 In this module, we are going to look at how web services can be provisioned because in NGN, web services are mostly associated with HTTP protocol. So the overall framework which governs the provisioning of web services is actually dependent upon how the user interacts with the application and in that case, it is mostly HTTP. So the web services control functions actually are based upon HTTP because the HTTP payload carries these control functions. So the overall framework is generalized which is dependent upon HTTP and we can classify these web services into three broad categories. The first one is the legacy web service. The second one is the conversation service. And the last one is actually the IP based television services. So we'd look at exactly how each one of these is provisioned once the framework of HTTP is used. Now the overall control functionality is governed by the web services control functions which determine the choice of appropriate web server, whichever has the most appropriate web pages, HTML for example, upon the user's request. For that, directory is consulted for a list of potential web servers which have the right reply to this particular request. And then the user profile is also consulted because the user actually has certain configurations, preferences and the user may also have some record which needs to be consulted. For instance, the transaction history of the user, which is going to eventually determine what kind of services can be provisioned. So it actually gets down to this much simplicity that web server now creates a particular web service which is as per the demand of the user. For static web services, it is as simple as that. But once we are looking at the conversation service, which is actually going to involve two parties having a symmetric communication with each other, an example is the IP telephony. Then HTTP is used to encapsulate the web service control functions that pertain to IP multimedia component. The IP multimedia component is going to be another server on the network side that can talk to the end user to provide certain telephony configurations and initial settings. So the service component actually creates the conversation service between these calling party and the call party using standard application programming interface. For instance, if the user is using Skype telephony, then correspondingly the appropriate configurations are made such that the dialing process and the call receiving process are simulated like real telephone. So the IMS IP multimedia subsystem actually manages the call service and establishes all the connection requests and responses between the client and the server. So if you look at the legacy web services, it is as simple as encapsulated web service control function requests. Now the web service control functions actually using the web media functions which are governed by the multimedia transcoding and encoding formats to allow communication between the client and the server. Here you can see we have a web server that web server responds to the client requests depending upon what services can be invoked and which web server to be contacted. In the second example of web based conversation service, we have the IP multimedia subsystem that emulates the PSTN and PLMN kind of network services for SS7, etc. So we have that on the network side, on the engine side, I mean. And we have the client request encapsulated in HTTP managed through WSCF and after consulting the appropriate user profile, then the requests are used to establish connection between the two parties. And then we have the last one that is IP TV service. In IP TV service, it's mostly a downstream service where the content is actually pre-stored or streamed live from the streaming servers or the storage servers. It's audio visual content. So again, the request is made in exactly the same way both in web based conversation service appropriate codecs are used. And then in IP TV services appropriate codecs and encoding schemes have to be utilized. So if the video format is not provisioned by the server to the client, which is supported, in that case, the web media functions actually perform the transcoding or translation of format from one to the other.