google/api

Table of Contents

google/api/annotations.proto

Top

File-level Extensions

ExtensionTypeBaseNumberDescription
http HttpRule .google.protobuf.MethodOptions 72295728

See `HttpRule`.

google/api/http.proto

Top

CustomHttpPattern

A custom pattern is used for defining custom HTTP verb.

FieldTypeLabelDescription
kind string

The name of this custom HTTP verb.

path string

The path matched by this custom verb.

Http

Defines the HTTP configuration for an API service. It contains a list of

[HttpRule][google.api.HttpRule], each specifying the mapping of an RPC method

to one or more HTTP REST API methods.

FieldTypeLabelDescription
rules HttpRule repeated

A list of HTTP configuration rules that apply to individual API methods. **NOTE:** All service configuration rules follow "last one wins" order.

fully_decode_reserved_expansion bool

When set to true, URL path parameters will be fully URI-decoded except in cases of single segment matches in reserved expansion, where "%2F" will be left encoded. The default behavior is to not decode RFC 6570 reserved characters in multi segment matches.

HttpRule

gRPC Transcoding

gRPC Transcoding is a feature for mapping between a gRPC method and one or

more HTTP REST endpoints. It allows developers to build a single API service

that supports both gRPC APIs and REST APIs. Many systems, including [Google

APIs](https://github.com/googleapis/googleapis),

[Cloud Endpoints](https://cloud.google.com/endpoints), [gRPC

Gateway](https://github.com/grpc-ecosystem/grpc-gateway),

and [Envoy](https://github.com/envoyproxy/envoy) proxy support this feature

and use it for large scale production services.

`HttpRule` defines the schema of the gRPC/REST mapping. The mapping specifies

how different portions of the gRPC request message are mapped to the URL

path, URL query parameters, and HTTP request body. It also controls how the

gRPC response message is mapped to the HTTP response body. `HttpRule` is

typically specified as an `google.api.http` annotation on the gRPC method.

Each mapping specifies a URL path template and an HTTP method. The path

template may refer to one or more fields in the gRPC request message, as long

as each field is a non-repeated field with a primitive (non-message) type.

The path template controls how fields of the request message are mapped to

the URL path.

Example:

service Messaging {

rpc GetMessage(GetMessageRequest) returns (Message) {

option (google.api.http) = {

get: "/v1/{name=messages/*}"

};

}

}

message GetMessageRequest {

string name = 1; // Mapped to URL path.

}

message Message {

string text = 1; // The resource content.

}

This enables an HTTP REST to gRPC mapping as below:

- HTTP: `GET /v1/messages/123456`

- gRPC: `GetMessage(name: "messages/123456")`

Any fields in the request message which are not bound by the path template

automatically become HTTP query parameters if there is no HTTP request body.

For example:

service Messaging {

rpc GetMessage(GetMessageRequest) returns (Message) {

option (google.api.http) = {

get:"/v1/messages/{message_id}"

};

}

}

message GetMessageRequest {

message SubMessage {

string subfield = 1;

}

string message_id = 1; // Mapped to URL path.

int64 revision = 2; // Mapped to URL query parameter `revision`.

SubMessage sub = 3; // Mapped to URL query parameter `sub.subfield`.

}

This enables a HTTP JSON to RPC mapping as below:

- HTTP: `GET /v1/messages/123456?revision=2&sub.subfield=foo`

- gRPC: `GetMessage(message_id: "123456" revision: 2 sub:

SubMessage(subfield: "foo"))`

Note that fields which are mapped to URL query parameters must have a

primitive type or a repeated primitive type or a non-repeated message type.

In the case of a repeated type, the parameter can be repeated in the URL

as `...?param=A¶m=B`. In the case of a message type, each field of the

message is mapped to a separate parameter, such as

`...?foo.a=A&foo.b=B&foo.c=C`.

For HTTP methods that allow a request body, the `body` field

specifies the mapping. Consider a REST update method on the

message resource collection:

service Messaging {

rpc UpdateMessage(UpdateMessageRequest) returns (Message) {

option (google.api.http) = {

patch: "/v1/messages/{message_id}"

body: "message"

};

}

}

message UpdateMessageRequest {

string message_id = 1; // mapped to the URL

Message message = 2; // mapped to the body

}

The following HTTP JSON to RPC mapping is enabled, where the

representation of the JSON in the request body is determined by

protos JSON encoding:

- HTTP: `PATCH /v1/messages/123456 { "text": "Hi!" }`

- gRPC: `UpdateMessage(message_id: "123456" message { text: "Hi!" })`

The special name `*` can be used in the body mapping to define that

every field not bound by the path template should be mapped to the

request body. This enables the following alternative definition of

the update method:

service Messaging {

rpc UpdateMessage(Message) returns (Message) {

option (google.api.http) = {

patch: "/v1/messages/{message_id}"

body: "*"

};

}

}

message Message {

string message_id = 1;

string text = 2;

}

The following HTTP JSON to RPC mapping is enabled:

- HTTP: `PATCH /v1/messages/123456 { "text": "Hi!" }`

- gRPC: `UpdateMessage(message_id: "123456" text: "Hi!")`

Note that when using `*` in the body mapping, it is not possible to

have HTTP parameters, as all fields not bound by the path end in

the body. This makes this option more rarely used in practice when

defining REST APIs. The common usage of `*` is in custom methods

which don't use the URL at all for transferring data.

It is possible to define multiple HTTP methods for one RPC by using

the `additional_bindings` option. Example:

service Messaging {

rpc GetMessage(GetMessageRequest) returns (Message) {

option (google.api.http) = {

get: "/v1/messages/{message_id}"

additional_bindings {

get: "/v1/users/{user_id}/messages/{message_id}"

}

};

}

}

message GetMessageRequest {

string message_id = 1;

string user_id = 2;

}

This enables the following two alternative HTTP JSON to RPC mappings:

- HTTP: `GET /v1/messages/123456`

- gRPC: `GetMessage(message_id: "123456")`

- HTTP: `GET /v1/users/me/messages/123456`

- gRPC: `GetMessage(user_id: "me" message_id: "123456")`

Rules for HTTP mapping

1. Leaf request fields (recursive expansion nested messages in the request

message) are classified into three categories:

- Fields referred by the path template. They are passed via the URL path.

- Fields referred by the [HttpRule.body][google.api.HttpRule.body]. They

are passed via the HTTP

request body.

- All other fields are passed via the URL query parameters, and the

parameter name is the field path in the request message. A repeated

field can be represented as multiple query parameters under the same

name.

2. If [HttpRule.body][google.api.HttpRule.body] is "*", there is no URL

query parameter, all fields

are passed via URL path and HTTP request body.

3. If [HttpRule.body][google.api.HttpRule.body] is omitted, there is no HTTP

request body, all

fields are passed via URL path and URL query parameters.

Path template syntax

Template = "/" Segments [ Verb ] ;

Segments = Segment { "/" Segment } ;

Segment = "*" | "**" | LITERAL | Variable ;

Variable = "{" FieldPath [ "=" Segments ] "}" ;

FieldPath = IDENT { "." IDENT } ;

Verb = ":" LITERAL ;

The syntax `*` matches a single URL path segment. The syntax `**` matches

zero or more URL path segments, which must be the last part of the URL path

except the `Verb`.

The syntax `Variable` matches part of the URL path as specified by its

template. A variable template must not contain other variables. If a variable

matches a single path segment, its template may be omitted, e.g. `{var}`

is equivalent to `{var=*}`.

The syntax `LITERAL` matches literal text in the URL path. If the `LITERAL`

contains any reserved character, such characters should be percent-encoded

before the matching.

If a variable contains exactly one path segment, such as `"{var}"` or

`"{var=*}"`, when such a variable is expanded into a URL path on the client

side, all characters except `[-_.~0-9a-zA-Z]` are percent-encoded. The

server side does the reverse decoding. Such variables show up in the

[Discovery

Document](https://developers.google.com/discovery/v1/reference/apis) as

`{var}`.

If a variable contains multiple path segments, such as `"{var=foo/*}"`

or `"{var=**}"`, when such a variable is expanded into a URL path on the

client side, all characters except `[-_.~/0-9a-zA-Z]` are percent-encoded.

The server side does the reverse decoding, except "%2F" and "%2f" are left

unchanged. Such variables show up in the

[Discovery

Document](https://developers.google.com/discovery/v1/reference/apis) as

`{+var}`.

Using gRPC API Service Configuration

gRPC API Service Configuration (service config) is a configuration language

for configuring a gRPC service to become a user-facing product. The

service config is simply the YAML representation of the `google.api.Service`

proto message.

As an alternative to annotating your proto file, you can configure gRPC

transcoding in your service config YAML files. You do this by specifying a

`HttpRule` that maps the gRPC method to a REST endpoint, achieving the same

effect as the proto annotation. This can be particularly useful if you

have a proto that is reused in multiple services. Note that any transcoding

specified in the service config will override any matching transcoding

configuration in the proto.

The following example selects a gRPC method and applies an `HttpRule` to it:

http:

rules:

- selector: example.v1.Messaging.GetMessage

get: /v1/messages/{message_id}/{sub.subfield}

Special notes

When gRPC Transcoding is used to map a gRPC to JSON REST endpoints, the

proto to JSON conversion must follow the [proto3

specification](https://developers.google.com/protocol-buffers/docs/proto3#json).

While the single segment variable follows the semantics of

[RFC 6570](https://tools.ietf.org/html/rfc6570) Section 3.2.2 Simple String

Expansion, the multi segment variable **does not** follow RFC 6570 Section

3.2.3 Reserved Expansion. The reason is that the Reserved Expansion

does not expand special characters like `?` and `#`, which would lead

to invalid URLs. As the result, gRPC Transcoding uses a custom encoding

for multi segment variables.

The path variables **must not** refer to any repeated or mapped field,

because client libraries are not capable of handling such variable expansion.

The path variables **must not** capture the leading "/" character. The reason

is that the most common use case "{var}" does not capture the leading "/"

character. For consistency, all path variables must share the same behavior.

Repeated message fields must not be mapped to URL query parameters, because

no client library can support such complicated mapping.

If an API needs to use a JSON array for request or response body, it can map

the request or response body to a repeated field. However, some gRPC

Transcoding implementations may not support this feature.

FieldTypeLabelDescription
selector string

Selects a method to which this rule applies. Refer to [selector][google.api.DocumentationRule.selector] for syntax details.

get string

Maps to HTTP GET. Used for listing and getting information about resources.

put string

Maps to HTTP PUT. Used for replacing a resource.

post string

Maps to HTTP POST. Used for creating a resource or performing an action.

delete string

Maps to HTTP DELETE. Used for deleting a resource.

patch string

Maps to HTTP PATCH. Used for updating a resource.

custom CustomHttpPattern

The custom pattern is used for specifying an HTTP method that is not included in the `pattern` field, such as HEAD, or "*" to leave the HTTP method unspecified for this rule. The wild-card rule is useful for services that provide content to Web (HTML) clients.

body string

The name of the request field whose value is mapped to the HTTP request body, or `*` for mapping all request fields not captured by the path pattern to the HTTP body, or omitted for not having any HTTP request body. NOTE: the referred field must be present at the top-level of the request message type.

response_body string

Optional. The name of the response field whose value is mapped to the HTTP response body. When omitted, the entire response message will be used as the HTTP response body. NOTE: The referred field must be present at the top-level of the response message type.

additional_bindings HttpRule repeated

Additional HTTP bindings for the selector. Nested bindings must not contain an `additional_bindings` field themselves (that is, the nesting may only be one level deep).

Scalar Value Types

.proto Type Notes Python Type
double float
float float
int32 Uses variable-length encoding. Inefficient for encoding negative numbers – if your field is likely to have negative values, use sint32 instead. int
int64 Uses variable-length encoding. Inefficient for encoding negative numbers – if your field is likely to have negative values, use sint64 instead. int/long
uint32 Uses variable-length encoding. int/long
uint64 Uses variable-length encoding. int/long
sint32 Uses variable-length encoding. Signed int value. These more efficiently encode negative numbers than regular int32s. int
sint64 Uses variable-length encoding. Signed int value. These more efficiently encode negative numbers than regular int64s. int/long
fixed32 Always four bytes. More efficient than uint32 if values are often greater than 2^28. int
fixed64 Always eight bytes. More efficient than uint64 if values are often greater than 2^56. int/long
sfixed32 Always four bytes. int
sfixed64 Always eight bytes. int/long
bool boolean
string A string must always contain UTF-8 encoded or 7-bit ASCII text. str/unicode
bytes May contain any arbitrary sequence of bytes. str