Examples

The following simplified examples demonstrate some of the key CloudSlang concepts.

Each of the examples below can be run by doing the following:

  1. Create a new folder.
  2. Create new CloudSlang(.sl) files and copy the code into them.
  3. Use the CLI to run the flow.

For more information on getting set up to run flows, see the CloudSlang CLI and Hello World Example sections.

Example 1 - User-defined Navigation and Publishing Outputs

This example is a full working version from which many of the example snippets above have been taken. The flow takes in two inputs, divides them and prints the answer. In case of a division by zero, the flow does not print the output of the division, but instead ends with a user-defined result of ILLEGAL.

Download code

Flow - division.sl

namespace: examples.divide

flow:
  name: division

  inputs:
    - input1
    - input2

  workflow:
    - divider:
        do:
          divide:
            - dividend: ${input1}
            - divisor: ${input2}
        publish:
          - answer: ${quotient}
        navigate:
          - ILLEGAL: ILLEGAL
          - SUCCESS: printer
    - printer:
        do:
          print:
            - text: ${input1 + "/" + input2 + " = " + str(answer)}
        navigate:
          - SUCCESS: SUCCESS

  outputs:
    - quotient: ${answer}

  results:
    - ILLEGAL
    - SUCCESS

Operations - divide.sl

namespace: examples.divide

operation:
  name: divide

  inputs:
    - dividend
    - divisor

  python_action:
    script: |
      if divisor == '0':
        quotient = 'division by zero error'
      else:
        quotient = str(float(dividend) / float(divisor))

  outputs:
    - quotient

  results:
    - ILLEGAL: ${quotient == 'division by zero error'}
    - SUCCESS

Operation - print.sl

namespace: examples.divide

operation:
  name: print

  inputs:
    - text

  python_action:
    script: print text

  results:
    - SUCCESS

Example 2 - Default Navigation

In this example the flow takes in two inputs, one of which determines the success of its first step.

  • If the first step succeeds, the flow continues with the default navigation sequentially by performing the next step. That step returns a default result of SUCCESS and therefore skips the on_failure step, ending the flow with a result of SUCCESS.
  • If the first step fails, the flow moves to the on_failure step by default navigation. When the on_failure step is done, the flow ends with a default result of FAILURE.

Download code

Flow - nav_flow.sl

namespace: examples.defaultnav

flow:
  name: nav_flow

  inputs:
    - navigation_type
    - email_recipient

  workflow:
    - produce_default_navigation:
        do:
          produce_default_navigation:
            - navigation_type

    # default navigation - go to this step on success
    - do_something:
        do:
          something:

    # default navigation - go to this step on failure
    - on_failure:
      - send_error_mail:
          do:
            send_email_mock:
              - recipient: ${email_recipient}
              - subject: "Flow failure"

Operation - produce_default_navigation.sl

namespace: examples.defaultnav

operation:
  name: produce_default_navigation

  inputs:
    - navigation_type

  python_action:
    script: |
      print 'Default navigation based on input of - ' + navigation_type

  results:
    - SUCCESS: ${navigation_type == 'success'}
    - FAILURE

Operation - something.sl

namespace: examples.defaultnav

operation:
  name: something

  python_action:
      script: |
        x = 'Doing something important'
        print x

  results:
    - FAILURE: ${x == 'important thing not done'}
    - SUCCESS

Operation - send_email_mock.sl

namespace: examples.defaultnav

operation:
  name: send_email_mock

  inputs:
    - recipient
    - subject

  python_action:
    script: |
      print 'Email sent to ' + recipient + ' with subject - ' + subject

Example 3 - Subflow

This example uses the flow from Example 1 as a subflow. It takes in four numbers (or uses default ones) to call division_flow twice. If either division returns the ILLEGAL result, navigation is routed to the on_failure step and the flow ends with a result of FAILURE. If both divisions are successful, the on_failure step is skipped and the flow ends with a result of SUCCESS.

Note

To run this flow, the files from Example 1 should be placed in the same folder as this flow file or use the --cp flag at the command line.

Download code

Flow - master_divider.sl

namespace: examples.divide

flow:
  name: master_divider

  inputs:
    - dividend1: "3"
    - divisor1: "2"
    - dividend2: "1"
    - divisor2: "0"

  workflow:
    - division1:
        do:
          division:
            - input1: ${dividend1}
            - input2: ${divisor1}
        publish:
          - ans: ${quotient}
        navigate:
          - SUCCESS: division2
          - ILLEGAL: failure_step
    - division2:
        do:
          division:
            - input1: ${dividend2}
            - input2: ${divisor2}
        publish:
          - ans: ${quotient}
        navigate:
          - SUCCESS: SUCCESS
          - ILLEGAL: failure_step
    - on_failure:
      - failure_step:
          do:
            print:
              - text: ${ans}

Example 4 - Loops

This example demonstrates the different types of values that can be looped on and various methods for handling loop breaks.

Download code

Flow - loops.sl

namespace: examples.loops

flow:
  name: loops

  inputs:
    - sum:
        default: '0'
        private: true

  workflow:
    - fail3a:
        loop:
          for: value in [1,2,3,4,5]
          do:
            fail3:
              - text: ${str(value)}
        navigate:
          - SUCCESS: fail3b
          - FAILURE: fail3b
    - fail3b:
        loop:
          for: value in [1,2,3,4,5]
          do:
            fail3:
              - text: ${str(value)}
          break: []
    - custom3:
        loop:
          for: value in "1,2,3,4,5"
          do:
            custom3:
              - text: ${value}
          break:
            - CUSTOM
        navigate:
          - CUSTOM: aggregate
          - SUCCESS: skip_this
    - skip_this:
        do:
          print:
            - text: "This will not run."
        navigate:
          - SUCCESS: aggregate
    - aggregate:
        loop:
          for: value in range(1,6)
          do:
            print:
              - text: ${str(value)}
              - sum
          publish:
            - sum: ${str(int(sum) + int(out))}
          break: []
        navigate:
          - SUCCESS: print
    - print:
        do:
          print:
            - text: ${sum}
        navigate:
          - SUCCESS: SUCCESS

Operation - fail3.sl

namespace: examples.loops

operation:
  name: fail3

  inputs:
    - text

  python_action:
    script: print text

  results:
    - FAILURE: ${int(text) == 3}
    - SUCCESS

Operation - custom3.sl

namespace: examples.loops

operation:
  name: custom3

  inputs:
    - text

  python_action:
    script: print text

  results:
    - CUSTOM: ${int(text) == 3}
    - SUCCESS

Operation - print.sl

namespace: examples.loops

operation:
  name: print

  inputs:
    - text

  python_action:
    script: print text

  outputs:
    - out: ${text}

  results:
    - SUCCESS

Example 5 - Parallel Loop

This example demonstrates the usage of a parallel loop including aggregation.

Download code

Flow - parallel_loop_aggregate.sl

namespace: examples.parallel

flow:
  name: parallel_loop_aggregate

  inputs:
  - values: "1 2 3 4"

  workflow:
    - print_values:
        parallel_loop:
          for: value in values.split()
          do:
            print_branch:
              - ID: ${str(value)}
        publish:
          - name_list: "${', '.join(map(lambda x : str(x['name']), branches_context))}"
          - first_name: ${branches_context[0]['name']}
          - last_name: ${branches_context[-1]['name']}
          - total: "${str(sum(map(lambda x : int(x['num']), branches_context)))}"
        navigate:
          - SUCCESS: SUCCESS

  outputs:
    - name_list
    - first_name
    - last_name
    - total

  results:
    - SUCCESS

Operation - print_branch.sl

namespace: examples.parallel

operation:
  name: print_branch

  inputs:
    - ID

  python_action:
    script: |
        name = 'branch ' + str(ID)
        print 'Hello from ' + name

  outputs:
    - name
    - num: ${ID}

Example 6 - Operation Paths

This example demonstrates the various ways to reference an operation or subflow from a flow step.

This example uses the following folder structure:

  • examples
    • paths
      • flow.sl
      • op1.sl
      • folder_a
        • op2.sl
      • folder_b
        • op3.sl
        • folder_c
          • op4.sl

Download code

Flow - flow.sl

namespace: examples.paths

imports:
  alias: examples.paths.folder_b

flow:
  name: flow

  workflow:
    - default_path:
        do:
          op1:
            - text: "default path"
        navigate:
          - SUCCESS: fully_qualified_path
    - fully_qualified_path:
        do:
          examples.paths.folder_a.op2:
            - text: "fully qualified path"
        navigate:
          - SUCCESS: using_alias
    - using_alias:
        do:
          alias.op3:
            - text: "using alias"
        navigate:
          - SUCCESS: alias_continuation
    - alias_continuation:
        do:
          alias.folder_c.op4:
            - text: "alias continuation"
        navigate:
          - SUCCESS: SUCCESS

  results:
    - SUCCESS

Operation - op1.sl

namespace: examples.paths

operation:
  name: op1

  inputs:
    - text

  python_action:
    script: print text

Operation - op2.sl

namespace: examples.paths.folder_a

operation:
  name: op2

  inputs:
    - text

  python_action:
    script: print text

Operation - op3.sl

namespace: examples.paths.folder_b

operation:
  name: op3

  inputs:
    - text

  python_action:
    script: print text

Operation - op4.sl

namespace: examples.paths.folder_b.folder_c

operation:
  name: op4

  inputs:
    - text

  python_action:
    script: print text