before presenting a detailed description of the automatic call transfer system an overview will be presented to illustrate how the system may be used in a commercial application . the system is based on an automated call dispatch ( acd ) architecture that supports a set of distributed service logic programs ( slps ) in accordance with the present invention . a more complete description of a presently preferred acd architecture and of the slp technology is provided below , following the present basic discussion of the automatic call transfer system featured in fig1 . fig1 illustrates an exemplary application in which both internet content data and telephony data are administered by the automated call dispatch ( acd ) server . the illustrated embodiment shows how a typical help desk application or sales support application would be implemented using the invention . the end user has access to a computer 10 that is connected to a computer network such as the internet 12 . computer 10 includes suitable software such as a web browser so that internet content can be displayed in the web browser screen 14 . the user also has a telephone 16 connected to suitable telephone network 18 . although a separate telephone 16 has been illustrated here , the invention can also be implemented using internet - based telephony . in such an embodiment the user would communicate by voice ( and also optionally by video conferencing ) using the computer 10 . the user &# 39 ; s voice is digitized and transmitted as packets over internet 12 . the help desk or sales support office may have one or more help desks or sales agents , each provided with computer equipment and telephones . fig1 shows two agent work stations , which each include a computer terminal 20 a and 20 b and a telephone handset 22 a and 22 b . the telephone handsets are connected to a private branch exchange ( pbx ) telephone system 24 . the pbx telephone system 24 is suitably connected to the telephone network 18 , allowing it to place and receive calls over the telephone network . the help center or sales support center also includes an automated call dispatch ( acd ) server 26 . the acd server is connected to the computer terminals 20 a and 20 b and also to the pbx telephone system 24 . much of the functionality of the call transfer system resides in the acd server . details of the server are provided below . for purposes of illustration it will be assumed that the help desk or sales support center is maintained by an enterprise that also has a public web site . web server 30 is illustrated in fig1 to provide this functionality . web server 30 serves web pages and other internet content data to users &# 39 ; computer terminals , such as computer 10 via internet 12 . as will be more fully explained , the web server 30 is provided with a small servlet 32 which allows the web server to interface with the acd server 26 . the servlet 32 is a small executable program installed on web server 30 to allow information passed to the web server 30 to be suitably forwarded on to the acd server 26 for call transfer purposes . for example , if the user operating computer 10 inputs his or her telephone number to request a call back from an available sales agent , the information provided in response to a web page served by web server 30 is captured by the servlet 32 and forwarded to the acd server 26 . the acd server 26 receives the user &# 39 ; s telephone number from the servlet and then uses it to initiate a call back to the user when an available agent is free . in the presently preferred embodiment the servlet 32 is capable of supporting a wide variety of different features which require user - supplied information to be transferred to the acd server . in this regard , the call back feature is but one example . fig2 shows the acd architecture of a presently preferred embodiment . a layered architecture is used , in which each layer is represented as a rectangular box . the topmost layer is the graphical user interface presentation layer 40 . this layer actually resides within the browser application software of the various parties that will use the system . the user graphical user interface ( gui ) 42 dictates what an end user , such as the user of computer 10 in fig1 , will see in his or her browser window when accessing the web site hosted by web server 30 ( fig1 ). the agent gui 44 controls what each help desk agent or sales support agent will see in his or her browser window when using the system . thus agent gui 44 controls what appears in the browser displays of computer terminals 20 a and 20 b . other graphical user interfaces are possible . illustrated in fig2 is an administrator gui 46 and a supervisor gui 48 . the administrator gui 46 might be used , for example , to change settings in the system software associated with web server 30 and acd server 26 . the supervisor gui 48 might be used , for example , by supervisors responsible for managing the help desk agents or sales support agents . the next layer below the gui presentation layer 40 is application interface layer 42 . it is in this layer that the web server servlet 32 is preferably placed . as illustrated , the servlet 32 is capable of communicating with any of the graphical user interfaces found within the gui presentation layer 40 . also found within application interface layer 42 is a server application agent 46 . the server application agent performs the primary interface function of connecting all users ( through their associated guis ) to the server application layer 48 . a corresponding client application agent 50 , residing in the server application layer 48 , provides the other end of the link . the preferred embodiments are based on multithreaded code in which each incoming or outgoing call is represented as a thread . the server application layer 48 includes additional manager modules that provide different services for the underlying data model layer 52 . these managers include a routing manager 54 , an agent queue manager 56 and a call queue manager 58 . the routing manager is responsible for all call routing operations . the details of this manager are provided below . the agent queue manager and the call queue manager are responsible for respectively handling the list of agents that are available to handle an incoming call and the list of incoming calls waiting to be handled . routing manager 54 receives incoming calls from the call queue manager 58 and assigns them to the appropriate agent as provided by the agent queue manager 56 . the call routing function can be quite sophisticated , if desired . because an incoming call may have associated with it a particular set of data obtained through previous interactive response or through web page input , the routing manager 54 has the ability to assign an incoming call to a selected agent that is appropriate for the nature of the incoming call . best , an inquiry from a user regarding television sets would be routed automatically to an agent who handles that product line . an incoming call for a credit application would be routed to a different agent in the financial department . at the core of the preferred embodiment is the acd call model and its associated queues , depicted at 60 . as will be more fully explained , the call model is an object - oriented model that combines internet content data and telephony data , keeping an association between both so that when a call is routed all previously obtained context information is routed with the call . the presently preferred implementation interfaces with both telephony and internet media platforms . thus the presently preferred acd architecture includes a telephony and media platform layer 62 with its associated telephony and media interface module 64 . this layer provides the physical connectivity interface with the telephone network and with the internet or computer network . the application interface layer 42 , server application layer 48 and data model layer 52 are preferably implemented using persistent storage as indicated diagrammatically at 66 . because the user , agents , administrator and supervisor will all access the acd system remotely in the preferred embodiments , the acd architecture can be further divided into client side applications and server side applications . the client side applications include the guis in the gui presentation layer 40 . the server side applications comprise all of the applications and modules of the remaining layers . fig3 shows the acd server architecture in greater detail . the client application ( which could be implementing any of the guis illustrated in fig2 ) is shown in fig3 at 70 . it communicates using tcp / ip protocol or other suitable network protocol . the communication link can be implemented using http , ipp , or the like , to specify the uniform resource locator ( url ) of the acd server . as illustrated in fig3 , the client application 70 communicates with the client application agent 50 ( a component of the server application layer 48 of fig2 ). the client application 70 also communicates with the web server servlet 32 which may be deployed on the web server 30 ( fig1 ). the client application agent 50 communicates with an acd provider module 72 that is part of the call model 60 of the data model layer 52 . the call queue manager 58 , routing manager 54 and agent queue manager 56 also communicate with this acd provider . the acd provider &# 39 ; s primary function is to maintain each call as a thread . the acd provider instantiates threads for representing each call from a main thread 74 that has been diagrammatically illustrated in the server application layer 48 . the main thread is the starting point of the server application . it controls the other acd server application threads as well as the call model 60 . the main thread has the ability to shut down modules and restart them . this gives the system the ability to perform run time updates of any of the modules making up the system . the acd provider module 72 maintains records in persistent storage of the addresses and terminal identification data of each party participating in a call . these address and terminal components of the call model are illustrated at 74 and 76 , respectively . to support internet web - based applications on the server side , the main thread can instantiate a web application thread . web server servlet 32 sends requests to the web application thread through the ipp channel . through the same channel , the web application thread sends information back to servlet 32 . servlet 32 then presents the information to the user &# 39 ; s browser . this allows the system to pass content to the user &# 39 ; s browser , thereby opening up interesting possibilities for interactive exchange . an agent at the help desk center or sales support office could , for example , cause information to be sent to an end user &# 39 ; s web browser . thus the agent could show the end user additional web content or multimedia content in response to a user &# 39 ; s inquiry . a user interested in dvd players might be taken to a different web page where a particular model is described . the agent is able to control such action through the servlet functionality . the routing application is one of the main functions of the acd server . the acd server takes calls from telephone , web or internet protocol terminal , and then finds an agent who can answer the call in the event the calling party wants to talk with an agent in person . the routing application identifies a suitable agent for each call based on predefined routing logic . each agent has certain assigned duties and responsibilities , which are known to the routing application . depending on the context of the user &# 39 ; s call ( which is determined through prior interaction with the user ) the routing application selects an available agent who has the necessary qualifications to handle that type of inquiry . most of the time , management of the call center can be handled remotely by a supervisor or administrator with the help of the acd client side application . on the server side , a client application controller thread responds to instructions from the supervisor or administrator and to send event and command messages to other client applications in response to the supervisor or administrator &# 39 ; s instructions . communication between the client and server applications takes place over a suitable communication channel . in the presently preferred embodiments the tcp socket and ipp mechanisms are used for this purpose . the client application can also communicate with a server application through the http channel . in other words , client applications can send a request to a web server on the server side to invoke a servlet . the servlet then communicates with the web application thread inside the server application . the web application thread processes the request and sends the results back . web push technology can be used to return messages back to the client asynchronously . as noted above , one embodiment of the invention provides a call back feature whereby the user is able to enter his or her telephone number into a field on a web page and the system will then call that person back , at the number provided , once an appropriate agent is available . this feature is implemented using a call back scheduling module that is part of the acd server application . the call back scheduling module maintains a call back queue which sends a call request to the acd call model . in the preferred embodiments all communication between modules is done through the acd call model . the call model provides a common data structure for all acd server application threads . basically , when one application threads wants to send an event notification to another application thread , it first changes the state of the call model object and then generates the event message . thereafter , it invokes an event - listener state on the call model object to pass the event to the other application thread . fig4 illustrates how such inter module communication occurs within the acd call model . in fig4 logical relationships among modules are shown in solid connecting lines . event - listener operations are shown in dot - dash lines and per call communications are shown in dotted lines . the routing manager 54 listens for events from a number of the entities within the acd call model , namely : the call center call object 80 , acd manager connection object 82 , acd connection object 84 , terminal connection object 86 , acd manager address object 88 , and acd address object 90 . the call queue manager 58 and the agent queue manager 56 also listen for events disseminated by the acd address object 90 . fig6 a through 6d illustrate how the acd call model supports call routing . referring to fig6 a , the routing manager instantiates a call object 100 associated with a thread dedicated to the incoming call . the call object in turn associates a connection object 102 that is associated with the caller address 104 and an acd connection object 106 that is associated with the acd address 108 . the acd address may be a direct dial extension within the pbx system 24 ( fig1 ). note that at this point the routing manager has established a connection relationship between the incoming caller and the acd server system . next , as illustrated in fig6 b , the routing manager 54 causes call object 100 to associate a connection object 110 that is associated with an interactive voice response system address 112 . the interactive voice response system may be used to elicit information from the caller , so that the system can appropriately route the call to the proper agent . of course , the attachment of an interactive voice response system at this point is merely intended to illustrate one way of operating the invention . if , for example , the incoming call does not require interactive voice response services , then the routing manager would connect to other resources instead . an example of such resource is shown in fig6 c . in fig6 c it is assumed that the interactive voice response session has finished and that the user is to be temporarily placed on hold while an appropriate agent can be identified and connected . the routing manager causes call object 100 to attach connection object 114 which is associated with the address 116 of a music system . thus the incoming caller is entertained by a musical program while the routing is in process . when an agent is available the agent queue manager 56 ( fig4 ) notifies the routing manager and a connection object 118 with knowledge of the agent &# 39 ; s address 120 is associated with call object 100 . this places the caller and agent in communication with one another , not only through the telephony channel but also through any web - based resources that the parties are using . the acd connection object stores web - related resource information , such as information gathered via the servlet 32 . in this way , the agent who picks up the incoming call has access to all information supplied by the caller through interaction over the web . likewise , the agent has access to all information supplied by the caller during interaction with the interactive voice response system . to further understand how the interaction transpires , refer to fig7 , 8 and 9 . fig7 shows the message flow between the interactive voice response system and the acd system . specifically , fig7 shows the sequence of messages that are passed among the following entities : telephony / media platform 150 ( via the telephony media interface 64 of fig2 ) acd address and queues 152 ( see acd address object 90 of fig4 ) call queue manager 58 ( see also fig4 ) routing manager 54 ( see also fig2 , 4 and 6 a – d ) acd call model 60 ( see also fig2 ) interactive voice response system 154 . each of the messages shown in fig7 represents an event message if it contains the designation ev in the message name . the first four event messages 160 , 162 , 164 and 166 essentially communicate a request to the interactive voice response system 154 to play an enunciation message 168 requesting the user to enter a numeric value on the telephone key pad . the next event message 170 is the digit entered by the user . as illustrated , this digit is sent to the acd call model 60 . the acd call model 60 notifies the interactive voice response system that a digit has been received ( message 172 ) and the interactive voice response system may either send out a further play enunciation to the user or it can signify ( message 174 ) that the interactive session is done . this indication results in a cascade of messages that ultimately notify the acd address and queues object 152 that the call is ready to be routed . fig8 is a similar diagram illustrating how messages are passed within the acd when a new call is processed after the interactive voice response session . as illustrated , messages are passed among the following entities : agent queue manager 56 ( see also fig3 and 4 ) acd address and agent queues 180 ( see acd address object 90 of fig4 ) call queue manager 58 ( see fig4 ) routing manager 54 ( see fig2 and 4 ) acd call model 60 and telephony media platform 150 . the timeline of fig8 begins with a call ready to route message 182 , which is also the final message of the time line of fig7 . in response to this message the routing manager 54 gets the next available agent from the agent queue ( message 184 ), get the call from the call queue ( message 186 ) and then instruct the acd call model 60 to implement the connection . more specifically , the routing manager 54 sends a message to the acd call model which causes the agent to be connected to the call object ( see fig6 d ). the incoming caller is presumed to already be attached to the call object in this example , as was illustrated in the sequence of fig6 a – 6d . in fig8 the actual connection of the call is signified by an event message 190 , which is sent from the telephony / media platform 150 to the call model . thereafter , a cascade of messages are sent to tell the agent queue manager 56 that the selected agent is now handling the call and should therefore be removed from the queue . when the call ends , a similar message 200 is sent , causing the agent to be placed back in the queue . fig9 shows a similar sequence of events that would occur when an agent is available to take a new call . in this case , a sequence of messages 202 are sent between the agent queue manager 56 and the acd address and agent queues 180 prior to notifying the routing manager 54 that an agent is available to take the call ( message 204 ). thereafter , the exchange of messages is similar to that illustrated in fig8 . there are various kinds of service logic programs ( slps ). the common feature of a slp is that it can be created in any development tools and compiled into a software components that can be loaded and run in a host machine with a standard xml interface that defines the following typed interface : 1 . the slp can be located anywhere in the internet . it has a url and a property set describing the following properties . 2 . slp has a shared object service interface defining an event - condition - action table that can be dynamically updated . the interface can point to a . all the call object information dynamically created by the call processing system . b . all the context information collected from the user or the system during the course of the call . 3 . a gui component that support the provisioning of the slp parameters . the gui component support the remote update of the slp . it also support the tracking of slps that has been used by other entities . when there is a change to the slp the other entities may be notified if the entity “ subscribed to or is using the slp ”. 4 . a set of system service interface for making calls , collect user information , and play media to the users . 5 . a set of declarative rules or procedure based program that can communicate with external programs using structured messages such as xml . 6 . slp can be loaded and dynamically link to the slp execution engine to implement the application logic . 7 . slp can be dynamically associated with an addressable entities . the association allows a call processing program to locate the reference to the slp from the addressable entity . it also allows the slp to find the call processing program from the addressable entities . it is assumed that the call processing entity has a reference to the addressable entities . the dynamic loading of slp is accomplished by a web based hyperlink dictionary ( whd ). whd keeps the location of slps that is used by the applications and has the knowledge of how to locate slp . conventional database systems provide data sharing capability for users to define and manipulate corporate information . current internet provides browsers and http servers for sharing web pages and common gateway interface programs . the scope of information sharing was extended to web page sharing . in such an environment , the internet becomes the common protocol for distributed machines ( ip terminals and servers ). on top of the ip protocols , http becomes the most common protocol that is used by internet communities . many of the new generation tools are transformed from enterprise or departmental centric computing environment to a totally distributed web - centric environment . many vendors provide a web - enabled wrapper over database systems to take advantage of the web . however , these approaches are not suitable for truly distributed multimedia applications where users are basically distributed over internet domains separated by firewalls . there are no easy and low cost methods to deliver information between users if the information is stored in conventional databases . furthermore , because conventional databases use data storage and transport protocols developed before the invention of html and xml , a substantial amount of translation is needed to support multimedia display , encoding and storage . refer to fig1 for a depiction of how conventional databases use data storage and transport protocols . based on the above observation , we propose a web - centric data management scheme to support distributed internet multimedia applications . illustrated in fig1 , the main function to be provided is a meta - database call web hyperlink dictionary ( whd ) that manages urls and properties of the url for multimedia objects . the whd can provide efficient search and update capability to various html and xml encoded information . furthermore , the whd can provide direct manipulation of controllable internet appliances such as camera , telephone , and switches . whd maintains all the control and linkage information needed to support the interactive ‘ message based ’ information exchange between active programs ( agents ) running in different machines either as client or as server . using the whd , the wcc system support a unified contact center operation . for example , when a call , chat or email goes to the acd system , acd will check the service logic based on the destination address input from call , chat or email and system time . the service logic is preloaded to the system from our whd . if the supervisor or administrator changes the service logic , the new service logic will be saved to whd and updated information will be passed to whoever are interested in the change through share object service . if the destination address does not have a service logic program associated with , acd system will connect the signal with destination address such as call queue , email system , music and video . if the destination address has service logic , the acd system will continue to execute the service logic until reach to end of points . unlike prior systems , the system of the present invention advantageously unifies the following entities : 1 . multimedia message types : chat , web page , form , voice , and video . 2 . virtual addressable entities : an addressable entities that can be an user , agent , supervisor , manager , administrator , group , department , company , and communities are all modeled as a virtual group of different size and can be linked in a hyper graph . the graph can be cyclic . 3 . unified contact rules : time , space , preference , performance , security , and other routing control parameters are modeled as slp and slp is distributed by virtual groups . it can be based on any user definable rules for routing . for example , users can define the rules based upon the time when the message is received . users can construct hierarchical addressable entities and specify business rules using slp . the multimedia messages can be routed through the slp hierarchy . 4 . the rules can be defined interactively through user friendly user interface from any where any time . the modification of the rule can be verified and propagated to distributed locations where wcc is deployed to . to better understand the capabilities of the present invention , the following will present examples of slps in use . refer to fig1 when considering these examples . 1 . multimedia customer interaction ( mci ) slp . the mci slp connects to a caller when all the agents are busy . the mci slp can collect the user input from an instant messaging channel , voice channel , and data channel . the mci slp can push web pages , input form , video link , and other web content to the caller . for example , a simple pseudo code of the script can be : “ if the all agent is busy , play music at url c :\\ imaserver \\ wav \\ music 1 . wav ” for the call .” and “ if the all agent is busy , display message “ all agents are busy now ” for the instant message .” 2 . multi - level call routing slp : the mcr slp can route the call based on the information collected from the mci slp . the mcr slp can route the call to next mcr slp based on a set of rules specified in a set of executable software component linked by a script language . slp can execute sequentially or in parallel . 3 . personal assistance slp : pa slp supports advanced call control features such as routing calls based on contents of shopping cards or user input questions . ps slp also provide the linkage to connect to external data and knowledge base to assist the agent in supporting and customers . & lt ; abstract & gt ; play a menu prompt , then take the branch based on user from the foregoing it will be appreciated that the invention may be implemented as an object - oriented , agent - based server system . although the presently preferred embodiments employ object oriented technology , the invention can be implemented in other ways without departing from the spirit of the invention as set forth in the appended claims .