ColdFusion Developer's Guide

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■ MyGateway(String gatewayID, String configurationFile)
■ MyGateway(String gatewayID)
■ MyGateway()
When ColdFusion starts, it calls the constructor for each event gateway instance that you
configure in ColdFusion. (ColdFusion also calls the gateway Start method after the event
gateway is instantiated.). ColdFusion first attempts to use the two-parameter constructor.
Because each event gateway instance must have a unique ID, ColdFusion provides redundant
support for providing the ID. If the event gateway implements only the default constructor,
ColdFusion provides the ID by calling the event gateway’s setGatewayID method.
If the event gateway does not implement the two-parameter constructor, it does not get
configuration file information from ColdFusion.
The constructor normally calls the static GatewayServices.getGatewayServices method
to access ColdFusion event gateway services. Although you need not do this, it is a good
coding practice.
A minimal constructor that takes only a gateway ID might look like the following:
public MyGateway(String gatewayID) {
this.gatewayID = gatewayID;
this.gatewayService = GatewayServices.getGatewayServices();
}
The gateway constructor must throw a coldfusion.server.ServiceRuntimeException exception
if there is an error that otherwise cannot be handled. For example, you should throw this
exception if the event gateway requires a configuration file and cannot read the file contents.
If your gateway uses a configuration file, the constructor should load the file, even if the
Start method also loads the file. You should do this because the constructor does not run in
an independent thread, and ColdFusion can display an error in the ColdFusion Administrator
of the file fails to load. If the Start method, which does run in a separate thread, fails to load
the file, ColdFusion logs the error, but it cannot provide immediate feedback in the
administrator.
The sample Socket event gateway has a single constructor that takes two parameters. It tries to
load a configuration file. If you specify a configuration file in the ColdFusion Administrator,
or the file path is invalid, it gets an IO exception. It then uses the default port and logs a
message indicating what it did. The following example shows the Gateway constructor code
and the loadProperties method it uses:
public SocketGateway(String id, String configpath)
{
gatewayID = id;
gatewayService = GatewayServices.getGatewayServices();
// log things to socket-gateway.log in the CF log directory
1608 Creating Custom Event Gateways