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Documentation of classes that access web-services on behalf of CodeSnip.
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DelphiDabbler Standard Web Service
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A DelphiDabbler Standard Web Service object has the following attributes:
* It connects to the web service over HTTP.
* Requests are made using HTTP Post. Information is POSTed to the web service
either in the form of URL encoded query strings or as raw post data. Which
format is used depends on web service.
* Web services respond with plain text. The text is encoded as the default for
the server which defaults to ISO-8859-1.
* The response text is split into lines by CRLF pairs. There is always at least
one line in a response. Any trailing CRLFs should be stripped from the
response text.
* The first line of the response always contains a status code. A zero code
indicates success, while non-zero codes indicate an error. The meaning of the
error code is specific to the web service. Consult the documentation of the
service for details.
* A successful response *may* include further information, starting from the
second line of the text. The meaning of this text depends on the web service.
Consult the documentation of the service for details.
* An error response *must* include an error message starting from the second
line of the text. Error messages *may* have more than one line.
Some web services also require that the correct user agent string for the
service is used. Such web services return HTTP error 403 if the user agent is
not valid. User agent strings *may* also specify the version of the web service
to be used.
The response format in ABNF is:
response = status_code [CRLF data] [CRLF]
status_code = success_code / error_code
success_code = "0"
error_code = ["-"] 1*DIGIT
data = data_line [CRLF data]
data_line = 0*[VCHAR | WSP]
The class TStdWebService, which inherits from TBaseWebService, provides core
functionality for working with standard web services. In particular it:
* Provides methods for posting data in the form of query strings to the web
service.
* Handles the response, checking the status code. When an error code is received
an exception is raised using the error message from the response. In the case
of a successful response the status code line is stripped and the remaining
data made available for processing by descendant classes.
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