Abstract: A system for, and method of, filtering an XML document with XPath expressions and a selective data dissemination system incorporating the system or the method. In one embodiment, the filtering system includes: (1) a tree builder that builds a document data tree for the XML document and an XPath expression tree based on substrings in the XPath expressions and (2) a tree prober, associated with the tree builder, that employs the XPath expression tree to probe the document data tree and obtain matches with the substrings.

Abstract: Techniques are provided for executing an operation in which a client invokes a replicated object. According to one technique, a primary replica of a replicated object receives a first request from a client, wherein the first request includes a request identifier. Rather than immediately attempting to process the request, the primary replica determines whether a record exists that corresponds to the request identifier. If a record exists that corresponds to the request identifier, then the primary replica responds to the first request with a reply associated with the record. If no record exists that corresponds to the request identifier, then the primary replica performs the steps of: starting a transaction; as part of the transaction, processing the request; as part of the transaction, storing a record associated with the request identifier and a reply to the request; committing the transaction; and delivering the reply to the client. The client may itself be a replicated object.