I'm new in Netty, and I decided to start with 4.0.0, because I thought it should be better, because it's newer. My server application should receive data from gps devices, and the process is like this - at first I'm receiving 2 bytes, which are length of device imei, and then I'm receiving imei with that length, then I should send 0x01 to device if I want to accept data from it. After my answer device sends me gps data with AVL protocol. Now my server is working without Netty, and I want to change it to work with netty.
This is what I have done:
I have created server class like this
public class BusDataReceiverServer {
private final int port;
private final Logger LOG = LoggerFactory.getLogger(BusDataReceiverServer.class);
public BusDataReceiverServer(int port) {
this.port = port;
}
public void run() throws Exception {
LOG.info("running thread");
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try{
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.childHandler(new BusDataReceiverInitializer());
b.bind(port).sync().channel().closeFuture().sync();
}catch (Exception ex){
LOG.info(ex.getMessage());
}
finally {
LOG.info("thread closed");
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
new BusDataReceiverServer(3129).run();
}
}
and created initializer class
public class BusDataReceiverInitializer extends ChannelInitializer<SocketChannel> {
#Override
protected void initChannel(SocketChannel socketChannel) throws Exception {
ChannelPipeline pipeline = socketChannel.pipeline();
pipeline.addLast("imeiDecoder", new ImeiDecoder());
pipeline.addLast("busDataDecoder", new BusDataDecoder());
pipeline.addLast("encoder", new ResponceEncoder());
pipeline.addLast("imeiHandler", new ImeiReceiverServerHandler());
pipeline.addLast("busDataHandler", new BusDataReceiverServerHandler());
}
}
then I have created decoders and encoder and 2 handlers. My imeiDecoder and encoder, and ImeiReceiverServerHandler are working. This is my ImeiReceiverServerHandler
public class ImeiReceiverServerHandler extends ChannelInboundHandlerAdapter {
private final Logger LOG = LoggerFactory.getLogger(ImeiReceiverServerHandler.class);
#Override
public void messageReceived(ChannelHandlerContext ctx, MessageList<Object> msgs) throws Exception {
MessageList<String> imeis = msgs.cast();
String imei = imeis.get(0);
ctx.write(Constants.BUS_DATA_ACCEPT);
ctx.fireMessageReceived(msgs);
}
#Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
super.channelInactive(ctx); //To change body of overridden methods use File | Settings | File Templates.
}
#Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
super.exceptionCaught(ctx, cause); //To change body of overridden methods use File | Settings | File Templates.
}
}
Now, after accepting I don't understand how to continue receive gps data and forward it to handler BusDataReceiverServerHandler.
If anyone could help me with this or could offer me useful documentation, I will be very grateful. Or if it is possible to do this with Netty 3, for this I will also be thankful.
I have not used Netty 4, so I am not sure if my answer will be 100% accurate or the best way to do things in Netty 4, but what you need to do is track the state of your connection / client session in order to know when to forward messages to your second handler.
E.g.
private enum HandlerState { INITIAL, IMEI_RECEIVED; }
private HandlerState state = HandlerState.INITIAL;
#Override
public void messageReceived(ChannelHandlerContext ctx, MessageList<Object> msgs) throws Exception
{
if (state == HandlerState.INITIAL)
{
MessageList<String> imeis = msgs.cast();
String imei = imeis.get(0);
ctx.write(Constants.BUS_DATA_ACCEPT);
state = HandlerState.IMEI_RECEIVED;
} else
{
// Forward message to next handler...
// Not sure exactly how this is done in Netty 4
// Maybe: ctx.fireMessageReceived(msgs);
// Or maybe it is:
// ctx.nextInboundMessageBuffer().add(msg);
// ctx.fireInboundBufferUpdated();
// I believe you could also remove the IMEI handler from the
// pipeline instead of having it keep state, if it is not going to do anything
// further.
}
}
So either track state in the handler, or remove the handler from the pipeline once it has finished if it will not be used further. When tracking state, you can either keep the state in the handler itself (as shown above), or keep the state variables in the context / attribute map (however that is done in netty 4).
The reason to not keep the state in the handler itself would be if you were going to make the handler shareable (one instance used across multiple channels). It is not necessary to do this, but there could be some resource savings if you have a large number of concurrent channels.
Related
We are trying to Solve the Problem of Handling Huge Volume of Http POST Requests, and while using Netty Server, I was able to handle only ~50K requests/sec which is too low.
My question is how to tune this Server to ensure to handle > 1.5 million requests/second?
Netty4 Server
// Configure the server.
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap b = new ServerBootstrap();
b.option(ChannelOption.SO_BACKLOG, 1024);
b.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.handler(new LoggingHandler(LogLevel.INFO))
.childHandler(new HttpServerInitializer(sslCtx));
Channel ch = b.bind(PORT).sync().channel();
System.err.println("Open your web browser and navigate to " +
(SSL? "https" : "http") + "://127.0.0.1:" + PORT + '/');
ch.closeFuture().sync();
} finally {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
Initializer
public class HttpServerInitializer extends ChannelInitializer<SocketChannel> {
private final SslContext sslCtx;
public HttpServerInitializer(SslContext sslCtx) {
this.sslCtx = sslCtx;
}
#Override
public void initChannel(SocketChannel ch) {
ChannelPipeline p = ch.pipeline();
if (sslCtx != null) {
p.addLast(sslCtx.newHandler(ch.alloc()));
}
p.addLast(new HttpServerCodec());
p.addLast("aggregator", new HttpObjectAggregator(Integer.MAX_VALUE));
p.addLast(new HttpServerHandler());
}
}
Handler
public class HttpServerHandler extends ChannelInboundHandlerAdapter {
private static final String CONTENT = "SUCCESS";
#Override
public void channelReadComplete(ChannelHandlerContext ctx) {
ctx.flush();
}
#Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
if (msg instanceof HttpRequest) {
HttpRequest req = (HttpRequest) msg;
final FullHttpRequest fReq = (FullHttpRequest) req;
Charset utf8 = CharsetUtil.UTF_8;
final ByteBuf buf = fReq.content();
String in = buf.toString( utf8 );
System.out.println(" In ==> "+in);
buf.release();
if (HttpHeaders.is100ContinueExpected(req)) {
ctx.write(new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.CONTINUE));
}
in = null;
if (HttpHeaders.is100ContinueExpected(req)) {
ctx.write(new DefaultFullHttpResponse(HTTP_1_1, CONTINUE));
}
boolean keepAlive = HttpHeaders.isKeepAlive(req);
FullHttpResponse response = new DefaultFullHttpResponse(HTTP_1_1, OK, Unpooled.wrappedBuffer(CONTENT.getBytes()));
response.headers().set(CONTENT_TYPE, "text/plain");
response.headers().set(CONTENT_LENGTH, response.content().readableBytes());
if (!keepAlive) {
ctx.write(response).addListener(ChannelFutureListener.CLOSE);
} else {
response.headers().set(CONNECTION, Values.KEEP_ALIVE);
ctx.write(response);
}
}
}
#Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
{
cause.printStackTrace();
ctx.close();
}
}
Your question is very generic. However, I'll try to give you an answer regarding the netty optimizations and your code improvements.
Your code issues:
System.out.println(" In ==> "+in); - you shouldn't use this in high load cocurrent handler. Why? Because code inside println method is synchronized and thus gives penalties to your performance;
You do 2 class casts. To HttpRequest and to FullHttpRequest. You may use just last one;
Netty specific issues in your code:
You need to add epoll transport (in case your server is Linux like). It will give + ~30% out of box; How to.
You need to add native OpenSSL bindings. It will give + ~20%. How to.
EventLoopGroup bossGroup = new NioEventLoopGroup(); - you need to correctly setup sizes of bossGroup and workerGroup groups. Depending on your test scenarios. You didn't provide any info regarding your test cases, so I can't give you advice here;
new HttpObjectAggregator(Integer.MAX_VALUE) - you actually don't need this handler in your code. So for better performance, you may remove it.
new HttpServerHandler() - you don't need to create this handler for every channel. As it doesn't hold any state it may be shared across all pipelines. Search for #Sharable in netty.
new LoggingHandler(LogLevel.INFO) - you don't need this handler for high load tests as it logs a lot. Make your own logging when necessary;
buf.toString( utf8 ) - this is very wrong. You convert income bytes to string. But this doesn't make any sense as all data is already decoded in netty HttpServerCodec. So you do double work here;
Unpooled.wrappedBuffer(CONTENT.getBytes()) - you wrap constant message on every request. And thus - do unnecessary work on every request. You may create ByteBuf only once and do retain(), duplicate() depending on how you'll do this;
ctx.write(response) - you may consider using ctx.write(response, ctx.voidPromise()) in order to allocate less;
This is not all. However, fixing above issues would be a good start.
I am using netty for developing my server.
I am also implementing the Idle state handling in netty.
I got it working but an issue I recently found out.
I can't access the channel context attributes inside the userEventTriggered method.
here is my code and can anybody tell me why it is not possible.
I am setting it like
public static final AttributeKey<Agent> CLIENT_MAPPING = AttributeKey.valueOf("clientMapping");
...
ctx.attr(CLIENT_MAPPING).set(agent);
and inside handler, I am getting the value like (this is working perfectly)
Agent agent = ctx.attr(CLIENT_MAPPING).get();
But inside userEventTriggered it is returning null. (I am sure that it is set before this function is being called.)
public class Server
{
...
public void run() throws Exception
{
...
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup).
channel(NioServerSocketChannel.class).
childHandler(new SslServerInitializer());
...
}
}
class SslServerInitializer extends ChannelInitializer<SocketChannel>
{
#Override
public void initChannel(SocketChannel ch) throws Exception
{
ChannelPipeline pipeline = ch.pipeline();
....
pipeline.addLast("idleStateHandler", new IdleStateHandler(0, 0, Integer.parseInt(Main.configurations.get("netty.idleTimeKeepAlive.ms"))));
pipeline.addLast("idleTimeHandler", new ShelloidIdleTimeHandler());
}
}
class ShelloidIdleTimeHandler extends ChannelDuplexHandler
{
#Override
public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception
{
if (evt instanceof IdleStateEvent)
{
try
{
// This I am getting null, but I confirmed that I set the attribute from my handler and is accessible inside handler.
Agent agt = ctx.attr(WebSocketSslServerHandler.CLIENT_MAPPING).get();
ctx.channel().writeAndFlush(new TextWebSocketFrame("{\"type\":\"PING\", \"userId\": \"" + agt.getUserId() + "\"}"));
}
catch (Exception ex)
{
ctx.disconnect();
ex.printStackTrace();
}
}
}
}
Are you sure you set and get it in the same ChannelHandler? If you want to set and get it in different ChannelHandler you need to use Channel.attr(...)
I am using Netty 4 RC1. I initialize my pipeline at the client side:
public class NodeClientInitializer extends ChannelInitializer<SocketChannel> {
#Override
protected void initChannel(SocketChannel sc) throws Exception {
// Frame encoding and decoding
sc.pipeline()
.addLast("logger", new LoggingHandler(LogLevel.DEBUG))
// Business logic
.addLast("handler", new NodeClientHandler());
}
}
NodeClientHandler has the following relevant code:
public class NodeClientHandler extends ChannelInboundByteHandlerAdapter {
private void sendInitialInformation(ChannelHandlerContext c) {
c.write(0x05);
}
#Override
public void channelActive(ChannelHandlerContext c) throws Exception {
sendInitialInformation(c);
}
}
I connect to the server using:
public void connect(final InetSocketAddress addr) {
Bootstrap bootstrap = new Bootstrap();
ChannelFuture cf = null;
try {
// set up the pipeline
bootstrap.group(new NioEventLoopGroup())
.channel(NioSocketChannel.class)
.handler(new NodeClientInitializer());
// connect
bootstrap.remoteAddress(addr);
cf = bootstrap.connect();
cf.addListener(new ChannelFutureListener() {
#Override
public void operationComplete(ChannelFuture op) throws Exception {
logger.info("Connect to {}", addr.toString());
}
});
cf.channel().closeFuture().syncUninterruptibly();
} finally {
bootstrap.shutdown();
}
}
So, what I basically want to do is to send some initial information from the client to the server, after the channel is active (i.e. the connect was successful). However, when doing the c.write() I get the following warning and no package is send:
WARNING: Discarded 1 outbound message(s) that reached at the head of the pipeline. Please check your pipeline configuration.
I know there is no outbound handler in my pipeline, but I didn't think I need one (at this point) and I thought Netty would take care to transport the ByteBuffer over to the server. What am I doing wrong here in the pipeline configuration?
Netty only handle messages of type ByteBuf by default if you write to the Channel. So you need to wrap it in a ByteBuf. See also the Unpooled class with its static helpers to create ByteBuf instances.
When you design an a client that is going to connect to a lot of servers, like a crawler.
You will code something like that :
// the pipeline
public class CrawlerPipelineFactory implements ChannelPipelineFactory {
public ChannelPipeline getPipeline() throws Exception {
return Channels.pipeline(new CrawlerHandler());
}
}
// the channel handler
public class CrawlerHandler extends SimpleChannelHandler {
#Override
public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
// ...
}
}
// the main :
public static void main(){
ChannelFactory factory = new NioClientSocketChannelFactory(Executors.newCachedThreadPool(),Executors.newCachedThreadPool());
ClientBootstrap scannerBootstrap = new ClientBootstrap(factory);
scannerBootstrap.setPipelineFactory(new CrawlerPipelineFactory());
while(true){
MyURL url = stack.pop();
ChannelFuture connect = scannerBootstrap.connect(url.getSocketAddress());
}
}
Now when you are in your ApplicationHandler, the stuff that implements your SimpleChannelHandler or WhatEverStreamHandler, (CrawlerHander in the example) the only piece of information you get is the socketAdress you are connecting to that you can recover in "public void channelConnected()" function.
Ok but what if I want to recover some user data, like the MyURL object you see in my code example ?
I use a dirty hack, I use a Map<"ip:port",MyURL> so I can retrieve the associated data in channelConnected because I know ip:port i'm connected on.
This hack is really dirty, it won't work if you are connecting simultaneously to the same server (or you'll have to bind to a local port and use a key like "localport:ip:remoteport" but it's so dirty).
So I'm seeking what is the good way to pass data the the CrawlerHander ?
It would be cool if we could pass this data via the connect() method of the bootstrap. I know I can pass argument in my ChannelPipelineFactory.getPipeline() because it's invoked via connect(). But now we can't, so here is another dirty hack I use :
EDIT:
// the main
while(!targets.isEmpty()){
client.connect("localhost",111); // we will never connect to localhost, it's a hack
}
// the pipleline
public ChannelPipeline getPipeline() throws Exception {
return Channels.pipeline(
new CrawlerHandler(targets.pop()) // I specify each new host to connect here
);
}
// in my channel handler
// Now I have the data I want in the constructor, so I m sure I get them before everything is called
public class CrawlerHandler extends SimpleChannelHandler {
ExtraParameter target;
public CrawlerHandler(ExtraParameter target) {
this.target = target;
// but, and it's the most dirty part, I have to abort the connection to localhost, and reinit a new connection to the real target
boolean bFirstConnect=true;
#Override
public void connectRequested(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
if(bFirstConnect){
bFirstConnect = false;
ctx.getChannel().connect(target.getSocketAddr());
}
You can pass variables to Channel via Bootstrap.
Netty.io 4.1 & SO - Adding an attribute to a Channel before creation
Update to this answer while very late.
You can pass the data to the newly connected channel/channel handler using ChannelLocal or in ChannelHandlerContext (or in the Channel it self in latest Netty 3.x) using a connect future listener. In below example, ChannelLocal is used.
public class ChannelDataHolder {
public final static ChannelLocal<String> CHANNEL_URL = new ChannelLocal<String>(true);
}
// for each url in bootstrap
MyURL url = ....;
ChannelFuture cf = scannerBootstrap.connect(url.getSocketAddress());
final String urlString = url.getUrl();
cf.addListener(new ChannelFutureListener() {
#Override
public void operationComplete(ChannelFuture future) throws Exception {
ChannelDataHolder.CHANNEL_URL.set(future.getChannel(), urlString);
}
});
//In the handler
public class CrawlerHandler extends SimpleChannelHandler {
#Override
public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
String urlString = ChannelDataHolder.CHANNEL_URL.get(ctx.getChannel());
// ...use the data here
}
}
Note: instead of ChannelLocal, you can set and get the data using
ChannelHandlerContext.setAttachment()/getAttachment()
Channel.setAttachment()/getAttachment() in latest 3.x version of Netty
but both approaches does not support type safety.
I'm a newbie to Netty.
I'm looking for some samples. (Preferably but not necessarity using Camel Netty Component and Spring)
Specifically a sample Netty app that consumes TCP messages.
Also how can I write a JUnit test that can test this netty app?
Thanks,
Dar
I assume you still want to integrate with Camel. I would first look at the camel documentation . After that frustrates you, you will need to start experimenting. I have one example where I created a Camel Processor as a Netty Server. The Netty components work such that a From endpoint is a server which consumes and a To endpoint is a client which produces. I needed a To endpoint that was a server and the component did not support that. I simply implemented a Camel Processor as a spring bean that started a Netty Server when it was initialized. The JBoss Netty documentation and samples are very good though. It is worthwhile to step through them.
Here is my slimmed down example. It is a server that sends a message to all the clients that are connected. If you are new to Netty I highly suggest going through the samples I linked to above:
public class NettyServer implements Processor {
private final ChannelGroup channelGroup = new DefaultChannelGroup();
private NioServerSocketChannelFactory serverSocketChannelFactory = null;
private final ExecutorService executor = Executors.newCachedThreadPool();
private String listenAddress = "0.0.0.0"; // overridden by spring-osgi value
private int listenPort = 51501; // overridden by spring-osgi value
#Override
public void process(Exchange exchange) throws Exception {
byte[] bytes = (byte[]) exchange.getIn().getBody();
// send over the wire
sendMessage(bytes);
}
public synchronized void sendMessage(byte[] message) {
ChannelBuffer cb = ChannelBuffers.copiedBuffer(message);
//writes to all clients connected.
this.channelGroup.write(cb);
}
private class NettyServerHandler extends SimpleChannelUpstreamHandler {
#Override
public void channelOpen(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
super.channelOpen(ctx, e);
//add client to the group.
NettyServer.this.channelGroup.add(e.getChannel());
}
// Perform an automatic recon.
#Override
public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
super.channelConnected(ctx, e);
// do something here when a clien connects.
}
#Override
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) {
// Do something when a message is received...
}
#Override
public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) {
// Log the exception/
}
}
private class PublishSocketServerPipelineFactory implements ChannelPipelineFactory {
#Override
public ChannelPipeline getPipeline() throws Exception {
// need to set the handler.
return Channels.pipeline(new NettyServerHandler());
}
}
// called by spring to start the server
public void init() {
try {
this.serverSocketChannelFactory = new NioServerSocketChannelFactory(this.executor, this.executor);
final ServerBootstrap serverBootstrap = new ServerBootstrap(this.serverSocketChannelFactory);
serverBootstrap.setPipelineFactory(new PublishSocketServerPipelineFactory());
serverBootstrap.setOption("reuseAddress", true);
final InetSocketAddress listenSocketAddress = new InetSocketAddress(this.listenAddress, this.listenPort);
this.channelGroup.add(serverBootstrap.bind(listenSocketAddress));
} catch (Exception e) {
}
}
// called by spring to shut down the server.
public void destroy() {
try {
this.channelGroup.close();
this.serverSocketChannelFactory.releaseExternalResources();
this.executor.shutdown();
} catch (Exception e) {
}
}
// injected by spring
public void setListenAddress(String listenAddress) {
this.listenAddress = listenAddress;
}
// injected by spring
public void setListenPort(int listenPort) {
this.listenPort = listenPort;
}
}
The camel release has a lot of examples but without a simple one for netty component.
Netty component can be use to setup a socket server to consume message and produce response back to the client. After some time of search on the web, I create my own tutorial using netty component in camel as a simple Camel-Netty hello world example to show:
Using netty component in camel to receive TCP message
Using POJO class to process the received message and create response
Sending response back to client.