mirror of
https://github.com/kennethreitz/dive-into-python3.git
synced 2026-06-05 23:10:17 +00:00
syntax highlighting for everyone!
This commit is contained in:
Mark Pilgrim
+53
-52
@@ -13,11 +13,11 @@ mark{display:inline}
|
||||
<meta name=viewport content='initial-scale=1.0'>
|
||||
</head>
|
||||
<form action=http://www.google.com/cse><div><input type=hidden name=cx value=014021643941856155761:l5eihuescdw><input type=hidden name=ie value=UTF-8> <input name=q size=25> <input type=submit name=root value=Search></div></form>
|
||||
<p>You are here: <a href=index.html>Home</a> <span>‣</span> <a href=table-of-contents.html#http-web-services>Dive Into Python 3</a> <span>‣</span>
|
||||
<p>You are here: <a href=index.html>Home</a> <span class=u>‣</span> <a href=table-of-contents.html#http-web-services>Dive Into Python 3</a> <span class=u>‣</span>
|
||||
<p id=level>Difficulty level: <span title=advanced>♦♦♦♦♢</span>
|
||||
<h1>HTTP Web Services</h1>
|
||||
<blockquote class=q>
|
||||
<p><span>❝</span> A ruffled mind makes a restless pillow. <span>❞</span><br>— Charlotte Brontë
|
||||
<p><span class=u>❝</span> A ruffled mind makes a restless pillow. <span class=u>❞</span><br>— Charlotte Brontë
|
||||
</blockquote>
|
||||
<p id=toc>
|
||||
<h2 id=divingin>Diving In</h2>
|
||||
@@ -137,7 +137,7 @@ The second time you request the same data, you include the ETag hash in an <code
|
||||
<p>Again with the <kbd>curl</kbd>:
|
||||
|
||||
<pre class=screen>
|
||||
<a><samp class=p>you@localhost:~$ </samp><kbd>curl -I <mark>-H "If-None-Match: \"3075-ddc8d800\""</mark> http://wearehugh.com/m.jpg</kbd> <span>①</span></a>
|
||||
<a><samp class=p>you@localhost:~$ </samp><kbd>curl -I <mark>-H "If-None-Match: \"3075-ddc8d800\""</mark> http://wearehugh.com/m.jpg</kbd> <span class=u>①</span></a>
|
||||
<samp>HTTP/1.1 304 Not Modified
|
||||
Date: Sun, 31 May 2009 18:04:39 GMT
|
||||
Server: Apache
|
||||
@@ -188,7 +188,7 @@ Cache-Control: max-age=31536000, public</samp></pre>
|
||||
<p>Let’s say you want to download a resource over <abbr>HTTP</abbr>, such as <a href=xml.html>an Atom feed</a>. Being a feed, you’re not just going to download it once; you’re going to download it over and over again. (Most feed readers will check for changes once an hour.) Let’s do it the quick-and-dirty way first, and then see how you can do better.
|
||||
<pre class=screen>
|
||||
<samp class=p>>>> </samp><kbd>import urllib.request</kbd>
|
||||
<a><samp class=p>>>> </samp><kbd>data = urllib.request.urlopen('http://diveintopython3.org/examples/feed.xml').read()</kbd> <span>①</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>data = urllib.request.urlopen('http://diveintopython3.org/examples/feed.xml').read()</kbd> <span class=u>①</span></a>
|
||||
<samp class=p>>>> </samp><kbd>print(data)</kbd>
|
||||
<samp><?xml version='1.0' encoding='utf-8'?>
|
||||
<feed xmlns='http://www.w3.org/2005/Atom' xml:lang='en'>
|
||||
@@ -213,13 +213,13 @@ Cache-Control: max-age=31536000, public</samp></pre>
|
||||
|
||||
<pre class=screen>
|
||||
<samp class=p>>>> </samp><kbd>from http.client import HTTPConnection</kbd>
|
||||
<a><samp class=p>>>> </samp><kbd>HTTPConnection.debuglevel = 1</kbd> <span>①</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>HTTPConnection.debuglevel = 1</kbd> <span class=u>①</span></a>
|
||||
<samp class=p>>>> </samp><kbd>from urllib.request import urlopen</kbd>
|
||||
<a><samp class=p>>>> </samp><kbd>response = urlopen('http://diveintopython3.org/examples/feed.xml')</kbd> <span>②</span></a>
|
||||
<samp><a>send: b'GET /examples/feed.xml HTTP/1.1 <span>③</span></a>
|
||||
<a>Host: diveintopython3.org <span>④</span></a>
|
||||
<a>Accept-Encoding: identity <span>⑤</span></a>
|
||||
<a>User-Agent: Python-urllib/3.0' <span>⑥</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>response = urlopen('http://diveintopython3.org/examples/feed.xml')</kbd> <span class=u>②</span></a>
|
||||
<samp><a>send: b'GET /examples/feed.xml HTTP/1.1 <span class=u>③</span></a>
|
||||
<a>Host: diveintopython3.org <span class=u>④</span></a>
|
||||
<a>Accept-Encoding: identity <span class=u>⑤</span></a>
|
||||
<a>User-Agent: Python-urllib/3.0' <span class=u>⑥</span></a>
|
||||
Connection: close
|
||||
reply: 'HTTP/1.1 200 OK'
|
||||
…further debugging information omitted…</samp></pre>
|
||||
@@ -236,19 +236,19 @@ reply: 'HTTP/1.1 200 OK'
|
||||
|
||||
<pre class=screen>
|
||||
# continued from previous example
|
||||
<a><samp class=p>>>> </samp><kbd>print(response.headers.as_string())</kbd> <span>①</span></a>
|
||||
<samp><a>Date: Sun, 31 May 2009 19:23:06 GMT <span>②</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>print(response.headers.as_string())</kbd> <span class=u>①</span></a>
|
||||
<samp><a>Date: Sun, 31 May 2009 19:23:06 GMT <span class=u>②</span></a>
|
||||
Server: Apache
|
||||
<a>Last-Modified: Sun, 31 May 2009 06:39:55 GMT <span>③</span></a>
|
||||
<a>ETag: "bfe-93d9c4c0" <span>④</span></a>
|
||||
<a>Last-Modified: Sun, 31 May 2009 06:39:55 GMT <span class=u>③</span></a>
|
||||
<a>ETag: "bfe-93d9c4c0" <span class=u>④</span></a>
|
||||
Accept-Ranges: bytes
|
||||
<a>Content-Length: 3070 <span>⑤</span></a>
|
||||
<a>Cache-Control: max-age=86400 <span>⑥</span></a>
|
||||
<a>Content-Length: 3070 <span class=u>⑤</span></a>
|
||||
<a>Cache-Control: max-age=86400 <span class=u>⑥</span></a>
|
||||
Expires: Mon, 01 Jun 2009 19:23:06 GMT
|
||||
Vary: Accept-Encoding
|
||||
Connection: close
|
||||
Content-Type: application/xml</samp>
|
||||
<a><samp class=p>>>> </samp><kbd>data = response.read()</kbd> <span>⑦</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>data = response.read()</kbd> <span class=u>⑦</span></a>
|
||||
<samp class=p>>>> </samp><kbd>len(data)</kbd>
|
||||
<samp>3070</samp></pre>
|
||||
<ol>
|
||||
@@ -282,7 +282,7 @@ reply: 'HTTP/1.1 200 OK'
|
||||
|
||||
<pre class=screen>
|
||||
# continued from the previous example
|
||||
<a><samp class=p>>>> </samp><kbd>print(response2.headers.as_string())</kbd> <span>①</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>print(response2.headers.as_string())</kbd> <span class=u>①</span></a>
|
||||
<samp>Date: Mon, 01 Jun 2009 03:58:00 GMT
|
||||
Server: Apache
|
||||
Last-Modified: Sun, 31 May 2009 22:51:11 GMT
|
||||
@@ -295,9 +295,9 @@ Vary: Accept-Encoding
|
||||
Connection: close
|
||||
Content-Type: application/xml</samp>
|
||||
<samp class=p>>>> </samp><kbd>data2 = response2.read()</kbd>
|
||||
<a><samp class=p>>>> </samp><kbd>len(data2)</kbd> <span>②</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>len(data2)</kbd> <span class=u>②</span></a>
|
||||
<samp>3070</samp>
|
||||
<a><samp class=p>>>> </samp><kbd>data2 == data</kbd> <span>③</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>data2 == data</kbd> <span class=u>③</span></a>
|
||||
<samp>True</samp></pre>
|
||||
<ol>
|
||||
<li>The server is still sending the same array of “smart” headers: <code>Cache-Control</code> and <code>Expires</code> to allow caching, <code>Last-Modified</code> and <code>ETag</code> to enable “not-modified” tracking. Even the <code>Vary: Accept-Encoding</code> header hints that the server would support compression, if only you would ask for it. But you didn’t.
|
||||
@@ -315,11 +315,11 @@ Content-Type: application/xml</samp>
|
||||
|
||||
<pre class=screen>
|
||||
<samp class=p>>>> </samp><kbd>import httplib2</kbd>
|
||||
<a><samp class=p>>>> </samp><kbd>h = httplib2.Http('.cache')</kbd> <span>①</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>response, content = h.request('http://diveintopython3.org/examples/feed.xml')</kbd> <span>②</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>response.status</kbd> <span>③</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>h = httplib2.Http('.cache')</kbd> <span class=u>①</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>response, content = h.request('http://diveintopython3.org/examples/feed.xml')</kbd> <span class=u>②</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>response.status</kbd> <span class=u>③</span></a>
|
||||
<samp>200</samp>
|
||||
<a><samp class=p>>>> </samp><kbd>content[:52]</kbd> <span>④</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>content[:52]</kbd> <span class=u>④</span></a>
|
||||
<samp>b"<?xml version='1.0' encoding='utf-8'?>\r\n<feed xmlns="</samp>
|
||||
<samp class=p>>>> </samp><kbd>len(content)</kbd>
|
||||
<samp>3070</samp></pre>
|
||||
@@ -331,7 +331,7 @@ Content-Type: application/xml</samp>
|
||||
</ol>
|
||||
|
||||
<blockquote class=note>
|
||||
<p><span>☞</span>You probably only need one <code>httplib2.Http</code> object. There are valid reasons for creating more than one, but you should only do so if you know why you need them. “I need to request data from two different <abbr>URL</abbr>s” is not a valid reason. Re-use the <code>Http</code> object and just call the <code>request()</code> method twice.
|
||||
<p><span class=u>☞</span>You probably only need one <code>httplib2.Http</code> object. There are valid reasons for creating more than one, but you should only do so if you know why you need them. “I need to request data from two different <abbr>URL</abbr>s” is not a valid reason. Re-use the <code>Http</code> object and just call the <code>request()</code> method twice.
|
||||
</blockquote>
|
||||
|
||||
<h3 id=httplib2-caching>How <code>httplib2</code> Handles Caching</h3>
|
||||
@@ -340,10 +340,10 @@ Content-Type: application/xml</samp>
|
||||
|
||||
<pre class=screen>
|
||||
# continued from the <a href=#introducing-httplib2>previous example</a>
|
||||
<a><samp class=p>>>> </samp><kbd>response2, content2 = h.request('http://diveintopython3.org/examples/feed.xml')</kbd> <span>①</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>response2.status</kbd> <span>②</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>response2, content2 = h.request('http://diveintopython3.org/examples/feed.xml')</kbd> <span class=u>①</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>response2.status</kbd> <span class=u>②</span></a>
|
||||
<samp>200</samp>
|
||||
<a><samp class=p>>>> </samp><kbd>content2[:52]</kbd> <span>③</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>content2[:52]</kbd> <span class=u>③</span></a>
|
||||
<samp>b"<?xml version='1.0' encoding='utf-8'?>\r\n<feed xmlns="</samp>
|
||||
<samp class=p>>>> </samp><kbd>len(content2)</kbd>
|
||||
<samp>3070</samp></pre>
|
||||
@@ -360,14 +360,14 @@ Content-Type: application/xml</samp>
|
||||
# Please exit out of the interactive shell
|
||||
# and launch a new one.
|
||||
<samp class=p>>>> </samp><kbd>import httplib2</kbd>
|
||||
<a><samp class=p>>>> </samp><kbd>httplib2.debuglevel = 1</kbd> <span>①</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>h = httplib2.Http('.cache')</kbd> <span>②</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>response, content = h.request('http://diveintopython3.org/examples/feed.xml')</kbd> <span>③</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>len(content)</kbd> <span>④</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>httplib2.debuglevel = 1</kbd> <span class=u>①</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>h = httplib2.Http('.cache')</kbd> <span class=u>②</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>response, content = h.request('http://diveintopython3.org/examples/feed.xml')</kbd> <span class=u>③</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>len(content)</kbd> <span class=u>④</span></a>
|
||||
<samp>3070</samp>
|
||||
<a><samp class=p>>>> </samp><kbd>response.status</kbd> <span>⑤</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>response.status</kbd> <span class=u>⑤</span></a>
|
||||
<samp>200</samp>
|
||||
<a><samp class=p>>>> </samp><kbd>response.fromcache</kbd> <span>⑥</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>response.fromcache</kbd> <span class=u>⑥</span></a>
|
||||
<samp>True</samp></pre>
|
||||
<ol>
|
||||
<li>Let’s turn on debugging and see <a href=#whats-on-the-wire>what’s on the wire</a>. This is the <code>httplib2</code> equivalent of turning on debugging in <code>http.client</code>. <code>httplib2</code> will print all the data being sent to the server and some key information being sent back.
|
||||
@@ -389,8 +389,8 @@ Content-Type: application/xml</samp>
|
||||
<pre class=screen>
|
||||
# continued from the previous example
|
||||
<samp class=p>>>> </samp><kbd>response2, content2 = h.request('http://diveintopython3.org/examples/feed.xml',</kbd>
|
||||
<a><samp class=p>... </samp><kbd> headers={'cache-control':'no-cache'})</kbd> <span>①</span></a>
|
||||
<a><samp>connect: (diveintopython3.org, 80) <span>②</span></a>
|
||||
<a><samp class=p>... </samp><kbd> headers={'cache-control':'no-cache'})</kbd> <span class=u>①</span></a>
|
||||
<a><samp>connect: (diveintopython3.org, 80) <span class=u>②</span></a>
|
||||
send: b'GET /examples/feed.xml HTTP/1.1
|
||||
Host: diveintopython3.org
|
||||
user-agent: Python-httplib2/$Rev: 259 $
|
||||
@@ -400,9 +400,9 @@ reply: 'HTTP/1.1 200 OK'
|
||||
…further debugging information omitted…</samp>
|
||||
<samp class=p>>>> </samp><kbd>response2.status</kbd>
|
||||
<samp>200</samp>
|
||||
<a><samp class=p>>>> </samp><kbd>response2.fromcache</kbd> <span>③</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>response2.fromcache</kbd> <span class=u>③</span></a>
|
||||
<samp>False</samp>
|
||||
<a><samp class=p>>>> </samp><kbd>print(dict(response2.items()))</kbd> <span>④</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>print(dict(response2.items()))</kbd> <span class=u>④</span></a>
|
||||
<samp>{'status': '200',
|
||||
'content-length': '3070',
|
||||
'content-location': 'http://diveintopython3.org/examples/feed.xml',
|
||||
@@ -434,14 +434,14 @@ reply: 'HTTP/1.1 200 OK'
|
||||
<samp class=p>>>> </samp><kbd>import httplib2</kbd>
|
||||
<samp class=p>>>> </samp><kbd>httplib2.debuglevel = 1</kbd>
|
||||
<samp class=p>>>> </samp><kbd>h = httplib2.Http('.cache')</kbd>
|
||||
<a><samp class=p>>>> </samp><kbd>response, content = h.request('http://diveintopython3.org/')</kbd> <span>①</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>response, content = h.request('http://diveintopython3.org/')</kbd> <span class=u>①</span></a>
|
||||
<samp>connect: (diveintopython3.org, 80)
|
||||
send: b'GET / HTTP/1.1
|
||||
Host: diveintopython3.org
|
||||
accept-encoding: deflate, gzip
|
||||
user-agent: Python-httplib2/$Rev: 259 $'
|
||||
reply: 'HTTP/1.1 200 OK'</samp>
|
||||
<a><samp class=p>>>> </samp><kbd>print(dict(response.items()))</kbd> <span>②</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>print(dict(response.items()))</kbd> <span class=u>②</span></a>
|
||||
<samp>{'-content-encoding': 'gzip',
|
||||
'accept-ranges': 'bytes',
|
||||
'connection': 'close',
|
||||
@@ -454,7 +454,7 @@ reply: 'HTTP/1.1 200 OK'</samp>
|
||||
'server': 'Apache',
|
||||
'status': '304',
|
||||
'vary': 'Accept-Encoding,User-Agent'}</samp>
|
||||
<a><samp class=p>>>> </samp><kbd>len(content)</kbd> <span>③</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>len(content)</kbd> <span class=u>③</span></a>
|
||||
<samp>6657</samp></pre>
|
||||
<ol>
|
||||
<li>Instead of the feed, this time we’re going to download the site’s home page, which is <abbr>HTML</abbr>. Since this is the first time you’lve ever requested this page, <code>httplib2</code> has little to work with, and it sends out a minimum of headers with the request.
|
||||
@@ -464,22 +464,22 @@ reply: 'HTTP/1.1 200 OK'</samp>
|
||||
|
||||
<pre class=screen>
|
||||
# continued from the previous example
|
||||
<a><samp class=p>>>> </samp><kbd>response, content = h.request('http://diveintopython3.org/')</kbd> <span>①</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>response, content = h.request('http://diveintopython3.org/')</kbd> <span class=u>①</span></a>
|
||||
<samp>connect: (diveintopython3.org, 80)
|
||||
send: b'GET / HTTP/1.1
|
||||
Host: diveintopython3.org
|
||||
<a>if-none-match: "7f806d-1a01-9fb97900" <span>②</span></a>
|
||||
<a>if-modified-since: Tue, 02 Jun 2009 02:51:48 GMT <span>③</span></a>
|
||||
<a>if-none-match: "7f806d-1a01-9fb97900" <span class=u>②</span></a>
|
||||
<a>if-modified-since: Tue, 02 Jun 2009 02:51:48 GMT <span class=u>③</span></a>
|
||||
accept-encoding: deflate, gzip
|
||||
user-agent: Python-httplib2/$Rev: 259 $'
|
||||
<a>reply: 'HTTP/1.1 304 Not Modified' <span>④</span></a></samp>
|
||||
<a><samp class=p>>>> </samp><kbd>response.fromcache</kbd> <span>⑤</span></a>
|
||||
<a>reply: 'HTTP/1.1 304 Not Modified' <span class=u>④</span></a></samp>
|
||||
<a><samp class=p>>>> </samp><kbd>response.fromcache</kbd> <span class=u>⑤</span></a>
|
||||
<samp>True</samp>
|
||||
<a><samp class=p>>>> </samp><kbd>response.status</kbd> <span>⑥</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>response.status</kbd> <span class=u>⑥</span></a>
|
||||
<samp>200</samp>
|
||||
<a><samp class=p>>>> </samp><kbd>response.dict['status']</kbd> <span>⑦</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>response.dict['status']</kbd> <span class=u>⑦</span></a>
|
||||
<samp>'304'</samp>
|
||||
<a><samp class=p>>>> </samp><kbd>len(content)</kbd> <span>⑧</span></a>
|
||||
<a><samp class=p>>>> </samp><kbd>len(content)</kbd> <span class=u>⑧</span></a>
|
||||
<samp>6657</samp></pre>
|
||||
<ol>
|
||||
<li>You request the same page again, with the same <code>Http</code> object (and the same local cache).
|
||||
@@ -501,11 +501,11 @@ user-agent: Python-httplib2/$Rev: 259 $'
|
||||
<samp>connect: (diveintopython3.org, 80)
|
||||
send: b'GET / HTTP/1.1
|
||||
Host: diveintopython3.org
|
||||
<a>accept-encoding: deflate, gzip <span>①</span></a>
|
||||
<a>accept-encoding: deflate, gzip <span class=u>①</span></a>
|
||||
user-agent: Python-httplib2/$Rev: 259 $'
|
||||
reply: 'HTTP/1.1 200 OK'</samp>
|
||||
<samp class=p>>>> </samp><kbd>print(dict(response.items()))</kbd>
|
||||
<samp><a>{'-content-encoding': 'gzip', <span>②</span></a>
|
||||
<samp><a>{'-content-encoding': 'gzip', <span class=u>②</span></a>
|
||||
'accept-ranges': 'bytes',
|
||||
'connection': 'close',
|
||||
'content-length': '6657',
|
||||
@@ -681,7 +681,8 @@ reply: 'HTTP/1.1 301 Moved Permanently'</samp>
|
||||
<li><a href=http://code.google.com/p/doctype/wiki/ArticleHttpCaching>How to control caching with <abbr>HTTP</abbr> headers</a> on Google Doctype
|
||||
</ul>
|
||||
|
||||
<p class=v><a rel=prev class=todo><span>☜</span></a> <a rel=next class=todo><span>☞</span></a>
|
||||
<p class=v><a rel=prev class=todo><span class=u>☜</span></a> <a rel=next class=todo><span class=u>☞</span></a>
|
||||
<p class=c>© 2001–9 <a href=about.html>Mark Pilgrim</a>
|
||||
<script src=j/jquery.js></script>
|
||||
<script src=j/prettify.js></script>
|
||||
<script src=j/dip3.js></script>
|
||||
|
||||
Reference in New Issue
Block a user