diff --git a/website/index.html b/website/index.html index 45f0fc6e55..9807cd0c5e 100644 --- a/website/index.html +++ b/website/index.html @@ -14,7 +14,7 @@

Node

-

Purely evented I/O for Purely event-based I/O for V8 javascript.

An example of a web server written with Node which responds with @@ -39,18 +39,22 @@ Server running at http://127.0.0.1:8000/

See the API documentation for more examples. -

Node's goal is to provide easy, scalable concurrency. In the above example, -the 2 second delay does not prevent the server from handling new requests. - -Node tells the operating system (through epoll or -kqueue or /dev/poll or select) that it -should be notified when the 2 seconds are up or if a new connection is -made—then it goes to sleep. If someone new connects, then it executes -the callback, if the timeout expires, it executes the inner callback. -Each connection is only a small heap allocation. - -

This is in contrast to most scripting languages where OS threads are employed for -concurrency. But thread-based networking +

Node's goal is to provide an easy way to build scalable network +programs. +In the above example, the 2 second delay does not prevent the server from +handling new requests. +Node tells the operating system (through +epoll, +kqueue, +/dev/poll, +or select) +that it should be notified when the 2 seconds are up or if a new connection +is made—then it goes to sleep. If someone new connects, then it +executes the callback, if the timeout expires, it executes the inner +callback. Each connection is only a small heap allocation. + +

This is in contrast to today's more common model +where OS threads are employed for concurrency. But thread-based networking is relatively inefficient @@ -60,55 +64,46 @@ very difficult to use. + +

Node will show much better memory efficency under high-loads -than other systems -which allocate 2mb thread stacks for each connection. +than systems which allocate 2mb thread stacks for each connection. + +

Users of Node are free from worries of dead-locking the +process—there are no locks. In fact, there arn't even blocking +functions. Because nothing blocks, Node can be given to less-than-export +programmers to build servers. -Node is similar to systems like +

Node is similar to systems like Ruby's Event Machine or Python's Twisted. -But Node also provides full access to the file system in a non-blocking way. -(This is done by using an internal thread pool to handle file system calls.) -Because Javascript does not have I/O libraries and because nothing in -Node blocks, a Node programmer is going to find it difficult to write slow -servers—even if they don't understand how the concurrency system -works. - -

Notice in the above example the puts() call is made -immediately. - -

Node's HTTP API has grown out of my difficulties while developing for -Merb and Ebb. Because of limiting low-level design choices, streaming data -through Rack-based frameworks is difficult or impossible. Streaming is -important for large requests or responses (uploads or downloads), so that -the data is not buffered in memory. Other small problems, the incorrect -assumption that all message headers have unique fields are dealt with. The -result is a fast, scalable, and complete low-level HTTP API which can be -built upon. - -

Evented program is different. It requires the program to change how they -view the problem. But it provides many benefits and it more closely matches -what the machine is actually doing. In someways threaded programming is like -fitting a square block into a round hole, and all of the deadlocks and -memory inefficiencies that come from that are a result of the struggle. -Javascript, thankfully, has no concept of threads -and never will. It has a very lucid closures and anonymous functions, -which make evented programming tolerable. - -

"But what about multiple-processor concurrency?", you ask. "Threads are -necessary to scale programs to multi-core computers." The name Node -should give some hint at how it is envisioned being used. Processes are -necessary to scale to multi-core computers, not memory-sharing threads. The +But Node takes the paradigm. +In other systems, there is always a blocking call to start the event-loop. +Typically one sets up behavior through callbacks and at the end starts the +server through a call like EventMachine::run(). In Node, +there is no such thing. By default Node enters the event loop after +executing the input script. Node exits the event loop when there are no more +callbacks to perform. + +

Node's HTTP server has grown out of my difficulties developing +and working with web servers. For example, streaming data through most web +frameworks is difficult or impossible. Or like the oft-made false +assumption that all message headers have unique fields. Node attempts to +correct these problems by providing a low-level but complete HTTP API. +Coupled with Node's purely evented infrastructure, it will make a solid foundation for +future frameworks. + +

But what about multiple-processor concurrency? Threads are necessary +to scale programs to multi-core computers. The name Node should +give some hint at how it is envisioned being used. Processes are necessary +to scale to multi-core computers, not memory-sharing threads. The fundamentals of scalable systems are fast networking and non-blocking design—the rest is message passing. In the future, I'd like Node to -be able to spawn new processes, have a library for passing JSON messages, -and be able accept connections from multiple processes (a pre-fork server); -but these are things that fit into the current design and do not require -threads. +to be able to spawn new processes (probably using the Web Workers +API), but this is something that fits well into the current design.

Node is released under an MIT license.

@@ -129,7 +124,8 @@ href="http://s3.amazonaws.com/four.livejournal/20090527/node-0.0.1.tar.gz">node-

Node eventually wants to support all POSIX operating systems (including Windows with mingw) but at the moment it is only being tested on Linux, Macintosh, and FreeBSD. The build system requires Python. V8, on which -Node is built, supports only IA-32 and ARM processors. +Node is built, supports only IA-32 and ARM processors. V8 is included in the +Node distribution. There are no dependencies. 

 ./configure