Define the term presence. What are the standards developed to provide presence information?

  • Presence is used on networks to indicate the status of available parties and their location.
  • Presence provides identity, status and location.
  • The service that manages presence is called the presence service.
  • Many presence services rely on agents called watchers, which are small programs that relay a client’s ability to connect.
  • Presence information is used in cloud computing services like VoIP, instant messaging services(IM) and GPS.
  • Presence is playing an important role in cell phones.
  • Eg: AroundMe on the Apple iPhone.
  • The presence service is provided by the GPS locator inside the phone, which provides a location through AT&T (the service provider) to the application.
  • Presence is an essential and growing component of cloud-based services.
  • Microsoft’s Windows Identity Foundation is a claims-based presence system.
  • A standard called the Extensible Messaging and Presence Protocol (XMPP) can be used with a federation system called the Jabber XCP to provide presence information.
  • Jabber XCP is popular because it is an extensible development platform which is platform-independent and supports several communications protocols.
  • In SOA protocols such as SOAP/REST/HTTP support unidirectional data exchange. You request a service/data, and a response is supplied.
  • SOA architectures don’t scale well and can’t supply high-speed data transfers required by the services that are based on presence service technologies.
  • SOA also has the problem of services that have trouble penetrating firewalls.
  • Jabber and XMPP were created to solve these barriers

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