openstack/openstack-manuals
Code Issues Proposed changes

change to module001-ch008-queues-messaging

Browse Source 
changed rpc worker and rpc cast sentence
changed reply to plural
paces around "and"
removed "we"
revised sentence
added space "using <command>"
added a space before A
added space and capitals after </emphasis>

Change-Id: I3f9d5fb147aaacd42e5790aa751547e5821482a7
This commit is contained in:
Shilla Saebi 2014-03-14 01:48:54 -04:00 committed by shillasaebi
parent eaee19793c
commit 0f0fd7299d
1 changed files with 34 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

68
doc/training-guides/module001-ch008-queues-messaging.xml
View File

@ -64,21 +64,21 @@
<para><guilabel>Nova RPC Mappings</guilabel></para> <para><guilabel>Nova RPC Mappings</guilabel></para>
<para>The figure below shows the internals of a message broker node <para>The figure below shows the internals of a message broker node
(referred to as a RabbitMQ node in the diagrams) when a single (referred to as a RabbitMQ node in the diagrams) when a single
instance is deployed and shared in an OpenStack cloud. Every Nova instance is deployed and shared in an OpenStack cloud. Every component
component connects to the message broker and, depending on its within Nova connects to the message broker and, depending on its
personality, such as a compute node or a network node, may personality, such as a compute node or a network node, may
use the queue either as an Invoker (such as API or Scheduler) or a use the queue either as an Invoker (such as API or Scheduler) or a
Worker (such as Compute or Network). Invokers and Workers do not Worker (such as Compute or Network). Invokers and Workers do not
actually exist in the Nova object model, but we are going to use actually exist in the Nova object model, but in this example they are used
them as an abstraction for sake of clarity. An Invoker is a as an abstraction for the sake of clarity. An Invoker is a
component that sends messages in the queuing system via two component that sends messages in the queuing system using <command>rpc.call
operations: 1) rpc.call and ii) rpc.cast; a Worker is a component </command> and <command>rpc.cast</command>. A worker is a component
that receives messages from the queuing system and reply that receives messages from the queuing system and replies
accordingly to rcp.call operations.</para> accordingly to rcp.call operations.</para>
<para>Figure 2 shows the following internal elements:</para> <para>Figure 2 shows the following internal elements:</para>
<itemizedlist> <itemizedlist>
<listitem> <listitem>
<para><emphasis role="bold">Topic Publisher:</emphasis>a Topic <para><emphasis role="bold">Topic Publisher:</emphasis> A Topic
Publisher comes to life when an rpc.call or an rpc.cast Publisher comes to life when an rpc.call or an rpc.cast
operation is executed; this object is instantiated and used to operation is executed; this object is instantiated and used to
push a message to the queuing system. Every publisher connects push a message to the queuing system. Every publisher connects
@ -86,7 +86,7 @@
limited to the message delivery.</para> limited to the message delivery.</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">Direct Consumer:</emphasis>a Direct <para><emphasis role="bold">Direct Consumer:</emphasis> A Direct
Consumer comes to life if (an only if) a rpc.call operation is Consumer comes to life if (an only if) a rpc.call operation is
executed; this object is instantiated and used to receive a executed; this object is instantiated and used to receive a
response message from the queuing system; Every consumer response message from the queuing system; Every consumer
@ -97,7 +97,7 @@
Topic Publisher (only rpc.call operations).</para> Topic Publisher (only rpc.call operations).</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">Topic Consumer:</emphasis>a Topic <para><emphasis role="bold">Topic Consumer:</emphasis> A Topic
Consumer comes to life as soon as a Worker is instantiated and Consumer comes to life as soon as a Worker is instantiated and
exists throughout its life-cycle; this object is used to exists throughout its life-cycle; this object is used to
receive messages from the queue and it invokes the appropriate receive messages from the queue and it invokes the appropriate
@ -111,7 +111,7 @@
exchange key is ‘topic.host’).</para> exchange key is ‘topic.host’).</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">Direct Publisher:</emphasis>a Direct <para><emphasis role="bold">Direct Publisher:</emphasis> A Direct
Publisher comes to life only during rpc.call operations and it Publisher comes to life only during rpc.call operations and it
is instantiated to return the message required by the is instantiated to return the message required by the
request/response operation. The object connects to a request/response operation. The object connects to a
@ -119,7 +119,7 @@
incoming message.</para> incoming message.</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">Topic Exchange:</emphasis>The <para><emphasis role="bold">Topic Exchange:</emphasis> The
Exchange is a routing table that exists in the context of a Exchange is a routing table that exists in the context of a
virtual host (the multi-tenancy mechanism provided by Qpid or virtual host (the multi-tenancy mechanism provided by Qpid or
RabbitMQ); its type (such as topic vs. direct) determines the RabbitMQ); its type (such as topic vs. direct) determines the
@ -127,14 +127,14 @@
topic-based exchange for every topic in Nova.</para> topic-based exchange for every topic in Nova.</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">Direct Exchange:</emphasis>this is a <para><emphasis role="bold">Direct Exchange:</emphasis> This is a
routing table that is created during rpc.call operations; routing table that is created during rpc.call operations;
there are many instances of this kind of exchange throughout there are many instances of this kind of exchange throughout
the life-cycle of a message broker node, one for each rpc.call the life-cycle of a message broker node, one for each rpc.call
invoked.</para> invoked.</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">Queue Element:</emphasis>A Queue is <para><emphasis role="bold">Queue Element:</emphasis> A Queue is
a message bucket. Messages are kept in the queue until a a message bucket. Messages are kept in the queue until a
Consumer (either Topic or Direct Consumer) connects to the Consumer (either Topic or Direct Consumer) connects to the
queue and fetch it. Queues can be shared or can be exclusive. queue and fetch it. Queues can be shared or can be exclusive.
@ -302,56 +302,56 @@
<para>The following parameters are default:</para> <para>The following parameters are default:</para>
<itemizedlist> <itemizedlist>
<listitem> <listitem>
<para><emphasis role="bold">Insist:</emphasis> insist on <para><emphasis role="bold">Insist:</emphasis> Insist on
connecting to a server. In a configuration with multiple connecting to a server. In a configuration with multiple
load-sharing servers, the Insist option tells the server that load-sharing servers, the Insist option tells the server that
the client is insisting on a connection to the specified the client is insisting on a connection to the specified
server. Default is False.</para> server. Default is False.</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">Connect_timeout:</emphasis> the <para><emphasis role="bold">Connect_timeout:</emphasis> The
timeout in seconds before the client gives up connecting to timeout in seconds before the client gives up connecting to
the server. The default is no timeout.</para> the server. The default is no timeout.</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">SSL:</emphasis> use SSL to connect <para><emphasis role="bold">SSL:</emphasis> Use SSL to connect
to the server. The default is False.</para> to the server. The default is False.</para>
</listitem> </listitem>
</itemizedlist> </itemizedlist>
<para>More precisely consumers need the following parameters:</para> <para>More precisely consumers need the following parameters:</para>
<itemizedlist> <itemizedlist>
<listitem> <listitem>
<para><emphasis role="bold">Connection:</emphasis> the above <para><emphasis role="bold">Connection:</emphasis> The above
mentioned Connection object.</para> mentioned Connection object.</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">Queue:</emphasis>name of the <para><emphasis role="bold">Queue:</emphasis> Name of the
queue.</para> queue.</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">Exchange:</emphasis>name of the <para><emphasis role="bold">Exchange:</emphasis> Name of the
exchange the queue binds to.</para> exchange the queue binds to.</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">Routing_key:</emphasis>the <para><emphasis role="bold">Routing_key:</emphasis> The
interpretation of the routing key depends on the value of the interpretation of the routing key depends on the value of the
exchange_type attribute.</para> exchange_type attribute.</para>
</listitem> </listitem>
</itemizedlist> </itemizedlist>
<itemizedlist> <itemizedlist>
<listitem> <listitem>
<para><emphasis role="bold">Direct exchange:</emphasis>if the <para><emphasis role="bold">Direct exchange:</emphasis> If the
routing key property of the message and the routing_key routing key property of the message and the routing_key
attribute of the queue are identical, then the message is attribute of the queue are identical, then the message is
forwarded to the queue.</para> forwarded to the queue.</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">Fanout exchange:</emphasis>messages <para><emphasis role="bold">Fanout exchange:</emphasis> Messages
are forwarded to the queues bound the exchange, even if the are forwarded to the queues bound the exchange, even if the
binding does not have a key.</para> binding does not have a key.</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">Topic exchange:</emphasis>if the <para><emphasis role="bold">Topic exchange:</emphasis> If the
routing key property of the message matches the routing key of routing key property of the message matches the routing key of
the key according to a primitive pattern matching scheme, then the key according to a primitive pattern matching scheme, then
the message is forwarded to the queue. The message routing key the message is forwarded to the queue. The message routing key
@ -365,7 +365,7 @@
</itemizedlist> </itemizedlist>
<itemizedlist> <itemizedlist>
<listitem> <listitem>
<para><emphasis role="bold">Durable:</emphasis>this flag <para><emphasis role="bold">Durable:</emphasis> This flag
determines the durability of both exchanges and queues; determines the durability of both exchanges and queues;
durable exchanges and queues remain active when a RabbitMQ durable exchanges and queues remain active when a RabbitMQ
server restarts. Non-durable exchanges/queues (transient server restarts. Non-durable exchanges/queues (transient
@ -374,29 +374,29 @@
bind to transient exchanges. Default is True.</para> bind to transient exchanges. Default is True.</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">Auto_delete:</emphasis>if set, the <para><emphasis role="bold">Auto_delete:</emphasis> If set, the
exchange is deleted when all queues have finished using it. exchange is deleted when all queues have finished using it.
Default is False.</para> Default is False.</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">Exclusive:</emphasis>exclusive <para><emphasis role="bold">Exclusive:</emphasis> Exclusive
queues (such as non-shared) may only be consumed from by the queues (such as non-shared) may only be consumed from by the
current connection. When exclusive is on, this also implies current connection. When exclusive is on, this also implies
auto_delete. Default is False.</para> auto_delete. Default is False.</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">Exchange_type:</emphasis>AMQP <para><emphasis role="bold">Exchange_type:</emphasis> AMQP
defines several default exchange types (routing algorithms) defines several default exchange types (routing algorithms)
that covers most of the common messaging use cases.</para> that covers most of the common messaging use cases.</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">Auto_ack:</emphasis>acknowledgement <para><emphasis role="bold">Auto_ack:</emphasis> Acknowledgement
is handled automatically once messages are received. By is handled automatically once messages are received. By
default auto_ack is set to False, and the receiver is required default auto_ack is set to False, and the receiver is required
to manually handle acknowledgment.</para> to manually handle acknowledgment.</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">No_ack:</emphasis>it disable <para><emphasis role="bold">No_ack:</emphasis> It disables
acknowledgement on the server-side. This is different from acknowledgement on the server-side. This is different from
auto_ack in that acknowledgement is turned off altogether. auto_ack in that acknowledgement is turned off altogether.
This functionality increases performance but at the cost of This functionality increases performance but at the cost of
@ -404,7 +404,7 @@
can deliver them to the application.</para> can deliver them to the application.</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">Auto_declare:</emphasis>if this is <para><emphasis role="bold">Auto_declare:</emphasis> If this is
True and the exchange name is set, the exchange will be True and the exchange name is set, the exchange will be
automatically declared at instantiation. Auto declare is on by automatically declared at instantiation. Auto declare is on by
default. Publishers specify most the parameters of consumers default. Publishers specify most the parameters of consumers
@ -412,19 +412,19 @@
specify the following:</para> specify the following:</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">Delivery_mode:</emphasis>the default <para><emphasis role="bold">Delivery_mode:</emphasis> The default
delivery mode used for messages. The value is an integer. The delivery mode used for messages. The value is an integer. The
following delivery modes are supported by RabbitMQ:</para> following delivery modes are supported by RabbitMQ:</para>
</listitem> </listitem>
</itemizedlist> </itemizedlist>
<itemizedlist> <itemizedlist>
<listitem> <listitem>
<para><emphasis role="bold">1 or “transient”:</emphasis>the <para><emphasis role="bold">1 or “transient”:</emphasis> The
message is transient. Which means it is stored in memory only, message is transient. Which means it is stored in memory only,
and is lost if the server dies or restarts.</para> and is lost if the server dies or restarts.</para>
</listitem> </listitem>
<listitem> <listitem>
<para><emphasis role="bold">2 or “persistent”:</emphasis>the <para><emphasis role="bold">2 or “persistent”:</emphasis> The
message is persistent. Which means the message is stored both message is persistent. Which means the message is stored both
in-memory, and on disk, and therefore preserved if the server in-memory, and on disk, and therefore preserved if the server
dies or restarts.</para> dies or restarts.</para>