npm package: @launchql/protobufjs-cli
Description: Translates between file formats and generates static code as well as TypeScript definitions.
Author: Daniel Wirtz
Latest version: 1.1.5

protobufjs-cli
==============
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Command line interface (CLI) for [protobuf.js](https://github.com/dcodeIO/protobuf.js).

This can be used to translate between file formats and to generate static code as well as TypeScript definitions.

* [pbjs for JavaScript](#pbjs-for-javascript)
* [pbts for TypeScript](#pbts-for-typescript)
* [Reflection vs. static code](#reflection-vs-static-code)
* [Command line API](#command-line-api)<br />

### pbjs for JavaScript

```
Translates between file formats and generates static code.

  -t, --target     Specifies the target format. Also accepts a path to require a custom target.

                   json          JSON representation
                   json-module   JSON representation as a module
                   proto2        Protocol Buffers, Version 2
                   proto3        Protocol Buffers, Version 3
                   static        Static code without reflection (non-functional on its own)
                   static-module Static code without reflection as a module

  -p, --path       Adds a directory to the include path.

  -o, --out        Saves to a file instead of writing to stdout.

  --sparse         Exports only those types referenced from a main file (experimental).

  Module targets only:

  -w, --wrap       Specifies the wrapper to use. Also accepts a path to require a custom wrapper.

                   default   Default wrapper supporting both CommonJS and AMD
                   commonjs  CommonJS wrapper
                   amd       AMD wrapper
                   es6       ES6 wrapper (implies --es6)
                   closure   A closure adding to protobuf.roots where protobuf is a global

  -r, --root       Specifies an alternative protobuf.roots name.

  -l, --lint       Linter configuration. Defaults to protobuf.js-compatible rules:

                   eslint-disable block-scoped-var, no-redeclare, no-control-regex, no-prototype-builtins

  --es6            Enables ES6 syntax (const/let instead of var)

  Proto sources only:

  --keep-case      Keeps field casing instead of converting to camel case.

  Static targets only:

  --no-create      Does not generate create functions used for reflection compatibility.
  --no-encode      Does not generate encode functions.
  --no-decode      Does not generate decode functions.
  --no-verify      Does not generate verify functions.
  --no-convert     Does not generate convert functions like from/toObject
  --no-delimited   Does not generate delimited encode/decode functions.
  --no-beautify    Does not beautify generated code.
  --no-comments    Does not output any JSDoc comments.
  --no-service     Does not output service classes.

  --force-long     Enforces the use of 'Long' for s-/u-/int64 and s-/fixed64 fields.
  --force-number   Enforces the use of 'number' for s-/u-/int64 and s-/fixed64 fields.
  --force-message  Enforces the use of message instances instead of plain objects.

usage: pbjs [options] file1.proto file2.json ...  (or pipe)  other | pbjs [options] -
```

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):

```
$> pbjs -t json file1.proto file2.proto > bundle.json
```

Now, either include this file in your final bundle:

```js
var root = protobuf.Root.fromJSON(require("./bundle.json"));
```

or load it the usual way:

```js
protobuf.load("bundle.json", function(err, root) {
    ...
});
```

Generated static code, on the other hand, works with just the **minimal** library. For example

```
$> pbjs -t static-module -w commonjs -o compiled.js file1.proto file2.proto
```

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

```
Generates TypeScript definitions from annotated JavaScript files.

  -o, --out       Saves to a file instead of writing to stdout.

  -g, --global    Name of the global object in browser environments, if any.

  --no-comments   Does not output any JSDoc comments.

  Internal flags:

  -n, --name      Wraps everything in a module of the specified name.

  -m, --main      Whether building the main library without any imports.

usage: pbts [options] file1.js file2.js ...  (or)  other | pbts [options] -
```

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`:

```
$> pbjs -t static-module -w commonjs -o compiled.js file1.proto file2.proto
$> pbts -o compiled.d.ts compiled.js
```

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:

1. Instead of using `new SomeMessage(...)`, always use `SomeMessage.create(...)` because reflection objects do not provide a constructor.
2. 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.MyEnum` instead of `root.lookup("MyMessage.MyEnum")`).

For example, the following generates a JSON module `bundle.js` and a `bundle.d.ts`, but no static code:

```
$> pbjs -t json-module -w commonjs -o bundle.js file1.proto file2.proto
$> pbjs -t static-module file1.proto file2.proto | pbts -o bundle.d.ts -
```

### 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.

| Source | Library | Advantages | Tradeoffs
|--------|---------|------------|-----------
| .proto | full    | Easily editable<br />Interoperability with other libraries<br />No compile step | Some parsing and possibly network overhead
| JSON   | light   | Easily editable<br />No parsing overhead<br />Single bundle (no network overhead) | protobuf.js specific<br />Has a compile step
| static | minimal | Works where `eval` access is restricted<br />Fully documented<br />Small footprint for small protos | Can be hard to edit<br />No reflection<br />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:

```js
var pbjs = require("protobufjs-cli/pbjs"); // or require("protobufjs-cli").pbjs / .pbts

pbjs.main([ "--target", "json-module", "path/to/myproto.proto" ], function(err, output) {
    if (err)
        throw err;
    // do something with output
});
```

**License:** [BSD 3-Clause License](https://opensource.org/licenses/BSD-3-Clause)