php|architect's Guide to Web Scraping with PHP - Wind Business ...

66 ” PEAR::HTTP_Client
U sing the Client
HTTP_Client persists explicit sets of headers and requests parameters across multiple
requests, which are set using the setDefaultHeader and setRequestParameter methods
respectively. The client constructor also accepts arrays of these. Default headers
and request parameters can be cleared by calling reset on the client instance.
Internally, the client class actually creates a new instance of HTTP_Request per request.
The request operation is set depending on which of the client instance methods
are called; get, head, and post are supported.
The capabilities of the client described up to this point can all be accomplished
by reusing the same request instance for multiple requests. H o wever, the client also
handles two things that the request class does not: cookies and redirects.
By default, cookies are persisted automatically across requests without any additional
configuration. HTTP_Client_CookieManager is used internally for this. F or custom
cookie handling, this class can be extended and an instance of it passed as the
third parameter to the client constructor. If this is done, that instance will be used
rather than an instance of the native cookie manager class being created by default.
The maximum number of redirects to process can be set using the setMaxRedirects
method of the client class. Internally, requests will be created and sent as needed to
process the redirect until a non-redirecting response is received or the maximum
redirect limit is reached. In the former case, the client method being called will return
an integer containing the response code rather than true as the request class
does. In the latter case, the client method will return an error instance. N ote that
the client class will process redirects contained in meta tags of HTML documents in
addition to those performed at the HTTP level.
To retrieve information for the last response received, use the currentResponse
method of the client instance. It will return an associative array containing the keys
’code’, ’headers’, and ’body’ with values corresponding to the return values of request
methods getResponseCode, getResponseHeader, and getResponseBody respectively.
By default, all responses are stored and can be accessed individually as sho wn belo
w . To disable storage of all responses except the last one, call enableHistory on the
client instance and pass it false.