Class WebSocketServerExtensionHandler

java.lang.Object
io.netty.channel.ChannelHandlerAdapter
io.netty.channel.ChannelInboundHandlerAdapter
io.netty.channel.ChannelDuplexHandler
io.netty.handler.codec.http.websocketx.extensions.WebSocketServerExtensionHandler
All Implemented Interfaces:
ChannelHandler, ChannelInboundHandler, ChannelOutboundHandler
Direct Known Subclasses:
WebSocketServerCompressionHandler
public class WebSocketServerExtensionHandler extends ChannelDuplexHandler
This handler negotiates and initializes the WebSocket Extensions. It negotiates the extensions based on the client desired order, ensures that the successfully negotiated extensions are consistent between them, and initializes the channel pipeline with the extension decoder and encoder. Find a basic implementation for compression extensions at io.netty.handler.codec.http.websocketx.extensions.compression.WebSocketServerCompressionHandler.

  • Constructor Details

    • WebSocketServerExtensionHandler

      public WebSocketServerExtensionHandler(WebSocketServerExtensionHandshaker... extensionHandshakers)
      Constructor
      Parameters:
      extensionHandshakers - The extension handshaker in priority order. A handshaker could be repeated many times with fallback configuration.

  • Method Details

    • channelRead

      public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception
      Description copied from class: ChannelInboundHandlerAdapter
      Calls ChannelHandlerContext.fireChannelRead(Object) to forward to the next ChannelInboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.
      Specified by:
      channelRead in interface ChannelInboundHandler
      Overrides:
      channelRead in class ChannelInboundHandlerAdapter
      Throws:
      Exception

    • onHttpRequestChannelRead

      protected void onHttpRequestChannelRead(ChannelHandlerContext ctx, HttpRequest request) throws Exception
      This is a method exposed to perform fail-fast checks of user-defined http types.

      eg:
      If the user has defined a specific HttpRequest type i.e.CustomHttpRequest and channelRead(ChannelHandlerContext, Object) can receive LastHttpContent.EMPTY_LAST_CONTENT msg types too, can override it like this: 

          public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        if (msg != LastHttpContent.EMPTY_LAST_CONTENT) {
            if (msg instanceof CustomHttpRequest) {
                onHttpRequestChannelRead(ctx, (CustomHttpRequest) msg);
            } else {
                // if it's handling other HttpRequest types it MUST use onHttpRequestChannelRead again
                // or have to delegate it to super.channelRead (that can perform redundant checks).
                // If msg is not implementing HttpRequest, it can call ctx.fireChannelRead(msg) on it
                // ...
                super.channelRead(ctx, msg);
            }
        } else {
            // given that msg isn't a HttpRequest type we can just skip calling super.channelRead
            ctx.fireChannelRead(msg);
        }
    }
      IMPORTANT: It already call super.channelRead(ctx, request) before returning.
      Throws:
      Exception

    • write

      public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception
      Description copied from class: ChannelDuplexHandler
      Calls ChannelOutboundInvoker.write(Object, ChannelPromise) to forward to the next ChannelOutboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.
      Specified by:
      write in interface ChannelOutboundHandler
      Overrides:
      write in class ChannelDuplexHandler
      Parameters:
      ctx - the ChannelHandlerContext for which the write operation is made
      msg - the message to write
      promise - the ChannelPromise to notify once the operation completes
      Throws:
      Exception - thrown if an error occurs

    • onHttpResponseWrite

      protected void onHttpResponseWrite(ChannelHandlerContext ctx, HttpResponse response, ChannelPromise promise) throws Exception
      This is a method exposed to perform fail-fast checks of user-defined http types.

      eg:
      If the user has defined a specific HttpResponse type i.e.CustomHttpResponse and write(ChannelHandlerContext, Object, ChannelPromise) can receive ByteBuf msg types too, it can be overridden like this: 

          public void write(final ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
        if (msg != Unpooled.EMPTY_BUFFER invalid input: '&'invalid input: '&' !(msg instanceof ByteBuf)) {
            if (msg instanceof CustomHttpResponse) {
                onHttpResponseWrite(ctx, (CustomHttpResponse) msg, promise);
            } else {
                // if it's handling other HttpResponse types it MUST use onHttpResponseWrite again
                // or have to delegate it to super.write (that can perform redundant checks).
                // If msg is not implementing HttpResponse, it can call ctx.write(msg, promise) on it
                // ...
                super.write(ctx, msg, promise);
            }
        } else {
            // given that msg isn't a HttpResponse type we can just skip calling super.write
            ctx.write(msg, promise);
        }
    }
      IMPORTANT: It already call super.write(ctx, response, promise) before returning.
      Throws:
      Exception

    • isExtensionNegotiationEnabled

      protected boolean isExtensionNegotiationEnabled(ChannelHandlerContext ctx, HttpResponse response)
      Returns true if WebSocket extensions negotiated from the request should be acknowledged for this response.

      This method can be overridden to make the final extension negotiation decision when the handshake response is written.