Source code
package io.netty.example.sctp;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.MultiThreadIoEventLoopGroup;
import io.netty.channel.nio.NioIoHandler;
import io.netty.channel.sctp.SctpChannel;
import io.netty.channel.sctp.nio.NioSctpServerChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
/**
* Echoes back any received data from a SCTP client.
*/
public final class SctpEchoServer {
static final int PORT = Integer.parseInt(System.getProperty("port", "8007"));
public static void main(String[] args) throws Exception {
// Configure the server.
EventLoopGroup group = new MultiThreadIoEventLoopGroup(NioIoHandler.newFactory());
final SctpEchoServerHandler serverHandler = new SctpEchoServerHandler();
try {
ServerBootstrap b = new ServerBootstrap();
b.group(group)
.channel(NioSctpServerChannel.class)
.option(ChannelOption.SO_BACKLOG, 0x64)
.handler(new LoggingHandler(LogLevel.INFO))
.childHandler(new ChannelInitializer<SctpChannel>() {
@Override
public void initChannel(SctpChannel ch) throws Exception {
ch.pipeline().addLast(
//new LoggingHandler(LogLevel.INFO),
serverHandler);
}
});
// Start the server.
ChannelFuture f = b.bind(PORT).sync();
// Wait until the server socket is closed.
f.channel().closeFuture().sync();
} finally {
// Shut down all event loops to terminate all threads.
group.shutdownGracefully();
}
}
}
Run 1
The code is well-structured, following a clear bootstrap pattern typical of Netty applications. It has logical sections for configuration, startup, and shutdown. Nesting is shallow, with the anonymous inner class adding only one level of depth. The intent is clear: an SCTP echo server. The code is concise, though some lines could be combined or split. Action granularity is mostly one action per line, though method chaining groups setup actions. The reading flow is natural, with the exception of the anonymous inner class inline definition mid-chain which slightly disrupts flow. Overall, this is readable code that could be improved by extracting the ChannelInitializer to a named class or using a lambda if the interface allowed it.
Run 2
The code is well-structured and follows a clear logical flow: configure event loop group, set up bootstrap, start server, and handle shutdown. Nesting is minimal, with only one anonymous inner class for channel initialization. Variable names like 'b', 'f', and 'group' could be more descriptive, slightly reducing clarity. The commented-out LoggingHandler line is dead code that should be removed. Each line generally performs one action, and indentation is consistent. The try-finally block for resource cleanup is appropriate. Overall, the code is concise and readable, typical of Netty examples, though minor naming and cleanup improvements would enhance it further.
Run 3
The code is well-structured and follows Netty server bootstrap patterns clearly. The class has a single purpose with minimal, logically organized fields and methods. Nesting is shallow: only one anonymous class and one try-finally block. Intent is evident from the class name, comments, and method names. The code is concise without being cryptic; imports and formatting are clean. Each meaningful action generally resides on its own line, especially in the bootstrap configuration chain. The reading flow is natural: configure server, bind, wait for close, then shut down gracefully. Minor deductions: the commented-out LoggingHandler line adds slight noise, and the magic number 0x64 for SO_BACKLOG could be a named constant for improved clarity.
Run 1
Code Structure: Logically separates configuration, startup, waiting, and cleanup, with resource shutdown in a finally block. Nesting: Mostly shallow, although the anonymous ChannelInitializer introduces moderate nesting. Clarity of intent: The class name, documentation, and lifecycle comments clearly communicate the server's purpose; short names b, f, and ch and the hexadecimal backlog value slightly reduce clarity. Code length: Concise overall, but the commented-out logging handler and multiline addLast call add unnecessary clutter. Action granularity: Statements generally perform one action each, and fluent configuration places each setting on its own line. Reading flow: Execution proceeds naturally from setup through shutdown, with consistent indentation and useful spacing; the embedded initializer slightly interrupts the main lifecycle flow.
Run 2
Code Structure: Clearly separates configuration, startup, waiting, and cleanup, with reliable resource cleanup in a finally block. Nesting: Mostly shallow, though the anonymous channel initializer adds a modest nesting layer. Clarity of intent: The class documentation, descriptive API calls, and comments make the server's purpose clear; short names b, f, and ch and the hexadecimal backlog value slightly reduce clarity. Code length: Compact and appropriate, although the commented-out logging handler introduces unnecessary clutter. Action granularity: Statements generally express one action, and the fluent configuration chain places each setting on its own line. Reading flow: Execution follows a natural lifecycle from event-loop creation through shutdown; consistent indentation and section comments support easy scanning.
Run 3
Code Structure: Clearly separates configuration, startup, waiting, and cleanup, with reliable resource cleanup in finally. Nesting: Mostly shallow, although the anonymous ChannelInitializer inside the fluent configuration adds some visual complexity. Clarity of intent: The class documentation, descriptive API calls, and comments establish the server's purpose; abbreviated variables b and f, hexadecimal backlog 0x64, and commented-out logging slightly reduce clarity. Code length: Compact and appropriate, with little unnecessary code beyond the disabled logging line. Action granularity: Statements generally express one action, and configuration calls appear on separate lines; chained calls remain easy to follow. Reading flow: Execution proceeds naturally from setup to shutdown, supported by consistent indentation and section comments.