Table of Contents
Advertisement
DEVELOPING COLDFUSION 9 APPLICATIONS
Using External Resources
Structure of an event gateway application
To develop an event gateway application, you create and use some or all of the following elements:
• One or more listener CFCs that handle any incoming messages and send any necessary responses.
• In some applications, ColdFusion pages that generate outgoing messages directly.
• An event gateway instance configuration in the ColdFusion Administrator. This configuration could require a
separate event gateway configuration file.
• In some applications, a GatewayHelper object to provide access to additional features of the protocol or technology;
for example, to manage instant messaging buddy lists.
The role of the listener CFC
All incoming event messages must be handled by one or more listener CFCs. You specify the listener CFCs when you
configure an event gateway in the ColdFusion Administrator. Specify at least one CFC in the administrator. Some
gateway types can use more than one CFC. By default, the ColdFusion event gateway service delivers events by calling
the
method of the CFC.
onIncomingMessage
The event gateway developer must inform the event gateway application developer of methods that the listener CFC
must implement (could be only the
message data, contained in the CFEvent instance, that the listener CFC must handle. Outgoing messages have the same
event message data structure as incoming messages.
Many gateways let the listener CFCs send a response by calling the
require a return value. Listener CFCs can also use the
than the
tag.
cfreturn
The role of ColdFusion pages
ColdFusion CFM pages cannot receive event messages. However, they can send messages using an event gateway.
Therefore, an event gateway application that initiates outgoing messages could use one or more
functions to send the messages. An application that sends an SMS message to notify users when a package ships, for
example, could use the
SendGatewayMessage
The role of the ColdFusion Administrator
The Gateway Instances page in the ColdFusion Administrator associates a specific event gateway instance with one or
more listener CFCs that processes messages from the event gateway. It tells the ColdFusion event gateway service to
send messages received by the event gateway to the listener CFC. It also lets you specify a configuration file for the event
gateway instance and whether to start the event gateway instance (and therefore any responder application) when
ColdFusion starts. For more information on using the Administrator, see the ColdFusion Administrator online Help.
The role of the GatewayHelper object
A ColdFusion event gateway provides an information conduit: at its most basic, it receives and dispatches event
messages. In some cases, however, an event gateway must provide additional functionality. An instant messaging event
gateway, for example, must provide such services as managing buddies and providing status information. To support
such use, an event gateway can enable access to a GatewayHelper object. The event gateway developer writes a Java
class that provides the necessary utility routines as Java methods, and ColdFusion application developers can get an
instance of the class by calling the CFML
methods using normal ColdFusion object access techniques. The ColdFusion instant messaging event gateways and
the example socket event gateway provide GatewayHelper objects.
method) and of the structure and contents of the event
onIncomingMessage
SendGatewayMessage
function to send the notification.
method. The application calls the GatewayHelper object
GetGatewayHelper
Last updated 8/5/2010
function, but ColdFusion does not
cfreturn
function, which provides more flexibility
SendGatewayMessage
1261
Advertisement
Table of Contents
