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welcome back to back space Academy in
this lecture I'm going to go through a

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high-level overview of the simple
workflow service or SWF for short for

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the associate level certifications
you're going to need to have just a

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understanding of SWF you're not going to
need to be an expert in applying and

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study with and using it from a hands-on
perspective but you do need to

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understand what the terminology around
SWF how it works how you would implement

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it and what and what an example of it
would look like. SWF it coordinates

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work across distributed application
components and it helps implement

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complex business processes and
application workflows it's suitable for

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long-running execution it's not really
suitable it can be used for batch

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processes but it's more suitable for
long-running processes for business

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processes and for long-running workflows
and enables complex interactions between

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a different applications on different
platforms between AWS and on-premise

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infrastructure and even with different
users on AWS the features of SWF the

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tasks are executed with no duplicates
the routing it provides routing and

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queuing of the tasks and it also
provides timeout and execution status of

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tasks and the workflows they can have
child workflow so you can have a

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hierarchy of workflows it also allows
the user data input and execution of

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results to be output as well the
components of SWF a workflow that is the

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control flow logic for the execution of
tasks it's like our our business process

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flow or our workflow so that is the
control flow logic and then we have a

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domain and that contains a work flow or
a number of workflows and we have tasks

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and they can be performed by executable
code they can be a web service call or

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they can even be an end user input they
can be performed in parallel or Sara Lee

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and so they form the basis of our
workflow then we have actors and the

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actors interact directly with SWF to
coordinate tasks so what is an actor so

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an actor can be a workflow starter it
can be a decider or an activity worker a

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workflow starter that can initiate the
execution of a workflow a decider that

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implements the workflow logic and
notifies SWF of changes during the

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workflow execution and the activity
figures will they do the work so they

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perform the activity tasks of the
workflow tasks must be registered using

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either the console or register activity
type action which you can do through the

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API and CLI as well
when scheduled you can specify a task

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list which is a basically a queue and
decision and activity tasks they have

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separate lists or queues particular
tasks can be assigned to a particular

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activity workers you've required through
task routing. SWF it's implemented by

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having communication between the swf
service and our applications so our

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applications can communicate to SWF
through the software development kits

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that are available for a number of
languages through the SWF API and that

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allows us to do HTTP POST calls to the
API and we also have a flow framework

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which is available for Java or Ruby
which also has a number of features that

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simplify creating communication paths to
SWF an SWF can also be set up using the

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console or the command line interface so what does an

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example look like of SWF workflow so
here is a very simple example that was

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on the AWS website so it's for a video
transcoding a transcoding application

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and it's a very simple process that just
grabs a video in codes at video and adds

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digital rights management or copyright
protection to that video and then it

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finishes so we have actors as we
remember from the previous slide we have

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workflow starters we have workers and we
also have decider actors so L started

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our process there we can see in the
middle there Amazon SWS we have in code

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tasks DRM tasks and we also have decide
at asset that occur there that make

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decisions within that workflow so it
starts there with our web server front-end

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that is our workflow starter it's our
starter actor and that will accept the

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video URL and that will communicate with
Amazon SWF to start the process to start

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this workflow from there swf will create
a task for encoding and it will put that

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task into a task list and it will sit
there until such time as an activity

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worker is available to do that task when
that task is finished it will return the

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results and those results will be looked
at by the decider actor and then the

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decider will decide or will communicate
back to the SWF service and from there

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if everything is ok it will go on to the
next task being the DRM task and again

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that will go into another task list and
when a worker is available then that

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task will be completed and then we go
back the decider will decide that the

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execution has been completed and that
will be the end of that process so

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that's a very simple
application but as you can see SWF

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takes a lot of the headache out of
implementing business processes to

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implementing workflows in a very
systematic way so that the end of that

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lesson on SWF and I look forward to you
in the next ones