e24a5d8839
Motivation: This allows using handlers for Streams in normal Netty-style. Frames are read/written to the channel as messages, not directly as a callback/method call. Handlers allow mixing and can ease HTTP/1 and HTTP/2 interoperability by eventually supporting HTTP/1 handlers in HTTP/2 and vise versa. Modifications: New handler Http2MultiplexCodec that converts from the current HTTP/2 API to a message-based API and child channels for streams. Result: The basics are done for server-side: new streams trigger creation of new channels in much the same appearance to how new connections trigger new channel creation. The basic frames HEADERS and DATA are handled, but also GOAWAY and RST_STREAM. Inbound flow control is implemented, but outbound is not. That will be done later, along with not completing write promises on the child channel until the write actually completes on the parent. There is not yet support for outbound priority/weight, push promises, and many other features. There is a generic Object that may be set on stream frames. This also paves the way for client-side support which needs a way to refer to yet-to-be-created streams (due to how HEADERS allocates a stream id, and the allocation order must be the same as transmission order).
95 lines
3.6 KiB
Java
95 lines
3.6 KiB
Java
/*
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* Copyright 2016 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License, version 2.0 (the
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* "License"); you may not use this file except in compliance with the License. You may obtain a
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* copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software distributed under the License
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* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
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* or implied. See the License for the specific language governing permissions and limitations under
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* the License.
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*/
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package io.netty.example.http2.helloworld.multiplex.server;
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import static io.netty.buffer.Unpooled.copiedBuffer;
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import static io.netty.buffer.Unpooled.unreleasableBuffer;
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import static io.netty.handler.codec.http.HttpResponseStatus.OK;
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import io.netty.buffer.ByteBuf;
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import io.netty.buffer.ByteBufUtil;
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import io.netty.channel.ChannelDuplexHandler;
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import io.netty.channel.ChannelHandler.Sharable;
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import io.netty.channel.ChannelHandlerContext;
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import io.netty.handler.codec.http2.DefaultHttp2DataFrame;
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import io.netty.handler.codec.http2.DefaultHttp2Headers;
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import io.netty.handler.codec.http2.DefaultHttp2HeadersFrame;
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import io.netty.handler.codec.http2.Http2DataFrame;
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import io.netty.handler.codec.http2.Http2Headers;
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import io.netty.handler.codec.http2.Http2HeadersFrame;
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import io.netty.util.CharsetUtil;
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/**
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* A simple handler that responds with the message "Hello World!".
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*
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* <p>This example is making use of the "multiplexing" http2 API, where streams are mapped to child
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* Channels. This API is very experimental and incomplete.
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*/
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@Sharable
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public class HelloWorldHttp2Handler extends ChannelDuplexHandler {
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static final ByteBuf RESPONSE_BYTES = unreleasableBuffer(copiedBuffer("Hello World", CharsetUtil.UTF_8));
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@Override
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public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
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super.exceptionCaught(ctx, cause);
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cause.printStackTrace();
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ctx.close();
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}
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@Override
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public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
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if (msg instanceof Http2HeadersFrame) {
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onHeadersRead(ctx, (Http2HeadersFrame) msg);
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} else if (msg instanceof Http2DataFrame) {
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onDataRead(ctx, (Http2DataFrame) msg);
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} else {
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super.channelRead(ctx, msg);
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}
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}
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/**
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* If receive a frame with end-of-stream set, send a pre-canned response.
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*/
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public void onDataRead(ChannelHandlerContext ctx, Http2DataFrame data) throws Exception {
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if (data.isEndStream()) {
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sendResponse(ctx, data.content().retain());
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}
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}
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/**
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* If receive a frame with end-of-stream set, send a pre-canned response.
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*/
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public void onHeadersRead(ChannelHandlerContext ctx, Http2HeadersFrame headers)
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throws Exception {
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if (headers.isEndStream()) {
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ByteBuf content = ctx.alloc().buffer();
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content.writeBytes(RESPONSE_BYTES);
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ByteBufUtil.writeAscii(content, " - via HTTP/2");
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sendResponse(ctx, content);
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}
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}
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/**
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* Sends a "Hello World" DATA frame to the client.
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*/
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private void sendResponse(ChannelHandlerContext ctx, ByteBuf payload) {
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// Send a frame for the response status
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Http2Headers headers = new DefaultHttp2Headers().status(OK.codeAsText());
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ctx.write(new DefaultHttp2HeadersFrame(headers));
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ctx.writeAndFlush(new DefaultHttp2DataFrame(payload, true));
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}
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}
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