Durable Functions orchestration patterns in Azure - Step-by-Step Execution

Process Flow - Durable Functions orchestration patterns

Start Orchestration

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Call Activity Function

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Wait for Activity Completion

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Decide Next Step

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Call Another

The orchestration starts, calls activity functions, waits for their results, decides next steps, and either continues or ends.

Execution Sample

Azure

1. Start orchestration
2. Call activity A
3. Wait for A to complete
4. If success, call activity B
5. End orchestration

This orchestration calls two activities in sequence, waiting for each to finish before continuing.

Process Table

Step	Action	Function Called	Status	Next Step
1	Start orchestration	Orchestrator	Running	Call activity A
2	Call activity	Activity A	Started	Wait for completion
3	Wait for completion	Activity A	Completed	Check result
4	Check result	Orchestrator	Success	Call activity B
5	Call activity	Activity B	Started	Wait for completion
6	Wait for completion	Activity B	Completed	End orchestration
7	End orchestration	Orchestrator	Completed	Stop

💡 Orchestration ends after all activities complete successfully.

Status Tracker

Variable	Start	After Step 3	After Step 6	Final
orchestrationStatus	Not started	Running	Running	Completed
activityAStatus	Not started	Completed	Completed	Completed
activityBStatus	Not started	Not started	Completed	Completed

Key Moments - 3 Insights

Why does the orchestration wait after calling an activity function?

Because Durable Functions orchestrator pauses until the activity function completes, ensuring reliable sequencing as shown in steps 2 and 3 of the execution_table.

What happens if an activity function fails?

The orchestration can catch the failure and decide next steps, but in this example, success is assumed at step 4 to continue calling the next activity.

Can orchestration call multiple activities in parallel?

Yes, but this example shows sequential calls. Parallel calls would involve starting multiple activities before waiting, changing the flow after step 2.

Visual Quiz - 3 Questions

Look at the execution_table, what is the orchestrationStatus after step 3?

A Not started

B Running

C Completed

D Failed

💡 Hint

Check the variable_tracker column 'After Step 3' for orchestrationStatus.

At which step does the orchestration decide to call activity B?

A Step 2

B Step 3

C Step 4

D Step 5

💡 Hint

Look at the 'Next Step' column in execution_table at step 4.

If activity A failed, how would the orchestration flow change?

A It would handle failure and decide next steps

B It would end immediately

C It would call activity B anyway

D It would restart activity A automatically

💡 Hint

Refer to key_moments about failure handling in orchestration.

Concept Snapshot

Durable Functions orchestrate workflows by calling activity functions.
They wait for each activity to complete before continuing.
Orchestrations can run activities sequentially or in parallel.
Failures can be caught and handled to control flow.
This ensures reliable, stateful serverless workflows.

Full Transcript

Durable Functions orchestration patterns involve starting an orchestration that calls activity functions. The orchestration waits for each activity to complete before deciding the next step. This can be sequential or parallel. The orchestration tracks status variables for each activity and itself. If an activity fails, the orchestration can catch the failure and decide how to proceed. This pattern ensures reliable and stateful workflows in serverless environments.