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Welcome back. This lesson compares Cloud Functions and Cloud Workflows so you can choose the right orchestration approach for event-driven applications on Google Cloud. We build on Cloud Functions best practices and optimization techniques and expand the perspective to multi-service coordination, long-running sequences, and stateful orchestrations. Quick overview:
  • Use Cloud Functions for single-purpose, short-lived event handlers.
  • Use Cloud Workflows when you need to coordinate multiple steps, persist state across steps, or run long-running processes.

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Key differences: execution model, duration, and control flow

A slide titled "Service Comparison Matrix" showing a table that compares Cloud Functions and Cloud Workflows across aspects like execution model, duration, complexity, state management, error handling, pricing, and use cases. The matrix contrasts event-driven, short-lived, stateless functions with stateful, long-running, multi-step workflows.

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Duration and state: when time and persistence matter

  • Cloud Functions: best for tasks that complete quickly. For persistent data, rely on external stores (Cloud Storage, Firestore, Cloud SQL).
  • Cloud Workflows: maintain execution context across steps; outputs flow into subsequent steps without needing an external store for intermediate state.

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Complexity and orchestration

  • Cloud Functions: keep functions focused and stateless. Suitable for simple event handlers or small microservices.
  • Cloud Workflows: model complex business processes (branching, parallel steps, waits for approvals, external API calls) declaratively in a workflow definition.

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Error handling and retries

  • Cloud Functions: rely on trigger-level retries or custom retry logic inside the function.
  • Cloud Workflows: define retry policies, backoff, and alternate paths in the workflow. Useful for resilient, multi-step integrations.

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Pricing considerations

Both are usage-based but charge on different metrics. Evaluate expected invocation counts, compute duration (Functions), and number of state transitions/callouts (Workflows) to estimate costs for your scenario. See Cloud Functions pricing and Cloud Workflows pricing for current details.

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Typical use cases and examples

Example scenarios:
  • Cloud Function: calculate an estimated fare and assign a nearby driver when a ride request arrives — one trigger, one responsibility, short execution.
  • Cloud Workflow: a driver onboarding process that collects documents, verifies IDs, waits for human approval, and activates accounts — many steps, branching paths, and waits.

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Exam-style question

What would you choose for a long-running process involving multiple GCP APIs where state must be maintained? Answer: Cloud Workflows — they are designed to orchestrate steps, persist execution state between steps, and provide rich error handling and retry strategies.
Simple decision rule: ask yourself “Do I need just a single event response?” If yes, Cloud Functions are usually the right fit. If no — if you need orchestration, retries, multiple API calls, or long-running stateful sequences — choose Cloud Workflows.

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Decision guidance

  • Choose Cloud Functions when: you need a fast, single-purpose event response, minimal orchestration, and stateless execution.
  • Choose Cloud Workflows when: you need to coordinate multiple steps, preserve state across steps, implement complex branching or retry policies, or support long-running processes.
A consolidated visual decision flow can help guide the choice below.
A simple decision flowchart titled "Decision Flowchart – When to Use Which Service" showing a diamond labeled "Single Event Response?" With "Yes" it leads to a blue box "Cloud Functions — Event-driven," and with "No" it leads to an orange box "Cloud Workflows — Orchestration."
Further reading and references: See you in the next lesson.

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