It is clear that the information about TV programmes and schedules are finding its place in the Internet. Even though the user is able to find a lot of information about programmes in the Internet, until now the controlling of the video recorder while browsing, was not possible. Use of the STORit box, as the Internet gateway for the personal computer at home, has this significant advantage. It enables sending of typical video recorder commands (Record, Play, Cancel…) to the digital video recorder, while browsing through the Internet. The result of a simple click on the programme's UPI link in the web page is an issued command for recording of this programme.
Figure 7 : Confirmation request follows a click on chosen TV programme in the programme page.
The Apache server, which serves as the Internet gateway (proxy) for the user's PC, runs in the STORit box. Therefore all Internet traffic, including HTTP hyperlink requests, is filtered by the Apache server. To be able to issue an HTTP request, different from standard requests for web pages, we have defined alternative hyperlink structure for UPI links. These links are included in HTML documents as ordinary http links. In such way, the Apache server is able to distinguish between requests for web pages and requests for recording TV programmes or playing recorded programmes.
Figure 8 : STORit box confirms successful set up of recording.
When a recording request is intercepted by the Apache server (it is a GET method of the HTTP protocol), the UPI hyperlink is processed by the Apache server rewrite module. The UPI hyperlink is parsed into several components (UPI identifier, programme's name, requested method (RECORD, PLAY…)). The rewrite module invokes execution of a CGI programme (sendUPI) in the STORit box, which requests confirmation of the recording (or any other) command from user (pop-up window, Figure 7). In case of the confirmation, it sends the appropriate command to STORit box controller and returns the reply from the controller (Figure 8). In case the programme title is not included in the UPI hyperlink, pop-up window refers to a programme through its UPI identifier (Figure 9). For communication between the Apache and STORit box controller, a collection of API calls has been defined.
Figure 9 : Record confirmation request in case the UPI hyperlink does not contain a programme title.
Special UPI link format (case insensitive), defined for the purpose of controlling a digital video recorder from a web browser has the following structure:
[http://hostname/][<path>/]STORit/<upi
identifier>
[?[METHOD=<method>][+TITLE=<title>][+other parameters]]
The first part of the link is like a usual http link, which can be an absolute http link (with http://hostname/) or a relative one (without http://hostname/). The Apache server handles the absolute link as an http proxy request, while the relative link is handled as an http request to the STORit box. The key word STORit is mandatory to enable use of popular Web browsers, Netscape and Microsoft Internet Explorer. If the hostname and path were omitted, Microsoft Internet Explorer would not send the upi link to the proxy server on the STORit box. Upi identifier is a unique programme identifier, with a defined structure (ex. upi:bbc:1234 , see chapter 8). The Method parameter defines the command we want the video recorder to execute (PLAY, RECORD...) and title is the programme title (e.g. Star Wars : The Phantom Menace). If the method has additional parameters, they can be given as other parameters. The Upi identifier parameter is mandatory, the others are optional. The default method is RECORD (in case of missing method parameter). Some examples of upi links are:
For communication between the Apache server (a CGI programme sendUPI) and digital video-recorder a preliminary set of commands has been defined (API). These are: