10. The method according to claim 1 or 3 , wherein the central unit provides search to users for searching content of messages and searching or subscribing to sources of messages based on at least a part of message content and one or more search criteria.
10. The method according to claim 1 or 3 , wherein the central unit provides search to users for searching content of messages and searching or subscribing to sources of messages based on at least a part of message content and one or more search criteria. 11. The method according to claim 10 , wherein the search criteria comprise one or more keywords, locations, languages, rank and hit statistics, date range, content type including hyperlink, text, video, audio, image, categories, shared ontology, semantic syntax, filter criteria, predefined search templates, conditions and customized commands.