Lesson 3 - First Flow¶
Goal¶
In this lesson we’ll write a simple flow that will call the print operation. We’ll learn about the main components that make up a flow.
Get Started¶
First, we need to create a new_hire.sl file in the hiring folder so we can start writing the new hire flow. We’ll build it one step at a time. So for now, all it will do is call the print operation we wrote in the previous lesson.
Namespace¶
Just like in our operation file, we need to start the flow file with a namespace. Since we’re storing new_hire.sl in the tutorials/hiring folder the namespace must reflect that.
namespace: tutorials.hiring
For more information, see namespace in the DSL reference.
Imports¶
After the namespace you can list the namespace of any CloudSlang files
that you will need to reference in your flow. Our flow will need to
reference the operation in print.sl, so we’ll add the namespace from
that file, tutorials.base
, to the optional imports
key. We map an alias
that we will use as a reference in the flow to the namespace we are importing.
Let’s call the alias base
.
imports:
base: tutorials.base
Now we can use base.print
to refer to the print
operation in a step.
We’ll do that in a moment.
For more information, see imports in the DSL reference.
For ways to refer to an operation or subflow without creating an alias, see the CloudSlang DSL Reference and the Operation Paths example.
Flow Name¶
Each flow begins with the flow
key which will map to the contents of
the flow body. The first part of that body is a key:value pair defining
the name of the flow. The name of the flow must be the same as the name
of the file it is stored in.
flow:
name: new_hire
For more information, see flow in the DSL reference.
Steps¶
The next part of our flow will be the workflow. The workflow
key
maps to a list of all the steps in the flow. We’ll start off with just
one step, the one that calls our print operation. Each step in a
workflow starts with a key that is its name. We’ll call our step
print_start
.
workflow:
- print_start:
For more information, see workflow in the DSL reference.
A step can contain several parts, but we’ll start with a simple step
with the only required part, the do
key. We want to call the print
operation. In this case we’ll reference it using the alias we created up
in the flow’s imports
section. Also, we’ll have to pass any required
inputs to the operation. In our case, there’s one input named text
which we’ll add to a list under the operation call and pass it a value.
do:
base.print:
- text: "Starting new hire process"
navigate:
- SUCCESS: SUCCESS
In addition to the required do
, a step can also contain the optional
publish
and navigate
keys. Here we added a navigate
section.
We’ll explain more about publish
and navigate
a little later in lessons
5 - Default Navigation and 7 - Custom Navigation respectively.
For more information, see do, publish and navigate in the DSL reference.
Run It¶
Now our flow is all ready to run. To do so, save the file and enter the following at the prompt.
run --f <folder path>/tutorials/hiring/new_hire.sl --cp <folder path>/tutorials/base
Note
The --cp
flag is used to add folders where the flow’s
dependencies are found to the classpath. For more information, see
Run with Dependencies in the DSL reference.
You should see the name of the step and the string sent to the print operation printed to the screen.
Download the Code¶
Up Next¶
In the next lesson we’ll write a more complex operation that also returns outputs and results.
New Code - Complete¶
new_hire.sl
namespace: tutorials.hiring
imports:
base: tutorials.base
flow:
name: new_hire
workflow:
- print_start:
do:
base.print:
- text: "Starting new hire process"
navigate:
- SUCCESS: SUCCESS
results:
- SUCCESS