From 078d686a0ac0aed212db97d73bd1e4a9387a4956 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Lo=C3=AFc=20Hoguin?= Date: Sun, 6 Jul 2014 13:10:35 +0200 Subject: Provide installable man pages make docs: generate Markdown and man pages in doc/ make install-docs: install man pages to be usable directly Docs are generated from the ezdoc files in doc/src/. --- guide/erlang_web.md | 181 ---------------------------------------------------- 1 file changed, 181 deletions(-) delete mode 100644 guide/erlang_web.md (limited to 'guide/erlang_web.md') diff --git a/guide/erlang_web.md b/guide/erlang_web.md deleted file mode 100644 index fa3d922..0000000 --- a/guide/erlang_web.md +++ /dev/null @@ -1,181 +0,0 @@ -Erlang and the Web -================== - -The Web is concurrent ---------------------- - -When you access a website there is little concurrency -involved. A few connections are opened and requests -are sent through these connections. Then the web page -is displayed on your screen. Your browser will only -open up to 4 or 8 connections to the server, depending -on your settings. This isn't much. - -But think about it. You are not the only one accessing -the server at the same time. There can be hundreds, if -not thousands, if not millions of connections to the -same server at the same time. - -Even today a lot of systems used in production haven't -solved the C10K problem (ten thousand concurrent connections). -And the ones who did are trying hard to get to the next -step, C100K, and are pretty far from it. - -Erlang meanwhile has no problem handling millions of -connections. At the time of writing there are application -servers written in Erlang that can handle more than two -million connections on a single server in a real production -application, with spare memory and CPU! - -The Web is concurrent, and Erlang is a language designed -for concurrency, so it is a perfect match. - -Of course, various platforms need to scale beyond a few -million connections. This is where Erlang's built-in -distribution mechanisms come in. If one server isn't -enough, add more! Erlang allows you to use the same code -for talking to local processes or to processes in other -parts of your cluster, which means you can scale very -quickly if the need arises. - -The Web has large userbases, and the Erlang platform was -designed to work in a distributed setting, so it is a -perfect match. - -Or is it? Surely you can find solutions to handle that many -concurrent connections with your favorite language... But all -these solutions will break down in the next few years. Why? -Firstly because servers don't get any more powerful, they -instead get a lot more cores and memory. This is only useful -if your application can use them properly, and Erlang is -light-years away from anything else in that area. Secondly, -today your computer and your phone are online, tomorrow your -watch, goggles, bike, car, fridge and tons of other devices -will also connect to various applications on the Internet. - -Only Erlang is prepared to deal with what's coming. - -The Web is soft real time -------------------------- - -What does soft real time mean, you ask? It means we want the -operations done as quickly as possible, and in the case of -web applications, it means we want the data propagated fast. - -In comparison, hard real time has a similar meaning, but also -has a hard time constraint, for example an operation needs to -be done in under N milliseconds otherwise the system fails -entirely. - -Users aren't that needy yet, they just want to get access -to their content in a reasonable delay, and they want the -actions they make to register at most a few seconds after -they submitted them, otherwise they'll start worrying about -whether it successfully went through. - -The Web is soft real time because taking longer to perform an -operation would be seen as bad quality of service. - -Erlang is a soft real time system. It will always run -processes fairly, a little at a time, switching to another -process after a while and preventing a single process to -steal resources from all others. This means that Erlang -can guarantee stable low latency of operations. - -Erlang provides the guarantees that the soft real time Web -requires. - -The Web is asynchronous ------------------------ - -Long ago, the Web was synchronous because HTTP was synchronous. -You fired a request, and then waited for a response. Not anymore. -It all began when XmlHttpRequest started being used. It allowed -the client to perform asynchronous calls to the server. - -Then Websocket appeared and allowed both the server and the client -to send data to the other endpoint completely asynchronously. The -data is contained within frames and no response is necessary. - -Erlang processes work the same. They send each other data contained -within messages and then continue running without needing a response. -They tend to spend most of their time inactive, waiting for a new -message, and the Erlang VM happily activate them when one is received. - -It is therefore quite easy to imagine Erlang being good at receiving -Websocket frames, which may come in at unpredictable times, pass the -data to the responsible processes which are always ready waiting for -new messages, and perform the operations required by only activating -the required parts of the system. - -The more recent Web technologies, like Websocket of course, but also -SPDY and HTTP/2.0, are all fully asynchronous protocols. The concept -of requests and responses is retained of course, but anything could -be sent in between, by both the client or the browser, and the -responses could also be received in a completely different order. - -Erlang is by nature asynchronous and really good at it thanks to the -great engineering that has been done in the VM over the years. It's -only natural that it's so good at dealing with the asynchronous Web. - -The Web is omnipresent ----------------------- - -The Web has taken a very important part of our lives. We're -connected at all times, when we're on our phone, using our computer, -passing time using a tablet while in the bathroom... And this -isn't going to slow down, every single device at home or on us -will be connected. - -All these devices are always connected. And with the number of -alternatives to give you access to the content you seek, users -tend to not stick around when problems arise. Users today want -their applications to be always available and if it's having -too many issues they just move on. - -Despite this, when developers choose a product to use for building -web applications, their only concern seem to be "Is it fast?", -and they look around for synthetic benchmarks showing which one -is the fastest at sending "Hello world" with only a handful -concurrent connections. Web benchmarks haven't been representative -of reality in a long time, and are drifting further away as -time goes on. - -What developers should really ask themselves is "Can I service -all my users with no interruption?" and they'd find that they have -two choices. They can either hope for the best, or they can use -Erlang. - -Erlang is built for fault tolerance. When writing code in any other -language, you have to check all the return values and act accordingly -to avoid any unforeseen issues. If you're lucky, you won't miss -anything important. When writing Erlang code, you can just check -the success condition and ignore all errors. If an error happen, -the Erlang process crashes and is then restarted by a special -process called a supervisor. - -The Erlang developer thus has no need to fear about unhandled -errors, and can focus on handling only the errors that should -give some feedback to the user and let the system take care of -the rest. This also has the advantage of allowing him to write -a lot less code, and letting him sleep at night. - -Erlang's fault tolerance oriented design is the first piece of -what makes it the best choice for the omnipresent, always available -Web. - -The second piece is Erlang's built-in distribution. Distribution -is a key part of building a fault tolerant system, because it -allows you to handle bigger failures, like a whole server going -down, or even a data center entirely. - -Fault tolerance and distribution are important today, and will be -vital in the future of the Web. Erlang is ready. - -Erlang is the ideal platform for the Web ----------------------------------------- - -Erlang provides all the important features that the Web requires -or will require in the near future. Erlang is a perfect match -for the Web, and it only makes sense to use it to build web -applications. -- cgit v1.2.3