Event gateways are an exciting, new feature in Macromedia ColdFusion MX 7 that arose from one simple idea: that there are many applications out there that aren't part of the Web and don't communicate through the HTTP protocol.
These applications are on all types of devices. They run the gamut from the ubiquitous instant messaging clients to SMS on mobile phones to new things that haven't even been invented yet. ColdFusion does a great job powering applications that run on the Web -why not power non-Web applications too? Not only should it be possible for ColdFusion developers to write applications for non-Web applications and devices, but it should be easier to write them in ColdFusion than any other way.
ColdFusion MX 7 ships with several exciting types of event gateways that make it easy for you to get off the ground running with things like SMS. The server contains a simple Java API so that you can write your event gateway to connect to just about anything you want. With this extensibility, third-party software vendors can easily provide event gateways so that CFMX can talk to their non-CFMX applications.
Requirements
To complete this tutorial you will need to install the following software and files: ColdFusion MX 7 (www.macromedia.com/cfusion/tdrc/ index.cfm?product=coldfusion&promoid=devcenter_tutorial_product_090903)
Overview of Event Gateways in ColdFusion 7
ColdFusion 7 contains a new subsystem to support event gateways. The gateway types are Java classes that implement an application programming interface (API) provided by ColdFusion. Figure 1 shows the process for event gateway communication. The gateways communicate with the CF Event Gateway Services subsystem through CFEvent objects. The subsystem, in turn, queues the CFEvent object requests and passes them to the ColdFusion runtime engine for processing, as input to ColdFusion components (Listener CFCs). The Listener CFC might return output to the Event Gateway Services subsystem and then back to the event gateway.
Among the event gateways provided with ColdFusion MX 7 are: SMS for mobile text messaging; XMPP for open-standard instant messenger networks such as Jabber; Lotus Sametime for enterprise instant messenger communications; and asynchronous CFML for sending requests from your CFML to a CFC for processing in a separate thread. ColdFusion 7 also provides some sample event gateways types (with source code), including JMS for messaging applications that support the J2EE standard; TCP/IP Socket for use with a telnet client to interact with your applications; and Directory Watcher for watching a file system directory and to run your CFC when a user or application creates, edits, or deletes a file in that directory.
You create gateway instances from a gateway type. Instances correspond to individual copies of a gateway that are running. This is an object that is started/stopped (through the Administrator). Each gateway instance specifies a CFC to handle incoming messages. You can have more than one instance of an event gateway type, and each instance will have its own configuration. For example, you can have multiple instances of a given gateway type, each with different logins, phone numbers, buddy names, directories to watch, and so forth.
