API Design with Apigee X: REST, OpenAPI, GraphQL

Welcome to the foundational lecture on REST! In today's digital world, REST is the architectural style that powers the vast majority of web services and APIs. Understanding its principles isn't just theory—it's a core requirement for anyone building or managing modern applications.

In this lecture, we'll demystify REST (Representational State Transfer) and break down the essential constraints that make it so scalable and reliable. We will explore the key concepts of resources, representations, and stateless communication. Most importantly, we'll move beyond the "what" to the "how" by diving into the industry-standard best practices for designing clean, intuitive, and future-proof RESTful APIs that are a pleasure for developers to use.

What you will learn:

• The core principles and constraints of the REST architectural style.

• How to think in terms of "resources" when designing an API.

• Best practices for naming conventions, URI structure, and versioning.

• How to design APIs that are logical, predictable, and easy to consume.

Ready to make your APIs talk? This lecture gets to the heart of RESTful communication: HTTP Methods and Status Codes. These are the verbs and the responses that form the universal language of the web, and mastering them is essential for building functional and robust APIs.

We will take a detailed look at the primary HTTP methods (GET, POST, PUT, DELETE, and PATCH), explaining exactly what each one does and, just as importantly, when to use it. You'll learn the critical concepts of safety and idempotency. Then, we'll decode the most common HTTP status codes, from success messages (200 OK) and creation confirmations (201 Created) to client errors (4xx) and server issues (5xx). By the end of this session, you'll be able to design API interactions that are not only functional but also provide clear, meaningful feedback to the client.

What you will learn:

• A deep understanding of the primary HTTP verbs: GET, POST, PUT, DELETE, and PATCH.

• The key differences between safe and idempotent methods.

• How to use HTTP status codes correctly to signal the outcome of an API request.

• How to build a clear and predictable communication contract between your API and its clients.

This lecture offers a clear and structured overview of the OpenAPI Specification (OAS)—the industry-standard way to describe RESTful APIs in a consistent, human- and machine-readable format.

You’ll gain a deep conceptual understanding of what OAS is, why it matters, and where it fits into the API lifecycle. We’ll explore the key elements of an OpenAPI document, including endpoints, parameters, data models, metadata, and authentication definitions.

Additionally, we’ll examine the strategic benefits of using OpenAPI in enterprise environments—such as enabling a design-first approach, generating interactive documentation, and supporting tools like Apigee X and Generative AI.

By the end of this session, you’ll have a solid grasp of the OpenAPI Specification’s role as the central API contract, without needing to write or implement any code.

What You’ll Learn:

• What OpenAPI (OAS) is and why it’s important

• Key components of an OpenAPI 3.0 document

• Benefits of using OAS across the API lifecycle

• How OAS integrates conceptually with API management tools like Apigee X

In this lecture, we'll dive into GraphQL, a powerful query language for your APIs that provides a more efficient and flexible alternative to the traditional REST architectural style. We will explore the core concepts behind GraphQL and understand why it has become so popular for modern application development.

By the end of this lecture, you will be able to:

• Define what GraphQL is and explain its fundamental principles.

• Compare and contrast GraphQL with REST, highlighting key differences.

• Understand the problem of over-fetching and under-fetching data and how GraphQL solves it.

• Identify the basic components of a GraphQL service, including Schemas, Queries, and Mutations.

Welcome to the introduction to gRPC (gRPC Remote Procedure Call), a modern, high-performance, open-source framework developed by Google. In this lecture, we'll explore how gRPC uses Protocol Buffers and HTTP/2 to enable efficient and robust communication, particularly in microservices architectures. ?

By the end of this lecture, you will be able to:

• Explain what gRPC is and its core architecture.

• Describe the role of Protocol Buffers (Protobufs) as its Interface Definition Language (IDL).

• Understand the benefits of using gRPC, such as high performance, streaming capabilities, and language independence.

• Compare gRPC with other API styles like REST and identify ideal use cases for it in enterprise systems.

APIs primarily speak two languages: JSON and XML. In this lecture, we'll get hands-on with these essential data formats and explore the techniques required to manage, transform, and validate them effectively within your API proxies. Mastering these payloads is a critical skill for any API developer or architect. ?️

By the end of this lecture, you will be able to:

• Confidently differentiate between the syntax and structure of JSON and XML.

• Describe common policies and strategies for parsing and validating both payload types.

• Explain the process of extracting specific data from a JSON or XML document.

• Understand the fundamental concepts behind data transformation (e.g., converting XML to JSON).

This lecture explains the practical challenges of working with gRPC-style scenarios in enterprise API management and why real-world API design often requires architectural trade-offs.

Creating high-quality API documentation is essential for developer adoption, but it's often a manual and time-consuming process. In this lecture, we'll explore how Generative AI is revolutionizing this space by automating the creation of clear, comprehensive, and consistent documentation

By the end of this lecture, you will be able to:

• Explain how Generative AI can be used to analyze API specifications and code.

• Describe the benefits of using AI for documentation, including increased speed and accuracy.

• Identify popular tools and models that automate API documentation generation.

• Understand how leveraging GenAI can significantly improve the developer experience for your APIs.

Download the Lab Part 1 Guide (PDF).

You’ll learn how to import an existing OpenAPI specification into Apigee X to auto-generate a proxy.

In this first part of our lab, we'll walk through one of the most common and powerful workflows in Apigee: creating a fully functional API proxy directly from an OpenAPI specification. This spec-first approach saves time and ensures your proxy perfectly matches your API's design.

By the end of this lecture, you will be able to:

• Follow a step-by-step process to import an OpenAPI specification into Apigee.

• Examine the flows and resources that Apigee automatically generates.

• Understand how the specification's paths and verbs translate into proxy logic.

• Deploy and test the newly created API proxy to confirm it's working correctly.

The Lab Part 2 Guide (PDF) walks you through leveraging GenAI to assist in writing OpenAPI definitions.

What if you don't have an OpenAPI specification to start with? In this lab, we'll leverage the power of Generative AI to create one for us! You'll learn how to translate a simple, natural language description of an API's requirements into a well-structured OpenAPI specification, accelerating the design phase significantly.

By the end of this lecture, you will be able to:

• Write effective prompts to instruct a GenAI tool to design an API.

• Generate a complete OpenAPI specification from a text-based description.

• Review and refine the AI-generated output for accuracy and completeness.

• Appreciate how AI can serve as a powerful assistant in the API lifecycle.

Download both resources below:
• Part 3 Guide — covers setup for GraphQL backend proxies.
• Complete Lab Guide (Parts 1–3) — for full reference.
(Note: gRPC setup is discussed conceptually in the video but not demonstrated in practice.)

Now let's switch gears from REST to GraphQL. While GraphQL backends offer great flexibility, they still require the security and management that an API gateway provides. This lab will guide you through the specific steps needed to configure an Apigee API proxy to manage and protect a GraphQL service. ?

By the end of this lecture, you will be able to:

• Understand the unique considerations for proxying a GraphQL API in Apigee.

• Create and configure an API proxy that securely routes requests to a GraphQL backend.

• Test the proxy by sending GraphQL queries through it.

• Recognize where to apply GraphQL-specific policies for security and traffic management.

Google has recently updated the Apigee X onboarding experience. Earlier tutorials and older courses typically used the free Evaluation (Eval) environment, which was automatically provisioned for new accounts using the introductory Google Cloud credits. New Apigee X projects now present a Basic, Intermediate, and Comprehensive environment strategy instead, so the user interface and provisioning workflow are different from what you may see in older learning resources.

In this lecture, we demonstrate how to provision an Intermediate Apigee X environment for your project. This is an essential step because several advanced features used later in this course—including JavaScript, Python, Java, and other Extensible Policies—are not supported in the Basic environment. These capabilities require an Intermediate (or Comprehensive) environment.

By the end of this lecture, you will understand the new Apigee X environment options, know why the Intermediate environment is required for advanced API development, and have a correctly configured environment that is ready for the hands-on labs throughout the remainder of this course.

In this first part of the lab, we lay the foundation for creating a custom JavaScript policy in Apigee X. Before writing any business validation logic, we prepare the API proxy, configure the required flow structure, and add the JavaScript policy to the proxy so it is ready for implementation in the next lecture.

This setup also demonstrates why an Intermediate (or Comprehensive) Apigee X environment is required. Unlike standard policies, JavaScript is an Extensible Policy, which cannot be deployed in the Basic environment. By completing this lecture, you will have a correctly configured API proxy that is ready for implementing custom business logic and advanced request validation in the subsequent parts of the lab.

In this second part of the lab, we integrate the JavaScript policy into the API proxy execution flow and configure it to participate in request processing. You will learn how to attach the policy at the appropriate flow stage, understand its execution sequence, and see how custom business logic becomes part of the API request pipeline.

This lecture focuses on the practical integration of an Extensible Policy within Apigee X, preparing the proxy for implementing and testing custom validation logic in the final part of the lab. By the end of this lecture, your API proxy will be fully configured and ready to execute JavaScript-based business rules during API requests.

In this final part of the lab, we validate that our custom JavaScript policy is working as intended by testing it with different API requests and examining the runtime behavior. You will verify that the policy executes correctly within the API proxy flow, enforces the required business validation rules, and produces the expected responses for both successful and failure scenarios.

This lecture brings together everything developed in the previous two parts—environment setup, policy creation, and flow integration—to demonstrate a complete end-to-end implementation of a custom Extensible Policy in Apigee X. By the end of this lecture, you will have confidence in designing, integrating, and validating JavaScript-based policies for enterprise API gateways.

In this lecture, we take the next step in securing APIs by implementing API Key authentication using Apigee X. You will learn how API Products, Developer Apps, and the Verify API Key policy work together to control and authorize access to your APIs. We configure these core security components, associate an API key with an application, and validate incoming requests using the built-in verification policy.

By the end of this lecture, you will understand the complete API Key authentication workflow in Apigee X and be able to configure, secure, and test APIs using API Products, Developer Apps, and the Verify API Key policy—an essential foundation for enterprise API security.

Architectural Optimization: Streamlining Proxy Execution Paths via Custom Validation Logic

In production API management, standard flow routes can frequently become bogged down by redundant validation logic or unnecessary processing overhead. To design ultra-low-latency proxies, an architect must know how to restructure pipeline execution paths so that invalid consumer requests are rejected immediately at the edge, blocking them from ever hitting backend resources.

This lecture covers a step-by-step architectural optimization sequence. Moving directly into the API management development UI, we analyze a proxy workflow (custom-order-processing), identify processing bottlenecks, and refactor the request flow to achieve a lean, secure, and highly efficient execution lifecycle.

What You Will Learn:

• Analyzing the Execution Flow: A step-by-step breakdown of how the gateway handles conditional routing variables across PreFlow and PostFlow boundaries.

• Identifying Pipeline Bottlenecks: Why executing sequential conditional logic statements can create processing dead-ends, and how to safely strip away redundant policies.

• Injecting Custom Validation Logic: How to position custom JavaScript validation scripts (JS-ValidateOrderLogic) immediately after core security check blocks like API Key verification.

• Fail-Fast Error Handling Strategy: Configuring immediate error generation policies (InvalidOrderResponse) that gracefully terminate a request the millisecond validation conditions fail (validation.failed = true).

• Optimized Routing Architecture: Restructuring your proxy code so that only 100% verified, structurally sound payloads are allowed to continue onward to the TargetEndpoint.

Included Lab Resources:

To help you implement and explore this optimized proxy pipeline inside your own developer environments, the complete asset templates from our live optimization demonstration are attached directly to this lecture:

1. custom-order-processing_rev16_2026_06_21.zip (Complete Proxy Bundle) The fully integrated development bundle ready for deployment import. Importing this zip into your management interface will automatically spin up the entire endpoint configuration, conditional paths, and target flows.

2. Standalone Source Resource Files: For students who prefer to study or copy the code fragments directly, the core operational logic has also been unbundled as standalone text resources:

   • validate-order.js — The JavaScript source file containing the parsing rules, business validations, and conditional logic used to flag broken orders via the validation.failed variable context.

   • create-basic-auth.js — The programmatic credential transformation script that intercepts client headers (client_id / client_secret) and cleanly serializes them into an outbound HTTP Basic Authentication token for backend delivery.

   • RF-InvalidOrderResponse.xml — The explicit RaiseFault policy template mapping out how to return custom structured JSON error payloads back to the user when input validation conditions fail.

Download your lab assets from the resource section below, import the zip bundle, and let's explore how these optimized processing paths execute under live tracing!

Mastering End-to-End gRPC Proxying: Architecture, IaC, and Wire-Level Validation

Moving microservices into production requires more than just making them work—it requires architectural precision. In this hands-on lecture, we move completely away from manual cloud console configurations and step into an enterprise-grade, declarative workflow to deploy a high-performance gRPC pipeline.

We will bridge the edge of our network to our backend by configuring a transparent API Gateway proxy layer that routes traffic cleanly to a containerized backend service running on Google Cloud Run.

What You Will Learn:

• Infrastructure-as-Code (IaC) Blueprints: How to transition from manual UI clicking to professional, declarative deployments using pre-configured YAML and JSON templates.

• HTTP/2 Transport Configuration: The critical mapping patterns required to maintain end-to-end HTTP/2 cleartext (h2c) streams, preventing the data truncation and protocol downgrades that typically break gRPC pipelines.

• Advanced Wire-Level Probing: How to utilize grpcurl alongside granular debugging flags to safely audit security rules, trace transport headers, and validate system routing behavior.

• Production Debugging Realities: How to interpret low-level network responses, manage strict port enforcement settings, and differentiate between application-layer exceptions and gateway-layer delivery status.

Included Lab Resources:

To give you immediate practical value, this lecture includes the exact production blueprints used during the live demonstration:

1. service-config.yaml – Your plug-and-play declarative configuration for cloud-native gRPC container runtimes.

2. target-server-config.json – The explicit gateway routing contract to bind edge infrastructure to backend systems.

3. grpc-greeter-proxy revision bundle to import on the develop tab of Apigee X UI

By the end of this session, you won't just understand the theory behind high-performance API routing—you will possess the production blueprints, operational workflows, and debugging expertise required to engineer resilient gRPC bridges at scale.

Download your lab assets from the resource section, fire up your terminal, and let's build!

In this final lecture, you will review the key skills and concepts covered in the course, including RESTful API design, HTTP methods and status codes, OpenAPI specifications, GraphQL and gRPC concepts, JSON and XML payload handling, GenAI-assisted API documentation, and practical Apigee X implementation labs.

You will also understand how this course fits into the larger Apigee X learning roadmap. After completing this API design course, the recommended next step is to continue into Apigee X API security, followed by traffic management, monitoring, lifecycle management, CI/CD, and enterprise API strategy.

By the end of this lecture, you will have a clear summary of what you have achieved and where to continue next in your Apigee X learning journey.