Java Message Service, 2nd Edition

Connecting to the Outside World

There are often entities outside your corporation that you need to interact with. You may have trading partners, financial institutions, and vertical business portals to connect to and communicate with. These outside entities usually have established protocols that they already use for electronic communication. An Electronic Data Interchange (EDI) system may have nightly batch jobs that export flat files to an FTP site. A trading partner may expect to send and receive HTTP transmissions as its way of communicating with the outside world. A supply chain portal may require that you install one of their clients on your site in order to communicate with them through whatever protocol they dictate. Sometimes email is required as a way of sending a “Thank you for your order” message.

Ideally each of these outside entities would have a close working relationship with you and would allow you to install a JMS client at each site. That would make communication very easy—but it’s not how the world works. These other communication mechanisms may have been in place for a number of years and their users aren’t about to rip them out just because you want them to. They may not be capable of changing the way their systems work just to accommodate your JMS provider. These are “legacy systems”; in the future, they may gradually disappear, but for the time being, we have to figure out how to work with them.

There is recent activity in the area of providing a RESTful interface ...