International patent application, filed on even date herewith and entitled “Multiple Service Provision” (agent&#39;s reference J40600), the contents of which are incorporated herein by reference. 
     Client Domain Software Objects 
     A retail workspace object (RWS)  12  runs on the client machine and provides the client with a means of accessing services. 
     The RWS  12  may be a downloadable Java applet which runs in a known Java-enabled browser, or a stand-alone Java application program. The RWS allows the user to log on to the service session control system, to access service sessions by downloading front objects  13  and to log off via a GUI. 
     The RWS  12  is multi-threaded to allow front objects  13  to be used in parallel, both with each other and with the RWS  12 . For example, a user may participate in two services simultaneously and at the same time receive, via the RWS  12 , an invitation to join a third service. Thus, a user may have multiple front objects  13  of the same or different services running simultaneously on the client terminal. 
     When the user exits or suspends a session the front object  13  is destroyed. 
     Retailer Domain Software Objects 
     A gateway object  14  provides an initial point of contact for user access to the system. It mediates the authentication of the user&#39;s identity and password with the RWS  12 . Thereafter, the RWS  12  connects to a user account object  18  and the gateway plays no further part. 
     The gateway  14  is multi-threaded to ensure availability. That is to say, during the processing of a logon request received from one client terminal, the gateway  14  is able to process logon requests arriving from, different client terminals. 
     A user administration object  16  provides functionality to create new user accounts. 
     The user account object  18  serves as a single user&#39;s account within the  010  retailer domain. It holds or obtains a record of all the services to which the user is subscribed. The user account  18  also receives and stores, or obtains as needed, information from other objects in the retailer domain about any suspended sessions the user may have, all public sessions available and any session invitations the user may have received. 
     The user account object  18  also mediates interactions between the RWS  12  and the remainder of the retailer domain to start, join and resume sessions. It handles notifications from a session object  30  that sessions have been suspended or ended. 
     User account objects are present in the retailer domain even when the users which they represent are logged off the system. 
     A user account manager object  20  creates and maintains the user account objects  18  and provides a reference to the appropriate user account object  18  when a user logs on to the system to start a communications session with the retailer server RS. 
     An authentication server object  22  uses stored user authentication data to authenticate log on requests. 
     A service provider portfolio object (SPP)  24  maintains information on available services, including the service provider identities and their network addresses, and which session manager  28  is to be used to support a service (this allows loads to be managed across a plurality of session managers  28 ). 
     A session manager object  28  prompts a session factory object  26 , and a back factory object  34  (which is in the service provider domain) to instantiate session objects  30  and back objects  32  to support service sessions and then mediates between the user accounts  18 , the session objects  30  and the back objects  32  to support further service interactions (e.g. invite, join, suspend, resume). There is one or more session manager objects  28  in the system. 
     The session object  30  is a service generic object (i.e. an object used in multiple different types of services) which controls a service session and co-ordinates the interaction of the objects involved in that session. It handles generic session behaviour such as invitations and suspensions. For example, when a client front  13  suspends a user&#39;s session, the session object  30  responds by calls on the user account  18  and the custom back  32  and by transmitting an event message to the event handler  31 . 
     There is a single session object  30  instantiated per service session being controlled by the system. The session object  30  is created when the first participant starts the session and is destroyed when the last participant exits the session. The session object  30  is otherwise not destroyed, even if all its participants are suspended. 
     An event handler  31  is arranged to receive event messages generated by other objects in the retailer domain, in particular the user accounts  18  and the session objects  30 . 
     Service Provider Domain Software Objects 
     The back factory  34  instantiates back objects  32  at the initiation of the session manager  28 . 
     There is a single back object  32  per session object  30 . Each back object  32  exists only as long as the session object  30  handling the same service session exists. 
     It should be mentioned that objects in the service provision support system, in particular the gateway  14 , the user account manager  20 , the authentication server  22  and the service provider portfolio  24  may consist of multiple federated copies forming a single logical object, in order to provide scalability of the system. 
       FIG. 4  illustrates an example of a session lifecycle. The session is begun when a first participant (participant 1) starts the session. Throughout the lifetime of the session, various numbers of participants may join the session, suspend, and exit the session. The session exists until the last participant (in the example shown, participant 3) exits the session, when the session terminates. 
       FIGS. 5 to 13  illustrate interactions between objects in the system during changes in the session-related status of a user of the system. Messages sent between objects are indicated by solid arrows, and are numbered to indicate the sequence in which the messages are sent. Event channels (indicated by dotted solid arrows) are used in various cases by the session object  30 . Messages are sent by event channels to avoid blocking the session object  30 , as would occur if request-response procedures were used, and which would impact on the service to other participants. 
     Several of the interactions between the RWS  12  and the user account  18  identify particular session instances. Passing direct references to the session objects  30  to the RWS  12  may compromise security. To avoid this, the sessions are identified by the RWS  12  using stored “cookie” references, previously passed to it by the user account  18 , whereby the user account  18  is able to identify the actual session object  30  being referred to. 
     For clarity, the objects not involved in the interactions being described are omitted from  FIGS. 5 to 13 . 
     Referring to  FIG. 5 , the gateway  14  is the initial point of contact for user access to the system. The RWS  12  initiates a data communications session with the gateway and sends a logon message with the user name and password supplied by the user. Provided these values are authenticated by the authentication server  22 , the gateway  14  then retrieves a reference to the user&#39;s user account from the user account manager  20  and then contacts the appropriate user account  18  to confirm that the user is now logged on. The user account  18  transmits a message to the event handler  31  informing it of the logon event. 
     Further interaction then takes place between the RWS  12  and the user account  18  where the user account  18  returns user profile information including subscribed services, suspended sessions, public sessions and invitations received, access to which information the RWS  12  then makes available to the user via the client terminal. 
     Referring to  FIG. 6 , when the user initiates a session via the client terminal, the RWS  12  sends a session starting message to the user account  18  specifying the service requested. In order to create a front object  13 , the RWS  12  spawns a thread to download the appropriate front object, and downloads the appropriate front object  13  for the service from the retailer server RS. 
     The user account  18  obtains details for the service requested from the SPP  24 , including the identity of the session manager  28  to support the service session, and sends a message to the session manager  28  to create a new session. 
     The session manager  28  sends a message to the back factory  34  to instantiate a new back object  32  and sends a message to the session factory  26  to instantiate a new session object  30 . The back factory  34  and the session factory  26  return references to the new back object  32  and session object  30  respectively, which are then used by the session manager  28  to instruct the new session object  30  to attach to the new back object  32 . The session object&#39;s reference is also passed back to the front  13  subsequently via the RWS  12  to allow the front object  13  to attach to the session object  30 . 
     The user account  18  then sends a join-service message to the session manager  28  which in turn sends a request-join message to the created session object  30  to cause the user to join a session. 
     Finally, the RWS  12  instructs the front object  13  to send an attach message to the session  30 . This establishes the communications channel between the front object  13  and the session object  30 . The session object  30  then sends a participant-joined message to the back object  32 . The session object  30  also transmits a message to the event handler  31  to inform it of the start session event. 
     Referring to  FIG. 7 , a user can join a session to which he has received an invitation. The RWS  12  transmits a joined-session message to the user account object  18 , which passes a “cookie” reference to indicate which invite the user wishes to accept. The user account  18  obtains details of the service from the SPP  24  and sends a message to the session manager  28  to verify that the session is still current. The session manager  28  pings the session object  30  and the custom back  32  to confirm this. Meanwhile, the RWS  12  spawns a thread to download the appropriate front object  13  for the selected service. 
     Once the session is verified by the session manager  28 , the user account object  18  sends a join message to the session manager  28 , which results in a request-join message sent by the session manager  28  to the appropriate session object  30 . If the join request succeeds, the RWS  12  sends a message to instruct the front object  13  to attach to the session object  30 , identified by the reference transmitted by the user account  18 . The session object  30  then sends a participant-joined message to the custom back  32 , by event channel. The session object  30  also transmits a message to the event handler  31  to inform it of the session joining event. 
     Referring to  FIG. 8 , the suspension of a user from a session can be initiated by the front object  13  sending a suspend message to the session object  30 . The front object  13  then destroys itself. The session object  30  sends a participant-suspended message to the back object  32 , by event channel, and marks the participant in question as suspended. The session object  30  also sends a message to the user account  18  to notify it of the user&#39;s new status, and transmits a message to the event handler to inform it of the suspension event. 
     Finally, the user account  18  sends a message to inform the RWS  12  of the new suspension, passing a cookie reference to the session  30 , so that the user is able to resume the session thereafter. 
     Referring to  FIG. 9 , an alternative session suspension procedure can be initiated from the custom back  32 . In this case, suspension is initiated by the custom back  32  sending a suspend message to the session object  30 . The session object  30  sends a suspend message to the front object  13  in question, which then destroys itself. The session object  30  proceeds by sending a participant-suspended message to the back object  32 , and transmitting a message to the event handler  31  informing it of the suspension event. The process continues as described in relation to  FIG. 8 . 
     Referring to  FIG. 10 , the RWS  12  is made aware of all suspended sessions for the user by the user account  18  immediately when the user is logged on, and throughout an access session. Therefore, when a user elects to resume a session, the RWS  12  sends a resume message to the user account  18 , which indicates the session to be resumed, by means of a cookie reference. The user account  18  sends a verify-session message to the appropriate session manager  28 , which pings the session object  30  and back object  32  to verify that the session is still in progress. 
     Meanwhile, the RWS  12  downloads the appropriate front object  13  for the selected service. Once the session manager  28  has verified that the session remains available, the RWS  12  instructs the front object  13  to send an attach-front message to the session object  30  to restore the front connection with the session object  30 . The session object  30  then sends a participant-resumed message to the back object  32 , by event channel. The session object  30  also transmits a message to the event handler  31  to inform it of the resumption event. 
     By providing for suspension of a participation in a service session as described, in addition to complete exiting from a service session, the state of the participation may be stored in the back object  32  for the duration of the suspension, and recovered when the participant opts to resume participation. Destruction of the of the front object  13  on suspension allows for efficient management of the client terminal resources, as a new front object  13  may be readily downloaded on resumption. 
     Referring to  FIG. 11 , when a user wishes to exit a session, the front  13  sends an end-participation message to the session object  30 , and then destroys itself. The session object  30  sends a participant-left message to the back object  32 . The session object  30  also transmits a message to the event handler  31  to inform it of the participant leaving event. The session object  30  then sends a session message to the user account  18  to notify it that the user has left the session. The session object  30  then destroys itself if there are no active or suspended participants left in the session, after sending a message to the event handler  31  to inform it of the session ending event. 
     Exiting the session may alternatively be initiated, as a result of service logic processing, from the back object  32  as illustrated in  FIG. 12 . In this case, exit is initiated by the back object  32  sending an end-participation message to the session object  30 . The session object  30  sends an end-participation message to the front object  13 , which then destroys itself. The session object  30  then sends a participant-left message to the back  32 , and to the event handler  31 . The process then continues as described in relation to  FIG. 11 . 
     Referring to  FIG. 13 , when the user logs off, the RWS  12  sends a logoff message to the user account  18 . The user account  18  transmits a message to the event handler  18  to inform it of the logoff event. 
     Other than the front  13  and the custom back  32 , all of the objects illustrated in  FIGS. 5 to 13  are generic to different services supported in the system, and are thus re-used for the provision of multiple different types of services. 
     A service session consists of a single custom back  32 , deployed within the service provider domain, together with a number of front objects  13 . One front object  13  is present per participation in the service. The front objects  13  may be distributed in several client terminals, and/or within a single client terminal. The interactions between the front object  13  and the back object  32  are mediated by the remainder of the system. 
     Thus, a service developer need not be concerned when developing a particular service with implementing the multi-party session control functions which are provided by the system. These functions include the generation of event messages which allow the service-specific pricing of the service provided to each user and service-specific costing of the service provided by the service provider to the retailer. All that the service provider needs to develop to implement a service, which nevertheless may be individually priced and costed, is the code for the service provision functionality in the service specific front object  13  and the code for the service provision functionality in the service specific back object  32 . 
     The event notifications made by the session object  30  to the event handler in  FIGS. 5 to 13  are examples only of the possible event messages. A more complete list of session-related events which may be notified by the session object  30  is as follows: 
     i) a user starting a service session, 
     ii) a participant joining an existing service session, 
     iii) a participant suspending participation in an existing service session, 
     iv) a participant resuming participation in an existing service session, 
     v) a participant leaving a service session, 
     vi) a participant inviting another user of the system to join a service session, 
     vii) a participant advertising a service session generally to users of the system inviting those users to join a service session, 
     viii) a user of the system declining an invitation to join a service session, 
     ix) a participant withdrawing a general advertisement to users of the system inviting those users to join a service session, 
     x) a service session ending. 
     It is a characteristic of the event messages transmitted to the event handler  31  that the events detailed in the event messages contain no history data. In other words, the events are not logically combined, and each message concerns only an instantaneous event which has just occurred in the session. This is to be compared with other known ways of generating events, which generally include calculating a duration, by referring to historical usage start date/time on receiving a usage stop date/time. By the events transmitted to the event handler not being logically combined, the flexibility of processing which may be subsequently applied to the events is maintained at a high level. 
     Each event message contains the following data: 
     1. A session ID. 
     2. The name of the service (or an identifier) being supplied during the session. 
     3. A category of the event (for example, session-related, participant-related, service-provider defined, invitation, or other category of event). 
     4. The event type (for example, start, stop, joined . . . ). 
     5. A date/time stamp. 
     6. A participant ID, which is unique in the context of the session. 
     7. The user name of the participant. 
     8. The identity of the party to be billed, which is constant for a particular participant throughout a session. 
     In the event categories referred to above, one event category is referred to as a service provider defined category. Discussions thus far have related to events automatically generated by the service provision support system. In order to provide further flexibility, a third party service provider may include a service-specific billing event to be generated at an appropriate point during a server session. Such service provider defined events are initiated in the service control component, in the service provider domain, and passed to the event handler in the same manner as the service-generic session events previously referred to. 
       FIG. 14  illustrates one embodiment of the event handler  31 , which performs pricing of service usage on a per-session basis. 
     Event messages enter the event handler at an event router object  100 . On receiving an event message indicating the start of a new service session, the event router generates a message which is sent to a session pricing factory object  102 , including the identity of the session. The session pricing factory object  102  proceeds to retrieve a service tariff policy object  106  from a tariff manager object  104 . 
     The service tariff policy request sent by the session pricing factory object includes the identity of the service to which the session pertains, and the service tariff policy returned by the tariff manager is service-specific. 
     One or more service tariff policy may be held by the tariff manager for each service provided by the entire service provision support system. In the case of more than one service tariff policy being held for a service, one such policy is selected depending on input parameters, such as the date/time of the start of the session, the billing status of the first participant in the session, etc. 
     A service tariff policy could also be shared between different services which are to be priced in the same manner. 
     The service tariff policies include data specifying how events are to be logically combined and/or filtered in order to price a participation in a session. 
     On receipt of the service tariff policy  106  from the tariff manager  104 , the session pricing factory object  102  instantiates a session pricing manager object  108 , which includes event filter rules data  110  and participation pricing engine spawn rules data  112 , derived from the service tariff policy which is particular to the service the session pricing manager is to handle. 
     A service session is started by a single participation, for which the session pricing manager spawns a single participation pricing engine object  114 . The participation pricing engine  114  contains pricing rules derived from the service tariff policy originally received from the tariff manager. 
     On instantiating the session pricing manager  108 , the session pricing factory object  102  returns a destination address for the session pricing manager  108  to the event router  100 . On receiving the session pricing manager address, the event router  100  transmits a message to the session pricing manager instructing it to connect to an event channel whereby the event messages received by the event router pertaining to the session handled by the session pricing manager are passed to the session pricing manager. 
     The event router itself receives event messages pertaining to a number of different sessions ongoing in the service provision support system, and routes the events to the various corresponding session pricing managers. 
     As will be appreciated from the above, the session pricing manager  108  receives event messages originating from a service session which informs the session pricing manager of a predetermined set of session-related events, if and when they occur in a service session. 
     As the session manager receives event messages indicating new participants joining a session, it spawns additional participation pricing engines. 
     The session pricing manager  108  applies event filter rules to discard events which are, for the service in question, not determinative of price. The session pricing manager copies each of the filtered events to a plurality of participating pricing engines  114 , to be logically combined in accordance with a defined charging algorithm to produce calculated price data for each participation in the session. The price data calculated and summary event information is then transmitted to a billing system log, to allow the charge to be debited against an account of the responsible party for each participation. 
     As will be appreciated, this arrangement allows the actions of not only the participant for which a participation is being priced to be taken into account in the pricing algorithm used, but also allows the actions, or changes in status, of other participants within the service session to be taken into account in the operation of the charging algorithm of the participation in question. 
     On receipt of a message indicating that the session has ended, the service pricing manager copies the message to each participation pricing engine and then destroys itself. Each participation pricing engine generates a record of the pricing data generated as a result of the events occurring within the session and relating to the participant which the participation pricing engine is responsible for, and transmits the pricing data to a billing log to be debited against the billed party account. Each participation pricing engine then destroys itself. 
     To exemplify a charging policy which may be used for an example service, for a conferencing service the system might charge the organiser of a conference session an entry fee of N for each participant in the session, and each participant is individually charged a usage fee of n per unit time. 
     An example session in this case may include participant 1, having a first user status, such as that of the organiser of this session, starting the session and inviting participants 2 and 3 to join the session at a second user status, such as that of normal participants. Participants 2 and 3 accept the invite. Participant 2 subsequently suspends. Participant 3 leaves the session. Participant 2 resumes and subsequently leaves the session, along with participant 1. 
     In this example scenario, the participation pricing engine acting on behalf of the conference organiser (participant 1) receives event messages informing it of other users joining the session, in the example given participants 2 and 3 joining. The entry fee is then charged three times by the participation pricing engine acting for participant 1. The participation pricing engines pricing the usage of participants 2 and 3 receives event messages including messages specifying when the party they are responsible for joins, suspends, resumes and leaves, and calculate a time-based charge accordingly. 
     To give a further example, a service in the form of a game may be charged at a fee of X per unit time, divided by the number of participants involved at any particular time, per participation. 
     In this example, three participants play the game. Participant 1 starts the session and invites participants 2 and 3, which then join the session. After a certain time, participant 1 leaves the session. Later, participants 2 and 3 leave. 
     In this example scenario, the participation pricing engine acting on behalf of participant 1 requires knowledge of the session-related status of each participant in the session, due to the charging policy adopted. When participants 1, 2 and 3 are active in the session, each participant is charged X/3 per unit time. When participant 1 leaves the session, participants 2 and 3 are charged X/2 per unit time, due to the reduced number of participants involved. 
     As will be appreciated from the two scenarios described above, the automatic generation of a comprehensive set of event messages which may be filtered and copied to individual participation pricing engines provides the ability to adopt charging policies for a service which are flexible and individually configurable, without requiring the service session logic, nor indeed the service logic itself, to have knowledge of the charging policies which will be adopted for the service. Furthermore, charging policies may be dynamically altered with time readily. All that is required in order to alter the charging policies for a particular service is to provide a new service tariff policy held in the tariff manager for the service in question. 
     In addition, each individual participation pricing engine may be configured on a user-dependent basis. Namely, user subscription data may be used to provide for user-specific pricing of participations in the session. This may include volume discounts, etc, to be applied to the pricing policies adopted by each participation pricing engine. In addition, the participation pricing engines may be configured in dependence on the role played by a participant in a session. For an example, a user may adopt an active/player or passive/viewer role in a session. The price charged for the participation may vary depending on the role played. In order to take such roles into account, the session pricing manager, on detecting a new participant joining a session, applies the PPE spawn rules data  112  in order to instantiate a participation pricing engine  114  in accordance not only with the service tariff policy, but also with the appropriate participation type characteristics. 
       FIG. 15  illustrates a further embodiment of the invention, in which the event router  100  copies event messages originating from a single session object  30  for dissemination to different parts of the event handling system which are responsible for different aspects of event handling. In the embodiment shown, these different parts include a customer pricing engine  200 , which may be similar to that described in relation to  FIG. 14 , a usage analysis engine  300 , and a third party costing engine  400 . 
     The event router  100  holds a channel allocation table which provides a register for determining the destination of events received from various different session objects, by quick reference. 
     The customer pricing engine  200  applies event filter rules and tariff policies to the events occurring during a session in order to generate billing records for each individual participant in the session. 
     The usage analysis engine  300  stores the event data passed to it for large numbers of service sessions, so as to build up a statistically significant view of the usage of services in the system. The usage analysis engine may then produce statistically-processed data for use in monitoring and improving the quality and range of services provided by the system. 
     The third party costing engine  400  receives the events originating from the session object  30 , and filters and logically combines the events occurring during a session in accordance with third party costing policies adopted for the service in question, in order to provide a method of calculating payments to be made by the service retailer to the service providers. 
     As will be understood from  FIG. 15 , the provision of a predetermined set of events which are automatically generated by the service provision support system is such as to allow flexible customer pricing policies to be generated directly from the messages received at a customer pricing engine. Furthermore, other processors may make use of the same event messages, or a copy thereof.