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, 100)
.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.
// Wait until the server socket is closed.
(b.bind(PORT).sync()).channel().closeFuture().sync();
} finally {
// Shut down all event loops to terminate all threads.
group.shutdownGracefully();
}
}
}
Run 1
The code is generally structured well with clear sections and reasonable naming. The main issue is the missing `b.bind(PORT)` assignment before `sync()`, which creates ambiguous flow. There's also a commented-out logging handler and an empty comment that clutter intent. The anonymous `ChannelInitializer` adds nesting and breaks the otherwise fluent chain. While the builder pattern improves readability, the final binding line combines multiple actions (`bind`, `sync`, `channel`, `closeFuture`, `sync`) into one expression, reducing action granularity. The code is concise but slightly disorganized in flow. Adding the missing assignment, removing dead comments, and extracting the channel future would significantly improve clarity.
Run 2
The code is generally clean and follows standard Netty server patterns. Structure is logical with clear separation: setup, configuration, startup, and shutdown. Nesting is minimal except for the necessary anonymous ChannelInitializer class. Intent is clear from the class name, comments, and method names. The fluent API chain for bootstrap configuration improves readability. However, there are minor issues: the commented-out LoggingHandler line is dead code that should be removed, the variable name 'b' is too abbreviated, and there's an unnecessary blank line before the bind call. The empty comment section also slightly disrupts reading flow. The port constant parsing on a single line is acceptable. Overall, the code demonstrates good practices with room for minor polish.
Run 3
The code is generally well-structured, with clear intent, consistent formatting, and proper resource cleanup in a finally block. It uses a flat structure with minimal nesting, and the fluent builder pattern for ServerBootstrap reads naturally. Actions are mostly one per logical step. However, it loses points due to: (1) an incomplete comment block ('Start the server.' followed by a blank comment with no explanation), (2) a slightly awkward one-liner combining bind, sync, channel closeFuture, and sync — which reduces clarity and granularity on that line, and (3) the presence of a commented-out line of code, which introduces minor ambiguity. Overall, readability is strong but not perfect due to these small inconsistencies.
Run 1
Code Structure: Imports, configuration, initialization, and cleanup are logically organized, with lifecycle management in try/finally. Nesting: Mostly shallow, though the anonymous ChannelInitializer adds indentation within the fluent configuration. Clarity of intent: The class documentation and descriptive API calls clearly convey an SCTP echo server; the abbreviated variable b and commented-out logging code slightly reduce clarity. Code length: Concise overall, with minor clutter from redundant comments and extra blank lines. Action granularity: Configuration steps occupy separate lines, but binding, synchronization, channel access, and waiting for closure are combined into one statement. Reading flow: Generally follows setup, execution, and shutdown naturally, although the empty 'Start the server' section and binding under the waiting comment make the execution flow less clear.
Run 2
Code Structure: Logically separates setup, channel initialization, execution, and cleanup, with reliable cleanup in a finally block. Nesting: Mostly shallow; the anonymous initializer adds moderate nesting but remains manageable. Clarity of intent: The class documentation, descriptive API calls, and comments explain the echo server's purpose, though the variable name 'b' is vague and the handler implementation is external. Code length: Concise overall, with minor clutter from a commented-out logging handler, extra blank lines, and an unused ChannelFuture import. Action granularity: Configuration steps generally occupy separate lines, but the final chained statement combines binding, synchronization, and waiting for closure. Reading flow: Setup-to-shutdown progression is natural, although the empty section after 'Start the server' and the combined startup/wait statement weaken alignment between comments and actions.
Run 3
Code Structure: Logically organized into configuration, execution, and cleanup, with reliable resource shutdown in finally. Nesting: Generally shallow, though the anonymous ChannelInitializer adds indentation within the fluent configuration chain. Clarity of intent: The class documentation and descriptive API calls clearly identify an SCTP echo server; the abbreviated variable b and commented-out logging slightly reduce clarity. Code length: Concise overall, but excess blank lines and an unused ChannelFuture import add clutter. Action granularity: Configuration steps appear on separate lines, while binding, synchronization, channel access, and waiting are combined into one dense expression. Reading flow: Mostly natural and sequential, but the separated 'Start the server' comment and combined start-and-wait statement interrupt the otherwise clear progression.