protobufjs
Protocol Buffers are a language-neutral, platform-neutral, extensible way of serializing structured data for use in communications protocols, data storage, and more, originally designed at Google (see).
protobuf.js is a pure JavaScript implementation with TypeScript support for node.js and the browser. It's easy to use, blazingly fast and works out of the box with .proto files!
Apollo GraphQL fork
We have forked the source repo because we need to make changes to the package for use in Apollo Server.
Version 1.0.0 was forked from master which contained version 6.8.8 plus a few unreleased commits. sha
Contents
Installation How to include protobuf.js in your project.
Usage A brief introduction to using the toolset.
Examples A few examples to get you started.
Command line How to use the command line utility.
Additional documentation A list of available documentation resources.
Performance A few internals and a benchmark on performance.
Compatibility Notes on compatibility regarding browsers and optional libraries.
Building How to build the library and its components yourself.
Installation
node.js
Note that this library's versioning scheme is not semver-compatible for historical reasons. For guaranteed backward compatibility, always depend on ~6.A.B instead of ^6.A.B (hence the --save-prefix above).
Browsers
Development:
Production:
Remember to replace the version tag with the exact release your project depends upon.
The library supports CommonJS and AMD loaders and also exports globally as protobuf.
Distributions
Where bundle size is a factor, there are additional stripped-down versions of the full library (~19kb gzipped) available that exclude certain functionality:
When working with JSON descriptors (i.e. generated by pbjs) and/or reflection only, see the light library (~16kb gzipped) that excludes the parser. CommonJS entry point is:
When working with statically generated code only, see the minimal library (~6.5kb gzipped) that also excludes reflection. CommonJS entry point is:
Usage
Because JavaScript is a dynamically typed language, protobuf.js introduces the concept of a valid message in order to provide the best possible performance (and, as a side product, proper typings):
Valid message
A valid message is an object (1) not missing any required fields and (2) exclusively composed of JS types understood by the wire format writer.
There are two possible types of valid messages and the encoder is able to work with both of these for convenience:
Message instances (explicit instances of message classes with default values on their prototype) always (have to) satisfy the requirements of a valid message by design and
Plain JavaScript objects that just so happen to be composed in a way satisfying the requirements of a valid message as well.
In a nutshell, the wire format writer understands the following types:
s-/u-/int32 s-/fixed32
number (32 bit integer)
value | 0 if signed
value >>> 0 if unsigned
s-/u-/int64 s-/fixed64
Long-like (optimal)
number (53 bit integer)
Long.fromValue(value) with long.js
parseInt(value, 10) otherwise
float double
number
Number(value)
bool
boolean
Boolean(value)
string
string
String(value)
bytes
Uint8Array (optimal)
Buffer (optimal under node)
Array.<number> (8 bit integers)
base64.decode(value) if a string
Object with non-zero .length is assumed to be buffer-like
enum
number (32 bit integer)
Looks up the numeric id if a string
message
Valid message
Message.fromObject(value)
Explicit
undefinedandnullare considered as not set if the field is optional.Repeated fields are
Array.<T>.Map fields are
Object.<string,T>with the key being the string representation of the respective value or an 8 characters long binary hash string forLong-likes.Types marked as optimal provide the best performance because no conversion step (i.e. number to low and high bits or base64 string to buffer) is required.
Toolset
With that in mind and again for performance reasons, each message class provides a distinct set of methods with each method doing just one thing. This avoids unnecessary assertions / redundant operations where performance is a concern but also forces a user to perform verification (of plain JavaScript objects that might just so happen to be a valid message) explicitly where necessary - for example when dealing with user input.
Note that Message below refers to any message class.
Message.verify(message:
Object):null|stringverifies that a plain JavaScript object satisfies the requirements of a valid message and thus can be encoded without issues. Instead of throwing, it returns the error message as a string, if any.Message.encode(message:
Message|Object[, writer:Writer]):Writerencodes a message instance or valid plain JavaScript object. This method does not implicitly verify the message and it's up to the user to make sure that the payload is a valid message.Message.encodeDelimited(message:
Message|Object[, writer:Writer]):Writerworks likeMessage.encodebut additionally prepends the length of the message as a varint.Message.decode(reader:
Reader|Uint8Array):Messagedecodes a buffer to a message instance. If required fields are missing, it throws autil.ProtocolErrorwith aninstanceproperty set to the so far decoded message. If the wire format is invalid, it throws anError.Message.decodeDelimited(reader:
Reader|Uint8Array):Messageworks likeMessage.decodebut additionally reads the length of the message prepended as a varint.Message.create(properties:
Object):Messagecreates a new message instance from a set of properties that satisfy the requirements of a valid message. Where applicable, it is recommended to preferMessage.createoverMessage.fromObjectbecause it doesn't perform possibly redundant conversion.Message.fromObject(object:
Object):Messageconverts any non-valid plain JavaScript object to a message instance using the conversion steps outlined within the table above.Message.toObject(message:
Message[, options:ConversionOptions]):Objectconverts a message instance to an arbitrary plain JavaScript object for interoperability with other libraries or storage. The resulting plain JavaScript object might still satisfy the requirements of a valid message depending on the actual conversion options specified, but most of the time it does not.
For reference, the following diagram aims to display relationships between the different methods and the concept of a valid message:
In other words:
verifyindicates that callingcreateorencodedirectly on the plain object will [result in a valid message respectively] succeed.fromObject, on the other hand, does conversion from a broader range of plain objects to create valid messages. (ref)
Examples
Using .proto files
It is possible to load existing .proto files using the full library, which parses and compiles the definitions to ready to use (reflection-based) message classes:
Additionally, promise syntax can be used by omitting the callback, if preferred:
Using JSON descriptors
The library utilizes JSON descriptors that are equivalent to a .proto definition. For example, the following is identical to the .proto definition seen above:
JSON descriptors closely resemble the internal reflection structure:
ReflectionObject
options
Namespace
ReflectionObject
nested
Root
Namespace
nested
Type
Namespace
fields
Enum
ReflectionObject
values
Field
ReflectionObject
rule, type, id
MapField
Field
keyType
OneOf
ReflectionObject
oneof (array of field names)
Service
Namespace
methods
Method
ReflectionObject
type, requestType, responseType, requestStream, responseStream
Bold properties are required. Italic types are abstract.
T.fromJSON(name, json)creates the respective reflection object from a JSON descriptorT#toJSON()creates a JSON descriptor from the respective reflection object (its name is used as the key within the parent)
Exclusively using JSON descriptors instead of .proto files enables the use of just the light library (the parser isn't required in this case).
A JSON descriptor can either be loaded the usual way:
Or it can be loaded inline:
Using reflection only
Both the full and the light library include full reflection support. One could, for example, define the .proto definitions seen in the examples above using just reflection:
Detailed information on the reflection structure is available within the API documentation.
Using custom classes
Message classes can also be extended with custom functionality and it is also possible to register a custom constructor with a reflected message type:
(*) Besides referencing its reflected type through AwesomeMessage.$type and AwesomeMesage#$type, the respective custom class is automatically populated with:
AwesomeMessage.createAwesomeMessage.encodeandAwesomeMessage.encodeDelimitedAwesomeMessage.decodeandAwesomeMessage.decodeDelimitedAwesomeMessage.verifyAwesomeMessage.fromObject,AwesomeMessage.toObjectandAwesomeMessage#toJSON
Afterwards, decoded messages of this type are instanceof AwesomeMessage.
Alternatively, it is also possible to reuse and extend the internal constructor if custom initialization code is not required:
Using services
The library also supports consuming services but it doesn't make any assumptions about the actual transport channel. Instead, a user must provide a suitable RPC implementation, which is an asynchronous function that takes the reflected service method, the binary request and a node-style callback as its parameters:
Below is a working example with a typescript implementation using grpc npm package.
Example:
Services also support promises:
There is also an example for streaming RPC.
Note that the service API is meant for clients. Implementing a server-side endpoint pretty much always requires transport channel (i.e. http, websocket, etc.) specific code with the only common denominator being that it decodes and encodes messages.
Usage with TypeScript
The library ships with its own type definitions and modern editors like Visual Studio Code will automatically detect and use them for code completion.
The npm package depends on @types/node because of Buffer and @types/long because of Long. If you are not building for node and/or not using long.js, it should be safe to exclude them manually.
Using the JS API
The API shown above works pretty much the same with TypeScript. However, because everything is typed, accessing fields on instances of dynamically generated message classes requires either using bracket-notation (i.e. message["awesomeField"]) or explicit casts. Alternatively, it is possible to use a typings file generated for its static counterpart.
Using generated static code
If you generated static code to bundle.js using the CLI and its type definitions to bundle.d.ts, then you can just do:
Using decorators
The library also includes an early implementation of decorators.
Note that decorators are an experimental feature in TypeScript and that declaration order is important depending on the JS target. For example, @Field.d(2, AwesomeArrayMessage) requires that AwesomeArrayMessage has been defined earlier when targeting ES5.
Supported decorators are:
Type.d(typeName?:
string) (optional) annotates a class as a protobuf message type. IftypeNameis not specified, the constructor's runtime function name is used for the reflected type.Field.d<T>(fieldId:
number, fieldType:string | Constructor<T>, fieldRule?:"optional" | "required" | "repeated", defaultValue?:T) annotates a property as a protobuf field with the specified id and protobuf type.MapField.d<T extends { [key: string]: any }>(fieldId:
number, fieldKeyType:string, fieldValueType.string | Constructor<{}>) annotates a property as a protobuf map field with the specified id, protobuf key and value type.OneOf.d<T extends string>(...fieldNames:
string[]) annotates a property as a protobuf oneof covering the specified fields.
Other notes:
Decorated types reside in
protobuf.roots["decorated"]using a flat structure, so no duplicate names.Enums are copied to a reflected enum with a generic name on decorator evaluation because referenced enum objects have no runtime name the decorator could use.
Default values must be specified as arguments to the decorator instead of using a property initializer for proper prototype behavior.
Property names on decorated classes must not be renamed on compile time (i.e. by a minifier) because decorators just receive the original field name as a string.
ProTip! Not as pretty, but you can use decorators in plain JavaScript as well.
Command line
Note that moving the CLI to its own package is a work in progress. At the moment, it's still part of the main package.
The command line interface (CLI) can be used to translate between file formats and to generate static code as well as TypeScript definitions.
pbjs for JavaScript
For production environments it is recommended to bundle all your .proto files to a single .json file, which minimizes the number of network requests and avoids any parser overhead (hint: works with just the light library):
Now, either include this file in your final bundle:
or load it the usual way:
Generated static code, on the other hand, works with just the minimal library. For example
will generate static code for definitions within file1.proto and file2.proto to a CommonJS module compiled.js.
ProTip! Documenting your .proto files with /** ... */-blocks or (trailing) /// ... lines translates to generated static code.
pbts for TypeScript
Picking up on the example above, the following not only generates static code to a CommonJS module compiled.js but also its respective TypeScript definitions to compiled.d.ts:
Additionally, TypeScript definitions of static modules are compatible with their reflection-based counterparts (i.e. as exported by JSON modules), as long as the following conditions are met:
Instead of using
new SomeMessage(...), always useSomeMessage.create(...)because reflection objects do not provide a constructor.Types, services and enums must start with an uppercase letter to become available as properties of the reflected types as well (i.e. to be able to use
MyMessage.MyEnuminstead ofroot.lookup("MyMessage.MyEnum")).
For example, the following generates a JSON module bundle.js and a bundle.d.ts, but no static code:
Reflection vs. static code
While using .proto files directly requires the full library respectively pure reflection/JSON the light library, pretty much all code but the relatively short descriptors is shared.
Static code, on the other hand, requires just the minimal library, but generates additional source code without any reflection features. This also implies that there is a break-even point where statically generated code becomes larger than descriptor-based code once the amount of code generated exceeds the size of the full respectively light library.
There is no significant difference performance-wise as the code generated statically is pretty much the same as generated at runtime and both are largely interchangeable as seen in the previous section.
.proto
full
Easily editable Interoperability with other libraries No compile step
Some parsing and possibly network overhead
JSON
light
Easily editable No parsing overhead Single bundle (no network overhead)
protobuf.js specific Has a compile step
static
minimal
Works where eval access is restricted
Fully documented
Small footprint for small protos
Can be hard to edit No reflection Has a compile step
Command line API
Both utilities can be used programmatically by providing command line arguments and a callback to their respective main functions:
Additional documentation
Protocol Buffers
protobuf.js
Frequently asked questions on our wiki
Community
Questions and answers on StackOverflow
Performance
The package includes a benchmark that compares protobuf.js performance to native JSON (as far as this is possible) and Google's JS implementation. On an i7-2600K running node 6.9.1 it yields:
These results are achieved by
generating type-specific encoders, decoders, verifiers and converters at runtime
configuring the reader/writer interface according to the environment
using node-specific functionality where beneficial and, of course
avoiding unnecessary operations through splitting up the toolset.
You can also run the benchmark ...
and the profiler yourself (the latter requires a recent version of node):
Note that as of this writing, the benchmark suite performs significantly slower on node 7.2.0 compared to 6.9.1 because moths.
Compatibility
Works in all modern and not-so-modern browsers except IE8.
Because the internals of this package do not rely on
google/protobuf/descriptor.proto, options are parsed and presented literally.If typed arrays are not supported by the environment, plain arrays will be used instead.
Support for pre-ES5 environments (except IE8) can be achieved by using a polyfill.
Support for Content Security Policy-restricted environments (like Chrome extensions without unsafe-eval) can be achieved by generating and using static code instead.
For descriptor.proto interoperability, see ext/descriptor
Building
To build the library or its components yourself, clone it from GitHub and install the development dependencies:
Building the respective development and production versions with their respective source maps to dist/:
Building the documentation to docs/:
Building the TypeScript definition to index.d.ts:
Browserify integration
By default, protobuf.js integrates into any browserify build-process without requiring any optional modules. Hence:
If int64 support is required, explicitly require the
longmodule somewhere in your project as it will be excluded otherwise. This assumes that a globalrequirefunction is present that protobuf.js can call to obtain the long module.If there is no global
requirefunction present after bundling, it's also possible to assign the long module programmatically:If you have any special requirements, there is the bundler for reference.
License: BSD 3-Clause License
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