Graphing§

In this section we will cover writing basic workflows in cylc.

The suite.rc File Format§

The suite.rc File Format§

# Comment
[section]
    key = value
    [[sub-section]]
        another-key = another-value  # Inline comment
        yet-another-key = """
A
Multi-line
String
"""

The suite.rc File Format§

Throughout this tutorial we will refer to settings in the following format:

The suite.rc File Format§

Tip

It is advisable to indent suite.rc files. This indentation, however, is ignored when the file is parsed so settings must appear before sub-sections.

[section]
    key = value  # This setting belongs to the section.
    [[sub-section]]
        key = value  # This setting belongs to the sub-section.

    # This setting belongs to the sub-section as indentation is ignored.
    # Always write settings before defining any sub-sections!
    key = value

The suite.rc File Format§

Note

[a]
   c = C
[b]
   d = D
[a]
   e = E

[a]
   c = C
   e = E
[b]
   d = D

Note§

a = foo
a = bar

a = bar

Graph Strings§

In Cylc we consider workflows in terms of tasks and dependencies.

purchase_ingredients => make_dough

digraph Mini_Cylc { make_dough purchase_ingredients -> make_dough }

Graph Strings§

purchase_ingredients => make_dough => bake_bread => sell_bread

digraph Mini_Cylc { purchase_ingredients -> make_dough bake_bread -> sell_bread make_dough -> bake_bread sell_bread }

Graph Strings§

purchase_ingredients => make_dough => bake_bread => sell_bread
pre_heat_oven => bake_bread
bake_bread => clean_oven

digraph Mini_Cylc { pre_heat_oven -> bake_bread bake_bread -> clean_oven bake_bread -> sell_bread clean_oven purchase_ingredients -> make_dough make_dough -> bake_bread sell_bread bake_bread }

Graph Strings§

purchase_ingredients => make_dough
pre_heat_oven & make_dough => bake_bread => sell_bread & clean_oven

Graph Strings§

Collectively these graph strings are referred to as a graph.

Note

foo => bar
bar => baz

bar => baz
foo => bar

Cylc Graphs§

[scheduling]
    [[dependencies]]
        graph = """
            purchase_ingredients => make_dough
            pre_heat_oven & make_dough => bake_bread => sell_bread & clean_oven
        """

Cylc Graphs§

../../../_images/cylc-graph.png

Cylc Graphs§

Hint

A graph can be drawn in multiple ways, for instance the following two examples are equivalent:

../../../_images/cylc-graph-reversible.png

The graph drawn by cylc graph may vary slightly from one run to another but the tasks and dependencies will always be the same.

Cylc Graphs§

In this practical we will create a new Cylc suite and write a graph for it to use.

Next session: Basic Cycling

Practical

In this practical we will create a new Cylc suite and write a graph for it to use.

  1. Create a Cylc suite.

    A Cylc suite is just a directory containing a suite.rc file.

    If you don’t have one already, create a cylc-run directory in your user space i.e:

    ~/cylc-run

    Within this directory create a new folder called graph-introduction, which is to be our suite directory. Move into it:

    mkdir ~/cylc-run/graph-introduction
cd ~/cylc-run/graph-introduction

    Inside this directory create a suite.rc file and paste in the following text:

    [scheduling]
    [[dependencies]]
        graph = """
            # Write graph strings here!
        """

  2. Write a graph.

    We now have a blank Cylc suite, next we need to define a workflow.

    Edit your suite.rc file to add graph strings representing the following graph:

    digraph graph_tutorial { foo -> bar -> baz -> qux pub -> bar -> wop }

  3. Use cylc graph to visualise the workflow.

    Once you have written some graph strings try using cylc graph to display the workflow. Run the following command:

    cylc graph .

    Note

    cylc graph takes the path to the suite as an argument. As we are inside the suite directory we can run cylc graph ..

    If the results don’t match the diagram above try going back to the suite.rc file and making changes.

    Tip

    In the top right-hand corner of the cylc graph window there is a refresh button which will reload the GUI with any changes you have made.

    ../../../_images/cylc-graph-refresh.png

    Solution

    There are multiple correct ways to write this graph. So long as what you see in cylc graph matches the above diagram then you have a correct solution.

    Two valid examples:

    foo & pub => bar => baz & wop
baz => qux

    foo => bar => baz => qux
pub => bar => wop

    The whole suite should look something like this:

    [scheduling]
    [[dependencies]]
        graph = """
            foo & pub => bar => baz & wop
            baz => qux
        """