再探 gRPC 在 ASP.NET Core 7 的 JSON 轉碼功能

之前筆記 gRPC 在 ASP.NET Core 7 的 JSON 轉碼功能 紀錄到如何使用 ASP.NET Core 7 加入的 JSON 轉碼功能:可以讓 gRPC service 也可以透過 rest api 的方式來呼叫。

不過眼尖的人一定也發現了,呼叫 gRPC service 與呼叫 rest api 的內容有些不同,雖然 response 一致,但是 request 卻差了許多:

  1. service 的 endpoint

    除了 protocol 不同之外,rest api 還包含了 path 及 parameter

    • gRPC

      grpc://localhost:7156

    • rest api

      https://localhost:7156/v1/greeter/name

  2. request 的 parameter 傳遞方式

    • gRPC

      {
        "name": "gRPC"
      }
      
    • rest api

      url parameter : https://localhost:7156/v1/greeter/{name}

今天打算來嘗試將 gRPC 與 rest api 的使用體驗調整的接近些,因為團隊主要的開發環境是 macOS 所以會基於 gRPC 在 ASP.NET Core 7 的 JSON 轉碼功能 (macOS) 來延伸設定,不過差異並不大 (只差在 appsettings.json 中 Kestrel 的 Endpoints 部份)

基本環境說明

  1. macOS Ventura 13.2
  2. .NET SDK 7.0.203
  3. JetBrains Rider 2023.1

    使用 gRPC service 預設專案範本

  4. NuGet packages

    • Microsoft.AspNetCore.Grpc.JsonTranscoding 7.0.5

設定方式

前三點皆與 gRPC 在 ASP.NET Core 7 的 JSON 轉碼功能 (macOS) 相同

  1. 將 NuGet package Microsoft.AspNetCore.Grpc.JsonTranscoding 加入 project
  2. 註冊轉碼功能:修改 Program.cs

    • builder.Services.AddGrpc();
      
    • builder.Services.AddGrpc().AddJsonTranscoding();
      
  3. 新增 google/api/http.protogoogle/api/annotations.proto

    引用額外的資料結構,以預設專案的例子可以在 Protos 資料下新增 google/api 並放入以下兩個檔案 (檔案位置會影響實際引用的設定,另個做法是與 .proj 放在同一層,引用填 .proj 的相對位置即可)

    • http.proto

      展開摺疊區塊

      // Copyright 2019 Google LLC.
      //
      // Licensed under the Apache License, Version 2.0 (the "License");
      // you may not use this file except in compliance with the License.
      // You may obtain a copy of the License at
      //
      //     http://www.apache.org/licenses/LICENSE-2.0
      //
      // Unless required by applicable law or agreed to in writing, software
      // distributed under the License is distributed on an "AS IS" BASIS,
      // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      // See the License for the specific language governing permissions and
      // limitations under the License.
      //
      
      syntax = "proto3";
      
      package google.api;
      
      option cc_enable_arenas = true;
      option go_package = "google.golang.org/genproto/googleapis/api/annotations;annotations";
      option java_multiple_files = true;
      option java_outer_classname = "HttpProto";
      option java_package = "com.google.api";
      option objc_class_prefix = "GAPI";
              
      // 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.
      message Http {
        // A list of HTTP configuration rules that apply to individual API methods.
        //
        // **NOTE:** All service configuration rules follow "last one wins" order.
        repeated HttpRule rules = 1;
              
        // 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.
        bool fully_decode_reserved_expansion = 2;
      }
              
      // # 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 | 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&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][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.
      //
      // 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](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.
      message HttpRule {
        // Selects a method to which this rule applies.
        //
        // Refer to [selector][google.api.DocumentationRule.selector] for syntax details.
        string selector = 1;
              
        // Determines the URL pattern is matched by this rules. This pattern can be
        // used with any of the {get|put|post|delete|patch} methods. A custom method
        // can be defined using the 'custom' field.
        oneof pattern {
          // Maps to HTTP GET. Used for listing and getting information about
          // resources.
          string get = 2;
              
          // Maps to HTTP PUT. Used for replacing a resource.
          string put = 3;
              
          // Maps to HTTP POST. Used for creating a resource or performing an action.
          string post = 4;
              
          // Maps to HTTP DELETE. Used for deleting a resource.
          string delete = 5;
              
          // Maps to HTTP PATCH. Used for updating a resource.
          string patch = 6;
              
          // 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.
          CustomHttpPattern custom = 8;
        }
              
        // 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;
              
        // 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;
              
        // 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 HttpRule additional_bindings = 11;
      }
              
      // A custom pattern is used for defining custom HTTP verb.
      message CustomHttpPattern {
        // The name of this custom HTTP verb.
        string kind = 1;
              
        // The path matched by this custom verb.
        string path = 2;
      }
      

    • annotations.proto

      展開摺疊區塊

      // Copyright (c) 2015, Google Inc.
      //
      // Licensed under the Apache License, Version 2.0 (the "License");
      // you may not use this file except in compliance with the License.
      // You may obtain a copy of the License at
      //
      //     http://www.apache.org/licenses/LICENSE-2.0
      //
      // Unless required by applicable law or agreed to in writing, software
      // distributed under the License is distributed on an "AS IS" BASIS,
      // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      // See the License for the specific language governing permissions and
      // limitations under the License.
              
      syntax = "proto3";
              
      package google.api;
              
      import "Protos/google/api/http.proto";
      import "google/protobuf/descriptor.proto";
              
      option go_package = "google.golang.org/genproto/googleapis/api/annotations;annotations";
      option java_multiple_files = true;
      option java_outer_classname = "AnnotationsProto";
      option java_package = "com.google.api";
      option objc_class_prefix = "GAPI";
              
      extend google.protobuf.MethodOptions {
        // See `HttpRule`.
        HttpRule http = 72295728;
      }
      

  4. 透過 HTTP binding 與 route 來標注 gRPC service

    修改範例中的 greet.proto 檔案:將原本使用 get 方法並透過 url parameter 傳遞參數改為 post 與 json

    • syntax = "proto3";
      //以實際放的位置為主
      import "Protos/google/api/annotations.proto";
      option csharp_namespace = "NET7GrpcService";
              
      package greet;
              
      // The greeting service definition.
      service Greeter {
        // Sends a greeting
        rpc SayHello (HelloRequest) returns (HelloReply){
            option (google.api.http) = {
              get: "/v1/greeter/{name}"
            };   
        }
      }
              
      // The request message containing the user's name.
      message HelloRequest {
        string name = 1;
      }
              
      // The response message containing the greetings.
      message HelloReply {
        string message = 1;
      }
      
    • syntax = "proto3";
      //以實際放的位置為主
      import "Protos/google/api/annotations.proto";
      option csharp_namespace = "NET7GrpcService";
              
      package greet;
              
      // The greeting service definition.
      service Greeter {
        // Sends a greeting
        rpc SayHello (HelloRequest) returns (HelloReply){
            option (google.api.http) = {
              post: "/Greeter/SayHello",
              body: "*"
            };   
        }
      }
              
      // The request message containing the user's name.
      message HelloRequest {
        string name = 1;
      }
              
      // The response message containing the greetings.
      message HelloReply {
        string message = 1;
      }
      
  5. (非必要,可在 macOS 上的啟用 insecure grpc) 設定 gRPC 與 rest api 走不同 port

    修改 appsettings.json

    • {
        "Logging": {
          "LogLevel": {
            "Default": "Information",
            "Microsoft.AspNetCore": "Warning"
          }
        },
        "AllowedHosts": "*",
        "Kestrel": {
          "EndpointDefaults": {
            "Protocols": "Http2"
          }
        }
      }
      
    • {
        "Logging": {
          "LogLevel": {
            "Default": "Information",
            "Microsoft.AspNetCore": "Warning"
          }
        },
        "AllowedHosts": "*",
        "Kestrel": {
          "Endpoints": {
            "Https": {
              "Url": "https://*:7019",
              "Protocols": "Http1"
            },
            "GrpcInsecure" : {
              "Url": "http://*:5187",
              "Protocols": "Http2"
            }
          }
        }
      }
      
  6. 實際效果

    兩者 port 不同,是因為 macOS 的源故

    • gRPC

      1grpc

    • rest api

      2rest

心得

這個調整純屬個人的喜好問題: gRPC 的 request body,rest 透過 POST 使用 json 感覺使用體驗比較一致,不過單就以範例這樣簡單的情境功能是完全相同的,只是如果 request 內容是個大型複雜型別的物件時,我個人相信 POST 是比較常見的做法

完整程式碼:yowko/grpc-aspdotnetcore7-json-post

參考資訊

  1. .NET 7 的新功能
  2. ASP.NET Core 7.0 的新功能
  3. ASP.NET Core gRPC 應用程式中的 gRPC JSON 轉碼
  4. gRPC JSON 轉碼與 Swagger/OpenAPI
  5. Build High Performance Services using gRPC and .NET7
  6. 針對 .NET Core 上的 gRPC 進行疑難排解
  7. yowko/grpc-aspdotnetcore7-json-post
  8. ASP.NET Core gRPC 的 Secure 與 Insecure 不同做法
  9. gRPC 在 ASP.NET Core 7 的 JSON 轉碼功能
  10. gRPC 在 ASP.NET Core 7 的 JSON 轉碼功能 (macOS)