The BizTalk Server runtime is built on a publish/subscribe architecture in which a message is published into the system, and then received by one or more active subscribers. Different flavors of this architecture exist, but the model implemented in BizTalk Server is often called content-based publish/subscribe.In a content-based publish/subscribe model, subscribers specify the messages they want to receive using a set of criteria about the message.ifferent flavors of this architecture exist, but the model implemented in BizTalk Server is often called content-based publish/subscribe. In a content-based publish/subscribe model, subscribers specify the messages they want to receive using a set of criteria about the message.