Abstract: A network-based messaging system comprises multiple agents to communicate messages between multiple users in real time using, for example, an XML document synchronization model. Each agent has properties defined in XML and can subscribe to properties of other agents. Each agent can notify other agents which subscribe to it of changes to its properties. The agents communicate using an XML or alternative extensible data interchange protocol. The agents include device agents to represent each of multiple user devices, which may include computers on a wireline network and mobile devices on a wireless network. The agents also include persona agents to represent each user. The persona agents collect information about the properties of other agents and publish the information to other, subscribing agents. Each persona agent comprises properties to maintain state information for each device used by the corresponding user. Most of the agents reside in a centralized agent system.

Abstract: A user interface for navigating among screens on a personal computer. The screens, which include layers of a shell user interface and various locations within applications, are presented as pages. In addition, commands and help information of an application are presented as a web of command pages. To this end, a unit of measure, called a “place” is defined. In general, an application is a place, and separate documents within an application may also define a place. Separate command windows and dialog boxes within an application or a document typically do not define a place. Backwards navigation takes the user to the previous place, and forward navigation (if possible) takes the user to the next place. Because the underlying data for a page may change between an initial visit to a page and navigation back to the page, data objects and page code are maintained separately, and are combined only when a request for a page is made.