I'm writing a Netty based HTTP/2 service that does "server sent events" (SSE) and I need to write a HTTP/2 test client class for use in integration tests, but I'm having hard time working out how to set up my client pipeline so that I can get individual events from the server.
I first tried using the HTTP/1.1 ↔ HTTP/2 adapter classes (InboundHttp2ToHttpAdapter + HttpToHttp2ConnectionHandler) but with this combo I only got the FullHttpResponse after the stream was closed, not the individual HttpContent objects.
Next, I tried setting up a pipeline where I send individual outgoing HTTP/2 frames and listen for incoming HTTP/2 frames, but it seem the outgoing HTTP/2 frame encoder is not properly installed, as I get the following exception:
Exception in thread "main" java.lang.RuntimeException: io.netty.handler.codec.UnsupportedMessageTypeException: io.netty.handler.codec.http2.DefaultHttp2HeadersFrame (expected: io.netty.buffer.ByteBuf)
at example.AsyncHttpClient.run(AsyncHttpClient.java:116)
at example.AsyncHttpClient.main(AsyncHttpClient.java:49)
Caused by: io.netty.handler.codec.UnsupportedMessageTypeException: io.netty.handler.codec.http2.DefaultHttp2HeadersFrame (expected: io.netty.buffer.ByteBuf)
at io.netty.handler.ssl.SslHandler.write(SslHandler.java:694)
at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738)
at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:730)
at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:816)
at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:723)
at io.netty.handler.codec.http2.Http2ConnectionHandler.write(Http2ConnectionHandler.java:498)
at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738)
at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:730)
at io.netty.channel.AbstractChannelHandlerContext.access$1900(AbstractChannelHandlerContext.java:38)
at io.netty.channel.AbstractChannelHandlerContext$AbstractWriteTask.write(AbstractChannelHandlerContext.java:1081)
at io.netty.channel.AbstractChannelHandlerContext$WriteAndFlushTask.write(AbstractChannelHandlerContext.java:1128)
at io.netty.channel.AbstractChannelHandlerContext$AbstractWriteTask.run(AbstractChannelHandlerContext.java:1070)
at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163)
at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:403)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:463)
at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:858)
at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:138)
at java.lang.Thread.run(Thread.java:745)
Any ideas about what I'm doing wrong? I find the package io.netty.handler.codec.http2 to be quite confusing with respect to how the classes should be composed. I have tried using the Netty examples on Github as a guide, but from what I can find, most of the use HTTP/1.1 <-> HTTP/2 adapter classes and that's not applicable in my case. If there are better examples on how to use these classes, please let me know!
Full source code (also on github):
package example;
import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.http2.DefaultHttp2Connection;
import io.netty.handler.codec.http2.DefaultHttp2ConnectionDecoder;
import io.netty.handler.codec.http2.DefaultHttp2ConnectionEncoder;
import io.netty.handler.codec.http2.DefaultHttp2FrameReader;
import io.netty.handler.codec.http2.DefaultHttp2FrameWriter;
import io.netty.handler.codec.http2.DefaultHttp2Headers;
import io.netty.handler.codec.http2.DefaultHttp2HeadersFrame;
import io.netty.handler.codec.http2.Http2ConnectionHandler;
import io.netty.handler.codec.http2.Http2ConnectionHandlerBuilder;
import io.netty.handler.codec.http2.Http2Exception;
import io.netty.handler.codec.http2.Http2FrameAdapter;
import io.netty.handler.codec.http2.Http2Headers;
import io.netty.handler.codec.http2.Http2SecurityUtil;
import io.netty.handler.ssl.ApplicationProtocolConfig;
import io.netty.handler.ssl.ApplicationProtocolNames;
import io.netty.handler.ssl.OpenSsl;
import io.netty.handler.ssl.SslContext;
import io.netty.handler.ssl.SslContextBuilder;
import io.netty.handler.ssl.SslHandler;
import io.netty.handler.ssl.SslProvider;
import io.netty.handler.ssl.SupportedCipherSuiteFilter;
import io.netty.handler.ssl.util.InsecureTrustManagerFactory;
import javax.net.ssl.SSLException;
import java.util.Collections;
import java.util.Map;
import static io.netty.channel.ChannelFutureListener.FIRE_EXCEPTION_ON_FAILURE;
public class AsyncHttpClient {
private final Channel channel;
public static void main(String[] args) throws InterruptedException {
final AsyncHttpClient client = new AsyncHttpClient("google.com", 443);
client.run("GET", "/", Collections.emptyMap());
Thread.sleep(10000);
}
AsyncHttpClient(String host, int port) throws InterruptedException {
final Bootstrap bootstrap = new Bootstrap()
.group(new NioEventLoopGroup())
.channel(NioSocketChannel.class)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
final Http2FrameAdapter adapter = new Http2FrameAdapter() {
@Override
public void onHeadersRead(ChannelHandlerContext ctx, int streamId, Http2Headers headers, int padding, boolean endStream) throws Http2Exception {
System.out.println("onHeadersRead(ctx, streamId, headers, padding, endStream)");
super.onHeadersRead(ctx, streamId, headers, padding, endStream);
}
@Override
public void onHeadersRead(ChannelHandlerContext ctx, int streamId, Http2Headers headers, int streamDependency, short weight, boolean exclusive, int padding, boolean endStream) throws Http2Exception {
System.out.println("onHeadersRead(ctx, streamId, headers, streamDependency, weight, exclusive, padding, endStream)");
super.onHeadersRead(ctx, streamId, headers, streamDependency, weight, exclusive, padding, endStream);
}
@Override
public int onDataRead(ChannelHandlerContext ctx, int streamId, ByteBuf data, int padding, boolean endOfStream) throws Http2Exception {
System.out.println("onDataRead(ctx, streamId, data, padding, endOfStream)");
return super.onDataRead(ctx, streamId, data, padding, endOfStream);
}
};
final DefaultHttp2Connection connection = new DefaultHttp2Connection(false);
final DefaultHttp2FrameReader frameReader = new DefaultHttp2FrameReader();
final DefaultHttp2FrameWriter frameWriter = new DefaultHttp2FrameWriter();
final DefaultHttp2ConnectionEncoder encoder = new DefaultHttp2ConnectionEncoder(connection, frameWriter);
final DefaultHttp2ConnectionDecoder decoder = new DefaultHttp2ConnectionDecoder(connection, encoder, frameReader);
final Http2ConnectionHandler connectionHandler = new Http2ConnectionHandlerBuilder()
.codec(decoder, encoder)
.frameListener(adapter)
.build();
final ChannelPipeline pipeline = ch.pipeline();
pipeline.addLast(createSslHandler(ch));
pipeline.addLast(connectionHandler);
}
});
final ChannelFuture channelFuture = bootstrap.connect(host, port);
this.channel = channelFuture.sync().channel();
}
void run(String method, String path, Map<String, String> headerMap) {
final DefaultHttp2Headers headers = new DefaultHttp2Headers(true);
headers.scheme("https");
headers.method(method);
headers.path(path);
for (Map.Entry<String, String> header : headerMap.entrySet()) {
headers.add(header.getKey(), header.getValue());
}
final DefaultHttp2HeadersFrame frame = new DefaultHttp2HeadersFrame(headers, false);
try {
channel.writeAndFlush(frame)
.addListener(FIRE_EXCEPTION_ON_FAILURE)
.sync();
} catch (Exception e) {
throw new RuntimeException(e);
}
}
private SslHandler createSslHandler(SocketChannel channel) {
try {
final SslProvider provider = OpenSsl.isAlpnSupported() ? SslProvider.OPENSSL : SslProvider.JDK;
final SslContext sslCtx = SslContextBuilder.forClient().sslProvider(provider)
/* NOTE: the cipher filter may not include all ciphers required by the HTTP/2 specification.
* Please refer to the HTTP/2 specification for cipher requirements. */
.ciphers(Http2SecurityUtil.CIPHERS, SupportedCipherSuiteFilter.INSTANCE)
.trustManager(InsecureTrustManagerFactory.INSTANCE)
.applicationProtocolConfig(new ApplicationProtocolConfig(
ApplicationProtocolConfig.Protocol.ALPN,
// NO_ADVERTISE is currently the only mode supported by both OpenSsl and JDK providers.
ApplicationProtocolConfig.SelectorFailureBehavior.NO_ADVERTISE,
// ACCEPT is currently the only mode supported by both OpenSsl and JDK providers.
ApplicationProtocolConfig.SelectedListenerFailureBehavior.ACCEPT,
ApplicationProtocolNames.HTTP_2))
.build();
return sslCtx.newHandler(channel.alloc());
} catch (SSLException e) {
throw new RuntimeException(e);
}
}
}
