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 revision.
SubMessage sub = 3; // Mapped to URL query parameter sub.subfield.
}
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¶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 | gRPC |
|---|
PATCH /v1/messages/123456 { "text": "Hi!" } | UpdateMessage(message_id: |
"123456" message { text: "Hi!" })
The special name
| HTTP | gRPC |
|---|
PATCH /v1/messages/123456 { "text": "Hi!" } | UpdateMessage(message_id: |
"123456" text: "Hi!")
Note that when using 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
- 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
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
Static Fields
ADDITIONAL_BINDINGS_FIELD_NUMBER
public static final int ADDITIONAL_BINDINGS_FIELD_NUMBER
Field Value
BODY_FIELD_NUMBER
public static final int BODY_FIELD_NUMBER
Field Value
CUSTOM_FIELD_NUMBER
public static final int CUSTOM_FIELD_NUMBER
Field Value
DELETE_FIELD_NUMBER
public static final int DELETE_FIELD_NUMBER
Field Value
GET_FIELD_NUMBER
public static final int GET_FIELD_NUMBER
Field Value
PATCH_FIELD_NUMBER
public static final int PATCH_FIELD_NUMBER
Field Value
POST_FIELD_NUMBER
public static final int POST_FIELD_NUMBER
Field Value
PUT_FIELD_NUMBER
public static final int PUT_FIELD_NUMBER
Field Value
RESPONSE_BODY_FIELD_NUMBER
public static final int RESPONSE_BODY_FIELD_NUMBER
Field Value
SELECTOR_FIELD_NUMBER
public static final int SELECTOR_FIELD_NUMBER
Field Value
Static Methods
getDefaultInstance()
public static HttpRule getDefaultInstance()
Returns
getDescriptor()
public static final Descriptors.Descriptor getDescriptor()
Returns
newBuilder()
public static HttpRule.Builder newBuilder()
Returns
newBuilder(HttpRule prototype)
public static HttpRule.Builder newBuilder(HttpRule prototype)
Parameter
Returns
public static HttpRule parseDelimitedFrom(InputStream input)
Parameter
Returns
Exceptions
public static HttpRule parseDelimitedFrom(InputStream input, ExtensionRegistryLite extensionRegistry)
Parameters
Returns
Exceptions
parseFrom(byte[] data)
public static HttpRule parseFrom(byte[] data)
Parameter
| Name | Description |
| data | byte[]
|
Returns
Exceptions
parseFrom(byte[] data, ExtensionRegistryLite extensionRegistry)
public static HttpRule parseFrom(byte[] data, ExtensionRegistryLite extensionRegistry)
Parameters
Returns
Exceptions
parseFrom(ByteString data)
public static HttpRule parseFrom(ByteString data)
Parameter
Returns
Exceptions
parseFrom(ByteString data, ExtensionRegistryLite extensionRegistry)
public static HttpRule parseFrom(ByteString data, ExtensionRegistryLite extensionRegistry)
Parameters
Returns
Exceptions
public static HttpRule parseFrom(CodedInputStream input)
Parameter
Returns
Exceptions
public static HttpRule parseFrom(CodedInputStream input, ExtensionRegistryLite extensionRegistry)
Parameters
Returns
Exceptions
public static HttpRule parseFrom(InputStream input)
Parameter
Returns
Exceptions
public static HttpRule parseFrom(InputStream input, ExtensionRegistryLite extensionRegistry)
Parameters
Returns
Exceptions
parseFrom(ByteBuffer data)
public static HttpRule parseFrom(ByteBuffer data)
Parameter
Returns
Exceptions
parseFrom(ByteBuffer data, ExtensionRegistryLite extensionRegistry)
public static HttpRule parseFrom(ByteBuffer data, ExtensionRegistryLite extensionRegistry)
Parameters
Returns
Exceptions
parser()
public static Parser<HttpRule> parser()
Returns
Methods
equals(Object obj)
public boolean equals(Object obj)
Parameter
Returns
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;
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;
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;
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;
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;
| Type | Description |
| List<? extends com.google.api.HttpRuleOrBuilder> | |
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;
| 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;
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;
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;
getDefaultInstanceForType()
public HttpRule getDefaultInstanceForType()
Returns
getDelete()
public String getDelete()
Maps to HTTP DELETE. Used for deleting a resource.
string delete = 5;
| Type | Description |
| String | The delete.
|
getDeleteBytes()
public ByteString getDeleteBytes()
Maps to HTTP DELETE. Used for deleting a resource.
string delete = 5;
getGet()
Maps to HTTP GET. Used for listing and getting information about
resources.
string get = 2;
getGetBytes()
public ByteString getGetBytes()
Maps to HTTP GET. Used for listing and getting information about
resources.
string get = 2;
getParserForType()
public Parser<HttpRule> getParserForType()
Returns
Overrides
getPatch()
Maps to HTTP PATCH. Used for updating a resource.
string patch = 6;
| Type | Description |
| String | The patch.
|
getPatchBytes()
public ByteString getPatchBytes()
Maps to HTTP PATCH. Used for updating a resource.
string patch = 6;
getPatternCase()
public HttpRule.PatternCase getPatternCase()
Returns
getPost()
Maps to HTTP POST. Used for creating a resource or performing an action.
string post = 4;
| 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;
getPut()
Maps to HTTP PUT. Used for replacing a resource.
string put = 3;
getPutBytes()
public ByteString getPutBytes()
Maps to HTTP PUT. Used for replacing a resource.
string put = 3;
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;
| 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;
| 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;
| 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;
getSerializedSize()
public int getSerializedSize()
Returns
Overrides
getUnknownFields()
public final UnknownFieldSet getUnknownFields()
Returns
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;
| 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;
| Type | Description |
| boolean | Whether the delete field is set.
|
hasGet()
Maps to HTTP GET. Used for listing and getting information about
resources.
string get = 2;
| 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;
| Type | Description |
| boolean | Whether the patch field is set.
|
hasPost()
Maps to HTTP POST. Used for creating a resource or performing an action.
string post = 4;
| Type | Description |
| boolean | Whether the post field is set.
|
hasPut()
Maps to HTTP PUT. Used for replacing a resource.
string put = 3;
| Type | Description |
| boolean | Whether the put field is set.
|
hashCode()
Returns
Overrides
internalGetFieldAccessorTable()
protected GeneratedMessageV3.FieldAccessorTable internalGetFieldAccessorTable()
Returns
Overrides
isInitialized()
public final boolean isInitialized()
Returns
Overrides
newBuilderForType()
public HttpRule.Builder newBuilderForType()
Returns
newBuilderForType(GeneratedMessageV3.BuilderParent parent)
protected HttpRule.Builder newBuilderForType(GeneratedMessageV3.BuilderParent parent)
Parameter
Returns
Overrides
newInstance(GeneratedMessageV3.UnusedPrivateParameter unused)
protected Object newInstance(GeneratedMessageV3.UnusedPrivateParameter unused)
Parameter
Returns
Overrides
toBuilder()
public HttpRule.Builder toBuilder()
Returns
writeTo(CodedOutputStream output)
public void writeTo(CodedOutputStream output)
Parameter
Overrides
Exceptions
