Abstract: A method and apparatus are provided for implementing a content based publish-and-subscribe system in a relational database system. A subscriber may request for messages by using a query language supported by the database server. The queries are then used as subscription rules for determining whether an incoming message is to be sent to the subscriber. Evaluation of incoming messages against subscription rules involves a two-tier process. The first tier involves filtering out all the subscription rules that could not possibly apply to the incoming message. The second tier involves further evaluation of the incoming message, if needed, to determine which subscribers are to receive the incoming message. In another aspect of the embodiment, in cases where the publisher is the relational database system itself, queries that request for messages are not stored as subscription rules because publication of the messages is implicit.

Abstract: A method and apparatus are provided for passing a client from a first server to which the client was connected for accessing a resource, to a second server for accessing the resource. While executing, the first server ceases to respond to the client. After the client detects that the first server has ceased to respond to the client, the client is automatically connected with the second server that has access to the resource. After automatically connecting the client, the client accesses the resource through the second server. The client stores information about the state of the session with the first server so that processing can continue where it left off after the client connects with the second server. The client may be pre-connected to the second server prior to the failure of the first server to reduce the latency caused by switching in response to a failure.