As with text search engine systems, video search systems may support several interfaces to allow developers to create new applications, or for users to access the service using multiple client applications other than browsers such as RSS readers, gadget containers such as desktop sidebars, or mashups which combine multiple services.
Systems may support interfaces including:
• Web Services (WS) – The simple object access protocol (SOAP) used over HTTP and described by the Web Services Description Language (WSDL) provides a standard framework for interaction with services such as video retrieval, but the latitude enabled in architecture and parameter semantics implies that video search Web services are not interoperable in general. Some amount of new interface code is typically required when switching from one Web service to another.
• Representational State Exchange (REST) - The REST presents architectural style [Field00] that can be applied to media search engine interactions. Flickr® for example, supports a REST API for photo retrieval. This design philosophy is highly robust (it describes the behavior of stateless exchange on the Web for example) but does not dictate a preferred language or syntax.
• Asynchronous JavaScript with XML (AJAX) - AJAX can be used for rendering dynamic user interfaces, and the underlying requests to the video Web server may have a REST flavor and may utilize WS.
• Real Simple Syndication (RSS) - Query results can be represented in XML using RSS, perhaps with specific namespace extensions as appropriate. This enables client-side persistent queries, in which the results are typically sorted temporally (most recent first) to best fit the usage paradigm of RSS readers.
• OpenSearch® - A9, an amazon.com company, developed OpenSearch® which provides a standardized query syntax that allows browsers and other applications to seamlessly support a wide range of search engine providers [Clin07]. Results are formatted in RSS and a paging mechanism is supported to allow stepping through large results lists efficiently.
• SQL / XML Query - A video collection may expose an SQL interface and applications may connect using ODBC. The Microsoft Indexing Service is an example of a service that supports an SQL interface but with an underlying architecture that is more indexing oriented than a traditional database. Several XML query languages are available for use with metadata stored in XML such as MPEG-7.
• Mini-applications (Gadgets, Widgets) – Microsoft’s Vista®, Google and Yahoo support interfaces to allow third parties such as video search engines to expose functionality through a small region of screen real estate in other applications or desktops. These are typically grouped via a sidebar.
• Notification, e-Mail - Systems can support persistent queries stored on the server and notify users via e-mail. Users can elect to be notified once a day rather than multiple times as new matching content arrives. Servers must efficiently manage stored queries from a potentially large set of users, and possibly pool similar queries.
