NIOExtras

NIOExtras is a good place for code that is related to NIO but not core. It can also be used to incubate APIs for tasks that are possible with core-NIO but are cumbersome today.

What makes a good contribution to NIOExtras?

• a protocol encoder/decoder pair (also called “codec”) that is often used but is small enough so it doesn’t need its own repository
• a helper to achieve a task that is harder-than-necessary to achieve with core-NIO

Code Quality / Stability

All code will go through code review like in the other repositories related to the SwiftNIO project.

swift-nio-extras part of the SwiftNIO 2 family of repositories and depends on the following:

• swift-nio, version 2.30.0 or better.
• Swift 5.6
• zlib and its development headers installed on the system. But don’t worry, you’ll find zlib on pretty much any UNIX system that can compile any sort of code.

To depend on swift-nio-extras, put the following in the dependencies of your Package.swift:

.package(url: "https://github.com/apple/swift-nio-extras.git", from: "1.0.0"),

Support for older Swift versions

The most recent versions of SwiftNIO Extras support Swift 5.6 and newer. The minimum Swift version supported by SwiftNIO Extras releases are detailed below:

SwiftNIO Extras	Minimum Swift Version
1.0.0 ..< 1.10.0	5.0
1.10.0 ..< 1.11.0	5.2
1.11.0 ..< 1.14.0	5.4
1.14.0 ..< 1.19.1	5.5.2
1.19.0 ...	5.6

On the nio-extras-0.1 branch, you can find the swift-nio-extras version for the SwiftNIO 1 family. It requires Swift 4.1 or better.

Current Contents

• QuiescingHelper: Helps to quiesce a server by notifying user code when all previously open connections have closed.
• LineBasedFrameDecoder Splits incoming ByteBuffers on line endings.
• FixedLengthFrameDecoder Splits incoming ByteBuffers by a fixed number of bytes.
• LengthFieldBasedFrameDecoder Splits incoming ByteBuffers by a number of bytes specified in a fixed length header contained within the buffer.
• LengthFieldPrepender Prepends the number of bytes to outgoing ByteBuffers as a fixed length header. Can be used in a codec pair with the LengthFieldBasedFrameDecoder.
• RequestResponseHandler Matches a request and a promise with the corresponding response.
• HTTPResponseCompressor Compresses the body of every HTTP/1 response message.
• DebugInboundsEventHandler Prints out all inbound events that travel through the ChannelPipeline.
• DebugOutboundsEventHandler Prints out all outbound events that travel through the ChannelPipeline.
• WritePCAPHandler A ChannelHandler that writes .pcap containing the traffic of the ChannelPipeline that you can inspect with Wireshark/tcpdump.