Hi Stefan,
On 2/1/07, Stefan Bischof <[EMAIL PROTECTED]> wrote:
Hi,
I am working on programming an ICAP-server (a HTTP-like protocol). So
far I just adapted the HTTP codec example. I created IcapRequestDecoder,
IcapResponseEncoder and ServerHandler (just like the HTTP example).
Sounds cool!
Now I have a question regarding errors:
Scenario:
The client sends me a message which violates the protocol. As far as I
understood, this problem should be detected in
IcapRequestDecoder.decode. Right?
Yes, you can *detect* the problem, but you could also just do what you are
supposed to do (i.e. parsing the message) and let the exception arise due to
a unexpected value. You don't need to perform every integrity check on a
received message as long as an exception can be thrown.
Once an exception is throw from a ProtocolDecoder, MINA wraps the exception
with ProtocolDecoderException, and forward it to your IoHandler's
exceptionCaught() handler method. You can check the type of the cause
(exception) using 'instanceof' keyword:
if (cause instanceof ProtocolDecoderException) {
Throwable causeOfCause = cause.getCause(); // what is thrown from
ProtocolDecoder
session.write(new FourOhOhMessage());
}
I've never thought about using MessageDecoderResult.NOT_OK, but using
ProtocolDecoderException is better IMHO. It sounds interesting though.
HTH,
Trustin
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