Choosing an Endpoints option

To have your API managed by Cloud Endpoints, you have three options depending on where your API is hosted and the type of communications protocol your API uses:

This page describes the Endpoints options to help you decide which one is right for you.

Choosing a computing option

Endpoints supports different Google Cloud computing options that can host your API's backend code. Endpoints works with either the Extensible Service Proxy (ESP) or the Extensible Service Proxy V2 (ESPv2) to provide API management. The following table summarizes the supported computing options:

ESP for OpenAPI ESP for gRPC ESPv2 for OpenAPI ESPv2 for gRPC Endpoints Frameworks
App Engine
standard environment generation 1		 Java 8 and Python 2.7 runtimes
App Engine
standard environment generation 2
App Engine
flexible environment
Cloud Run functions
Cloud Run
Knative serving
Compute Engine
GKE
Kubernetes
Other non-Google Cloud

For a comparison of the features provided by App Engine, GKE, and Compute Engine, see Choosing a computing option. If you are thinking of using App Engine, you need to choose either the standard or flexible environment. For a comparison of the two environments, see Choosing an App Engine environment.

About the computing option limitations

Endpoints for OpenAPI and Endpoints for gRPC can use ESP or ESPv2 as a proxy. For non-serverless platforms, ESP or ESPv2 is deployed as a container in front of your application or as a sidecar with your application. For serverless platforms, such as Cloud Run, Cloud Run functions, and App Engine, ESPv2 is deployed as a Cloud Run service as a remote proxy to manage your serverless platform applications.

After you deploy your API's backend code, ESP or ESPv2 intercepts all requests and performs any necessary checks (such as authentication) before forwarding the request to the API backend. When the backend responds, ESP gathers and reports telemetry using Service Infrastructure.

You can view metrics for your API and links to Google Cloud Observability logs and traces on the Endpoints Services page in the Google Cloud console.

App Engine standard generation 1 environment limitations

Endpoints for the App Engine standard generation 1 environment historically used Endpoints Frameworks, which only supports the Java 8 and Python 2.7 runtime environments.

Because the App Engine standard environment didn't support multi-container deployments when Endpoints Frameworks was under development, Endpoints Frameworks doesn't use ESP. Instead, Endpoints Frameworks includes a built-in API gateway that provides API management features that are comparable to the features that ESP provides for Endpoints for OpenAPI and Endpoints for gRPC.

gRPC APIs aren't supported on App Engine or Cloud Run functions

gRPC is a remote procedure call (RPC) framework that can run on any environment. With gRPC, a client application can directly call methods in a server application on a different machine as if it were a local object. A core feature of gRPC is bi-directional streaming with HTTP/2-based transport.

App Engine and Cloud Run functions do not support HTTP/2.

Supported programming languages

  • The OpenAPI Specification is a language-agnostic specification. You can implement your API in any programming language.
  • gRPC provides the protocol buffer compiler, protoc, for many major programming languages: C++, C#, Objective-C (for iOS), Dart, Go, Java (including support for Android), Node.js, Python, and Ruby. See the gRPC FAQ for the most up-to-date list.
  • Endpoints Frameworks supports only Java 8 and Python 2.7.

Describing your API

The Endpoints options provide different ways to describe your API.

Endpoints for OpenAPI

The OpenAPI Initiative is an industry-wide effort to standardize the description of REST APIs. Endpoints supports APIs that are described using version 2.0 of the OpenAPI Specification (formerly the Swagger Specification). You describe the surface of your API in a JSON or YAML file (referred to as an OpenAPI document). You can implement your API using any publicly available REST framework such as Django or Jersey. If you are unfamiliar with the OpenAPI Specification, see OpenAPI overview.

For more information, see Endpoints for OpenAPI.

Endpoints for gRPC

With gRPC, you define the structure of the data that you want to serialize in a proto file: this is an ordinary text file with a .proto extension. You also define the surface of your API in proto files, with RPC method parameters and return types specified as protocol buffer messages. If you are unfamiliar with gRPC, see What is gRPC? in the gRPC documentation.

For more information, see Endpoints for gRPC.

Endpoints Frameworks

Endpoints Frameworks is a web framework for the App Engine standard Python 2.7 and Java 8 runtime environments. You add metadata (using annotations in Java or decorators in Python) to your source code. The metadata describes the surface of the REST APIs for your application.

For more information, see Endpoints Frameworks.

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