1. A system for providing content of a publish-subscribe topic tree, the system comprising: a processor; and a computer readable storage medium connected to the processor, wherein the computer readable storage medium has stored thereon a program for controlling the processor, and wherein the processor is operative with the program to execute the program for: receiving a path for a requested topic, wherein the path specifies topic names leading from highest to lowest level topic names in the path, wherein the topic tree includes topic names and an added node identifier associated with each respective topic name of the topic tree, wherein certain digits of the node identifiers for parent nodes in the tree correspond to certain digits of node identifiers of child node(s) of each respective parent; searching a hash table for the topic names specified in the path, wherein the hash table also includes the topic names of the topic tree and includes the node identifier associated with each respective topic name of the topic tree; finding, in the hash table, the topic tree node identifiers for the topic names specified in the path; designating a highest level topic in the path as a current highest level topic; performing parent-child node matching for the node identifiers found in the hash table, including matching certain digits of the found node identifier(s) for the current highest level topic in the path to corresponding digits of the found node identifier(s) for a next lower level topic in the path to find a matching next level node, and then designating a next topic after the current highest level topic in the path to be a new, current highest level topic; repeating the parent-child node matching for each successive topic in the path, in order to find the node identifier for the lowest level node in the path; and retrieving content in the topic tree only for matching topic names that match the lowest level topic name in the requested topic path independently of whether the matching topic names are on the requested topic path in the tree, including retrieving the content in the topic tree for the matching topic name(s) no later than at least partly in concurrence with the parent-child node matching; and sending, for a requestor, the content retrieved for only the one topic name that matches the lowest level topic name in the requested topic path and for which the topic tree node was identified as the lowest level node in the path by the parent-child node matching.