1. A method for performing publisher-side content based filtering to select which subscribers shall receive each data-message sent by a publisher using an Object Management Group (OMG) Real-Time Publish-Subscribe (RTPS) protocol, the method comprising the following computer-implemented method steps executable by one or more computers in a networked system: (a) having the publisher and a plurality of subscribers being able to communicate with each other using the RTPS protocol, wherein each of the subscribers uses a content filter to subscribe to a subset of the information published by the publisher; (b) informing the publisher about the content filter used by each of the subscribers. (c) the publisher determining via a lookup table the set of subscribers for which a data-message passes the corresponding subscriber content filter and then sending the data-message; (d) the publisher evaluating the content filter of each of the subscribers on the data-message if the lookup table does not contain the set of subscribers to which the data-messages shall be sent; and (e) the publisher updating the lookup table based on the result of the evaluation of the content-filter of each of the subscribers for a particular data-message.