Mention NIOPosix in README. (#1940)

README.md

@@ -24,8 +24,9 @@ NIO 2.29.0 and older support Swift 5.0+.
 
 Within this repository we have a number of products that provide different functionality. This package contains the following products:
 
+- `NIO`. This is an umbrella module exporting `NIOCore`, `NIOEmbedded` and `NIOPosix`.
 - `NIOCore`. This provides the core abstractions and types for using SwiftNIO (see ["Conceptual Overview"](#conceptual-overview) for more details). Most NIO extension projects that provide things like new [`EventLoop`s][el] and [`Channel`s][c] or new protocol implementations should only need to depend on `NIOCore`.
-- `NIO`. This provides the primary [`EventLoopGroup`], [`EventLoop`][el], and [`Channel`s][c] for use on POSIX-based systems. This is our high performance core I/O layer. In general, this should only be imported by projects that plan to do some actual I/O, such as high-level protocol implementations or applications.
+- `NIOPosix`. This provides the primary [`EventLoopGroup`], [`EventLoop`][el], and [`Channel`s][c] for use on POSIX-based systems. This is our high performance core I/O layer. In general, this should only be imported by projects that plan to do some actual I/O, such as high-level protocol implementations or applications.
 - `NIOEmbedded`. This provides [`EmbeddedChannel`][ec] and [`EmbeddedEventLoop`][eel], implementations of the `NIOCore` abstractions that provide fine-grained control over their execution. These are most often used for testing, but can also be used to drive protocol implementations in a way that is decoupled from networking altogether.
 - `NIOConcurrencyHelpers`. This provides a few low-level concurrency primitives that are used by NIO implementations, such as locks and atomics.
 - `NIOFoundationCompat`. This extends a number of NIO types for better interoperation with Foundation data types. If you are working with Foundation data types such as `Data`, you should import this.
@@ -108,7 +109,7 @@ The basic building blocks of SwiftNIO are the following 8 types of objects:
 - [`EventLoop`][el], a protocol, provided by `NIOCore`.
 - [`Channel`][c], a protocol, provided by `NIOCore`.
 - [`ChannelHandler`][ch], a protocol, provided by `NIOCore`.
-- `Bootstrap`, several related structures, provided by `NIO`.
+- `Bootstrap`, several related structures, provided by `NIOCore`.
 - [`ByteBuffer`][bb], a struct, provided by `NIOCore`.
 - [`EventLoopFuture`][elf], a generic class, provided by `NIOCore`.
 - [`EventLoopPromise`][elp], a generic struct, provided by `NIOCore`.
@@ -121,7 +122,7 @@ The basic I/O primitive of SwiftNIO is the event loop. The event loop is an obje
 
 Event loops are gathered together into event loop *groups*. These groups provide a mechanism to distribute work around the event loops. For example, when listening for inbound connections the listening socket will be registered on one event loop. However, we don't want all connections that are accepted on that listening socket to be registered with the same event loop, as that would potentially overload one event loop while leaving the others empty. For that reason, the event loop group provides the ability to spread load across multiple event loops.
 
-In SwiftNIO today there is one [`EventLoopGroup`][elg] implementation, and two [`EventLoop`][el] implementations. For production applications there is the [`MultiThreadedEventLoopGroup`][mtelg], an [`EventLoopGroup`][elg] that creates a number of threads (using the POSIX [`pthreads`][pthreads] library) and places one `SelectableEventLoop` on each one. The `SelectableEventLoop` is an event loop that uses a selector (either [`kqueue`][kqueue] or [`epoll`][epoll] depending on the target system) to manage I/O events from file descriptors and to dispatch work. These [`EventLoop`s][el] and [`EventLoopGroup`s][elg] are provided by the `NIO` module. Additionally, there is the [`EmbeddedEventLoop`][eel], which is a dummy event loop that is used primarily for testing purposes, provided by the `NIOEmbedded` module.
+In SwiftNIO today there is one [`EventLoopGroup`][elg] implementation, and two [`EventLoop`][el] implementations. For production applications there is the [`MultiThreadedEventLoopGroup`][mtelg], an [`EventLoopGroup`][elg] that creates a number of threads (using the POSIX [`pthreads`][pthreads] library) and places one `SelectableEventLoop` on each one. The `SelectableEventLoop` is an event loop that uses a selector (either [`kqueue`][kqueue] or [`epoll`][epoll] depending on the target system) to manage I/O events from file descriptors and to dispatch work. These [`EventLoop`s][el] and [`EventLoopGroup`s][elg] are provided by the `NIOPosix` module. Additionally, there is the [`EmbeddedEventLoop`][eel], which is a dummy event loop that is used primarily for testing purposes, provided by the `NIOEmbedded` module.
 
 [`EventLoop`][el]s have a number of important properties. Most vitally, they are the way all work gets done in SwiftNIO applications. In order to ensure thread-safety, any work that wants to be done on almost any of the other objects in SwiftNIO must be dispatched via an [`EventLoop`][el]. [`EventLoop`][el] objects own almost all the other objects in a SwiftNIO application, and understanding their execution model is critical for building high-performance SwiftNIO applications.
 
@@ -145,7 +146,7 @@ In general, [`ChannelHandler`][ch]s are designed to be highly re-usable componen
 
 SwiftNIO ships with many [`ChannelHandler`][ch]s built in that provide useful functionality, such as HTTP parsing. In addition, high-performance applications will want to provide as much of their logic as possible in [`ChannelHandler`][ch]s, as it helps avoid problems with context switching.
 
-Additionally, SwiftNIO ships with a few [`Channel`][c] implementations. In particular, it ships with `ServerSocketChannel`, a [`Channel`][c] for sockets that accept inbound connections; `SocketChannel`, a [`Channel`][c] for TCP connections; and `DatagramChannel`, a [`Channel`][c] for UDP sockets. All of these are provided by the `NIO` module. It also provides[`EmbeddedChannel`][ec], a [`Channel`][c] primarily used for testing, provided by the `NIOEmbedded` module.
+Additionally, SwiftNIO ships with a few [`Channel`][c] implementations. In particular, it ships with `ServerSocketChannel`, a [`Channel`][c] for sockets that accept inbound connections; `SocketChannel`, a [`Channel`][c] for TCP connections; and `DatagramChannel`, a [`Channel`][c] for UDP sockets. All of these are provided by the `NIOPosix` module. It also provides[`EmbeddedChannel`][ec], a [`Channel`][c] primarily used for testing, provided by the `NIOEmbedded` module.
 
 ##### A Note on Blocking
 
@@ -161,7 +162,7 @@ While it is possible to configure and register [`Channel`][c]s with [`EventLoop`
 
 For this reason, SwiftNIO ships a number of `Bootstrap` objects whose purpose is to streamline the creation of channels. Some `Bootstrap` objects also provide other functionality, such as support for Happy Eyeballs for making TCP connection attempts.
 
-Currently SwiftNIO ships with three `Bootstrap` objects in the `NIO` module: [`ServerBootstrap`](https://apple.github.io/swift-nio/docs/current/NIO/Classes/ServerBootstrap.html), for bootstrapping listening channels; [`ClientBootstrap`](https://apple.github.io/swift-nio/docs/current/NIO/Classes/ClientBootstrap.html), for bootstrapping client TCP channels; and [`DatagramBootstrap`](https://apple.github.io/swift-nio/docs/current/NIO/Classes/DatagramBootstrap.html) for bootstrapping UDP channels.
+Currently SwiftNIO ships with three `Bootstrap` objects in the `NIOPosix` module: [`ServerBootstrap`](https://apple.github.io/swift-nio/docs/current/NIOPosix/Classes/ServerBootstrap.html), for bootstrapping listening channels; [`ClientBootstrap`](https://apple.github.io/swift-nio/docs/current/NIOPosix/Classes/ClientBootstrap.html), for bootstrapping client TCP channels; and [`DatagramBootstrap`](https://apple.github.io/swift-nio/docs/current/NIOPosix/Classes/DatagramBootstrap.html) for bootstrapping UDP channels.
 
 #### ByteBuffer
 
@@ -238,24 +239,21 @@ dependencies: [
 
 and then adding the appropriate SwiftNIO module(s) to your target dependencies.
 The syntax for adding target dependencies differs slightly between Swift
-versions. For example, if you want to depend on the `NIO` and `NIOHTTP1`
-modules, specify the following dependencies:
-
-#### Swift 5.0 and 5.1 (`swift-tools-version:5.[01]`)
-
-    dependencies: ["NIO", "NIOHTTP1"]
+versions. For example, if you want to depend on the `NIOCore`, `NIOPosix` and 
+`NIOHTTP1` modules, specify the following dependencies:
 
 #### Swift 5.2 and newer (`swift-tools-version:5.2`)
 
-    dependencies: [.product(name: "NIO", package: "swift-nio"),
+    dependencies: [.product(name: "NIOCore", package: "swift-nio"),
+                   .product(name: "NIOPosix", package: "swift-nio"),
                    .product(name: "NIOHTTP1", package: "swift-nio")]
 
 ### Using Xcode Package support
 
 If your project is set up as an Xcode project and you're using Xcode 11+, you can add SwiftNIO as a dependency to your
 Xcode project by clicking File -> Swift Packages -> Add Package Dependency. In the upcoming dialog, please enter
 `https://github.com/apple/swift-nio.git` and click Next twice. Finally, select the targets you are planning to use (for
-example `NIO`, `NIOHTTP1`, and `NIOFoundationCompat`) and click finish. Now will be able to `import NIO` (as well as all
+example `NIOCore`, `NIOHTTP1`, and `NIOFoundationCompat`) and click finish. Now will be able to `import NIOCore` (as well as all
 the other targets you have selected) in your project.
 
 To work on SwiftNIO itself, or to investigate some of the demonstration applications, you can clone the repository directly and use SwiftPM to help build it. For example, you can run the following commands to compile and run the example echo server:
@@ -346,18 +344,18 @@ apt-get install -y git curl libatomic1 libxml2 netcat-openbsd lsof perl
 dnf install swift-lang /usr/bin/nc /usr/bin/lsof /usr/bin/shasum
 ```
 
-[ch]: https://apple.github.io/swift-nio/docs/current/NIO/Protocols/ChannelHandler.html
-[c]: https://apple.github.io/swift-nio/docs/current/NIO/Protocols/Channel.html
-[chc]: https://apple.github.io/swift-nio/docs/current/NIO/Classes/ChannelHandlerContext.html
-[ec]: https://apple.github.io/swift-nio/docs/current/NIO/Classes/EmbeddedChannel.html
-[el]: https://apple.github.io/swift-nio/docs/current/NIO/Protocols/EventLoop.html
-[eel]: https://apple.github.io/swift-nio/docs/current/NIO/Classes/EmbeddedEventLoop.html
-[elg]: https://apple.github.io/swift-nio/docs/current/NIO/Protocols/EventLoopGroup.html
-[bb]: https://apple.github.io/swift-nio/docs/current/NIO/Structs/ByteBuffer.html
-[elf]: https://apple.github.io/swift-nio/docs/current/NIO/Classes/EventLoopFuture.html
-[elp]: https://apple.github.io/swift-nio/docs/current/NIO/Structs/EventLoopPromise.html
-[cp]: https://apple.github.io/swift-nio/docs/current/NIO/Classes/ChannelPipeline.html
-[mtelg]: https://apple.github.io/swift-nio/docs/current/NIO/Classes/MultiThreadedEventLoopGroup.html
+[ch]: https://apple.github.io/swift-nio/docs/current/NIOCore/Protocols/ChannelHandler.html
+[c]: https://apple.github.io/swift-nio/docs/current/NIOCore/Protocols/Channel.html
+[chc]: https://apple.github.io/swift-nio/docs/current/NIOCore/Classes/ChannelHandlerContext.html
+[ec]: https://apple.github.io/swift-nio/docs/current/NIOCore/Classes/EmbeddedChannel.html
+[el]: https://apple.github.io/swift-nio/docs/current/NIOCore/Protocols/EventLoop.html
+[eel]: https://apple.github.io/swift-nio/docs/current/NIOCore/Classes/EmbeddedEventLoop.html
+[elg]: https://apple.github.io/swift-nio/docs/current/NIOCore/Protocols/EventLoopGroup.html
+[bb]: https://apple.github.io/swift-nio/docs/current/NIOCore/Structs/ByteBuffer.html
+[elf]: https://apple.github.io/swift-nio/docs/current/NIOCore/Classes/EventLoopFuture.html
+[elp]: https://apple.github.io/swift-nio/docs/current/NIOCore/Structs/EventLoopPromise.html
+[cp]: https://apple.github.io/swift-nio/docs/current/NIOCore/Classes/ChannelPipeline.html
+[mtelg]: https://apple.github.io/swift-nio/docs/current/NIOPosix/Classes/MultiThreadedEventLoopGroup.html
 [pthreads]: https://en.wikipedia.org/wiki/POSIX_Threads
 [kqueue]: https://en.wikipedia.org/wiki/Kqueue
 [epoll]: https://en.wikipedia.org/wiki/Epoll