API resources overview

This page applies to Apigee and Apigee hybrid.

In API hub, every registered API is represented as an API resource. It serves as a comprehensive, centralized record that captures all metadata, specifications, and usage information about your API. Using API resources, you can efficiently manage and govern your entire API portfolio.

How API resources are added to API hub

API resources can be added or registered in API hub in the following ways:

  • Auto-registration while attaching runtime projects: When you attach a runtime project to API hub, all APIs in the runtime project are automatically registered as API resources in API hub. This auto-registration process enables API hub to register API resources from multiple API gateways ensuring that all your APIs are captured in the central repository.
  • Manual registration of APIs: You can manually register an API resource in API hub by providing the API metadata and specification files. This manual process is useful for registering APIs that are not available in the runtime project. For more information about manual registration, see Register an API.

Using plugins

Plugins, also known as on-ramp plugins, provide the framework that allows API hub to discover and ingest metadata from various API management platforms. The actual ingestion of data and the registration of APIs as API resources is managed through plugin instances. Each instance serves as an active entry point for metadata collection from its designated source.

When you use auto-registration by attaching a Google Cloud runtime project, API hub automatically creates a plugin instance in the background for that specific gateway service to ingest metadata and register your APIs as API resources. Alternatively, for non-Google Cloud or custom data sources, you can explicitly create plugin instances that establish a configured connection to your gateways to manually bring in metadata and populate your centralized portfolio.

For more information about using plugins, see Plugins overview.

API resource components

An API resource is composed of several key concepts:

  • API version: A version represents the state of an API at a specific point in time. An API can have multiple versions, allowing you to track its evolution and manage different releases independently. See Versions overview for more details.
  • Specifications: Each API version can have one or more specification files attached to it. A specification is a machine-readable document that describes the interface of your API. API hub supports various specification types, including:
    • OpenAPI for REST APIs
    • gRPC proto files for gRPC APIs
    • MCP schema for Model Context Protocol (MCP) APIs

    For more information about specifications, see Specifications overview.

  • API operations and MCP tools: These are the individual functions or capabilities represented as distinct entities of your API. API operations are of two types:
    1. HTTP operations: exposed as operations for API styles like REST and SOAP.
    2. MCP tools: exposed as tools for MCP APIs, which are designed for AI agents.

    For more information about API operations and MCP tools, see API operations and MCP tools.

  • API deployments: A deployment represents a location where a specific version of your API is running. This allows you to track where your APIs are deployed and how they are being used across different environments. See Deployments overview for more details.
  • API attributes: Attributes are key-value pairs that you can use to add descriptive information to your API resources. This metadata helps with organization, discovery, and governance. API hub supports two types of attributes:
    • System attributes: These are predefined attributes provided by API hub, such as API style, Target users, and Maturity level
    • Additional attributes: These are custom attributes that you can create to meet your organization's specific needs.

    For more information about adding and managing attributes, see Manage attributes.

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