PermessageDeflateExtension Class — netty Architecture

Source Code

codec-http/src/main/java/io/netty/handler/codec/http/websocketx/extensions/compression/PerMessageDeflateServerExtensionHandshaker.java lines 259–315

    private static class PermessageDeflateExtension implements WebSocketServerExtension {

        private final int compressionLevel;
        private final boolean serverNoContext;
        private final int serverWindowSize;
        private final boolean clientNoContext;
        private final int clientWindowSize;
        private final WebSocketExtensionFilterProvider extensionFilterProvider;
        private final int maxAllocation;

        PermessageDeflateExtension(int compressionLevel, boolean serverNoContext,
                int serverWindowSize, boolean clientNoContext, int clientWindowSize,
                WebSocketExtensionFilterProvider extensionFilterProvider, int maxAllocation) {
            this.compressionLevel = compressionLevel;
            this.serverNoContext = serverNoContext;
            this.serverWindowSize = serverWindowSize;
            this.clientNoContext = clientNoContext;
            this.clientWindowSize = clientWindowSize;
            this.extensionFilterProvider = extensionFilterProvider;
            this.maxAllocation = maxAllocation;
        }

        @Override
        public int rsv() {
            return RSV1;
        }

        @Override
        public WebSocketExtensionEncoder newExtensionEncoder() {
            return new PerMessageDeflateEncoder(compressionLevel, serverWindowSize, serverNoContext,
                                                extensionFilterProvider.encoderFilter());
        }

        @Override
        public WebSocketExtensionDecoder newExtensionDecoder() {
            return new PerMessageDeflateDecoder(clientNoContext, extensionFilterProvider.decoderFilter(),
                                                maxAllocation);
        }

        @Override
        public WebSocketExtensionData newReponseData() {
            HashMap<String, String> parameters = new HashMap<String, String>(4);
            if (serverNoContext) {
                parameters.put(SERVER_NO_CONTEXT, null);
            }
            if (clientNoContext) {
                parameters.put(CLIENT_NO_CONTEXT, null);
            }
            if (serverWindowSize != MAX_WINDOW_SIZE) {
                parameters.put(SERVER_MAX_WINDOW, Integer.toString(serverWindowSize));
            }
            if (clientWindowSize != MAX_WINDOW_SIZE) {
                parameters.put(CLIENT_MAX_WINDOW, Integer.toString(clientWindowSize));
            }
            return new WebSocketExtensionData(PERMESSAGE_DEFLATE_EXTENSION, parameters);
        }
    }