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.
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 with clear sections for configuration, startup, and shutdown. The class has a single responsibility and the main method follows a logical try-finally pattern. Nesting is minimal with only one anonymous inner class. Intent is clearly documented with Javadoc and inline comments. The fluent API chain is readable and follows Netty conventions. However, there are minor issues: the commented-out LoggingHandler line adds noise should be removed, and the chained method calls could be slightly more explicit for newcomers to Netty. Overall, the code is concise yet complete, with one action per line in most cases, making it easy to follow.
Run 2
The code demonstrates excellent readability. The structure is logical: package declaration, imports, a succinct class-level comment, a constant with sensible defaults, and a clear main method. Nesting is minimal—only the anonymous ChannelInitializer adds a second level, which is idiomatic for Netty. Intent is evident throughout: the comment 'Configure the server' and the fluent builder chain clearly outline setup steps. Code is concise without being cryptic; each configuration call is on its own line, enhancing action granularity. Reading flow is natural, progressing from group creation to bootstrap configuration, binding, and shutdown. The finally block properly handles cleanup. Minor deductions: the commented-out LoggingHandler line could be removed, and the SctpEchoServerHandler is defined in a separate file, which slightly interrupts the flow but is standard practice.
Run 3
The code is well-structured and follows a clear sequential flow: configure, bind, wait, shutdown. Nesting is minimal and imports are organized. Intent is explicit through meaningful names and comments. The chained builder pattern improves readability. Minor deductions for action granularity in the bootstrap setup (multiple actions per line in the chained method calls) and a non-descriptive variable name 'b'/'f'. The commented-out line is a small but unnecessary distraction. Overall, the code is concise, maintainable, and readable.
Run 1
Code Structure: Clearly separates server configuration, startup, waiting, and cleanup, with reliable resource cleanup in finally. Nesting: Moderate nesting from try/finally and the anonymous channel initializer, but it remains easy to follow. Clarity of intent: The class name, documentation, and comments explain the echo server's purpose; abbreviated variables b, f, and ch slightly reduce clarity. Code length: Concise overall, though the commented-out logging handler and expanded addLast call introduce minor clutter. Action granularity: Most statements perform a single logical action, and the fluent configuration places each step on its own line. Reading flow: Execution proceeds naturally from initialization through shutdown, with consistent indentation and useful section comments.
Run 2
Code Structure: Logically separates configuration, startup, waiting, and cleanup, with reliable cleanup expressed through try/finally. Nesting: Moderate nesting from the anonymous ChannelInitializer inside the try block, but still easy to follow. Clarity of intent: The class name, documentation, and lifecycle comments clearly explain the server's purpose; abbreviated variables b, f, and ch are less descriptive. Code length: Concise overall, though the commented-out logging handler and multiline addLast call add minor clutter. Action granularity: Statements generally express one action each, and the fluent configuration places each setting on its own line. Reading flow: Execution proceeds naturally from setup to shutdown, with consistent indentation; a blank line after the package declaration and removal of dead comments would improve presentation.
Run 3
Code Structure: Logically separates server configuration, startup, waiting, and cleanup, with reliable resource shutdown in finally. Nesting: Mostly shallow, although the anonymous ChannelInitializer inside the fluent configuration adds indentation. Clarity of intent: The class documentation, descriptive API calls, and lifecycle comments clearly communicate an SCTP echo server; abbreviated variables b, f, and ch slightly reduce clarity. Code length: Concise overall, with little unnecessary code, though the commented-out logging handler adds clutter. Action granularity: Statements generally perform one action, and chained configuration calls are neatly placed on separate lines. Reading flow: Execution follows a natural configure-bind-wait-cleanup sequence. Minor formatting distractions include the missing separation after the package declaration and the awkward multiline addLast call.