# httplib2 / libhttplib2.tex

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It may be found online % at: % % http://www.python.org/doc/current/doc/doc.html % ==== 0. ==== % Copy this file to /lib.tex, and edit that file % according to the instructions below. % ==== 1. ==== % The section prologue. Give the section a title and provide some % meta-information. References to the module should use % \refbimodindex, \refstmodindex, \refexmodindex or \refmodindex, as % appropriate. \section{\module{httplib2} A comprehensive HTTP client library. } % Choose one of these to specify the module module name. If there's % an underscore in the name, use % \declaremodule[modname]{...}{mod_name} instead. % \declaremodule{}{httplib2} % not standard, in Python % Portability statement: Uncomment and fill in the parameter to specify the % availability of the module. The parameter can be Unix, IRIX, SunOS, Mac, % Windows, or lots of other stuff. When Mac'' is specified, the availability % statement will say Macintosh'' and the Module Index may say Mac''. % Please use a name that has already been used whenever applicable. If this % is omitted, no availability statement is produced or implied. % % \platform{Unix} % These apply to all modules, and may be given more than once: \moduleauthor{Joe Gregorio}{joe@bitworking.org} % Author of the module code; % omit if not known. \sectionauthor{Joe Gregorio}{joe@bitworking.org} % Author of the documentation, % even if not a module section. % Leave at least one blank line after this, to simplify ad-hoc tools % that are sometimes used to massage these files. \modulesynopsis{A comprehensive HTTP client library, \module{httplib2} supports many features left out of other HTTP libraries.} % ==== 2. ==== % Give a short overview of what the module does. % If it is platform specific, mention this. % Mention other important restrictions or general operating principles. % For example: The \module{httplib2} module is a comprehensive HTTP client library with the following features: \begin{description} \item[HTTP and HTTPS] HTTPS support is only available if the socket module was compiled with SSL support. \item[Keep-Alive] Supports HTTP 1.1 Keep-Alive, keeping the socket open and performing multiple requests over the same connection if possible. \item[Authentication] The following three types of HTTP Authentication are supported. These can be used over both HTTP and HTTPS. \begin{itemize} \item Digest \item Basic \item WSSE \end{itemize} \item[Caching] The module can optionally operate with a private cache that understands the Cache-Control: header and uses both the ETag and Last-Modified cache validators. \item[All Methods] The module can handle any HTTP request method, not just GET and POST. \item[Redirects] Automatically follows 3XX redirects on GETs. \item[Compression] Handles both 'deflate' and 'gzip' types of compression. \item[Proxies] If the Socksipy module is installed then httplib2 can handle sock4, sock5 and http proxies. \item[Lost update support] Automatically adds back ETags into PUT requests to resources we have already cached. This implements Section 3.2 of Detecting the Lost Update Problem Using Unreserved Checkout \end{description} % ==== 3. ==== % List the public functions defined by the module. Begin with a % standard phrase. You may also list the exceptions and other data % items defined in the module, insofar as they are important for the % user. The \module{httplib2} module defines the following variables: % ---- 3.2. ---- % Data items are described using a datadesc'' block. This has only % one parameter: the item's name. \begin{datadesc}{debuglevel} The amount of debugging information to print. The default is 0. \end{datadesc} % --- 3.3. --- % Exceptions are described using a excdesc'' block. This has only % one parameter: the exception name. Exceptions defined as classes in % the source code should be documented using this environment, but % constructor parameters must be omitted. The \module{httplib2} module may raise the following Exceptions. Note that there is an option that turns exceptions into normal responses with an HTTP status code indicating an error occured. See \member{Http.force_exception_to_status_code} \begin{excdesc}{HttpLib2Error} The Base Exception for all exceptions raised by httplib2. \end{excdesc} \begin{excdesc}{RedirectMissingLocation} A 3xx redirect response code was provided but no Location: header was provided to point to the new location. \end{excdesc} \begin{excdesc}{RedirectLimit} The maximum number of redirections was reached without coming to a final URI. \end{excdesc} \begin{excdesc}{ServerNotFoundError} Unable to resolve the host name given. \end{excdesc} \begin{excdesc}{RelativeURIError} A relative, as opposed to an absolute URI, was passed into request(). \end{excdesc} \begin{excdesc}{FailedToDecompressContent} The headers claimed that the content of the response was compressed but the decompression algorithm applied to the content failed. \end{excdesc} \begin{excdesc}{UnimplementedDigestAuthOptionError} The server requested a type of Digest authentication that we are unfamiliar with. \end{excdesc} \begin{excdesc}{UnimplementedHmacDigestAuthOptionError} The server requested a type of HMACDigest authentication that we are unfamiliar with. \end{excdesc} % ---- 3.4. ---- % Other standard environments: % % classdesc - Python classes; same arguments are funcdesc % methoddesc - methods, like funcdesc but has an optional parameter % to give the type name: \begin{methoddesc}[mytype]{name}{args} % By default, the type name will be the name of the % last class defined using classdesc. The type name % is required if the type is implemented in C (because % there's no classdesc) or if the class isn't directly % documented (if it's private). % memberdesc - data members, like datadesc, but with an optional % type name like methoddesc. \begin{classdesc}{Http}{\optional{cache=None}, \optional{timeout=None}, \optional{proxy_info=None}} The class that represents a client HTTP interface. The \var{cache} parameter is either the name of a directory to be used as a flat file cache, or it must an object that implements the required caching interface. The \var{timeout} parameter is the socket level timeout. The \var{proxy_info} is an instance of \class{ProxyInfo} and is supplied if a proxy is to be used. Note that the Socksipy module must be installed for proxy support to work. \end{classdesc} \begin{classdesc}{Response}{info} Response is a subclass of \class{dict} and instances of this class are returned from calls to Http.request. The \var{info} parameter is either an \class{rfc822.Message} or an \class{httplib.HTTPResponse} object. \end{classdesc} \begin{classdesc}{FileCache}{dir_name, \optional{safe=safename}} FileCache implements a Cache as a directory of files. The \var{dir_name} parameter is the name of the directory to use. If the directory does not exist then FileCache attempts to create the directory. The optional \var{safe} parameter is a funtion which generates the cache filename for each URI. A FileCache object is constructed and used for caching when you pass a directory name into the constructor of \class{Http}. \end{classdesc} \begin{classdesc}{ProxyInfo}{proxy_type, proxy_host, proxy_port, \optional{proxy_rdns=None}, \optional{proxy_user=None}, \optional{proxy_pass=None}} The parameter \var{proxy_type} must be set to one of socks.PROXY_TYPE_XXX constants. The \var{proxy_host} and \var{proxy_port} must be set to the location of the proxy. The optional \var{proxy_rdns} should be set to True if the DNS server on the proxy should be used. The \var{proxy_user} and \var{proxy_pass} are supplied when the proxy is protected by authentication. \end{classdesc} % If your module defines new object types (for a built-in module) or % classes (for a module written in Python), you should list the % methods and instance variables (if any) of each type or class in a % separate subsection. \subsection{Http Objects} \label{http-objects} % This label is generally useful for referencing this section, but is % also used to give a filename when generating HTML. Http objects have the following methods: \begin{methoddesc}[Http]{request}{uri, \optional{method="GET", body=None, headers=None, redirections=DEFAULT_MAX_REDIRECTS, connection_type=None}} Performs a single HTTP request. The \var{uri} is the URI of the HTTP resource and can begin with either \code{http} or \code{https}. The value of \var{uri} must be an absolute URI. The \var{method} is the HTTP method to perform, such as \code{GET}, \code{POST}, \code{DELETE}, etc. There is no restriction on the methods allowed. The \var{body} is the entity body to be sent with the request. It is a string object. Any extra headers that are to be sent with the request should be provided in the \var{headers} dictionary. The maximum number of redirect to follow before raising an exception is \var{redirections}. The default is 5. The \var{connection_type} is the type of connection object to use. The supplied class should implement the interface of httplib.HTTPConnection. The return value is a tuple of (response, content), the first being and instance of the \class{Response} class, the second being a string that contains the response entity body. \end{methoddesc} \begin{methoddesc}[Http]{add_credentials}{name, password, \optional{domain=None}} Adds a name and password that will be used when a request requires authentication. Supplying the optional \var{domain} name will restrict these credentials to only be sent to the specified domain. If \var{domain} is not specified then the given credentials will be used to try to satisfy every HTTP 401 challenge. \end{methoddesc} \begin{methoddesc}[Http]{add_certificate}{key, cert, domain} Add a \var{key} and \var{cert} that will be used for an SSL connection to the specified domain. \var{keyfile} is the name of a PEM formatted file that contains your private key. \var{certfile} is a PEM formatted certificate chain file. \end{methoddesc} \begin{methoddesc}[Http]{clear_credentials}{} Remove all the names and passwords used for authentication. \end{methoddesc} \begin{memberdesc}[Http]{follow_redirects} If \code{True}, which is the default, safe redirects are followed, where safe means that the client is only doing a \code{GET} or \code{HEAD} on the URI to which it is being redirected. If \code{False} then no redirects are followed. Note that a False 'follow_redirects' takes precedence over a True 'follow_all_redirects'. Another way of saying that is for 'follow_all_redirects' to have any affect, 'follow_redirects' must be True. \end{memberdesc} \begin{memberdesc}[Http]{follow_all_redirects} If \code{False}, which is the default, only safe redirects are followed, where safe means that the client is only doing a \code{GET} or \code{HEAD} on the URI to which it is being redirected. If \code{True} then all redirects are followed. Note that a False 'follow_redirects' takes precedence over a True 'follow_all_redirects'. Another way of saying that is for 'follow_all_redirects' to have any affect, 'follow_redirects' must be True. \end{memberdesc} \begin{memberdesc}[Http]{force_exception_to_status_code} If \code{True}, which is the default, then no \module{httplib2} exceptions will be thrown. Instead, those error conditions will be turned into \class{Response} objects that will be returned normally. If \code{False}, then exceptions will be thrown. \end{memberdesc} \begin{memberdesc}[Http]{ignore_etag} Defaults to \code{False}. If \code{True}, then any etags present in the cached response are ignored when processing the current request, i.e. httplib2 does \strong{not} use 'if-match' for PUT or 'if-none-match' when GET or HEAD requests are made. This is mainly to deal with broken servers which supply an etag, but change it capriciously. \end{memberdesc} \subsection{Cache Objects} \label{cache-objects} % This label is generally useful for referencing this section, but is % also used to give a filename when generating HTML. If you wish to supply your own caching implementation then you will need to pass in an object that supports the following methods. Note that the \module{memcache} module supports this interface natively. \begin{methoddesc}[Cache]{get}{key} Takes a string \var{key} and returns the value as a string. \end{methoddesc} \begin{methoddesc}[Cache]{set}{key, value} Takes a string \var{key} and \var{value} and stores it in the cache. \end{methoddesc} \begin{methoddesc}[Cache]{delete}{key} Deletes the cached value stored at \var{key}. The value of \var{key} is a string. \end{methoddesc} \subsection{Response Objects} \label{response-objects} % This label is generally useful for referencing this section, but is % also used to give a filename when generating HTML. Response objects are derived from \class{dict} and map header names (lower case with the trailing colon removed) to header values. In addition to the dict methods a Response object also has: \begin{memberdesc}[Response]{fromcache} If \code{true} the the response was returned from the cache. \end{memberdesc} \begin{memberdesc}[Response]{version} The version of HTTP that the server supports. A value of 11 means '1.1'. \end{memberdesc} \begin{memberdesc}[Response]{status} The numerical HTTP status code returned in the response. \end{memberdesc} \begin{memberdesc}[Response]{reason} The human readable component of the HTTP response status code. \end{memberdesc} \begin{memberdesc}[Response]{previous} If redirects are followed then the \class{Response} object returned is just for the very last HTTP request and \var{previous} points to the previous \class{Response} object. In this manner they form a chain going back through the responses to the very first response. Will be \code{None} if there are no previous respones. \end{memberdesc} The Response object also populates the header \code{content-location}, that contains the URI that was ultimately requested. This is useful if redirects were encountered, you can determine the ultimate URI that the request was sent to. All Response objects contain this key value, including \code{previous} responses so you can determine the entire chain of redirects. If \member{Http.force_exception_to_status_code} is \code{True} and the number of redirects has exceeded the number of allowed number of redirects then the \class{Response} object will report the error in the status code, but the complete chain of previous responses will still be in tact. % ==== 4. ==== % Now is probably a good time for a complete example. (Alternatively, % an example giving the flavor of the module may be given before the % detailed list of functions.) \subsection{Examples \label{httplib2-example}} To do a simple \code{GET} request just supply the absolute URI of the resource: \begin{verbatim} import httplib2 h = httplib2.Http() resp, content = h.request("http://bitworking.org/") assert resp.status == 200 assert resp['content-type'] == 'text/html' \end{verbatim} Here is more complex example that does a PUT of some text to a resource that requires authentication. The Http instance also uses a file cache in the directory \code{.cache}. \begin{verbatim} import httplib2 h = httplib2.Http(".cache") h.add_credentials('name', 'password') resp, content = h.request("https://example.org/chap/2", "PUT", body="This is text", headers={'content-type':'text/plain'} ) \end{verbatim} Here is an example that connects to a server that supports the Atom Publishing Protocol. \begin{verbatim} import httplib2 h = httplib2.Http() h.add_credentials(myname, mypasswd) h.follow_all_redirects = True headers = {'Content-Type': 'application/atom+xml'} body = """ Atom-Powered Robots Run Amok urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a 2003-12-13T18:30:02Z John Doe Some text. """ uri = "http://www.example.com/collection/" resp, content = h.request(uri, "POST", body=body, headers=headers) \end{verbatim} % Note that there is no trailing ">>> " prompt shown. Here is an example of providing data to an HTML form processor. In this case we presume this is a POST form. We need to take our data and format it as "application/x-www-form-urlencoded" data and use that as a body for a POST request. \begin{verbatim} >>> import httplib2 >>> import urllib >>> data = {'name': 'fred', 'address': '123 shady lane'} >>> body = urllib.urlencode(data) >>> body 'name=fred&address=123+shady+lane' >>> h = httplib2.Http() >>> resp, content = h.request("http://example.com", method="POST", body=body) \end{verbatim} % Note that there is no trailing ">>> " prompt shown. Here is an example of using a proxy server: \begin{verbatim} import httplib2 import socks httplib2.debuglevel=4 h = httplib2.Http(proxy_info = httplib2.ProxyInfo(socks.PROXY_TYPE_HTTP, 'localhost', 8000)) r,c = h.request("http://bitworking.org/news/") \end{verbatim}