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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 <use_the_cli> to run the flow.

For more information on getting set up to run flows, see the CloudSlang CLI <cloudslang_cli> and Hello World Example </overview/hello_world> 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 </code/examples_code/examples/divide.zip>

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 </code/examples_code/examples/defaultnav.zip>

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 </code/examples_code/examples/divide.zip>

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 </code/examples_code/examples/loops.zip>

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 </code/examples_code/examples/parallel.zip>

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 </code/examples_code/examples/paths.zip>

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