# Patent

## Title
Managing concurrent data updates in a composite services delivery system

## Abstract

Embodiments of the present invention provide a method, system and computer program product for deploying and delivering composite services in an NGN network. A collision detection and resolution method for updating a model in a composite services enablement environment can include establishing for a single session having a corresponding model, multiple channels of communication for different corresponding channels of access to a service. The method further can include synchronizing updates to the model by individual ones of the channels of access to the services for each of the channels of access to the services. The method yet further can include detecting collisions in synchronizing the updates to the model. Finally, the method can include rejecting the updates to the model when collisions are detected.

## Background
REFERENCE TO CO-PENDING APPLICATIONS FOR PATENT
The present application is related to the following co-assigned U.S. Patent Applications, which are incorporated herein by reference herein:
U.S. application Ser. No. 11/297,536 entitled “COMPOSITE SERVICES DELIVERY”, filed on Dec. 8, 2005.
U.S. application Ser. No. 11/297,535 entitled “COMPOSITE SERVICES DELIVERY UTILIZING LIGHTWEIGHT MESSAGING”, filed on Dec. 8, 2005.
U.S. application Ser. No. 11/296,952 entitled “INITIATING VOICE ACCESS TO A SESSION FROM A VISUAL ACCESS CHANNEL TO THE SESSION IN A COMPOSITE SERVICES DELIVERY SYSTEM”, filed on Dec. 8, 2005.
U.S. application Ser. No. 11/296,939 entitled “AUTO-ESTABLISHMENT OF A VOICE CHANNEL OF ACCESS TO A SESSION FOR A COMPOSITE SERVICE FROM A VISUAL CHANNEL OF ACCESS TO THE SESSION FOR THE COMPOSITE SERVICE”, filed on Dec. 8, 2005.
U.S. application Ser. No. 11/297,573 entitled “SYNCHRONIZED VIEW STATE FOR COMPOSITE SERVICES DELIVERY”, filed on Dec. 8, 2005.
U.S. application Ser. No. 11/297,080 entitled “VISUAL CHANNEL REFRESH RATE CONTROL FOR COMPOSITE SERVICES DELIVERY”, filed on Dec. 8, 2005.
U.S. application Ser. No. 11/297,497 entitled “SEAMLESS REFLECTION OF MODEL UPDATES IN A VISUAL PAGE FOR A VISUAL CHANNEL IN A COMPOSITE SERVICES DELIVERY SYSTEM”, filed on Dec. 8, 2005.
U.S. application Ser. No. 11/297,496 entitled “SELECTIVE VIEW SYNCHRONIZATION FOR COMPOSITE SERVICES DELIVERY”, filed on Dec. 8, 2005.
U.S. application Ser. No. 11/296,937 entitled “MODEL AUTOCOMPLETION FOR COMPOSITE SERVICES SYNCHRONIZATION”, filed on Dec. 8, 2005.
U.S. application Ser. No. 11/297,693 entitled “UPDATE NOTIFICATION FOR PEER VIEWS IN A COMPOSITE SERVICES DELIVERY ENVIRONMENT”, filed on Dec. 8, 2005.
U.S. application Ser. No. 11/297,079 entitled “SECURE ACCESS TO A COMMON SESSION IN A COMPOSITE SERVICES DELIVERY ENVIRONMENT”, filed on Dec. 8, 2005.
U.S. application Ser. No. 11/297,542 entitled “VIEW COORDINATION FOR CALLERS IN A COMPOSITE SERVICES ENABLEMENT ENVIRONMENT”, filed on Dec. 8, 2005.
U.S. application Ser. No. 11/297,541 entitled “COMPOSITE SERVICES ENABLEMENT OF VISUAL NAVIGATION INTO A CALL CENTER”, filed on Dec. 8, 2005.
U.S. application Ser. No. 11/297,601 entitled “VOICE NAVIGATION OF A VISUAL VIEW FOR A SESSION IN A COMPOSITE SERVICES ENABLEMENT ENVIRONMENT”, filed on Dec. 8, 2005.
U.S. application Ser. No. 11/297,593 entitled “SPEECH DISAMBIGUATION IN A COMPOSITE SERVICES ENABLEMENT ENVIRONMENT”, filed on Dec. 8, 2005.
U.S. application Ser. No. 11/297,061 entitled “CHANNEL PRESENCE IN A COMPOSITE SERVICES ENABLEMENT ENVIRONMENT”, filed on Dec. 8, 2005.
U.S. application Ser. No. 11/297,594 entitled “COMPOSITE SERVICES GENERATION TOOL”, filed on Dec. 8, 2005.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of next generation networking (NGN) and more particularly to the deployment and delivery of composite services over an NGN network.
2. Description of the Related Art
Next generation networking (NGN) refers to emerging computing networking technologies that natively support data, video and voice transmissions. In contrast to the circuit switched telephone networks of days gone by, NGN networks are packet switched and combine voice and data in a single network. Generally, NGN networks are categorized by a split between call control and transport. Also, in NGN networks, all information is transmitted via packets which can be labeled according to their respective type. Accordingly, individual packets are handled differently depending upon the type indicated by a corresponding label.
The IP Multimedia Subsystem (IMS) is an open, standardized, operator friendly, NGN multimedia architecture for mobile and fixed services. IMS is a Voice over Internet Protocol (VoIP) implementation based upon a variant of the session initiation protocol (SIP), and runs over the standard Internet protocol (IP). Telecom operators in NGN networks offer network controlled multimedia services through the utilization of IMS. The aim of IMS is to provide new services to users of an NGN network in addition to currently available services. This broad aim of IMS is supported through the extensive use of underlying IP compatible protocols and corresponding IP compatible interfaces. In this way, IMS can merge the Internet with the wireless, cellular space so as to provide to cellular technologies ubiquitous access useful services deployed on the Internet.
Multimedia services can be distributed both within NGN networks and non-NGN networks, alike, through the use of markup specified documents. In the case of a service having a visual interface, visually oriented markup such as the extensible hypertext markup language (XHTML) and its many co-species can specify the visual interface for a service when rendered in a visual content browser through a visual content channel, for instance a channel governed by the hypertext transfer protocol (HTTP). By comparison, an audio interface can be specified for a service by voice oriented markup such as the voice extensible markup language (VoiceXML). In the case of an audio interface, a separate voice channel, for instance a channel governed according to SIP.
In many circumstances, it is preferred to configure services to be delivered across multiple, different channels of differing modalities, including the voice mode and the visual mode. In this regard, a service provider not always can predict the interactive modality through which a service is to be accessed by a given end user. To accommodate this uncertainty, a service can be prepared for delivery through each anticipated modality, for instance by way of voice markup and visual markup. Generating multiple different markup documents to satisfy the different modalities of access, however, can be tedious. In consequence, merging technologies such as the XHTML+VoiceXML (X+V) have been utilized to simplify the development process.
Specifically, X+V represents one technical effort to produce a multimodal application development environment. In X+V, XHTML and VoiceXML can be mixed in a single document. The XHTML portion of the document can manage visual interactions with an end user, while the VoiceXML portion of the document can manage voice interactions with the end user. In X+V, command, control and content navigation can be enabled while simultaneously rendering multimodal content. In this regard, the X+V profile specifies how to compute grammars based upon the visual hyperlinks present in a page.
Processing X+V documents, however, requires the use of a proprietary browser in the client devices utilized by end users when accessing the content. Distributing multimedia services to a wide array of end user devices, including pervasive devices across NGN networks, can be difficult if one is to assume that all end user devices are proprietarily configured to handle X+V and other unifying technologies. Rather, at best, it can only be presumed that devices within an NGN network are equipped to process visual interactions within one, standard channel of communication, and voice interactions within a second, standard channel of communication.
Thus, despite the promise of X+V, to truly support multiple modalities of interaction with services distributed about an NGN or, even a non-NGN network, different channels of communications must be established for each different modality of access. Moreover, each service must be separately specified for each different modality. Finally, once a session has been established across one modality of access to a service, one is not able to change mid-session to a different modality of access to the same service within the same session. As a result, the interactions across different channels accommodating different modalities of interaction remain unsynchronized and separate. Consequently, end users cannot freely switch between modalities of access for services in an NGN network.
BRIEF SUMMARY OF THE INVENTION
Embodiments of the present invention address deficiencies of the art in respect to deploying and delivering a service to be accessed through different channels of access in an NGN network, and provide a novel and non-obvious method, system and apparatus for deploying and delivering composite services in an NGN network. As used herein, a composite service is a service deployed across an NGN network that has been enabled to be accessed through multiple, different modalities of access in correspondingly different channels while maintaining the synchronization of the state of the service between the different channels of access.
In a first embodiment of the invention, a composite service enabling data processing system can include multiple channel servlets enabled to establish for a common session, multiple different channels of access to the composite service. The system also can include a location registry including a table of entries associating the different channels of access with the common session. The system yet further can include a model servlet configured for coupling to a model for the common session and for modifying state data in the model for the common session. The model servlet can be enabled to synchronize views for each of the different channels of access to the composite service responsive to changes detected in the model. Finally, the system can include a conflict detector coupled to the model servlet and enabled to permit updates to the model without record locking when no collisions are detected.
In another embodiment of the invention, a collision detection and resolution method for updating a model in a composite services enablement environment can include establishing multiple channels of access for a common session for a composite service, and synchronizing changes of state for a model corresponding to the common session in a view for each of the channels of access to the common session. The method yet further can include detecting collisions in synchronizing the updates to the model. Finally, the method can include rejecting the updates to the model when collisions are detected.
In one aspect of the embodiment, detecting collisions in synchronizing the updates to the model can include receiving a request to update the model from one of the channels of access and identifying in the request a previous value and a new value to be applied to the model. The previous value in the request can be matched to a previous value in the model. Consequently, a collision can be determined where the previous value in the request does not match the previous value in the model. Furthermore, a notification of a collision can be provided to an updating one of the channels of access when a collision is detected based upon a request to update the model by the updating one of the channels of access.
Additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The aspects of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.



BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention. The embodiments illustrated herein are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown, wherein:
FIG. 1 is a pictorial illustration of an IMS configured for use with a data processing system arranged to deploy and deliver composite services in an NGN network;
FIG. 2 is a schematic illustration of a data processing system arranged to deploy and deliver composite services in an NGN network;
FIG. 3 is a flow chart illustrating a process for delivering composite services in an NGN network; and,
FIG. 4 is a flow chart illustrating a process for managing concurrent updates in the composite services deployment and delivery data processing system of FIG. 2.



DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention provide a method, system and computer program product for delivering composite services in an NGN network. In accordance with an embodiment of the present invention, a composite services enabler can establish different channels of access to a common session for accessing the common session through corresponding different modalities of access including voice and visual modes. Specifically, interactions with a common session to a composite service can be provided across selected ones of the different channels, each channel corresponding to a different modality of access to the common session. In the case of a voice modality and a visual modality, a separate markup document can be utilized in each selected channel according to the particular modality for that channel.
Importantly, within the composite services enabler, each channel utilized for accessing a common session can be associated with each other channel accessing the common session. In consequence, the state of the common session—stored within a model in a model-view-controller architecture in the composite services enabler—can be maintained irrespective of the channel used to change the state of the service. Moreover, the composite services enabler can synchronize the representation of the service in each view for the selected ones of the different channels.
The synchronization of the model across the views for a common session need not be a real time synchronization. Rather, each different view can synchronize with the model periodically according to a refresh interval. As such, it is possible that an attempt to update the model in a particular view may not reflect the current state of the model prior to applying the update due to the concurrent updating of the model by another view over a different channel of access for the common session. Consequently, in the present invention, a conflict detector coupled to the model servlet can manage concurrent updates to the model by ensuring that the previous value in a request to update the model matches the value of the data to be updated in the model. If so, the update can proceed. If not, the request can be rejected as another view will have updated the model in the period of time between the last refresh for the view and the request to update the model.
Advantageously, the system of the present invention can be embodied within an IMS in a NGN network. In illustration, FIG. 1 is a pictorial illustration of an IMS configured for use with a data processing system enabled to establish a voice channel of access to a session for a composite service from a visual channel of access to the session in an NGN network. As shown in FIG. 1, a composite service enablement data processing system 200 can be arranged to deploy and deliver a composite multimedia service 180 in an NGN network 120. As used herein, a “composite multimedia service” can be a service configured to be accessed through multiple different views of different modalities across correspondingly different channels of communications.
More specifically, the composite multimedia service 180 can be accessed through several different modalities, including a visual mode, an instant messaging mode and a voice mode. Each modality of access can be produced by a developer 190 through the use of a service deployment tool 170. The service deployment tool 170 can be configured to produce the different modalities of access for the composite multimedia service 180, including visual markup to provide visual access to the composite multimedia service 180, and voice markup to provide audible access to the composite multimedia service 180.
One or more gateway server platforms 110 can be coupled to the composite service enablement data processing system 200. Each of gateway server platforms 110 can facilitate the establishment of a communication channel for accessing the composite multimedia service 180 according to a particular modality of access. For example, the gateway server platforms 110 can include a content server such as a Web server enabled to serve visual markup for accessing the composite multimedia service 180 over the NGN network 120 through a visual mode. Likewise, the gateway server platforms 110 can include a voice server enabled to provide audible access to the composite multimedia service 180 over the NGN network 120 through an audible mode.
End users 130 can access the composite multimedia service 180 utilizing any one of a selection of client access devices 150. Application logic within each of the client access devices 150 can provide an interface for a specific modality of access. Examples include a content browser within a personal computing device, an audible user interface within a pervasive device, a telephonic user interface within a telephone handset, and the like. Importantly, each of the provided modalities of access can utilize a separate one of multiple channels 160 established with a corresponding gateway server platform 110 over the network 120 for the same session with the composite multimedia service 180. In this regard, a session with the composite multimedia service 180 can subsist across the multiple channels 160 to provide different modalities of access to the composite multimedia service 180 for one of the end users 130.
In more particular illustration, FIG. 2 is a schematic illustration of the composite service enablement data processing system 200 of FIG. 1. The composite service enablement data processing system 200 can operate in an application server 275 and can include multiple channel servlets 235 configured to process communicative interactions with corresponding sessions 225 for a composite multimedia service over different channels of access 245, 250, 255 for different endpoint types 260A, 260B, 260C in an NGN network. In this regard, the channel servlets 235 can process voice interactions as a voice enabler and voice server to visual endpoint 260A incorporating a voice interface utilizing the Real Time Protocol (RTP) over HTTP, or a voice endpoint 260B utilizing SIP. Likewise, the channel servlets 235 can process visual interactions as a Web application to a visual endpoint 160A. As yet another example, the channel servlets 235 can process instant message interactions as an instant messaging server to an instant messaging endpoint 260C.
More specifically, the channel servlets 235 can be enabled to process HTTP requests for interactions with a corresponding session 225 for a composite multimedia service. The HTTP requests can originate from a visual mode oriented Web page over a visual channel 245, from a visual mode oriented instant messaging interface over an instant messaging channel 255, or even in a voice mode over a voice channel 250 enabled by SIP. Similarly, the channel servlets 235 can be enabled to process SIP requests for interactions with a corresponding session 225 for a composite multimedia service through a voice enabler which can include suitable voice markup, such as VoiceXML and call control extensible markup language (CCXML) coupled to a SIPlet which, in combination, can be effective in processing voice interactions for the corresponding session 225 for the composite multimedia service, as it is known in the art.
Each of the channel servlets 235 can be coupled to a model servlet 220. The model servlet 220 can mediate interactions with a model 210 for an associated one of the sessions 225. Each of the sessions 225 can be managed within a session manager 220 which can correlate different channels of communication established through the channel servlets 235 with a single corresponding one of the sessions 225. The correlation of the different channels of communication can be facilitated through the use of a coupled location registry 230. The location registry 230 can include a table indicating a host name of systems and channels active for the corresponding one of the sessions 225.
The model servlet 215 can include program code enabled to access a model 210 for a corresponding session 225 for a composite multimedia service providing different channels of access 245, 250, 255 through different endpoints 260A, 260B, 260C. For instance, the model 210 can be encapsulated within an entity bean within a bean container. Moreover, the model 210 can store session data for a corresponding one of the sessions 225 irrespective of the channel of access 245, 250, 255 through which the session data for the corresponding one of the sessions 225 is created, removed or modified. The model servlet 215 further can be coupled to a conflict detector 400. The conflict detector 400 can be enabled to detect collisions in updating the model 210 and to permit updates to the model 210 only where no collisions are detected.
Notably, changes in state for each of the sessions 225 for a composite multimedia service can be synchronized across the different views 260 for the different channels of access 245, 250, 255 through a listener architecture. The listener architecture can include one or more listeners 240 for each model 210. Each listener can correspond to a different channel of access 245, 250, 255 and can detect changes in state for the model 210. Responsive to detecting changes in state for the model 210 for a corresponding one of the sessions 225 for a composite multimedia service, a listener 240 can provide a notification to subscribing view 260 through a corresponding one of the channel servlets 235 so as to permit the subscribing views 260 to refresh to incorporate the detected changes in state for the model 210.
FIG. 3 is a flow chart illustrating a process for managing multiple channels of access to a single session for a composite service in the data processing system of FIG. 2. Beginning in block 310, a first channel of access can be opened for the composite multimedia service and a session can be established in block 320 with the composite multimedia service. Data for the session can be stored in a model for the session which can be established in block 330. If additional channels of access are to be established for the session in decision block 340, the process can continue in block 350. In block 350, an additional channel of access can be established for the same session for as many additional channels as required.
When no further channels of access are to be established in decision block 340, in block 360 a listener can be registered for each established channel of access for the session. Subsequently, in block 370 events can be received in each listener. In decision block 380, when a model change is detected, in block 390, the model change can be provided to each endpoint for selected ones of the established channels of access. In consequence, the endpoints can receive and apply the changes to corresponding views for the selected ones of the established channels of access for the same session, irrespective of the particular channel of access through which the changes to the model had been applied.
Notably, when updates are to be concurrently applied to the model from different channels of access, a collision can occur. In this regard, a conflict detector coupled to the model servlet can determine which update is valid and which update is not valid. In illustration, FIG. 4 is a flow chart illustrating a process for managing concurrent updates in the composite services deployment and delivery data processing system of FIG. 2. Beginning in block 410, a request to update the model for a common session can be received from a view for a channel of access to the common session. The request can include both a previous value and the proposed new value.
As the model may have changed in the period of time between the last updating of the view and the request by the view to update the model, in decision block 420, it can be determined whether the previous value in the request matches the previous value in the model. If not, in block 430 the request can be rejected and the view can be notified. Optionally, the view can be refreshed to reflect the current model. As yet another option, the view can be queried to apply the change notwithstanding the disparity of the previous value. In any case, in decision block 420, if the previous value in the request matches the previous value in the model, the request can be processed and the update applied to the model. In this way, collision detection and conflict management can be performed without requiring record locking for the model in order to avoid race conditions.
Embodiments of the invention can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment containing both hardware and software elements. In a preferred embodiment, the invention is implemented in software, which includes but is not limited to firmware, resident software, microcode, and the like. Furthermore, the invention can take the form of a computer program product accessible from a computer-usable or computer-readable medium providing program code for use by or in connection with a computer or any instruction execution system.
For the purposes of this description, a computer-usable or computer readable medium can be any apparatus that can contain, store, communicate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The medium can be an electronic, magnetic, optical, electromagnetic, or semiconductor system (or apparatus or device). Examples of a computer-readable medium include a semiconductor or solid state memory, magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disk and an optical disk. Current examples of optical disks include compact disk-read only memory (CD-ROM), compact disk-read/write (CD-R/W) and DVD.
A data processing system suitable for storing and/or executing program code will include at least one processor coupled directly or indirectly to memory elements through a system bus. The memory elements can include local memory employed during actual execution of the program code, bulk storage, and cache memories which provide temporary storage of at least some program code in order to reduce the number of times code must be retrieved from bulk storage during execution. Input/output or I/O devices (including but not limited to keyboards, displays, pointing devices, etc.) can be coupled to the system either directly or through intervening I/O controllers. Network adapters may also be coupled to the system to enable the data processing system to become coupled to other data processing systems or remote printers or storage devices through intervening private or public networks. Modems, cable modem and Ethernet cards are just a few of the currently available types of network adapters.

## Claims

1. A composite service enabling data processing system comprising:
a plurality of channel servlets executing in an application server in a data processing system for storing and executing program code including at least one processor coupled to memory elements through a system bus, the servlets enabled to establish multiple, different channels of access to a common session for a composite service;
a location registry comprising a table of entries associating the different channels of access with the common session for the composite service; and,
a model servlet executing in the application server and configured for coupling to a model for the common session, for modifying state data in the model for the common session, and to synchronize views for each of the different channels of access to the common session responsive to changes detected in the model; and,
a conflict detector for detecting collisions in concurrent requests to update the model for the common session by different ones of the channels of access, the conflict detector being coupled to the model servlet and enabled to permit updates to the model by individual ones of the channels of access without record locking through a comparison of a previous value of the model disposed in each of the concurrent requests to an actual previous value of the model.

2. The system of claim 1, wherein the channel servlets comprise a voice enabler and voice server enabled to establish for the single session, a communications channel for a voice channel of access to the composite service.

3. The system of claim 1, wherein the channel servlets and model servlet are disposed in an application server.

4. The system of claim 1, wherein the channel servlets and model servlet are disposed in an Internet protocol (IP) multimedia subsystem (IMS) in a next generation networking (NGN) network.

5. A collision detection and resolution method for updating a model in a composite services enablement environment, the method comprising:
establishing multiple channels of access to a common session for a composite service;
modifying state data in the model; and
synchronizing changes of state in the model corresponding to the common session in a view for each of the channels of access to the common session;
detecting collisions in concurrent requests to update the model for the common session by different ones of the channels of access; and
permitting updates to the model by individual ones of the channels of access without record locking through a comparison of a previous value of the model disposed in each of the concurrent requests to an actual previous value of the model.

6. The method of claim 5, wherein establishing multiple channels of access to a common session for a composite service, comprises:
establishing for the common session at least a voice channel of access to the common session, and a visual channel of access to the common session.

7. The method of claim 5, wherein establishing multiple channels of access to a common session for a composite service, comprises establishing for a common session to a composite service in a next generation networking (NGN) network at least a voice channel of access to the common session, and a visual channel of access to the common session.

8. The method of claim 5, synchronizing changes of state in a model corresponding to the common session in a view for each of the channels of access to the common session, comprises:
maintaining the state of the model for the common session;
creating listeners for changes of the state for the model;
detecting changes in the state for the model in the listeners; and,
updating the view for each of the channels of access to the common session responsive to detecting the changes of state for the model in the listeners.

9. The method of claim 5, wherein detecting collisions in synchronizing updates to the model, comprises:
receiving a request to update the model from one of the channels of access;
identifying in the request a previous value and a new value to be applied to the model;
matching the previous value in the request to a previous value in the model; and,
determining a collision where the previous value in the request does not match the previous value in the model.

10. The method of claim 5, wherein rejecting the updates to the model when collisions are detected, comprises providing a notification of a collision to an updating one of the channels of access when a collision is detected based upon a request to update the model by the updating one of the channels of access.

11. A computer program product comprising a non-transitory medium having computer usable program code for collision detection and resolution for updating a model in a composite services enablement environment, the computer program product including:
computer usable program code for establishing multiple channels of access to a common session for a composite service;
computer usable program code for modifying state data in the model;
computer usable program code for synchronizing changes of state in the model corresponding to the common session in a view for each of the channels of access to the common session;
computer usable program code for detecting collisions in concurrent requests to update the model for the common session by different ones of the channels of access; and
computer usable program code for permitting updates to the model by individual ones of the channels of access without record locking through a comparison of a previous value of the model disposed in each of the concurrent requests to an actual previous value of the model.

12. The computer program product of claim 11, wherein the computer usable program code for establishing multiple channels of access to a common session for a composite service, comprises computer usable program code for establishing at least a voice channel of access to the common session, and a visual channel of access to the common session.

13. The computer program product of claim 11, wherein the computer usable program code for establishing multiple channels of access to a common session for a composite service, comprises computer usable program code for establishing for a common session, in a next generation networking (NGN) network at least a voice channel of access to the common session, and a visual channel of access to the common session.

14. The computer program product of claim 11, wherein the computer usable program code for synchronizing changes of state for the model corresponding to the common session in a view for each of the channels of access to the common session, comprises:
computer usable program code for maintaining the state of the model for the common session;
computer usable program code for creating listeners for changes of the state for the model;
computer usable program code for detecting changes in the state for the model in the listeners; and,
computer usable program code for updating the view for each of the channels of access to the services responsive to detecting the changes of state for the model in the listeners.

15. The computer program product of claim 11, wherein the computer usable program code for detecting collisions in synchronizing updates to the model, comprises:
computer usable program code for receiving a request to update the model from one of the channels of access;
computer usable program code for identifying in the request a previous value and a new value to be applied to the model;
computer usable program code for matching the previous value in the request to a previous value in the model; and,
computer usable program code for determining a collision where the previous value in the request does not match the previous value in the model.

16. The computer program product of claim 11, wherein the computer usable program code for rejecting the updates to the model when collisions are detected, comprises computer usable program code for providing a notification of a collision to an updating one of the channels of access when a collision is detected based upon a request to update the model by the updating one of the channels of access.