Abstract: A system for using a lease to detect a failure and to perform tailure recovery is provided in using this system, a client requests a lease from a server to utilize a resource managed by the server for a period of time. Responsive to the request, the server grants the lease, and the client continually requests renewal of the lease. If the client fails to renew the lease, the server detects that an error has occurred to the client. Similarly, if the server fails to respond to a renew request, the client detects that an error has occurred to the server. As part of the lease establishment, the client and server exchange failure-recovery routines that each invokes if the other experiences a failure.

Abstract: An improved lookup service is provided that allows for the dynamic addition and deletion of services. This lookup service allows for the addition and deletion of services automatically, without user intervention. As a result, clients of the lookup service may continue using the lookup service and its associated services while the updates occur. Additionally, the lookup service provides a notification mechanism that can be used by clients to receive a notification when the lookup service is updated. By receiving such a notification, clients can avoid attempting to access a service that is no longer available and can make use of new services as soon as they are added to the lookup service.

Abstract: A database system wherein one or more entry databases store a plurality of entries. Each entry is of a given type that defines the fields of the entry. Each field contains or identifies an object with associated attributes or data. The type of each entry may further define behavior in the form of methods the entry can implement. An entry type which is a subtype of another inherits all fields and behavior of its super-type, and contains additional fields and/or defines new/modified behavior. Entries may be expressed in a Java™ programming language. The database system may further employ a search engine which allows queries to be made upon entries in the database. In one implementation, the queries include a read operation, a take operation, and a notify operation. Each query request includes a command indicating the type of operation, and a template which is an entry object having some or all of its fields set to specific values that must be matched exactly.

Abstract: A method implemented by a computer-based electronic assistant to receive and manage incoming calls to a subscriber including the steps of receiving an incoming call to the subscriber from a caller; establishing a first connection between the electronic assistant and the caller; establishing a second connection between the electronic assistant and the subscriber; over the second connection, electronically notifying the subscriber of the incoming call; in response to receiving a call accept command from the subscriber over the second connection, linking the caller and the subscriber so that they may communicate with each other; upon linking the subscriber to the caller, switching the electronic assistant to a background mode in which said electronic assistant continues to monitor the subscriber over the second connection while the subscriber is linked with the caller; and in response to receiving a summoning command, switching the electronic assistant into a foreground mode, wherein the electronic assistant whe

Abstract: A database system wherein one or more entry databases store a plurality of entries. Each entry is of a given type that defines the fields of the entry. Each of the fields contains or identifies an object with associated attributes or data. The type of each entry may further define behavior in the form of methods the entry is configured to implement. An entry type which is a subtype of another inherits all of the fields and behavior of its supertype, and contains additional fields and/or defines new/modified behavior. Entries may be expressed in a Java.TM. class of the Java.TM. programming language. The database system may further employ a search engine which allows queries to be made upon entries in the database. In one implementation, the queries include a read operation, a take operation, and a notify operation. Each query request includes a command indicating the type of operation, and a template which is an entry object having some or all of its fields set to specified values that must be matched exactly.

Abstract: A system for using a lease to detect a failure and to perform failure recovery is provided. In using this system, a client requests a lease from a server to utilize a resource managed by the server for a period of time. Responsive to the request, the server grants the lease, and the client continually requests renewal of the lease. If the client fails to renew the lease, the server detects that an error has occurred to the client. Similarly, if the server fails to respond to a renew request, the client detects that an error has occurred to the server. As part of the lease establishment, the client and server exchange failure-recovery routines that each invokes if the other experiences a failure.

Abstract: A method implemented by a computer-based electronic assistant to receive and manage incoming calls to a subscriber including the steps of receiving an incoming call to the subscriber from a caller; establishing a first connection between the electronic assistant and the caller; establishing a second connection between the electronic assistant and the subscriber; over the second connection, electronically notifying the subscriber of the incoming call; in response to receiving a call accept command from the subscriber over the second connection, linking the caller and the subscriber so that they may communicate with each other; upon linking the subscriber to the caller, switching the electronic assistant to a background mode in which said electronic assistant continues to monitor the subscriber over the second connection while the subscriber is linked with the caller; and in response to receiving a summoning command, switching the electronic assistant into a foreground mode, wherein the electronic assistant whe