Adobe COLDFUSION 9 Manual page 1262

DEVELOPING COLDFUSION 9 APPLICATIONS
Using External Resources
How event gateway applications work
The following diagram shows the architecture of ColdFusion event gateway applications:
SMSC server
Event
(for SMS
Event
messages )
Instant
Event
messaging
provider
Event
.
.
.
.
Other message
Event
generator /
Event
receiver
How event gateways interact
Typically, a ColdFusion event gateway instance, a Java object, listens for events coming from an external provider. For
example, a general socket event gateway listens for messages on an IP socket, and an SMS event gateway receives
messages from an SMSC server.
Each event gateway instance communicates with one or more listener CFCs through the ColdFusion event gateway
service. The listener CFCs receive CFEvent object instances that contain the messages, process them, and can send
responses back to the event gateway, which can send the messages to the external resources.
Alternatively, a ColdFusion application can initiate a message by calling a ColdFusion function that sends the message
to the event gateway. The event gateway then forwards the message to an external resource, such as an instant
messaging server. A CFC in the application listens for any responses to the sent message.
Some event gateways can be one way: they listen for a specific event and send it to a CFC, or they get messages from a
ColdFusion function and dispatch it, but they do not do both. The example DirectoryWatcherGateway discussed in
"Example event gateways" on page 1271 listens for events only, and the asynchronous CFML event gateway receives
messages from CFML only. (You could even say that the directory watcher gateway doesn't listen for events; it creates
its own events internally by periodically checking the directory state.) For information on the asynchronous CFML
event gateway, see "Using the CFML event gateway for asynchronous
Event gateway structure
Java programmers develop ColdFusion event gateways by writing Java classes that implement the
coldfusion.eventgateway.Gateway interface. ColdFusion event gateways normally consist of one or more threads that
listen for events from an event provider, such as a Socket, an SMSC server, or some other source. The event gateway
sends event messages to the ColdFusion event gateway service message queue, and provides a method that gets called
when an event gateway application CFC or CFM page sends an outgoing message.
CFEvent
Event Gateway
Instance
CFEvent
CFEvent
Event Gateway
Instance
CFEvent
.
.
.
.
CFEvent
Event Gateway
Instance
CFEvent
Java
Last updated 8/5/2010
CFEvent
Message
CFEvent
Message
ColdFusion
Event
Gateway
Service
CFEvent
Message
ColdFusion
CFCs" on page 1269.
Listener
CFC
Event Gateway
Application
Listener
CFC
Event Gateway
Application
.
.
.
Listener
CFC
CFM
Page
Event Gateway
Application
CFML
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