main() — netty Function Reference

Architecture documentation for the main() function in Http2Client.java from the netty codebase.

Function java Buffer Telemetry

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Buffer→ Telemetry→ main() — netty Function Reference

Dependency Diagram

graph TD
  d71a30c3_d0dc_c0a8_0a61_dcff363d01c6["main()"]
  16a5c16d_8fea_d2c5_8553_2fb22606ecb6["Http2Client"]
  d71a30c3_d0dc_c0a8_0a61_dcff363d01c6 -->|defined in| 16a5c16d_8fea_d2c5_8553_2fb22606ecb6
  style d71a30c3_d0dc_c0a8_0a61_dcff363d01c6 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

example/src/main/java/io/netty/example/http2/helloworld/client/Http2Client.java lines 71–149

    public static void main(String[] args) throws Exception {
        // Configure SSL.
        final SslContext sslCtx;
        if (SSL) {
            SslProvider provider = OpenSsl.isAlpnSupported() ? SslProvider.OPENSSL : SslProvider.JDK;
            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(
                    Protocol.ALPN,
                    // NO_ADVERTISE is currently the only mode supported by both OpenSsl and JDK providers.
                    SelectorFailureBehavior.NO_ADVERTISE,
                    // ACCEPT is currently the only mode supported by both OpenSsl and JDK providers.
                    SelectedListenerFailureBehavior.ACCEPT,
                    ApplicationProtocolNames.HTTP_2,
                    ApplicationProtocolNames.HTTP_1_1))
                .build();
        } else {
            sslCtx = null;
        }

        EventLoopGroup group = new MultiThreadIoEventLoopGroup(NioIoHandler.newFactory());
        Http2ClientInitializer initializer = new Http2ClientInitializer(sslCtx, Integer.MAX_VALUE);

        try {
            // Configure the client.
            Bootstrap b = new Bootstrap();
            b.group(group);
            b.channel(NioSocketChannel.class);
            b.option(ChannelOption.SO_KEEPALIVE, true);
            b.remoteAddress(HOST, PORT);
            b.handler(initializer);

            // Start the client.
            Channel channel = b.connect().syncUninterruptibly().channel();
            System.out.println("Connected to [" + HOST + ':' + PORT + ']');

            // Wait for the HTTP/2 upgrade to occur.
            Http2SettingsHandler http2SettingsHandler = initializer.settingsHandler();
            http2SettingsHandler.awaitSettings(5, TimeUnit.SECONDS);

            HttpResponseHandler responseHandler = initializer.responseHandler();
            int streamId = 3;
            HttpScheme scheme = SSL ? HttpScheme.HTTPS : HttpScheme.HTTP;
            AsciiString hostName = new AsciiString(HOST + ':' + PORT);
            System.err.println("Sending request(s)...");
            if (URL != null) {
                // Create a simple GET request.
                FullHttpRequest request = new DefaultFullHttpRequest(HTTP_1_1, GET, URL, Unpooled.EMPTY_BUFFER);
                request.headers().add(HttpHeaderNames.HOST, hostName);
                request.headers().add(HttpConversionUtil.ExtensionHeaderNames.SCHEME.text(), scheme.name());
                request.headers().add(HttpHeaderNames.ACCEPT_ENCODING, HttpHeaderValues.GZIP);
                request.headers().add(HttpHeaderNames.ACCEPT_ENCODING, HttpHeaderValues.DEFLATE);
                responseHandler.put(streamId, channel.write(request), channel.newPromise());
                streamId += 2;
            }
            if (URL2 != null) {
                // Create a simple POST request with a body.
                FullHttpRequest request = new DefaultFullHttpRequest(HTTP_1_1, POST, URL2,
                        wrappedBuffer(URL2DATA.getBytes(CharsetUtil.UTF_8)));
                request.headers().add(HttpHeaderNames.HOST, hostName);
                request.headers().add(HttpConversionUtil.ExtensionHeaderNames.SCHEME.text(), scheme.name());
                request.headers().add(HttpHeaderNames.ACCEPT_ENCODING, HttpHeaderValues.GZIP);
                request.headers().add(HttpHeaderNames.ACCEPT_ENCODING, HttpHeaderValues.DEFLATE);
                responseHandler.put(streamId, channel.write(request), channel.newPromise());
            }
            channel.flush();
            responseHandler.awaitResponses(5, TimeUnit.SECONDS);
            System.out.println("Finished HTTP/2 request(s)");

            // Wait until the connection is closed.
            channel.close().syncUninterruptibly();
        } finally {
            group.shutdownGracefully();
        }
    }