Merge pull request #1 from dorward/master

The first part of a sketchy intro to HTTP

chapters/how_the_web_works.md

@@ -0,0 +1,73 @@
+# How the web works
+
+TODO: Put some sort of quote in about documents which are linked
+together.
+
+Under the hood, the web is all about the HyperText
+Transfer Protocol. HTTP is the means by which a client (such as
+a web browser, or a search engine bot) can ask a server for 
+something and get a response which either includes whatever was
+requested or a message that says something was wrong with the
+request.
+
+## Anatomy of a request
+
+Let's take a look at an HTTP request.
+
+    GET / HTTP/1.1␤␍
+    Host: example.com␤␍
+    ␤␍
+
+### The Request-Line
+
+The first line is the *Request-Line*. This has three parts.
+
+The request method (`GET`) describes what you want to do to the resource.
+
+The request URI (`/`) identifies which resource the request is for.
+
+The protocol version (`HTTP/1.1`) states the version of HTTP in use. 
+1.1 has been around since the 90s. Version 2 is under development
+but it will be a long time before we see it in production.
+
+The line then ends with a carriage return **and** a line feed
+(`CRLF`).
+
+After the request line we have the HTTP request headers.
+
+### HTTP Headers
+
+Both requests and responses come in two parts. A set of headers and then, sometimes, some content.
+
+The format of a header is very simple:
+
+1. A name
+2. A colon (`:`)
+3. A value
+
+There are lots of different headers in HTTP, and more from 
+extensions, and we'll cover the more important ones throughout the 
+book.
+
+#### The Host header
+
+If this was HTTP 1.0 then we wouldn't need to send any headers, but IPv4 addresses are a
+precious commodity and we often have multiple websites hosted on a 
+single computer with a single network interface, all with their own
+hostname. 
+
+HTTP 1.1 makes it mandatory to state which website the request is for
+using a header.
+
+    Host = "Host" ":" host [ ":" port ] ;
+
+TODO: http://tools.ietf.org/html/rfc2616#section-5.2 - Read this 
+properly. Can the host header be omitted if an absolute URI is in 
+the header? Rephrase the bits about the Host header if that is an
+option.
+
+### Ending the header
+
+Finally, the request header is ended by two `CRLF` in a row. 
+
+

plan.md

@@ -43,3 +43,11 @@
 	* Why CGI is outdated
 
 	* How to rescue a CGI program
+
+------
+
+Content to think about squeezing in:
+
+* Caching
+* Content-Disposition
+* REST