Before we begin playing with our fresh & ready BizTalk instance we need to develop a deeper understanding for the basis on which BizTalk is build. There isn’t much to explain for those of you who have already tried for example MQ. Although there are obvious analogies between the two, BizTalk Server 2010 is far more sophisticated and loosely coupled.
The whole concept of message passing is based on the abstract object called Message Box. It’s represented by the database in which all the incoming and outgoing messages are stored. Especially those received, before there are delivered to their subscribers. And now we’ve got to the point: publish-subscribe pattern. This fairly simple concept (pattern) allows to integrate even the most complicated business processes thanks to the already mentioned loosely coupled components.
Publish-subscribe pattern describes the situation in which there is an unspecified number of subscribers and also an unspecified number of publishers. Each publisher’s task is to send message to BizTalk MessageBox. None of the publishers is aware how many, if any, there are subscribers which are awaiting for the newly posted message. This completely removes any connection between the sender and the receiver allowing for example message delivery to unspecified, unlimited number of subscribers. Already mentioned subscribes, as well as publishers, are totally unaware of the fact how many, if any, publishers, publishing messages addressed to them, actually are available. Each role (subscriber/publisher) is responsible for its task (message) and nothing more than that. Publishing and subscribing can be done though simple disk folders, WebServices, WCF-Services and serious of available BizTalk Adapters.
I’m not going to explain in more detail neither the physical MessageBox implementation and structure nor list available publishing and subscribing adapters. All the information are available and googlable, so we can focus on having fun. We start from simple File Adapters, Ports and Location. In Part 2.2 we’ll set up a simple file publisher and also a file subscriber and connect them using simple configuration through BizTalk Administrator Console. Stay tuned!