Combined message broker

A gate-keeping message broker spanning a firewall to provide interconnected message brokering services spanning the firewall. The gate-keeping message broker provides for the creation of an international business transaction information system ("IBTIS") for a user having service needs regarding the relocation of purchased goods across international borders. The IBTIS is configured to work with a plurality of internal service engines and reference servers that are present on both sides of the firewall. The gate-keeping message broker also provides form and syntax validation for messages that it brokers. It further provides content verification and completion services on the content of the messages, the verification being based on business-logic specific to the type of message being brokered.