Enhanced Presence Application Scenarios
In real-time communications, presence refers to information used to describe a user's availability, willingness, or capability to communicate with other users. The information is useful for a user to determine when and how to contact other users.
For example, Microsoft Lync 2010 displays a list of your contacts together with their status indicating if they are available, busy, inactive, away, or offline. Shown on an active Lync 2010 instance, the status information is color-coded and appears before each contact's name. When a contact's status shows Available, you know that the contact is likely to answer your instant message or voice call. A busy or inactive contact, however, is less likely to respond to your invitation. The Away or Offline status suggests that perhaps you should send the contact an e-mail message instead of text messages.
In addition to the availability status, the presence can also be described by other information that indicates a person’s ability and willingness to communicate with others. For example, you may leave a personal note to inform others of your current traveling itinerary and to provide them with a list of alternative communications means to reach you in case of emergency.
The user who makes his or her presence information available is known as a presence entity. A presence entity is also known as a presentity or presence publisher. Typically, a presence publisher corresponds to a person. But it can also be an application or another non-person entity. This entity could be a Web service or an interactive bot, involved in a communication process.
The presence can be viewed as some metadata or indexes that are used to optimize a search for relevant and appropriate communication partners. The flexibility of the enhanced presence also implies that its concept and mechanism can be straightforwardly applied to other application scenarios where metadata-provisioning or context-matching plays an important role. The following list shows some examples of enhanced presence applications: