SimpleAmqpClient - exception handling

[Kim Tran]

Alan,
First of all, thanks for the C++ Client library. It hides a bunch of
details that one has to deal with if using rabbitmq-c. SimpleAmqpClient
has good documentation and a number of good examples of how to use
classes/objects provided by the library to do messaging. However, it
seems little is described in terms of exception handling. Is there a
guidelines on how to handle various exceptions that could be thrown by
the library? For example, what can be restarted/reset within the
application vs giving up ? What are the differences between
ChannelException and ConnectionException? Is there a need to have
specific handling for low-level exception like ResourceLockedException?
How should they be handled ?

Thanks,
-Kim

[Alan Antonuk]

On Thu, Sep 18, 2014 at 3:21 PM, Kim Tran <ktra...@gmail.com> wrote:

Alan,
First of all, thanks for the C++ Client library.  It hides a bunch of details that one has to deal with if using rabbitmq-c. SimpleAmqpClient has good documentation and a number of good examples of how to use classes/objects provided by the library to do messaging.  However, it seems little is described in terms of exception handling.  Is there a guidelines on how to handle various exceptions that could be thrown by the library?

Unfortunately not, and looking at the exception contract with a more experienced eye; admittedly it's a bit of a mess. But heres where it stands:

ConnectionException (and sub-classes): this maps to an AMQP connection exception. If you see one of these your AmqpClient::Channel object is no longer connected to the broker. You should destroy the Channel object and create a new one.

ChannelException (and sub-classes): this maps to an AMQP channel exception. If you see one of these the last operation you performed on the AmqpClient::Channel object failed. The Channel object itself is still valid, you can continue to use it.

AmqpLibraryException and AmqpResponseLibraryException (they are pretty well the same thing): this wraps a rabbitmq-c library error. From SimpleAmqpClient perspective, if you see one of these, the connection is dead or in an indeterminate state, you should destroy the AmqpClient::Channel objects and start anew.

BadUriException - only thrown from one of the AmqpClient::Channel::Create* functions. No new connection will be returned.

ConnectionClosedException - should be thrown if an AmqpClient::Channel that is closed is used.

ConsumerCancelledException - thrown if the consumer is closed while waiting for a message. Consumer is closed, but AmqpClient::Channel object is still valid.

ConsumerTagNotFound - thrown if you pass a consumer tag that is invalid. AmqpClient::Channel object is still valid.

MessageReturnedException - thrown if you publish with the mandatory flag set, but the message isn't routed to a queue. AmqpClient::Channel object is still valid.

HTH

-Alan

[Kim Tran]

Thanks Alan!
Those are very useful.
-Kim

[Suri MS]

Hello Alan,

Can you please help with:

How can we explicitly destroy a channel object in the C++ client ?

Thanks,

Suri

[Suri MS]

Hi,

Could some expert, please , help me with the query?

Thanks in advance,

Suri

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