Open Stack

Hi,

The new API has an optional parameter called transport_url[0], which is
used to specify the connection parameters for the chosen transport.
This url is being passed to the driver instance, which has to parse
it and, eventually, merge it with its own connection parameters -
depending on the implementation. [1]

My question is: Do we really need it?

I agree it is useful for some implementations but, it can also make it
a bit more difficult for other implementations. For example, in qpid's
case, it could either use a single host or have a list of hosts for
HA. If transport_url is specified it will be necessary to either give
priority to it or append its netloc to the qpid_hosts list. However,
this behavior, most likely won't be the same for other
implementations.

I'm proposing to use rpc_backend and leave the connection parameters
definition to the implementation.

Also, from my experience with kombu managing connection URLs at a
higher level can be painful for both the lib and backends
implementation.

Thoughts?

Cheers,
FF

[0]
https://github.com/markmc/oslo-incubator/blob/messaging/openstack/common/messaging/transport.py#L25

[1]
https://github.com/FlaPer87/oslo-incubator/blob/messaging-qpid/openstack/common/messaging/_drivers/impl_qpid.py#L45

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