github.com/bakjos/protoreflect@v1.9.2/README.md (about)

     1  # Protocol Buffer and gRPC Reflection
     2  
     3  [![Build Status](https://circleci.com/gh/jhump/protoreflect/tree/master.svg?style=svg)](https://circleci.com/gh/jhump/protoreflect/tree/master)
     4  [![Go Report Card](https://goreportcard.com/badge/github.com/bakjos/protoreflect)](https://goreportcard.com/report/github.com/bakjos/protoreflect)
     5  
     6  This repo provides reflection APIs for [protocol buffers](https://developers.google.com/protocol-buffers/) (also known as "protobufs" for short)
     7  and [gRPC](https://grpc.io/). The core of reflection in protobufs is the
     8  [descriptor](https://github.com/google/protobuf/blob/199d82fde1734ab5bc931cd0de93309e50cd7ab9/src/google/protobuf/descriptor.proto).
     9  A descriptor is itself a protobuf message that describes a `.proto` source file or any element
    10  therein. So a collection of descriptors can describe an entire schema of protobuf types, including
    11  RPC services.
    12  
    13  [![GoDoc](https://godoc.org/github.com/bakjos/protoreflect?status.svg)](https://godoc.org/github.com/bakjos/protoreflect)
    14  
    15  ---
    16  
    17  ## Descriptors: The Language Model of Protocol Buffers
    18  
    19  ```go
    20  import "github.com/bakjos/protoreflect/desc"
    21  ```
    22  
    23  The `desc` package herein introduces a `Descriptor` interface and implementations of it that
    24  correspond to each of the descriptor types. These new types are effectively smart wrappers around
    25  the [generated protobuf types](https://github.com/golang/protobuf/blob/master/protoc-gen-go/descriptor/descriptor.pb.go)
    26  that make them _much_ more useful and easier to use.
    27  
    28  You can construct descriptors from file descriptor sets (which can be generated by `protoc`), and
    29  you can also load descriptors for messages and services that are linked into the current binary.
    30  "What does it mean for messages and services to be linked in?" you may ask. It means your binary
    31  imports a package that was generated by `protoc`. When you generate Go code from your `.proto`
    32  sources, the resulting package has descriptor information embedded in it. The `desc` package allows
    33  you to easily extract those embedded descriptors.
    34  
    35  Descriptors can also be acquired directly from `.proto` source files (using the `protoparse` sub-package)
    36  or by programmatically constructing them (using the `builder` sub-package).
    37  
    38  _[Read more ≫](https://godoc.org/github.com/bakjos/protoreflect/desc)_
    39  
    40  ```go
    41  import "github.com/bakjos/protoreflect/desc/protoparse"
    42  ```
    43  
    44  The `protoparse` package allows for parsing of `.proto` source files into rich descriptors. Without
    45  this package, you must invoke `protoc` to either generate a file descriptor set file or to generate
    46  Go code (which has descriptor information embedded in it). This package allows reading the source
    47  directly without having to invoke `protoc`.
    48  
    49  _[Read more ≫](https://godoc.org/github.com/bakjos/protoreflect/desc/protoparse)_
    50  
    51  ```go
    52  import "github.com/bakjos/protoreflect/desc/protoprint"
    53  ```
    54  
    55  The `protoprint` package allows for printing of descriptors to `.proto` source files. This is
    56  effectively the inverse of the `protoparse` package. Combined with the `builder` package, this
    57  is a useful tool for programmatically generating protocol buffer sources.
    58  
    59  _[Read more ≫](https://godoc.org/github.com/bakjos/protoreflect/desc/protoprint)_
    60  
    61  ```go
    62  import "github.com/bakjos/protoreflect/desc/builder"
    63  ```
    64  
    65  The `builder` package allows for programmatic construction of rich descriptors. Descriptors can
    66  be constructed programmatically by creating trees of descriptor protos and using the `desc` package
    67  to link those into rich descriptors. But constructing a valid tree of descriptor protos is far from
    68  trivial.
    69  
    70  So this package provides generous API to greatly simplify that task. It also allows for converting
    71  rich descriptors into builders, which means you can programmatically modify/tweak existing
    72  descriptors.
    73  
    74  _[Read more ≫](https://godoc.org/github.com/bakjos/protoreflect/desc/builder)_
    75  
    76  ---
    77  
    78  ## Dynamic Messages and Stubs
    79  
    80  ```go
    81  import "github.com/bakjos/protoreflect/dynamic"
    82  ```
    83  
    84  The `dynamic` package provides a dynamic message implementation. It implements `proto.Message` but
    85  is backed by a message descriptor and a map of fields->values, instead of a generated struct. This
    86  is useful for acting generically with protocol buffer messages, without having to generate and link
    87  in Go code for every kind of message. This is particularly useful for general-purpose tools that
    88  need to operate on arbitrary protocol buffer schemas. This is made possible by having the tools load
    89  descriptors at runtime.
    90  
    91  _[Read more ≫](https://godoc.org/github.com/bakjos/protoreflect/dynamic)_
    92  
    93  ```go
    94  import "github.com/bakjos/protoreflect/dynamic/grpcdynamic"
    95  ```
    96  
    97  There is also sub-package named `grpcdynamic`, which provides a dynamic stub implementation. The stub can
    98  be used to issue RPC methods using method descriptors instead of generated client interfaces.
    99  
   100  _[Read more ≫](https://godoc.org/github.com/bakjos/protoreflect/dynamic/grpcdynamic)_
   101  
   102  ---
   103  
   104  ## gRPC Server Reflection
   105  
   106  ```go
   107  import "github.com/bakjos/protoreflect/grpcreflect"
   108  ```
   109  
   110  The `grpcreflect` package provides an easy-to-use client for the
   111  [gRPC reflection service](https://github.com/grpc/grpc-go/blob/6bd4f6eb1ea9d81d1209494242554dcde44429a4/reflection/grpc_reflection_v1alpha/reflection.proto#L36),
   112  making it much easier to query for and work with the schemas of remote services.
   113  
   114  It also provides some helper methods for querying for rich service descriptors for the
   115  services registered in a gRPC server.
   116  
   117  _[Read more ≫](https://godoc.org/github.com/bakjos/protoreflect/grpcreflect)_