HTTP Transport

/**
 * Netty 3-based HTTP server transport for Elasticsearch REST API.
 * Supports HTTP request pipelining, CORS, compression, and various TCP optimizations.
 */
public class Netty3HttpServerTransport extends AbstractLifecycleComponent 
                                       implements HttpServerTransport {
    
    /**
     * Constructor for creating a new HTTP server transport instance
     * @param settings Elasticsearch configuration settings
     * @param networkService Network utility service
     * @param bigArrays Memory management for large arrays
     * @param threadPool Thread pool for async operations
     * @param xContentRegistry Registry for content parsers (JSON, YAML, etc.)
     * @param dispatcher HTTP request dispatcher for routing requests
     */
    public Netty3HttpServerTransport(Settings settings, NetworkService networkService,
                                   BigArrays bigArrays, ThreadPool threadPool,
                                   NamedXContentRegistry xContentRegistry,
                                   HttpServerTransport.Dispatcher dispatcher);
    
    /**
     * Returns the current configuration settings
     * @return Settings object with current configuration
     */
    public Settings settings();
    
    /**
     * Returns the bound transport address information
     * @return BoundTransportAddress containing publish and bound addresses
     */
    public BoundTransportAddress boundAddress();
    
    /**
     * Returns HTTP server information and statistics
     * @return HttpInfo object with server details
     */
    public HttpInfo info();
    
    /**
     * Returns current HTTP server statistics
     * @return HttpStats object with request/response metrics
     */
    public HttpStats stats();
    
    /**
     * Returns the current CORS configuration
     * @return Netty3CorsConfig object with CORS policy settings
     */
    public Netty3CorsConfig getCorsConfig();
    
    /**
     * Configures the server channel pipeline factory
     * @return ChannelPipelineFactory for HTTP server channels
     */
    public ChannelPipelineFactory configureServerChannelPipelineFactory();
    
    /**
     * Resolves the publish port for the HTTP transport
     * @param settings Configuration settings
     * @param boundAddresses List of bound addresses
     * @param publishAddress Address to publish
     * @return Resolved port number for publishing
     */
    public static int resolvePublishPort(Settings settings, 
                                       List<InetSocketTransportAddress> boundAddresses,
                                       InetAddress publishAddress);
}

/**
 * Maximum capacity for HTTP cumulation buffers to prevent memory issues
 * Default: unlimited (-1)
 */
public static final Setting<ByteSizeValue> SETTING_HTTP_NETTY_MAX_CUMULATION_BUFFER_CAPACITY =
    byteSizeSetting("http.netty.max_cumulation_buffer_capacity", new ByteSizeValue(-1), ...);

/**
 * Maximum number of components in HTTP composite buffers
 * Default: -1 (unlimited)
 */
public static final Setting<Integer> SETTING_HTTP_NETTY_MAX_COMPOSITE_BUFFER_COMPONENTS =
    intSetting("http.netty.max_composite_buffer_components", -1, ...);

/**
 * Number of worker threads for handling HTTP I/O operations
 * Default: 2 * number of available processors  
 */
public static final Setting<Integer> SETTING_HTTP_WORKER_COUNT =
    intSetting("http.netty.worker_count", ...);

/**
 * TCP no delay setting for HTTP connections
 * Default: true (Nagle's algorithm disabled)
 */
public static final Setting<Boolean> SETTING_HTTP_TCP_NO_DELAY =
    boolSetting("http.tcp_no_delay", NetworkService.TcpSettings.TCP_NO_DELAY, ...);

/**
 * TCP keep alive setting for HTTP connections
 * Default: true
 */
public static final Setting<Boolean> SETTING_HTTP_TCP_KEEP_ALIVE =
    boolSetting("http.tcp.keep_alive", NetworkService.TcpSettings.TCP_KEEP_ALIVE, ...);

/**
 * Use blocking server implementation (OIO instead of NIO)
 * Default: false (use NIO)
 */
public static final Setting<Boolean> SETTING_HTTP_TCP_BLOCKING_SERVER =
    boolSetting("http.tcp.blocking_server", NetworkService.TcpSettings.TCP_BLOCKING_SERVER, ...);

/**
 * TCP socket reuse address setting
 * Default: true
 */
public static final Setting<Boolean> SETTING_HTTP_TCP_REUSE_ADDRESS =
    boolSetting("http.tcp.reuse_address", NetworkService.TcpSettings.TCP_REUSE_ADDRESS, ...);

/**
 * TCP send buffer size for HTTP connections
 * Default: 0 (use system default)
 */
public static final Setting<ByteSizeValue> SETTING_HTTP_TCP_SEND_BUFFER_SIZE =
    byteSizeSetting("http.tcp.send_buffer_size", NetworkService.TcpSettings.TCP_SEND_BUFFER_SIZE, ...);

/**
 * TCP receive buffer size for HTTP connections
 * Default: 0 (use system default)
 */
public static final Setting<ByteSizeValue> SETTING_HTTP_TCP_RECEIVE_BUFFER_SIZE =
    byteSizeSetting("http.tcp.receive_buffer_size", NetworkService.TcpSettings.TCP_RECEIVE_BUFFER_SIZE, ...);

import org.elasticsearch.http.netty3.Netty3HttpServerTransport;
import org.elasticsearch.common.settings.Settings;

// Configure HTTP transport with custom settings
Settings settings = Settings.builder()
    .put("http.netty.worker_count", 8)
    .put("http.tcp_no_delay", true)
    .put("http.tcp.keep_alive", true)
    .put("http.tcp.send_buffer_size", "64kb")
    .put("http.tcp.receive_buffer_size", "64kb")
    .put("http.netty.max_cumulation_buffer_capacity", "256mb")
    .build();

// Create HTTP transport (typically done by Elasticsearch internally)
Netty3HttpServerTransport httpTransport = new Netty3HttpServerTransport(
    settings, 
    networkService,
    bigArrays, 
    threadPool,
    xContentRegistry, 
    dispatcher
);

// Access transport information
HttpInfo info = httpTransport.info();
HttpStats stats = httpTransport.stats();
BoundTransportAddress address = httpTransport.boundAddress();

/**
 * HTTP request wrapper that extends Elasticsearch's RestRequest
 */
public class Netty3HttpRequest extends RestRequest {
    /**
     * Constructor for wrapping Netty HTTP requests
     * @param xContentRegistry Registry for content parsing
     * @param request Netty HTTP request object
     * @param channel Netty channel for the request
     */
    public Netty3HttpRequest(NamedXContentRegistry xContentRegistry, 
                           HttpRequest request, Channel channel);
    
    /**
     * Returns the underlying Netty HTTP request
     * @return HttpRequest object from Netty
     */
    public HttpRequest request();
    
    /**
     * Returns the HTTP method for this request
     * @return RestRequest.Method (GET, POST, PUT, DELETE, etc.)
     */
    public RestRequest.Method method();
    
    /**
     * Returns the request URI
     * @return String containing the full request URI
     */
    public String uri();
    
    /**
     * Checks if the request has content body
     * @return true if request contains content data
     */
    public boolean hasContent();
    
    /**
     * Returns the request content as bytes
     * @return BytesReference containing request body
     */
    public BytesReference content();
    
    /**
     * Returns the remote client address
     * @return SocketAddress of the client
     */
    public SocketAddress getRemoteAddress();
    
    /**
     * Returns the local server address
     * @return SocketAddress of the server
     */
    public SocketAddress getLocalAddress();
    
    /**
     * Returns the underlying Netty channel
     * @return Channel object for this request
     */
    public Channel getChannel();
}

/**
 * HTTP response channel for sending responses back to clients
 */
public class Netty3HttpChannel implements RestChannel {
    /**
     * Constructor for HTTP response channel
     * @param transport Parent HTTP server transport
     * @param request Original HTTP request
     * @param messageEvent Netty message event
     * @param detailedErrorsEnabled Whether to include detailed error info
     * @param threadContext Thread context for request handling
     */
    public Netty3HttpChannel(Netty3HttpServerTransport transport,
                           Netty3HttpRequest request,
                           OrderedUpstreamMessageEvent messageEvent,
                           boolean detailedErrorsEnabled,
                           ThreadContext threadContext);
    
    /**
     * Creates a new bytes output stream for response content
     * @return BytesStreamOutput for writing response data
     */
    public BytesStreamOutput newBytesOutput();
    
    /**
     * Sends the HTTP response to the client
     * @param response RestResponse containing response data and headers
     */
    public void sendResponse(RestResponse response);
}

/**
 * Server channel pipeline includes:
 * - HTTP request decoder for parsing incoming requests
 * - HTTP response encoder for formatting outgoing responses  
 * - Content aggregator for handling chunked requests
 * - Optional compression/decompression handlers
 * - CORS handler for cross-origin requests
 * - Pipelining handler for managing multiple concurrent requests
 * - Custom request handler for Elasticsearch-specific processing
 */
public ChannelPipelineFactory configureServerChannelPipelineFactory() {
    return new ChannelPipelineFactory() {
        @Override
        public ChannelPipeline getPipeline() throws Exception {
            ChannelPipeline pipeline = Channels.pipeline();
            
            // Basic HTTP handling
            pipeline.addLast("decoder", new HttpRequestDecoder());
            pipeline.addLast("encoder", new ESNetty3HttpResponseEncoder());
            pipeline.addLast("aggregator", new HttpChunkAggregator(maxContentLength));
            
            // Optional compression
            if (compression) {
                pipeline.addLast("decoder_compress", new HttpContentDecompressor());
                pipeline.addLast("encoder_compress", new HttpContentCompressor(compressionLevel));
            }
            
            // CORS support
            if (corsConfig.isCorsSupportEnabled()) {
                pipeline.addLast("cors", new Netty3CorsHandler(corsConfig));
            }
            
            // HTTP pipelining
            if (pipelining) {
                pipeline.addLast("pipelining", new HttpPipeliningHandler(logger, maxEventsHeld));
            }
            
            // Elasticsearch request handler
            pipeline.addLast("handler", requestHandler);
            
            return pipeline;
        }
    };
}