openstack/nova
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fix list rendering in rpc doc

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list bullets have to be exactly 2 spaces indented from the parent, and
the top level is left justified, otherwise we get lots of <blockquote>
html tags inserted.

Part of bp: doc-migration

Change-Id: Ie8b311ca286601a47475b33ef80da272efc9be31
This commit is contained in:
Sean Dague 2017-08-03 07:50:27 -04:00
parent 12c0a66657
commit dafd133ab8
1 changed files with 59 additions and 53 deletions
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12
doc/source/reference/rpc.rst
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@ -19,9 +19,14 @@ AMQP and Nova
AMQP is the messaging technology chosen by the OpenStack cloud. The AMQP broker, either RabbitMQ or Qpid, sits between any two Nova components and allows them to communicate in a loosely coupled fashion. More precisely, Nova components (the compute fabric of OpenStack) use Remote Procedure Calls (RPC hereinafter) to communicate to one another; however such a paradigm is built atop the publish/subscribe paradigm so that the following benefits can be achieved:
* Decoupling between client and servant (such as the client does not need to know where the servant's reference is).
* Full a-synchronism between client and servant (such as the client does not need the servant to run at the same time of the remote call).
* Random balancing of remote calls (such as if more servants are up and running, one-way calls are transparently dispatched to the first available servant).
* Decoupling between client and servant (such as the client does not
need to know where the servant's reference is).
* Full a-synchronism between client and servant (such as the client
does not need the servant to run at the same time of the remote
call).
* Random balancing of remote calls (such as if more servants are up
and running, one-way calls are transparently dispatched to the first
available servant).
Nova uses direct, fanout, and topic-based exchanges. The architecture looks like the one depicted in the figure below:
@ -140,6 +145,7 @@ More precisely Consumers need the following parameters:
* Auto_ack: acknowledgment is handled automatically once messages are received. By default auto_ack is set to False, and the receiver is required to manually handle acknowledgment.
* No_ack: it disable acknowledgment on the server-side. This is different from auto_ack in that acknowledgment is turned off altogether. This functionality increases performance but at the cost of reliability. Messages can get lost if a client dies before it can deliver them to the application.
* Auto_declare: if this is True and the exchange name is set, the exchange will be automatically declared at instantiation. Auto declare is on by default.
Publishers specify most the parameters of Consumers (such as they do not specify a queue name), but they can also specify the following:
* Delivery_mode: the default delivery mode used for messages. The value is an integer. The following delivery modes are supported by RabbitMQ: