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/modern_web.md | 226 ---------------------------------------------------- 1 file changed, 226 deletions(-) delete mode 100644 guide/modern_web.md (limited to 'guide/modern_web.md') diff --git a/guide/modern_web.md b/guide/modern_web.md deleted file mode 100644 index 53670a4..0000000 --- a/guide/modern_web.md +++ /dev/null @@ -1,226 +0,0 @@ -The modern Web -============== - -Let's take a look at various technologies from the beginnings -of the Web up to this day, and get a preview of what's -coming next. - -Cowboy is compatible with all the technology cited in this -chapter except of course HTTP/2.0 which has no implementation -in the wild at the time of writing. - -The prehistoric Web -------------------- - -HTTP was initially created to serve HTML pages and only -had the GET method for retrieving them. This initial -version is documented and is sometimes called HTTP/0.9. -HTTP/1.0 defined the GET, HEAD and POST methods, and -was able to send data with POST requests. - -HTTP/1.0 works in a very simple way. A TCP connection -is first established to the server. Then a request is -sent. Then the server sends a response back and closes -the connection. - -Suffice to say, HTTP/1.0 is not very efficient. Opening -a TCP connection takes some time, and pages containing -many assets load much slower than they could because of -this. - -Most improvements done in recent years focused on reducing -this load time and reducing the latency of the requests. - -HTTP/1.1 --------- - -HTTP/1.1 quickly followed and added a keep-alive mechanism -to allow using the same connection for many requests, as -well as streaming capabilities, allowing an endpoint to send -a body in well defined chunks. - -HTTP/1.1 defines the OPTIONS, GET, HEAD, POST, PUT, DELETE, -TRACE and CONNECT methods. The PATCH method was added in more -recent years. It also improves the caching capabilities with -the introduction of many headers. - -HTTP/1.1 still works like HTTP/1.0 does, except the connection -can be kept alive for subsequent requests. This however allows -clients to perform what is called as pipelining: sending many -requests in a row, and then processing the responses which will -be received in the same order as the requests. - -REST ----- - -The design of HTTP/1.1 was influenced by the REST architectural -style. REST, or REpresentational State Transfer, is a style of -architecture for loosely connected distributed systems. - -REST defines constraints that systems must obey to in order to -be RESTful. A system which doesn't follow all the constraints -cannot be considered RESTful. - -REST is a client-server architecture with a clean separation -of concerns between the client and the server. They communicate -by referencing resources. Resources can be identified, but -also manipulated. A resource representation has a media type -and information about whether it can be cached and how. Hypermedia -determines how resources are related and how they can be used. -REST is also stateless. All requests contain the complete -information necessary to perform the action. - -HTTP/1.1 defines all the methods, headers and semantics required -to implement RESTful systems. - -REST is most often used when designing web application APIs -which are generally meant to be used by executable code directly. - -XmlHttpRequest --------------- - -Also know as AJAX, this technology allows Javascript code running -on a web page to perform asynchronous requests to the server. -This is what started the move from static websites to dynamic -web applications. - -XmlHttpRequest still performs HTTP requests under the hood, -and then waits for a response, but the Javascript code can -continue to run until the response arrives. It will then receive -the response through a callback previously defined. - -This is of course still requests initiated by the client, -the server still had no way of pushing data to the client -on its own, so new technology appeared to allow that. - -Long-polling ------------- - -Polling was a technique used to overcome the fact that the server -cannot push data directly to the client. Therefore the client had -to repeatedly create a connection, make a request, get a response, -then try again a few seconds later. This is overly expensive and -adds an additional delay before the client receives the data. - -Polling was necessary to implement message queues and other -similar mechanisms, where a user must be informed of something -when it happens, rather than when he refreshes the page next. -A typical example would be a chat application. - -Long-polling was created to reduce the server load by creating -less connections, but also to improve latency by getting the -response back to the client as soon as it becomes available -on the server. - -Long-polling works in a similar manner to polling, except the -request will not get a response immediately. Instead the server -leaves it open until it has a response to send. After getting -the response, the client creates a new request and gets back -to waiting. - -You probably guessed by now that long-polling is a hack, and -like most hacks it can suffer from unforeseen issues, in this -case it doesn't always play well with proxies. - -HTML5 ------ - -HTML5 is, of course, the HTML version after HTML4. But HTML5 -emerged to solve a specific problem: dynamic web applications. - -HTML was initially created to write web pages which compose -a website. But soon people and companies wanted to use HTML -to write more and more complex websites, eventually known as -web applications. They are for example your news reader, your -email client in the browser, or your video streaming website. - -Because HTML wasn't enough, they started using proprietary -solutions, often implemented using plug-ins. This wasn't -perfect of course, but worked well enough for most people. - -However, the needs for a standard solution eventually became -apparent. The browser needed to be able to play media natively. -It needed to be able to draw anything. It needed an efficient -way of streaming events to the server, but also receiving -events from the server. - -The solution went on to become HTML5. At the time of writing -it is being standardized. - -EventSource ------------ - -EventSource, sometimes also called Server-Sent Events, is a -technology allowing servers to push data to HTML5 applications. - -EventSource is one-way communication channel from the server -to the client. The client has no means to talk to the server -other than by using HTTP requests. - -It consists of a Javascript object allowing setting up an -EventSource connection to the server, and a very small protocol -for sending events to the client on top of the HTTP/1.1 -connection. - -EventSource is a lightweight solution that only works for -UTF-8 encoded text data. Binary data and text data encoded -differently are not allowed by the protocol. A heavier but -more generic approach can be found in Websocket. - -Websocket ---------- - -Websocket is a protocol built on top of HTTP/1.1 that provides -a two-ways communication channel between the client and the -server. Communication is asynchronous and can occur concurrently. - -It consists of a Javascript object allowing setting up a -Websocket connection to the server, and a binary based -protocol for sending data to the server or the client. - -Websocket connections can transfer either UTF-8 encoded text -data or binary data. The protocol also includes support for -implementing a ping/pong mechanism, allowing the server and -the client to have more confidence that the connection is still -alive. - -A Websocket connection can be used to transfer any kind of data, -small or big, text or binary. Because of this Websocket is -sometimes used for communication between systems. - -SPDY ----- - -SPDY is an attempt to reduce page loading time by opening a -single connection per server, keeping it open for subsequent -requests, and also by compressing the HTTP headers to reduce -the size of requests. - -SPDY is compatible with HTTP/1.1 semantics, and is actually -just a different way of performing HTTP requests and responses, -by using binary frames instead of a text-based protocol. -SPDY also allows the server to send extra responses following -a request. This is meant to allow sending the resources -associated with the request before the client requests them, -saving latency when loading websites. - -SPDY is an experiment that has proven successful and is used -as the basis for the HTTP/2.0 standard. - -Browsers make use of TLS Next Protocol Negotiation to upgrade -to a SPDY connection seamlessly if the protocol supports it. - -The protocol itself has a few shortcomings which are being -fixed in HTTP/2.0. - -HTTP/2.0 --------- - -HTTP/2.0 is the long-awaited update to the HTTP/1.1 protocol. -It is based on SPDY although a lot has been improved at the -time of writing. - -HTTP/2.0 is an asynchronous two-ways communication channel -between two endpoints. - -It is planned to be ready late 2014. -- cgit v1.2.3