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https://issues.apache.org/jira/browse/DIRMINA-368?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Emmanuel Lecharny closed DIRMINA-368.
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> IoFilter.messageSent should have access to WriteRequest instead of the
> written message.
> ---------------------------------------------------------------------------------------
>
> Key: DIRMINA-368
> URL: https://issues.apache.org/jira/browse/DIRMINA-368
> Project: MINA
> Issue Type: Improvement
> Components: Core
> Reporter: Trustin Lee
> Assignee: Trustin Lee
> Fix For: 2.0.0-M1
>
>
> IoFilter.filterWrite() accepts WriteRequest as its parameter to allow an
> IoFilter implementation to alter the WriteRequest or create a new
> WriteRequest. This is particularly useful when the filter transforms a
> received message. Good examples of this scenario are ProtocolCodecFilter and
> SSLFilter.
> Because these examples are wrapping an outgoing message with an internal
> type, the filter implementor was able to get the original message by
> unwrapping in IoFilter.messageSent() like the following:
> public void filterWrite(NextFilter nextFilter, IoSession session,
> WriteRequest req) {
> nextFilter.filterWrite(session, new WriteRequest(new
> TransformedMessage(req.getMessage())));
> }
> public void messageSent(NextFilter nextFilter, IoSession session, Object
> message) {
> if (message instanceof TransformedMessage) {
> nextFilter.messageSent(session, ((TransformedMessage)
> message).getOriginalMessage());
> return;
> }
> ......
> }
> But, what if the transformation is not wrapping but unwrapping? We can't
> perform the reverse-transformation like we did in the example above, because
> we don't know what the original message was in IoFilter.messageSent().
> public void filterWrite(NextFilter nextFilter, IoSession session,
> WriteRequest req) {
> nextFilter.filterWrite(session, new WriteRequest(
> ((OuterMessage) req.getMessage()).getInnerMessage())); //
> Unwrap on write.
> }
> public void messageSent(NextFilter nextFilter, IoSession session, Object
> message) {
> if (message instanceof InnerMessage) {
> // TODO Transform the message back to OuterMessage. But how?
> }
> ......
> }
> To fix this problem, there should be at least one common type that any
> IoFilter implementation can understand, and that type has to be the parameter
> of IoFilter.messageSent(). A good candidate is WriteRequest, which is
> already exposed in the IoFilter interface. With this change applied, the
> IoFilter implementation will look like the following:
> public void filterWrite(NextFilter nextFilter, IoSession session,
> WriteRequest req) {
> // Wrap on write.
> nextFilter.filterWrite(session, new TransformedWriteRequest(request));
> }
> public void messageSent(NextFilter nextFilter, IoSession session,
> WriteRequest request) {
> if (request instanceof TransformedWriteRequest) {
> // Unwrap on messageSent.
> nextFilter.messageSent(session, ((TransformedWriteRequest)
> request).getWriteRequest());
> return;
> }
> ......
> }
> private static class TransformedWriteRequest extends WriteRequestWrapper {
> private TransformedWriteRequest(WriteRequest req) {
> super(req);
> }
> public Object getMessage() {
> // Wrapping with TransformedWriteRequest is actually unwrapping
> the message.
> // and unwrapping this write request is actually wrapping the
> message back.
> return ((OuterMessage) super.getMessage()).getInnerMessage();
> }
> }
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