A message broker can allow any server in a cluster to publish to, and subscribe, to a message channel. A server subscribing to a channel can set up a message filter such that XQuery expressions can be used to filter against the messages arriving on the channel A message broker can also utilize a unique filtering algorithm to optimize data access. Static subscription information can be captured in order for a message broker to do client-side filtering. A message broker can also construct and maintain at least one table in memory that indicates whether any server in the cluster may ever do a dynamic subscription. For dynamic subscriptions, the publishing server can extract the information from a database, such as by executing a DBMS select on a subscription table using a primary key lookup.This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.