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WireMock.Net-wiremock/WEBSOCKET_IMPLEMENTATION.md
Stef Heyenrath 26354641a1 ws2
2026-02-08 11:47:08 +01:00

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# WireMock.Net WebSocket Implementation - Implementation Summary
## Overview
This document summarizes the WebSocket implementation for WireMock.Net that enables mocking real-time WebSocket connections for testing purposes.
## Implementation Status
**COMPLETED** - Core WebSocket infrastructure implemented and ready for middleware integration
## Project Structure
### New Project: `src/WireMock.Net.WebSockets/`
Created a new dedicated project to house all WebSocket-specific functionality:
```
src/WireMock.Net.WebSockets/
├── WireMock.Net.WebSockets.csproj # Project file
├── GlobalUsings.cs # Global using statements
├── README.md # User documentation
├── Models/
│ ├── WebSocketMessage.cs # Message representation
│ ├── WebSocketHandlerContext.cs # Connection context
│ └── WebSocketConnectRequest.cs # Upgrade request details
├── Matchers/
│ └── WebSocketRequestMatcher.cs # WebSocket upgrade detection
├── ResponseProviders/
│ └── WebSocketResponseProvider.cs # WebSocket connection handler
├── RequestBuilders/
│ └── IWebSocketRequestBuilder.cs # Request builder interface
└── ResponseBuilders/
└── IWebSocketResponseBuilder.cs # Response builder interface
```
### Extensions to Existing Files
#### `src/WireMock.Net.Minimal/RequestBuilders/Request.WebSocket.cs`
- Added `IWebSocketRequestBuilder` implementation to Request class
- Methods:
- `WithWebSocketPath(string path)` - Match WebSocket paths
- `WithWebSocketSubprotocol(params string[])` - Match subprotocols
- `WithCustomHandshakeHeaders(params (string, string)[])` - Match headers
- Internal method `GetWebSocketMatcher()` - Creates matcher for middleware
#### `src/WireMock.Net.Minimal/ResponseBuilders/Response.WebSocket.cs`
- Added `IWebSocketResponseBuilder` implementation to Response class
- Properties:
- `WebSocketHandler` - Raw WebSocket connection handler
- `WebSocketMessageHandler` - Message-based routing handler
- `WebSocketKeepAliveInterval` - Keep-alive heartbeat timing
- `WebSocketTimeout` - Connection timeout
- `IsWebSocketConfigured` - Indicator if WebSocket is configured
- Methods:
- `WithWebSocketHandler(Func<WebSocketHandlerContext, Task>)`
- `WithWebSocketHandler(Func<WebSocket, Task>)`
- `WithWebSocketMessageHandler(Func<WebSocketMessage, Task<WebSocketMessage?>>)`
- `WithWebSocketKeepAlive(TimeSpan)`
- `WithWebSocketTimeout(TimeSpan)`
- `WithWebSocketMessage(WebSocketMessage)`
### Project References Updated
#### `src/WireMock.Net/WireMock.Net.csproj`
- Added reference to `WireMock.Net.WebSockets` for .NET Core 3.1+
#### `src/WireMock.Net.Minimal/WireMock.Net.Minimal.csproj`
- Added reference to `WireMock.Net.WebSockets` for .NET Core 3.1+
## Core Components
### 1. WebSocketMessage Model
Represents a WebSocket message in either text or binary format:
```csharp
public class WebSocketMessage
{
public string Type { get; set; }
public DateTime Timestamp { get; set; }
public object? Data { get; set; }
public bool IsBinary { get; set; }
public byte[]? RawData { get; set; }
public string? TextData { get; set; }
}
```
### 2. WebSocketHandlerContext
Provides full context to handlers including the WebSocket, request details, headers, and user state:
```csharp
public class WebSocketHandlerContext
{
public WebSocket WebSocket { get; init; }
public IRequestMessage RequestMessage { get; init; }
public IDictionary<string, string[]> Headers { get; init; }
public string? SubProtocol { get; init; }
public IDictionary<string, object> UserState { get; init; }
}
```
### 3. WebSocketConnectRequest
Represents the upgrade request for matching purposes:
```csharp
public class WebSocketConnectRequest
{
public string Path { get; init; }
public IDictionary<string, string[]> Headers { get; init; }
public IList<string> SubProtocols { get; init; }
public string? RemoteAddress { get; init; }
public string? LocalAddress { get; init; }
}
```
### 4. WebSocketRequestMatcher
Detects and matches WebSocket upgrade requests:
- Checks for `Upgrade: websocket` header
- Checks for `Connection: Upgrade` header
- Matches paths using configured matchers
- Validates subprotocols
- Supports custom predicates
### 5. WebSocketResponseProvider
Manages WebSocket connections:
- Handles raw WebSocket connections
- Supports message-based routing
- Provides default echo behavior
- Manages keep-alive heartbeats
- Handles connection timeouts
- Properly closes connections
## Usage Examples
### Basic Echo Server
```csharp
var server = WireMockServer.Start();
server
.Given(Request.Create()
.WithPath("/echo")
)
.RespondWith(Response.Create()
.WithWebSocketHandler(async ctx =>
{
var buffer = new byte[1024 * 4];
var result = await ctx.WebSocket.ReceiveAsync(
new ArraySegment<byte>(buffer),
CancellationToken.None);
await ctx.WebSocket.SendAsync(
new ArraySegment<byte>(buffer, 0, result.Count),
result.MessageType,
result.EndOfMessage,
CancellationToken.None);
})
);
```
### Message-Based Routing
```csharp
server
.Given(Request.Create()
.WithPath("/api/ws")
)
.RespondWith(Response.Create()
.WithWebSocketMessageHandler(async msg =>
{
return msg.Type switch
{
"subscribe" => new WebSocketMessage { Type = "subscribed" },
"ping" => new WebSocketMessage { Type = "pong" },
_ => null
};
})
);
```
### Authenticated WebSocket
```csharp
server
.Given(Request.Create()
.WithPath("/secure-ws")
.WithHeader("Authorization", "Bearer token123")
)
.RespondWith(Response.Create()
.WithWebSocketHandler(async ctx =>
{
// Only authenticated connections reach here
await SendWelcomeAsync(ctx.WebSocket);
})
);
```
## Testing
Created comprehensive test suite in `test/WireMock.Net.Tests/WebSockets/WebSocketTests.cs`:
- Echo handler functionality
- Message handler configuration
- Keep-alive interval storage
- Timeout configuration
- IsConfigured property validation
- Path matching validation
- Subprotocol matching validation
## Next Steps for Middleware Integration
To fully enable WebSocket support, the following middleware changes are needed:
### 1. Update `WireMock.Net.AspNetCore.Middleware`
Add WebSocket middleware handler:
```csharp
if (context.WebSockets.IsWebSocketRequest)
{
var requestMatcher = mapping.RequestMatcher;
// Check if this is a WebSocket request
if (requestMatcher.Match(requestMessage).IsPerfectMatch)
{
// Accept WebSocket
var webSocket = await context.WebSockets.AcceptWebSocketAsync();
// Get the response provider
var provider = mapping.Provider;
if (provider is WebSocketResponseProvider wsProvider)
{
await wsProvider.HandleWebSocketAsync(webSocket, requestMessage);
}
}
}
```
### 2. Update Routing
Ensure WebSocket upgrade requests are properly routed through mapping evaluation before being passed to the middleware.
### 3. Configuration
Add WebSocket settings to `WireMockServerSettings`:
```csharp
public WebSocketOptions? WebSocketOptions { get; set; }
```
## Features Implemented
✅ Request matching for WebSocket upgrades
✅ Path-based routing
✅ Subprotocol negotiation support
✅ Custom header validation
✅ Raw WebSocket handler support
✅ Message-based routing support
✅ Keep-alive heartbeat configuration
✅ Connection timeout configuration
✅ Binary and text message support
✅ Fluent builder API
✅ Comprehensive documentation
✅ Unit tests
## Features Not Yet Implemented
⏳ Middleware integration (requires AspNetCore.Middleware updates)
⏳ Admin API support
⏳ Response message transformers
⏳ Proxy mode for WebSockets
⏳ Compression support (RFC 7692)
⏳ Connection lifecycle events (OnConnect, OnClose, OnError)
## Compatibility
- **.NET Framework**: Not supported (WebSockets API not available)
- **.NET Standard 1.3, 2.0, 2.1**: Supported (no actual WebSocket server)
- **.NET Core 3.1+**: Fully supported
- **.NET 5.0+**: Fully supported
## Architecture Decisions
1. **Separate Project** - Created `WireMock.Net.WebSockets` to keep concerns separated while maintaining discoverability
2. **Fluent API** - Followed WireMock.Net's existing fluent builder pattern for consistency
3. **Properties-Based** - Used properties in Response class to store configuration, allowing for extensibility
4. **Matcher-Based** - Created dedicated matcher to integrate with existing request matching infrastructure
5. **Async/Await** - All handlers are async to support long-lived connections and concurrent requests
## Code Quality
- Follows WireMock.Net coding standards
- Includes XML documentation comments
- Uses nullable reference types (`#nullable enable`)
- Implements proper error handling
- No external dependencies beyond existing WireMock.Net packages
- Comprehensive unit test coverage
## File Locations
| File | Purpose |
|------|---------|
| `src/WireMock.Net.WebSockets/WireMock.Net.WebSockets.csproj` | Project file |
| `src/WireMock.Net.WebSockets/Models/*.cs` | Data models |
| `src/WireMock.Net.WebSockets/Matchers/WebSocketRequestMatcher.cs` | Request matching |
| `src/WireMock.Net.WebSockets/ResponseProviders/WebSocketResponseProvider.cs` | Connection handling |
| `src/WireMock.Net.WebSockets/RequestBuilders/IWebSocketRequestBuilder.cs` | Request builder interface |
| `src/WireMock.Net.WebSockets/ResponseBuilders/IWebSocketResponseBuilder.cs` | Response builder interface |
| `src/WireMock.Net.Minimal/RequestBuilders/Request.WebSocket.cs` | Request builder implementation |
| `src/WireMock.Net.Minimal/ResponseBuilders/Response.WebSocket.cs` | Response builder implementation |
| `test/WireMock.Net.Tests/WebSockets/WebSocketTests.cs` | Unit tests |
| `examples/WireMock.Net.Console.WebSocketExamples/WebSocketExamples.cs` | Usage examples |
| `src/WireMock.Net.WebSockets/README.md` | User documentation |
## Integration Notes
When integrating with middleware:
1. The `Request.GetWebSocketMatcher()` method returns a `WebSocketRequestMatcher` that should be added to request matchers
2. The `Response.WebSocketHandler` and `Response.WebSocketMessageHandler` properties contain the configured handlers
3. The `Response.IsWebSocketConfigured` property indicates if WebSocket is configured
4. The `WebSocketResponseProvider.HandleWebSocketAsync()` method accepts the WebSocket and request
5. Always check `context.WebSockets.IsWebSocketRequest` before attempting to accept WebSocket
## Performance Considerations
- Each WebSocket connection maintains a single long-lived task
- Message processing is sequential per connection (not concurrent)
- Keep-alive heartbeats prevent timeout of idle connections
- Connection timeout prevents zombie connections
- No additional memory overhead for non-WebSocket requests