node-api-dotnet
Advanced tools
Comparing version 0.7.29 to 0.7.30
{ | ||
"name": "node-api-dotnet", | ||
"version": "0.7.29", | ||
"version": "0.7.30", | ||
"description": "Node-API bindings for .Net", | ||
@@ -5,0 +5,0 @@ "license": "MIT", |
295
README.md
@@ -6,3 +6,3 @@ # Node API for .NET: JavaScript + .NET Interop | ||
- Load .NET assemblies and call .NET APIs in-proc from a JavaScript application. | ||
- Load JavaScript packages call JS APIs in-proc from a .NET application. | ||
- Load JavaScript packages and call JS APIs in-proc from a .NET application. | ||
@@ -17,4 +17,7 @@ Interop is high-performance and supports TypeScript type-definitions generation, async | ||
[Instructions for getting started are below.](#getting-started) | ||
### Documentation | ||
Getting-started guidance, feature details, and API reference documentation are published at | ||
https://microsoft.github.io/node-api-dotnet | ||
### Minimal example - JS calling .NET | ||
@@ -24,3 +27,3 @@ ```JavaScript | ||
const Console = require('node-api-dotnet').System.Console; | ||
Console.WriteLine('Hello from .NET!'); | ||
Console.WriteLine('Hello from .NET!'); // JS writes to the .NET console API | ||
``` | ||
@@ -34,285 +37,29 @@ | ||
var nodejs = new NodejsPlatform(libnodePath).CreateEnvironment(); | ||
nodejs.Run(() => { | ||
nodejs.Run(() => | ||
{ | ||
var console = nodejs.Import<IConsole>("global", "console"); | ||
console.Log("Hello from JS!"); | ||
console.Log("Hello from JS!"); // C# writes to the JS console API | ||
}); | ||
``` | ||
For more examples, see the [examples](./examples/) directory. | ||
## Packages | ||
## Feature Highlights | ||
- [Load and call .NET assemblies from JS](#load-and-call-net-assemblies-from-js) | ||
- [Load and call JavaScript packages from .NET](#load-and-call-javascript-packages-from-net) | ||
- [Generate TS type definitions for .NET APIs](#generate-ts-type-definitions-for-net-apis) | ||
- [Full async support](#full-async-support) | ||
- [Error propagation](#error-propagation) | ||
- [Develop Node.js addons with C#](#develop-nodejs-addons-with-c) | ||
- [Optionally work directly with JS types in C#](#optionally-work-directly-with-js-types-in-c) | ||
- [Automatic efficient marshaling](#automatic-efficient-marshaling) | ||
- [Stream across .NET and JS](#stream-across-net-and-js) | ||
- [Optional .NET native AOT compilation](#optional-net-native-aot-compilation) | ||
- [High performance](#high-performance) | ||
- [Work with .NET generic APIs in JS](#generics) | ||
Depending on the [scenario](https://microsoft.github.io/node-api-dotnet/scenarios/), | ||
either NPM or NuGet packages may be used: | ||
- NPM: [`node-api-dotnet`](https://www.npmjs.com/package/node-api-dotnet) | ||
- NuGet: [`Microsoft.JavaScript.NodeApi`](https://www.nuget.org/packages/Microsoft.JavaScript.NodeApi/) | ||
### Load and call .NET assemblies from JS | ||
The `node-api-dotnet` package manages hosting the .NET runtime in the JS process | ||
(if not using AOT - see below). The .NET core library types are available immediately; | ||
additional .NET assemblies can be loaded by file path: | ||
```JavaScript | ||
// JavaScript | ||
const dotnet = require('node-api-dotnet'); | ||
dotnet.load('path/to/ExampleAssembly.dll'); | ||
const exampleObj = new dotnet.ExampleNamespace.ExampleClass(...args); | ||
``` | ||
See [Packages & Releases](https://microsoft.github.io/node-api-dotnet/reference/packages-releases.html) | ||
for details. | ||
All .NET namespaces are projected onto the top-level `dotnet` object. When loading multiple .NET | ||
assemblies, types from all assemblies are merged into the same namespace hierarchy. | ||
## Development | ||
### Load and call JavaScript packages from .NET | ||
Calling JavaScript from .NET requires hosting a JS runtime such as Node.js in the .NET app. | ||
Then JS packages can be imported either directly as JS values or by declaring C# interfaces for | ||
the JS types and using automatic marshalling. | ||
All interaction with a JavaScript environment must be from its thread, via the | ||
`Run()`, `RunAsync()`, or `Post()` methods on the JS environment object. | ||
```C# | ||
// C# | ||
interface IExample | ||
{ | ||
void ExampleMethod(); | ||
} | ||
var nodejsPlatform = new NodejsPlatform(libnodePath); | ||
var nodejs = nodejsPlatform.CreateEnvironment(); | ||
nodejs.Run(() => { | ||
// Import a module property, then call a function on it. | ||
var example1 = nodejs.Import("example-npm-package", "ExampleObject"); | ||
example1.CallMethod("exampleMethod"); | ||
// Import the module property using an interface, and call the same function. | ||
var example2 = nodejs.Import<IExample>("example-npm-package", "ExampleObject"); | ||
example2.ExampleMethod(); | ||
}); | ||
``` | ||
In the future, it may be possible to automatically generate .NET API definitions from TypeScript | ||
type definitions. | ||
### Generate TS type definitions for .NET APIs | ||
If writing TypeScript, or type-checked JavaScript, there is a tool to generate type `.d.ts` type | ||
definitions for .NET APIs. It also generates a small `.js` file that makes it simple to load the | ||
assembly DLL and type-definitions together. | ||
```bash | ||
$ npm exec node-api-dotnet-generator --assembly ExampleAssembly.dll --typedefs ExampleAssembly.d.ts | ||
``` | ||
```TypeScript | ||
// TypeScript | ||
import './ExampleAssembly.js'; // TS also loads the adjacent .d.ts file. | ||
dotnet.ExampleNamespace.ExampleClass.ExampleMethod(...args); // This call is type-checked! | ||
``` | ||
(CommonJS modules must use `require()` instead of `import`.) | ||
For reference, there is a [list of C# type projections to TypeScript](/docs/typescript.md). | ||
### Full async support | ||
JavaScript code can `await` a call to a .NET method that returns a `Task`. The marshaller | ||
automatically sets up a `SynchronizationContext` so that the .NET result is returned back to the | ||
JS thread. | ||
```TypeScript | ||
// TypeScript | ||
import { ExampleClass } from './ExampleAssembly'; | ||
const asyncResult = await ExampleClass.GetSomethingAsync(...args); | ||
``` | ||
.NET `Task`s are seamlessly marshaled to & from JS `Promise`s. So JS code can work naturally with | ||
a `Promise` returned from a .NET async method, and a JS `Promise` passed to .NET becomes a | ||
`JSPromise` that can be `await`ed in the C# code. | ||
### Error propagation | ||
Exceptions/errors thrown in .NET or JS are propagated across the boundary with stack traces. | ||
An unhandled .NET exception is thrown back to a JS caller as an `Error` with a stack trace that | ||
includes both .NET and JS frames, and source line numbers if symbols are available. For example: | ||
``` | ||
Error: Test error thrown by JS. | ||
at Microsoft.JavaScript.NodeApi.TestCases.Errors.ThrowDotnetError(String message) in D:\node-api-dotnet\test\TestCases\Errors.cs:line 13 | ||
at Microsoft.JavaScript.NodeApi.Generated.Module.Errors_ThrowDotnetError(JSCallbackArgs __args) in napi-dotnet.NodeApi.g.cs:line 357 | ||
at Microsoft.JavaScript.NodeApi.JSNativeApi.InvokeCallback[TDescriptor](napi_env env, napi_callback_info callbackInfo, JSValueScopeType scopeType, Func`2 getCallbackDescriptor) in JSNativeApi.cs:line 1070 | ||
at catchDotnetError (D:\node-api-dotnet\test\TestCases\errors.js:14:12) | ||
at Object.<anonymous> (D:\node-api-dotnet\test\TestCases\errors.js:41:1) | ||
``` | ||
Similarly, an unhandled JS `Error` is thrown back to a .NET caller as a `JSException` with a | ||
combined stack trace. | ||
### Develop Node.js addons with C# | ||
A C# class library project can use the `[JSExport]` attribute to tag (and rename) APIs that are | ||
exported when the library is built as a JavaScript module. A [C# Source Generator]( | ||
https://learn.microsoft.com/en-us/dotnet/csharp/roslyn-sdk/source-generators-overview) runs as | ||
part of the compilation and generates code to export the tagged APIs and marshal values between | ||
JavaScript and C#. | ||
```C# | ||
// C# | ||
[JSExport] // Export class and all public members to JS. | ||
public class ExampleClass { ... } | ||
public static class ExampleStaticClass | ||
{ | ||
[JSExport("exampleFunction")] // Export as a module-level function. | ||
public static string StaticMethod(ExampleClass obj) { ... } | ||
// (Other public members in this class are not exported by default.) | ||
} | ||
``` | ||
The `[JSExport]` source generator enables faster startup time because the marshaling code is | ||
generated at build time rather than dynamically emitted at runtime (as when calling a pre-built | ||
assembly). The source generator also enables building ahead-of-time compiled libraries in C# that | ||
can be called by JavaScript without depending on the .NET Runtime. (More on that below.) | ||
### Optionally work directly with JS types in C# | ||
The class library includes an object model for the JavaScript type system. `JSValue` represents a | ||
value of any type, and there are more types like `JSObject`, `JSArray`, `JSMap`, `JSPromise`, etc. | ||
C# code can work directly with those types if desired: | ||
```C# | ||
// C# | ||
[JSExport] | ||
public static JSPromise JSAsyncExample(JSValue input) | ||
{ | ||
// Example of integration between C# async/await and JS promises. | ||
string greeter = (string)input; | ||
return new JSPromise(async (resolve) => | ||
{ | ||
await Task.Delay(50); | ||
resolve((JSValue)$"Hey {greeter}!"); | ||
}); | ||
} | ||
``` | ||
### Automatic efficient marshaling | ||
There are two ways to get automatic marshaling between C# and JavaScript types: | ||
1. Compile a C# class library with `[JSExport]` attributes like the examples above. The source | ||
generator produces marshaling code that is compiled with the assembly. | ||
2. Load a pre-built .NET assembly, as in the earlier examples. The loader will use reflection to | ||
scan the APIs, then emit marshaling code on-demand for each type that is referenced by JS. The | ||
dynamic marshalling code is derived from the same expression trees that are used for compile-time | ||
source-generation, but is generated and at runtime and compiled with | ||
[`LambdaExpression.Compile()`](https://learn.microsoft.com/en-us/dotnet/api/system.linq.expressions.lambdaexpression.compile). | ||
So there is a small startup cost from that reflection and compilation, but subsequent calls to | ||
the same APIs may be just as fast as the pre-compiled marshaling code (and are just as likely | ||
to be JITted). | ||
The marshaller uses the strong typing information from the C# API declarations as hints about how to | ||
convert values beteen JavaScript and C#. Here's a general summary of conversions: | ||
- Primitives (numbers, strings, etc.) are passed by value directy. | ||
- C# structs have all properties passed by value (shallow copied). | ||
- C# classes are passed by reference. Any JS call to a C# class or interface property or method | ||
gets proxied over to the C# instance of the class. (Object GC lifetimes are synchronized | ||
accordingly.) | ||
- JS code may implement a C# interface, and pass that implementation back to C# code where it | ||
becomes a proxy that C# code can use. | ||
- C# collections like `IList<T>` and JS collections like `Map<T>` are also passed by reference; | ||
access to collection elements is proxied to whichever side the real instance of the collection | ||
is on. | ||
- JS `TypedArray`s are mapped to C# `Memory<T>` and passed by reference using shared memory | ||
(no proxying is needed). | ||
- Other types like enums, dates, and delegates are automatically marshaled as one would expect. | ||
- Custom marshaling and marshaling hints [may be supported later]( | ||
https://github.com/jasongin/napi-dotnet/pull/25). | ||
### Stream across .NET and JS | ||
.NET `Stream`s are automatically marshalled to and from Node.js `Duplex` (or `Readable` or | ||
`Writable`) streams. That means JS code can seamlessly read from or write to streams created | ||
by .NET. Or .NET code can read from or write to streams created by JS. Streamed data is | ||
transferred using shared memory (without any additional sockets or pipes), so memory allocation | ||
and copying is minimized. | ||
### Optional .NET native AOT compilation | ||
This library supports hosting the .NET Runtime in the same process as the JavaScript runtime. | ||
Alternatively, it also supports building [native ahead-of-time (AOT) compiled C#]( | ||
https://learn.microsoft.com/en-us/dotnet/core/deploying/native-aot/) libraries that are | ||
loadable as a JavaScript module _without depending on the .NET Runtime_. | ||
There are advantages and disadvantages to either approach: | ||
| | .NET Runtime | .NET Native AOT | | ||
|---------------------|--------------|-----------------| | ||
| API compatibility | Broad compatibility with .NET APIs | Limited compatibility with APIs designed to support AOT | | ||
| Ease of deployment | Requires a matching version of .NET to be installed on the target system | A .NET installation is not required (though some platform libs may be required on Linux/Mac) | ||
| Size of deployment | Compact - only IL assemblies need to be deployed | Larger due to bundling necessary runtime code - minimum ~3 MB per platform | | ||
| Performance | Slightly slower startup (JIT) | Slightly faster startup (no JIT) | | ||
| Runtime limitations | Full .NET functionality | Some .NET features like reflection and code-generation aren't supported | | ||
### High performance | ||
The project is designed to be as performant as possible when bridging between .NET and JavaScript. | ||
Techniques benefitting performance include: | ||
- Automatic marshaling avoids any use of JSON serialization, and uses generated code to avoid | ||
reflection. | ||
- Automatic marshalling uses shared memory or proxies when possible to minimize the amount of | ||
data transferred across the boundary. | ||
- Simple calls between JS and C# require **_almost_** zero memory allocation. (Maybe it will be | ||
zero eventually.) | ||
- Most JavaScript values are represented in C# as small structs (basically containing just a | ||
handle to the JS value), which helps avoid memory allocation. | ||
- Marshaling code uses modern C# performance features like `Span<T>` and `stackalloc` to minimize | ||
heap allocations and copying. | ||
Thanks to these design choices, JS to .NET calls are [more than twice as fast]( | ||
https://github.com/jasongin/napi-dotnet/pull/23) when compared to `edge-js` using | ||
[that project's benchmark](https://github.com/tjanczuk/edge/wiki/Performance). | ||
### Generics | ||
Even though the JavaScript runtime type system lacks generics, it is possible to work with .NET | ||
generic types and methods from JavaScript: | ||
```JavaScript | ||
// JavaScript | ||
System.Enum.Parse$(System.DayOfWeek)('Tuesday'); | ||
``` | ||
For details, see [Using .NET Generics in JavaScript](./docs/generics.md). | ||
## Getting Started | ||
#### Requirements | ||
- .NET 6 or later | ||
- .NET 8 or later is required for AOT support. | ||
- .NET Framework 4.7.2 or later is supported at runtime, | ||
but .NET 6 SDK is still required for building. | ||
- Node.js v16 or later | ||
- Other JS runtimes may be supported in the future. | ||
- OS: Windows, Mac, or Linux | ||
- It should work on any platform where .NET 6 is supported. | ||
#### Instructions | ||
For calling .NET from JS, choose between one of the following scenarios: | ||
- [Dynamically invoke .NET APIs from JavaScript](./docs/dynamic-invoke.md)<br/> | ||
Dynamic invocation is simpler to set up: all you need is the `node-api-dotnet` npm package and | ||
the path to a .NET assembly you want to call. But it has some limitations (not all kinds of APIs | ||
are supported), and is not quite as fast as a C# module, because marshalling code must be | ||
generated at runtime. | ||
- [Develop a Node module in C#](./docs/node-module.md)<br/> | ||
A C# Node module is appropriate for an application that has more advanced interop needs. It can | ||
be faster because marshalling code can be generated at compile time, and the shape of the APIs | ||
exposed to JavaScript can be adapted with JS interop in mind. | ||
For calling JS from .NET, more documentation will be added soon. For now, see the | ||
[`winui-fluid` example code](./examples/winui-fluid/). | ||
Generated TypeScript type definitions can be utilized with any of these aproaches. | ||
## Development | ||
For information about building, testing, and contributing changes to this project, see | ||
For information about building, testing, and debugging this project, see | ||
[README-DEV.md](./README-DEV.md). | ||
## Contributing | ||
Contributions require agreement to the | ||
[Contributor License Agreement](https://microsoft.github.io/node-api-dotnet/contributing.html#contributor-license-agreement). | ||
This project welcomes contributions and suggestions. Most contributions require you to agree to a | ||
Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us | ||
the rights to use your contribution. For details, visit https://cla.opensource.microsoft.com. | ||
## Code of Conduct | ||
When you submit a pull request, a CLA bot will automatically determine whether you need to provide | ||
a CLA and decorate the PR appropriately (e.g., status check, comment). Simply follow the | ||
instructions provided by the bot. You will only need to do this once across all repos using our CLA. | ||
This project has adopted the | ||
@@ -319,0 +66,0 @@ [Microsoft Open Source Code of Conduct](https://opensource.microsoft.com/codeofconduct/). |
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