openstack/mistral
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Merge "Fix some trivial SPAG errors in docs"

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Jenkins 2016-07-15 09:20:18 +00:00 committed by Gerrit Code Review
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doc/README.md
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@ -16,7 +16,7 @@
TODO: why REST URL is not generated with parameters? TODO: why REST URL is not generated with parameters?
## Running sphinx-audobuild ## Running sphinx-autobuild
[auto-loader](https://pypi.python.org/pypi/sphinx-autobuild/0.2.3) - rules for convenient development https://pypi.python.org/pypi/sphinx-autobuild/0.2.3. install, and run: [auto-loader](https://pypi.python.org/pypi/sphinx-autobuild/0.2.3) - rules for convenient development https://pypi.python.org/pypi/sphinx-autobuild/0.2.3. install, and run:

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doc/source/overview.rst
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@ -6,30 +6,30 @@ What is Mistral?
Mistral is a workflow service. Most business processes consist of multiple Mistral is a workflow service. Most business processes consist of multiple
distinct interconnected steps that need to be executed in a particular order distinct interconnected steps that need to be executed in a particular order
in a distributed environment. User can describe such process as a set of tasks in a distributed environment. A user can describe such a process as a set of
ans their transitions. After that it is possible to upload such description tasks and their transitions. After that it is possible to upload such a
to Mistral that will take care of state management, correct execution order, description to Mistral, which will take care of state management, correct
parallelism, synchronization and high availability. Mistral also provides execution order, parallelism, synchronization and high availability. Mistral
flexible task scheduling so that it can run a process according to a specified also provides flexible task scheduling so that it can run a process according
schedule (for example, every Sunday at 4.00pm) instead of running it to a specified schedule (for example, every Sunday at 4.00pm) instead of
immediately. In Mistral terminology such set of tasks and relations between running it immediately. In Mistral terminology such a set of tasks and
them called workflow. relations between them is called a **workflow**.
Main use cases Main use cases
-------------- --------------
Tasks Scheduling - Cloud Cron Task Scheduling - Cloud Cron
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
A user can use Mistral to schedule tasks to run within a cloud. Tasks can be A user can use Mistral to schedule tasks to run within a cloud. Tasks can be
anything from executing local processes (shell scripts, binaries) on specified anything from executing local processes (shell scripts, binaries) on specified
virtual instances to calling REST APIs accessible in a cloud environment. They virtual instances to calling REST APIs accessible in a cloud environment. They
can also be tasks related to cloud management like creating virtual instances, can also be tasks related to cloud management like creating or terminating
terminating instances and others. It is important that several tasks can be virtual instances. It is important that several tasks can be combined in a
combined in a single workflow and run in on-schedule manner (for example, on single workflow and run in a scheduled manner (for example, on Sundays at 2.00
Sundays at 2.00 am). Mistral will take care of their parallel execution, if am). Mistral will take care of their parallel execution (if it's logically
it's logically possible, as well as fault tolerance and will provide workflow possible) and fault tolerance, and will provide workflow execution
execution management/monitoring capabilities (stop, resume, current status, management/monitoring capabilities (stop, resume, current status, errors and
errors and other statistics). other statistics).
Cloud Environment Deployment Cloud Environment Deployment
^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -42,14 +42,14 @@ A user makes a request to run a complex multi-step business process and
wants it to be fault-tolerant so that if the execution crashes at some point wants it to be fault-tolerant so that if the execution crashes at some point
on one node then another active node of the system can automatically take on on one node then another active node of the system can automatically take on
and continue from the exact same point where it stopped. In this use case the and continue from the exact same point where it stopped. In this use case the
user splits the business process into a set of tasks and let Mistral handle user splits the business process into a set of tasks and lets Mistral handle
them in a sense that it serves as a coordinator and decides what particular them, in the sense that it serves as a coordinator and decides what particular
task should be started at what time. So that Mistral calls back with "Execute task should be started at what time. So that Mistral calls back with "Execute
action X, here is the data". If an application that executes action X dies action X, here is the data". If an application that executes action X dies
then another instance takes the responsibility to continue the work. then another instance takes the responsibility to continue the work.
BigData analysis & reporting Big Data analysis & reporting
^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
A data analyst can use Mistral as a tool for data crawling. For example, A data analyst can use Mistral as a tool for data crawling. For example,
in order to prepare a financial report the whole set of steps for gathering in order to prepare a financial report the whole set of steps for gathering
and processing required report data can be represented as a graph of related and processing required report data can be represented as a graph of related
@ -64,18 +64,18 @@ Ceilometer (CPU consumption 100%).
Rationale Rationale
--------- ---------
The main idea behind Mistral service includes the following main points: The main idea behind the Mistral service includes the following main points:
- Ability to upload custom workflow definitions. - Ability to upload custom workflow definitions.
- The actual task execution may not be performed by the service itself. - The actual task execution may not be performed by the service itself.
The service can rather serve a coordinator for other worker processes The service can rather serve as a coordinator for other worker processes
that do the actual work and notify back about task execution results. that do the actual work, and notify back about task execution results.
In other words, task execution may be asynchronous thus providing In other words, task execution may be asynchronous, thus providing
flexibility for plugging in any domain specific handling and opportunities flexibility for plugging in any domain specific handling and opportunities
to make this service scalable and highly available. to make this service scalable and highly available.
- The service provides a notion of task action which is a pluggable piece - The service provides a notion of **task action**, which is a pluggable piece
of logic that a workflow task is associated with. Out of the box the service of logic that a workflow task is associated with. Out of the box, the service
provides a set of standard actions for user convenience. However, the user provides a set of standard actions for user convenience. However, the user
can create custom actions based on the standard action pack. can create custom actions based on the standard action pack.