From bec18ed32a4dfcd98540736dfa9a33a505e9d67a Mon Sep 17 00:00:00 2001
From: Chad Retz <chad@temporal.io>
Date: Wed, 1 Oct 2025 13:30:00 -0500
Subject: [PATCH] DSL sample

Closes #32
---
 README.md                     |  1 +
 dsl/README.md                 | 26 +++++++++++++++
 dsl/activities.rb             | 53 +++++++++++++++++++++++++++++++
 dsl/dsl_workflow.rb           | 39 +++++++++++++++++++++++
 dsl/models.rb                 | 53 +++++++++++++++++++++++++++++++
 dsl/starter.rb                | 21 ++++++++++++
 dsl/worker.rb                 | 24 ++++++++++++++
 dsl/workflow1.yaml            | 28 ++++++++++++++++
 dsl/workflow2.yaml            | 58 +++++++++++++++++++++++++++++++++
 test/dsl/dsl_workflow_test.rb | 60 +++++++++++++++++++++++++++++++++++
 10 files changed, 363 insertions(+)
 create mode 100644 dsl/README.md
 create mode 100644 dsl/activities.rb
 create mode 100644 dsl/dsl_workflow.rb
 create mode 100644 dsl/models.rb
 create mode 100644 dsl/starter.rb
 create mode 100644 dsl/worker.rb
 create mode 100644 dsl/workflow1.yaml
 create mode 100644 dsl/workflow2.yaml
 create mode 100644 test/dsl/dsl_workflow_test.rb

diff --git a/README.md b/README.md
index 3d3e8f0..3c95489 100644
--- a/README.md
+++ b/README.md
@@ -22,6 +22,7 @@ Prerequisites:
   [Coinbase Ruby SDK](https://github.com/coinbase/temporal-ruby).
 * [context_propagation](context_propagation) - Use interceptors to propagate thread/fiber local data from clients
   through workflows/activities.
+* [dsl](dsl) - Demonstrates having a workflow interpret/invoke arbitrary steps defined in a DSL.
 * [encryption](encryption) - Demonstrates how to make a codec for end-to-end encryption.
 * [message_passing_simple](message_passing_simple) - Simple workflow that accepts signals, queries, and updates.
 * [polling/infrequent](polling/infrequent) - Implement an infrequent polling mechanism using Temporal's automatic Activity Retry feature.
diff --git a/dsl/README.md b/dsl/README.md
new file mode 100644
index 0000000..cffa0af
--- /dev/null
+++ b/dsl/README.md
@@ -0,0 +1,26 @@
+# DSL
+
+This sample demonstrates having a workflow interpret/invoke arbitrary steps defined in a DSL. It is similar to the DSL
+samples in [TypeScript](https://github.com/temporalio/samples-typescript/tree/main/dsl-interpreter), in
+[Go](https://github.com/temporalio/samples-go/tree/main/dsl), and in
+[Python](https://github.com/temporalio/samples-python/tree/main/dsl).
+
+To run, first see [README.md](../README.md) for prerequisites. Then, in another terminal, start the Ruby worker
+from this directory:
+
+    bundle exec ruby worker.rb
+
+Now, in another terminal, run the following from this directory to execute a workflow of steps defined in
+[workflow1.yaml](workflow1.yaml):
+
+    bundle exec ruby starter.rb workflow1.yaml
+
+This will run the workflow and show the final variables that the workflow returns. Looking in the worker terminal, each
+step executed will be visible.
+
+Similarly we can do the same for the more advanced [workflow2.yaml](workflow2.yaml) file:
+
+    bundle exec ruby starter.rb workflow2.yaml
+
+This sample gives a guide of how one can write a workflow to interpret arbitrary steps from a user-provided DSL. Many
+DSL models are more advanced and are more specific to conform to business logic needs.
\ No newline at end of file
diff --git a/dsl/activities.rb b/dsl/activities.rb
new file mode 100644
index 0000000..4c520cd
--- /dev/null
+++ b/dsl/activities.rb
@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+require 'temporalio/activity'
+require_relative 'models'
+
+module Dsl
+  module Activities
+    class Activity1 < Temporalio::Activity::Definition
+      activity_name :activity1
+
+      def execute(arg)
+        Temporalio::Activity::Context.current.logger.info("Executing activity1 with arg: #{arg}")
+        "[result from activity1: #{arg}]"
+      end
+    end
+
+    class Activity2 < Temporalio::Activity::Definition
+      activity_name :activity2
+
+      def execute(arg)
+        Temporalio::Activity::Context.current.logger.info("Executing activity2 with arg: #{arg}")
+        "[result from activity2: #{arg}]"
+      end
+    end
+
+    class Activity3 < Temporalio::Activity::Definition
+      activity_name :activity3
+
+      def execute(arg1, arg2)
+        Temporalio::Activity::Context.current.logger.info("Executing activity3 with args: #{arg1} and #{arg2}")
+        "[result from activity3: #{arg1} #{arg2}]"
+      end
+    end
+
+    class Activity4 < Temporalio::Activity::Definition
+      activity_name :activity4
+
+      def execute(arg)
+        Temporalio::Activity::Context.current.logger.info("Executing activity4 with arg #{arg}")
+        "[result from activity4: #{arg}]"
+      end
+    end
+
+    class Activity5 < Temporalio::Activity::Definition
+      activity_name :activity5
+
+      def execute(arg1, arg2)
+        Temporalio::Activity::Context.current.logger.info("Executing activity5 with args: #{arg1} and #{arg2}")
+        "[result from activity5: #{arg1} #{arg2}]"
+      end
+    end
+  end
+end
diff --git a/dsl/dsl_workflow.rb b/dsl/dsl_workflow.rb
new file mode 100644
index 0000000..34d01dd
--- /dev/null
+++ b/dsl/dsl_workflow.rb
@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+require 'temporalio/workflow'
+require_relative 'models'
+
+module Dsl
+  class DslWorkflow < Temporalio::Workflow::Definition
+    def execute(input)
+      # Run and return the final variable set
+      Temporalio::Workflow.logger.info('Running DSL workflow')
+      @variables = input.variables
+      execute_statement(input.root)
+      Temporalio::Workflow.logger.info('DSL workflow completed')
+      @variables
+    end
+
+    def execute_statement(stmt)
+      case stmt
+      when Models::Statement::Activity
+        # Invoke activity loading arguments from variables and optionally storing result as a variable
+        result = Temporalio::Workflow.execute_activity(
+          stmt.name,
+          *stmt.arguments.map { |a| @variables[a] },
+          start_to_close_timeout: 60
+        )
+        @variables[stmt.result] = result if stmt.result
+      when Models::Statement::Sequence
+        # Execute each statement in order
+        stmt.elements.each { |s| execute_statement(s) }
+      when Models::Statement::Parallel
+        # Execute all in parallel. Note, this will raise an exception when the first activity fails and will not cancel
+        # the others. We could provide a linked Cancellation to each and cancel it on error if we wanted.
+        Temporalio::Workflow::Future.all_of(
+          *stmt.branches.map { |s| Temporalio::Workflow::Future.new { execute_statement(s) } }
+        ).wait
+      end
+    end
+  end
+end
diff --git a/dsl/models.rb b/dsl/models.rb
new file mode 100644
index 0000000..cc33367
--- /dev/null
+++ b/dsl/models.rb
@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+require 'json/add/struct'
+require 'yaml'
+
+module Dsl
+  module Models
+    Input = Struct.new(:root, :variables) do
+      def self.from_yaml(yaml_str)
+        from_h(YAML.load(yaml_str))
+      end
+
+      def self.from_h(hash)
+        new(
+          root: Statement.from_h(hash['root'] || raise('Missing root')),
+          variables: hash['variables'] || {}
+        )
+      end
+    end
+
+    module Statement
+      def self.from_h(hash)
+        raise 'Expected single activity, sequence, or parallel field' unless hash.one?
+
+        type, sub_hash = hash.first
+        case type
+        when 'activity' then Activity.from_h(sub_hash)
+        when 'sequence' then Sequence.from_h(sub_hash)
+        when 'parallel' then Parallel.from_h(sub_hash)
+        else raise 'Expected single activity, sequence, or parallel field'
+        end
+      end
+
+      Activity = Struct.new(:name, :arguments, :result) do
+        def self.from_h(hash)
+          new(name: hash['name'], arguments: hash['arguments'], result: hash['result'])
+        end
+      end
+
+      Sequence = Struct.new(:elements) do
+        def self.from_h(hash)
+          new(elements: hash['elements'].map { |e| Statement.from_h(e) })
+        end
+      end
+
+      Parallel = Struct.new(:branches) do
+        def self.from_h(hash)
+          new(branches: hash['branches'].map { |e| Statement.from_h(e) })
+        end
+      end
+    end
+  end
+end
diff --git a/dsl/starter.rb b/dsl/starter.rb
new file mode 100644
index 0000000..03d9043
--- /dev/null
+++ b/dsl/starter.rb
@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+require 'temporalio/client'
+require_relative 'activities'
+require_relative 'models'
+require_relative 'dsl_workflow'
+
+# Create a Temporal client
+logger = Logger.new($stdout, level: Logger::INFO)
+client = Temporalio::Client.connect('localhost:7233', 'default', logger:)
+
+# Load YAML file
+yaml_str = File.read(ARGV.first || raise('Missing argument for YAML file'))
+input = Dsl::Models::Input.from_yaml(yaml_str)
+
+# Run workflow
+result = client.execute_workflow(
+  Dsl::DslWorkflow, input,
+  id: 'dsl-sample-workflow-id', task_queue: 'dsl-sample'
+)
+logger.info("Final variables: #{result}")
diff --git a/dsl/worker.rb b/dsl/worker.rb
new file mode 100644
index 0000000..a203b76
--- /dev/null
+++ b/dsl/worker.rb
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+require 'logger'
+require 'temporalio/client'
+require 'temporalio/worker'
+require_relative 'activities'
+require_relative 'dsl_workflow'
+
+# Create a Temporal client
+logger = Logger.new($stdout, level: Logger::INFO)
+client = Temporalio::Client.connect('localhost:7233', 'default', logger:)
+
+# Create worker with the activities and workflow
+worker = Temporalio::Worker.new(
+  client:,
+  task_queue: 'dsl-sample',
+  activities: [Dsl::Activities::Activity1, Dsl::Activities::Activity2, Dsl::Activities::Activity3,
+               Dsl::Activities::Activity4, Dsl::Activities::Activity5],
+  workflows: [Dsl::DslWorkflow]
+)
+
+# Run the worker until SIGINT
+logger.info('Starting worker (ctrl+c to exit)')
+worker.run(shutdown_signals: ['SIGINT'])
diff --git a/dsl/workflow1.yaml b/dsl/workflow1.yaml
new file mode 100644
index 0000000..85da523
--- /dev/null
+++ b/dsl/workflow1.yaml
@@ -0,0 +1,28 @@
+# This sample workflows execute 3 steps in sequence.
+# 1) Activity1, takes arg1 as input, and put result as result1.
+# 2) Activity2, takes result1 as input, and put result as result2.
+# 3) Activity3, takes args2 and result2 as input, and put result as result3.
+
+variables:
+  arg1: value1
+  arg2: value2
+
+root:
+  sequence:
+    elements:
+      - activity:
+          name: activity1
+          arguments:
+            - arg1
+          result: result1
+      - activity:
+          name: activity2
+          arguments:
+            - result1
+          result: result2
+      - activity:
+          name: activity3
+          arguments:
+            - arg2
+            - result2
+          result: result3
\ No newline at end of file
diff --git a/dsl/workflow2.yaml b/dsl/workflow2.yaml
new file mode 100644
index 0000000..cf19fdd
--- /dev/null
+++ b/dsl/workflow2.yaml
@@ -0,0 +1,58 @@
+# This sample workflow executes 3 steps in sequence.
+# 1) activity1, takes arg1 as input, and put result as result1.
+# 2) it runs a parallel block which runs below sequence branches in parallel
+#  2.1) sequence 1
+#    2.1.1) activity2, takes result1 as input, and put result as result2
+#    2.1.2) activity3, takes arg2 and result2 as input, and put result as result3
+#  2.2) sequence 2
+#    2.2.1) activity4, takes result1 as input, and put result as result4
+#    2.2.2) activity5, takes arg3 and result4 as input, and put result as result5
+# 3) activity3, takes result3 and result5 as input, and put result as result6.
+
+variables:
+  arg1: value1
+  arg2: value2
+  arg3: value3
+
+root:
+  sequence:
+    elements:
+      - activity:
+          name: activity1
+          arguments:
+            - arg1
+          result: result1
+      - parallel:
+          branches:
+            - sequence:
+                elements:
+                  - activity:
+                      name: activity2
+                      arguments:
+                        - result1
+                      result: result2
+                  - activity:
+                      name: activity3
+                      arguments:
+                        - arg2
+                        - result2
+                      result: result3
+            - sequence:
+                elements:
+                  - activity:
+                      name: activity4
+                      arguments:
+                        - result1
+                      result: result4
+                  - activity:
+                      name: activity5
+                      arguments:
+                        - arg3
+                        - result4
+                      result: result5
+      - activity:
+          name: activity3
+          arguments:
+            - result3
+            - result5
+          result: result6
\ No newline at end of file
diff --git a/test/dsl/dsl_workflow_test.rb b/test/dsl/dsl_workflow_test.rb
new file mode 100644
index 0000000..f3cc312
--- /dev/null
+++ b/test/dsl/dsl_workflow_test.rb
@@ -0,0 +1,60 @@
+# frozen_string_literal: true
+
+require 'test'
+require 'dsl/activities'
+require 'dsl/models'
+require 'dsl/dsl_workflow'
+require 'securerandom'
+require 'temporalio/client'
+require 'temporalio/testing'
+require 'temporalio/worker'
+
+module Dsl
+  class DslWorkflowTest < Test
+    def test_workflow
+      Temporalio::Testing::WorkflowEnvironment.start_local do |env|
+        # Load the YAML from workflow2.yaml
+        yaml_str = File.read(File.join(File.dirname(__FILE__), '../../dsl/workflow2.yaml'))
+        # Run workflow in a worker
+        worker = Temporalio::Worker.new(
+          client: env.client,
+          task_queue: "tq-#{SecureRandom.uuid}",
+          activities: [Activities::Activity1, Activities::Activity2, Activities::Activity3,
+                       Activities::Activity4, Activities::Activity5],
+          workflows: [DslWorkflow]
+        )
+        handle, result = worker.run do
+          handle = env.client.start_workflow(
+            DslWorkflow, Models::Input.from_yaml(yaml_str),
+            id: "wf-#{SecureRandom.uuid}", task_queue: worker.task_queue
+          )
+          [handle, handle.result]
+        end
+        # Confirm expected variable results
+        assert_equal(
+          {
+            'arg1' => 'value1',
+            'arg2' => 'value2',
+            'arg3' => 'value3',
+            'result1' => '[result from activity1: value1]',
+            'result2' => '[result from activity2: [result from activity1: value1]]',
+            'result3' => '[result from activity3: value2 [result from activity2: [result from activity1: value1]]]',
+            'result4' => '[result from activity4: [result from activity1: value1]]',
+            'result5' => '[result from activity5: value3 [result from activity4: [result from activity1: value1]]]',
+            'result6' => '[result from activity3: [result from activity3: value2 [result from activity2: ' \
+                         '[result from activity1: value1]]] [result from activity5: ' \
+                         'value3 [result from activity4: [result from activity1: value1]]]]'
+          },
+          result
+        )
+        # Collect all activity events and confirm they are in order expected
+        activity_names = handle.fetch_history_events
+                               .map { |e| e.activity_task_scheduled_event_attributes&.activity_type&.name }
+                               .compact
+        assert_equal 'activity1', activity_names[0]
+        assert_equal %w[activity2 activity3 activity4 activity5], activity_names[1, 4].sort
+        assert_equal 'activity3', activity_names[5]
+      end
+    end
+  end
+end