Class HttpRule (2.41.0) 

public final class HttpRule extends GeneratedMessageV3 implements HttpRuleOrBuilder

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, Cloud Endpoints, gRPC Gateway, and 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 gRPC
GET /v1/messages/123456 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 <code>revision</code>.
   SubMessage sub = 3;    // Mapped to URL query parameter <code>sub.subfield</code>.
 }

This enables a HTTP JSON to RPC mapping as below:

HTTP gRPC
GET /v1/messages/123456?revision=2&sub.subfield=foo

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&param=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 gRPC
PATCH /v1/messages/123456 { "text": "Hi!" } 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 gRPC
PATCH /v1/messages/123456 { "text": "Hi!" } 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 gRPC
GET /v1/messages/123456 GetMessage(message_id: "123456")
GET /v1/users/me/messages/123456 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. 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.
    • If HttpRule.body is "*", there is no URL query parameter, all fields are passed via URL path and HTTP request body.
    • If 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 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 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.

    Example:

    http: rules:

    Selects a gRPC method and applies HttpRule to it.

     - 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.

    While the single segment variable follows the semantics of RFC 6570 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.

Protobuf type google.api.HttpRule

Inheritance

Object > AbstractMessageLite<MessageType,BuilderType> > AbstractMessage > GeneratedMessageV3 > HttpRule

Implements

HttpRuleOrBuilder

Static Fields

ADDITIONAL_BINDINGS_FIELD_NUMBER

public static final int ADDITIONAL_BINDINGS_FIELD_NUMBER
Field Value
Type Description
int

BODY_FIELD_NUMBER

public static final int BODY_FIELD_NUMBER
Field Value
Type Description
int

CUSTOM_FIELD_NUMBER

public static final int CUSTOM_FIELD_NUMBER
Field Value
Type Description
int

DELETE_FIELD_NUMBER

public static final int DELETE_FIELD_NUMBER
Field Value
Type Description
int

GET_FIELD_NUMBER

public static final int GET_FIELD_NUMBER
Field Value
Type Description
int

PATCH_FIELD_NUMBER

public static final int PATCH_FIELD_NUMBER
Field Value
Type Description
int

POST_FIELD_NUMBER

public static final int POST_FIELD_NUMBER
Field Value
Type Description
int

PUT_FIELD_NUMBER

public static final int PUT_FIELD_NUMBER
Field Value
Type Description
int

RESPONSE_BODY_FIELD_NUMBER

public static final int RESPONSE_BODY_FIELD_NUMBER
Field Value
Type Description
int

SELECTOR_FIELD_NUMBER

public static final int SELECTOR_FIELD_NUMBER
Field Value
Type Description
int

Static Methods

getDefaultInstance()

public static HttpRule getDefaultInstance()
Returns
Type Description
HttpRule

getDescriptor()

public static final Descriptors.Descriptor getDescriptor()
Returns
Type Description
Descriptor

newBuilder()

public static HttpRule.Builder newBuilder()
Returns
Type Description
HttpRule.Builder

newBuilder(HttpRule prototype)

public static HttpRule.Builder newBuilder(HttpRule prototype)
Parameter
Name Description
prototype HttpRule
Returns
Type Description
HttpRule.Builder

parseDelimitedFrom(InputStream input)

public static HttpRule parseDelimitedFrom(InputStream input)
Parameter
Name Description
input InputStream
Returns
Type Description
HttpRule
Exceptions
Type Description
IOException

parseDelimitedFrom(InputStream input, ExtensionRegistryLite extensionRegistry)

public static HttpRule parseDelimitedFrom(InputStream input, ExtensionRegistryLite extensionRegistry)
Parameters
Name Description
input InputStream
extensionRegistry ExtensionRegistryLite
Returns
Type Description
HttpRule
Exceptions
Type Description
IOException

parseFrom(byte[] data)

public static HttpRule parseFrom(byte[] data)
Parameter
Name Description
data byte[]
Returns
Type Description
HttpRule
Exceptions
Type Description
InvalidProtocolBufferException

parseFrom(byte[] data, ExtensionRegistryLite extensionRegistry)

public static HttpRule parseFrom(byte[] data, ExtensionRegistryLite extensionRegistry)
Parameters
Name Description
data byte[]
extensionRegistry ExtensionRegistryLite
Returns
Type Description
HttpRule
Exceptions
Type Description
InvalidProtocolBufferException

parseFrom(ByteString data)

public static HttpRule parseFrom(ByteString data)
Parameter
Name Description
data ByteString
Returns
Type Description
HttpRule
Exceptions
Type Description
InvalidProtocolBufferException

parseFrom(ByteString data, ExtensionRegistryLite extensionRegistry)

public static HttpRule parseFrom(ByteString data, ExtensionRegistryLite extensionRegistry)
Parameters
Name Description
data ByteString
extensionRegistry ExtensionRegistryLite
Returns
Type Description
HttpRule
Exceptions
Type Description
InvalidProtocolBufferException

parseFrom(CodedInputStream input)

public static HttpRule parseFrom(CodedInputStream input)
Parameter
Name Description
input CodedInputStream
Returns
Type Description
HttpRule
Exceptions
Type Description
IOException

parseFrom(CodedInputStream input, ExtensionRegistryLite extensionRegistry)

public static HttpRule parseFrom(CodedInputStream input, ExtensionRegistryLite extensionRegistry)
Parameters
Name Description
input CodedInputStream
extensionRegistry ExtensionRegistryLite
Returns
Type Description
HttpRule
Exceptions
Type Description
IOException

parseFrom(InputStream input)

public static HttpRule parseFrom(InputStream input)
Parameter
Name Description
input InputStream
Returns
Type Description
HttpRule
Exceptions
Type Description
IOException

parseFrom(InputStream input, ExtensionRegistryLite extensionRegistry)

public static HttpRule parseFrom(InputStream input, ExtensionRegistryLite extensionRegistry)
Parameters
Name Description
input InputStream
extensionRegistry ExtensionRegistryLite
Returns
Type Description
HttpRule
Exceptions
Type Description
IOException

parseFrom(ByteBuffer data)

public static HttpRule parseFrom(ByteBuffer data)
Parameter
Name Description
data ByteBuffer
Returns
Type Description
HttpRule
Exceptions
Type Description
InvalidProtocolBufferException

parseFrom(ByteBuffer data, ExtensionRegistryLite extensionRegistry)

public static HttpRule parseFrom(ByteBuffer data, ExtensionRegistryLite extensionRegistry)
Parameters
Name Description
data ByteBuffer
extensionRegistry ExtensionRegistryLite
Returns
Type Description
HttpRule
Exceptions
Type Description
InvalidProtocolBufferException

parser()

public static Parser<HttpRule> parser()
Returns
Type Description
Parser<HttpRule>

Methods

equals(Object obj)

public boolean equals(Object obj)
Parameter
Name Description
obj Object
Returns
Type Description
boolean
Overrides

getAdditionalBindings(int index)

public HttpRule getAdditionalBindings(int index)

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).

repeated .google.api.HttpRule additional_bindings = 11;

Parameter
Name Description
index int
Returns
Type Description
HttpRule

getAdditionalBindingsCount()

public int getAdditionalBindingsCount()

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).

repeated .google.api.HttpRule additional_bindings = 11;

Returns
Type Description
int

getAdditionalBindingsList()

public List<HttpRule> getAdditionalBindingsList()

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).

repeated .google.api.HttpRule additional_bindings = 11;

Returns
Type Description
List<HttpRule>

getAdditionalBindingsOrBuilder(int index)

public HttpRuleOrBuilder getAdditionalBindingsOrBuilder(int index)

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).

repeated .google.api.HttpRule additional_bindings = 11;

Parameter
Name Description
index int
Returns
Type Description
HttpRuleOrBuilder

getAdditionalBindingsOrBuilderList()

public List<? extends HttpRuleOrBuilder> getAdditionalBindingsOrBuilderList()

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).

repeated .google.api.HttpRule additional_bindings = 11;

Returns
Type Description
List<? extends com.google.api.HttpRuleOrBuilder>

getBody()

public String getBody()

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.

string body = 7;

Returns
Type Description
String

The body.

getBodyBytes()

public ByteString getBodyBytes()

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.

string body = 7;

Returns
Type Description
ByteString

The bytes for body.

getCustom()

public CustomHttpPattern getCustom()

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.

.google.api.CustomHttpPattern custom = 8;

Returns
Type Description
CustomHttpPattern

The custom.

getCustomOrBuilder()

public CustomHttpPatternOrBuilder getCustomOrBuilder()

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.

.google.api.CustomHttpPattern custom = 8;

Returns
Type Description
CustomHttpPatternOrBuilder

getDefaultInstanceForType()

public HttpRule getDefaultInstanceForType()
Returns
Type Description
HttpRule

getDelete()

public String getDelete()

Maps to HTTP DELETE. Used for deleting a resource.

string delete = 5;

Returns
Type Description
String

The delete.

getDeleteBytes()

public ByteString getDeleteBytes()

Maps to HTTP DELETE. Used for deleting a resource.

string delete = 5;

Returns
Type Description
ByteString

The bytes for delete.

getGet()

public String getGet()

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

string get = 2;

Returns
Type Description
String

The get.

getGetBytes()

public ByteString getGetBytes()

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

string get = 2;

Returns
Type Description
ByteString

The bytes for get.

getParserForType()

public Parser<HttpRule> getParserForType()
Returns
Type Description
Parser<HttpRule>
Overrides

getPatch()

public String getPatch()

Maps to HTTP PATCH. Used for updating a resource.

string patch = 6;

Returns
Type Description
String

The patch.

getPatchBytes()

public ByteString getPatchBytes()

Maps to HTTP PATCH. Used for updating a resource.

string patch = 6;

Returns
Type Description
ByteString

The bytes for patch.

getPatternCase()

public HttpRule.PatternCase getPatternCase()
Returns
Type Description
HttpRule.PatternCase

getPost()

public String getPost()

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

string post = 4;

Returns
Type Description
String

The post.

getPostBytes()

public ByteString getPostBytes()

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

string post = 4;

Returns
Type Description
ByteString

The bytes for post.

getPut()

public String getPut()

Maps to HTTP PUT. Used for replacing a resource.

string put = 3;

Returns
Type Description
String

The put.

getPutBytes()

public ByteString getPutBytes()

Maps to HTTP PUT. Used for replacing a resource.

string put = 3;

Returns
Type Description
ByteString

The bytes for put.

getResponseBody()

public String getResponseBody()

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.

string response_body = 12;

Returns
Type Description
String

The responseBody.

getResponseBodyBytes()

public ByteString getResponseBodyBytes()

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.

string response_body = 12;

Returns
Type Description
ByteString

The bytes for responseBody.

getSelector()

public String getSelector()

Selects a method to which this rule applies.

Refer to selector for syntax details.

string selector = 1;

Returns
Type Description
String

The selector.

getSelectorBytes()

public ByteString getSelectorBytes()

Selects a method to which this rule applies.

Refer to selector for syntax details.

string selector = 1;

Returns
Type Description
ByteString

The bytes for selector.

getSerializedSize()

public int getSerializedSize()
Returns
Type Description
int
Overrides

hasCustom()

public boolean hasCustom()

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.

.google.api.CustomHttpPattern custom = 8;

Returns
Type Description
boolean

Whether the custom field is set.

hasDelete()

public boolean hasDelete()

Maps to HTTP DELETE. Used for deleting a resource.

string delete = 5;

Returns
Type Description
boolean

Whether the delete field is set.

hasGet()

public boolean hasGet()

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

string get = 2;

Returns
Type Description
boolean

Whether the get field is set.

hasPatch()

public boolean hasPatch()

Maps to HTTP PATCH. Used for updating a resource.

string patch = 6;

Returns
Type Description
boolean

Whether the patch field is set.

hasPost()

public boolean hasPost()

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

string post = 4;

Returns
Type Description
boolean

Whether the post field is set.

hasPut()

public boolean hasPut()

Maps to HTTP PUT. Used for replacing a resource.

string put = 3;

Returns
Type Description
boolean

Whether the put field is set.

hashCode()

public int hashCode()
Returns
Type Description
int
Overrides

internalGetFieldAccessorTable()

protected GeneratedMessageV3.FieldAccessorTable internalGetFieldAccessorTable()
Returns
Type Description
FieldAccessorTable
Overrides

isInitialized()

public final boolean isInitialized()
Returns
Type Description
boolean
Overrides

newBuilderForType()

public HttpRule.Builder newBuilderForType()
Returns
Type Description
HttpRule.Builder

newBuilderForType(GeneratedMessageV3.BuilderParent parent)

protected HttpRule.Builder newBuilderForType(GeneratedMessageV3.BuilderParent parent)
Parameter
Name Description
parent BuilderParent
Returns
Type Description
HttpRule.Builder
Overrides

newInstance(GeneratedMessageV3.UnusedPrivateParameter unused)

protected Object newInstance(GeneratedMessageV3.UnusedPrivateParameter unused)
Parameter
Name Description
unused UnusedPrivateParameter
Returns
Type Description
Object
Overrides

toBuilder()

public HttpRule.Builder toBuilder()
Returns
Type Description
HttpRule.Builder

writeTo(CodedOutputStream output)

public void writeTo(CodedOutputStream output)
Parameter
Name Description
output CodedOutputStream
Overrides
Exceptions
Type Description
IOException