lwp.3

视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.

\&
\&  # Pass request to the user agent and get a response back
\&  my $res = $ua\->request($req);
\&
\&  # Check the outcome of the response
\&  if ($res\->is_success) {
\&      print $res\->content;
\&  }
\&  else {
\&      print $res\->status_line, "\en";
\&  }
.Ve
.PP
The \f(CW$ua\fR is created once when the application starts up.  New request
objects should normally created for each request sent.
.SH "NETWORK SUPPORT"
.IX Header "NETWORK SUPPORT"
This section discusses the various protocol schemes and
the \s-1HTTP\s0 style methods that headers may be used for each.
.PP
For all requests, a \*(L"User-Agent\*(R" header is added and initialized from
the \f(CW$ua\fR\->agent attribute before the request is handed to the network
layer.  In the same way, a \*(L"From\*(R" header is initialized from the
\&\f(CW$ua\fR\->from attribute.
.PP
For all responses, the library adds a header called \*(L"Client-Date\*(R".
This header holds the time when the response was received by
your application.  The format and semantics of the header are the
same as the server created \*(L"Date\*(R" header.  You may also encounter other
\&\*(L"Client-XXX\*(R" headers.  They are all generated by the library
internally and are not received from the servers.
.Sh "\s-1HTTP\s0 Requests"
.IX Subsection "HTTP Requests"
\&\s-1HTTP\s0 requests are just handed off to an \s-1HTTP\s0 server and it
decides what happens.  Few servers implement methods beside the usual
\&\*(L"\s-1GET\s0\*(R", \*(L"\s-1HEAD\s0\*(R", \*(L"\s-1POST\s0\*(R" and \*(L"\s-1PUT\s0\*(R", but CGI-scripts may implement
any method they like.
.PP
If the server is not available then the library will generate an
internal error response.
.PP
The library automatically adds a \*(L"Host\*(R" and a \*(L"Content-Length\*(R" header
to the \s-1HTTP\s0 request before it is sent over the network.
.PP
For a \s-1GET\s0 request you might want to add a \*(L"If-Modified-Since\*(R" or
\&\*(L"If-None-Match\*(R" header to make the request conditional.
.PP
For a \s-1POST\s0 request you should add the \*(L"Content-Type\*(R" header.  When you
try to emulate \s-1HTML\s0 <\s-1FORM\s0> handling you should usually let the value
of the \*(L"Content-Type\*(R" header be \*(L"application/x\-www\-form\-urlencoded\*(R".
See lwpcook for examples of this.
.PP
The libwww-perl \s-1HTTP\s0 implementation currently support the \s-1HTTP/1\s0.1
and \s-1HTTP/1\s0.0 protocol.
.PP
The library allows you to access proxy server through \s-1HTTP\s0.  This
means that you can set up the library to forward all types of request
through the \s-1HTTP\s0 protocol module.  See LWP::UserAgent for
documentation of this.
.Sh "\s-1HTTPS\s0 Requests"
.IX Subsection "HTTPS Requests"
\&\s-1HTTPS\s0 requests are \s-1HTTP\s0 requests over an encrypted network connection
using the \s-1SSL\s0 protocol developed by Netscape.  Everything about \s-1HTTP\s0
requests above also apply to \s-1HTTPS\s0 requests.  In addition the library
will add the headers \*(L"Client-SSL-Cipher\*(R", \*(L"Client-SSL-Cert-Subject\*(R" and
\&\*(L"Client-SSL-Cert-Issuer\*(R" to the response.  These headers denote the
encryption method used and the name of the server owner.
.PP
The request can contain the header \*(L"If-SSL-Cert-Subject\*(R" in order to
make the request conditional on the content of the server certificate.
If the certificate subject does not match, no request is sent to the
server and an internally generated error response is returned.  The
value of the \*(L"If-SSL-Cert-Subject\*(R" header is interpreted as a Perl
regular expression.
.Sh "\s-1FTP\s0 Requests"
.IX Subsection "FTP Requests"
The library currently supports \s-1GET\s0, \s-1HEAD\s0 and \s-1PUT\s0 requests.  \s-1GET\s0
retrieves a file or a directory listing from an \s-1FTP\s0 server.  \s-1PUT\s0
stores a file on a ftp server.
.PP
You can specify a ftp account for servers that want this in addition
to user name and password.  This is specified by including an \*(L"Account\*(R"
header in the request.
.PP
User name/password can be specified using basic authorization or be
encoded in the \s-1URL\s0.  Failed logins return an \s-1UNAUTHORIZED\s0 response with
\&\*(L"WWW-Authenticate: Basic\*(R" and can be treated like basic authorization
for \s-1HTTP\s0.
.PP
The library supports ftp \s-1ASCII\s0 transfer mode by specifying the \*(L"type=a\*(R"
parameter in the \s-1URL\s0. It also supports transfer of ranges for \s-1FTP\s0 transfers
using the \*(L"Range\*(R" header.
.PP
Directory listings are by default returned unprocessed (as returned
from the ftp server) with the content media type reported to be
\&\*(L"text/ftp\-dir\-listing\*(R". The \f(CW\*(C`File::Listing\*(C'\fR module provides methods
for parsing of these directory listing.
.PP
The ftp module is also able to convert directory listings to \s-1HTML\s0 and
this can be requested via the standard \s-1HTTP\s0 content negotiation
mechanisms (add an \*(L"Accept: text/html\*(R" header in the request if you
want this).
.PP
For normal file retrievals, the \*(L"Content-Type\*(R" is guessed based on the
file name suffix. See LWP::MediaTypes.
.PP
The \*(L"If-Modified-Since\*(R" request header works for servers that implement
the \s-1MDTM\s0 command.  It will probably not work for directory listings though.
.PP
Example:
.PP
.Vb 2
\&  $req = HTTP::Request\->new(GET => \*(Aqftp://me:[e-mail]/\*(Aq);
\&  $req\->header(Accept => "text/html, */*;q=0.1");
.Ve
.Sh "News Requests"
.IX Subsection "News Requests"
Access to the \s-1USENET\s0 News system is implemented through the \s-1NNTP\s0
protocol.  The name of the news server is obtained from the
\&\s-1NNTP_SERVER\s0 environment variable and defaults to \*(L"news\*(R".  It is not
possible to specify the hostname of the \s-1NNTP\s0 server in news: URLs.
.PP
The library supports \s-1GET\s0 and \s-1HEAD\s0 to retrieve news articles through the
\&\s-1NNTP\s0 protocol.  You can also post articles to newsgroups by using
(surprise!) the \s-1POST\s0 method.
.PP
\&\s-1GET\s0 on newsgroups is not implemented yet.
.PP
Examples:
.PP
.Vb 1
\&  $req = HTTP::Request\->new(GET => \*(Aqnews:[e-mail]\*(Aq);
\&
\&  $req = HTTP::Request\->new(POST => \*(Aqnews:comp.lang.perl.test\*(Aq);
\&  $req\->header(Subject => \*(AqThis is a test\*(Aq,
\&               From    => \*([e-mail]\*(Aq);
\&  $req\->content(<<EOT);
\&  This is the content of the message that we are sending to
\&  the world.
\&  EOT
.Ve
.Sh "Gopher Request"
.IX Subsection "Gopher Request"
The library supports the \s-1GET\s0 and \s-1HEAD\s0 methods for gopher requests.  All
request header values are ignored.  \s-1HEAD\s0 cheats and returns a
response without even talking to server.
.PP
Gopher menus are always converted to \s-1HTML\s0.
.PP
The response \*(L"Content-Type\*(R" is generated from the document type
encoded (as the first letter) in the request \s-1URL\s0 path itself.
.PP
Example:
.PP
.Vb 1
\&  $req = HTTP::Request\->new(GET => \*(Aqgopher://gopher.sn.no/\*(Aq);
.Ve
.Sh "File Request"
.IX Subsection "File Request"
The library supports \s-1GET\s0 and \s-1HEAD\s0 methods for file requests.  The
\&\*(L"If-Modified-Since\*(R" header is supported.  All other headers are
ignored.  The \fIhost\fR component of the file \s-1URL\s0 must be empty or set
to \*(L"localhost\*(R".  Any other \fIhost\fR value will be treated as an error.
.PP
Directories are always converted to an \s-1HTML\s0 document.  For normal
files, the \*(L"Content-Type\*(R" and \*(L"Content-Encoding\*(R" in the response are
guessed based on the file suffix.
.PP
Example:
.PP
.Vb 1
\&  $req = HTTP::Request\->new(GET => \*(Aqfile:/etc/passwd\*(Aq);
.Ve
.Sh "Mailto Request"
.IX Subsection "Mailto Request"
You can send (aka \*(L"\s-1POST\s0\*(R") mail messages using the library.  All
headers specified for the request are passed on to the mail system.
The \*(L"To\*(R" header is initialized from the mail address in the \s-1URL\s0.
.PP
Example:
.PP
.Vb 3
\&  $req = HTTP::Request\->new(POST => \*(Aqmailto:[e-mail]\*(Aq);
\&  $req\->header(Subject => "subscribe");
\&  $req\->content("Please subscribe me to the libwww\-perl mailing list!\en");
.Ve
.Sh "\s-1CPAN\s0 Requests"
.IX Subsection "CPAN Requests"
URLs with scheme \f(CW\*(C`cpan:\*(C'\fR are redirected to the a suitable \s-1CPAN\s0
mirror.  If you have your own local mirror of \s-1CPAN\s0 you might tell \s-1LWP\s0
to use it for \f(CW\*(C`cpan:\*(C'\fR URLs by an assignment like this:
.PP
.Vb 1
\&  $LWP::Protocol::cpan::CPAN = "file:/local/CPAN/";
.Ve
.PP
Suitable \s-1CPAN\s0 mirrors are also picked up from the configuration for
the \s-1CPAN\s0.pm, so if you have used that module a suitable mirror should
be picked automatically.  If neither of these apply, then a redirect
to the generic \s-1CPAN\s0 http location is issued.
.PP
Example request to download the newest perl:
.PP
.Vb 1
\&  $req = HTTP::Request\->new(GET => "cpan:src/latest.tar.gz");
.Ve
.SH "OVERVIEW OF CLASSES AND PACKAGES"
.IX Header "OVERVIEW OF CLASSES AND PACKAGES"
This table should give you a quick overview of the classes provided by the
library. Indentation shows class inheritance.
.PP
.Vb 8
\& LWP::MemberMixin   \-\- Access to member variables of Perl5 classes
\&   LWP::UserAgent   \-\- WWW user agent class
\&     LWP::RobotUA   \-\- When developing a robot applications
\&   LWP::Protocol          \-\- Interface to various protocol schemes
\&     LWP::Protocol::http  \-\- http:// access
\&     LWP::Protocol::file  \-\- file:// access
\&     LWP::Protocol::ftp   \-\- ftp:// access
\&     ...
\&
\& LWP::Authen::Basic \-\- Handle 401 and 407 responses
\& LWP::Authen::Digest
\&
\& HTTP::Headers      \-\- MIME/RFC822 style header (used by HTTP::Message)
\& HTTP::Message      \-\- HTTP style message
\&   HTTP::Request    \-\- HTTP request
\&   HTTP::Response   \-\- HTTP response
\& HTTP::Daemon       \-\- A HTTP server class
\&
\& WWW::RobotRules    \-\- Parse robots.txt files
\&   WWW::RobotRules::AnyDBM_File \-\- Persistent RobotRules
\&
\& Net::HTTP          \-\- Low level HTTP client
.Ve
.PP
The following modules provide various functions and definitions.
.PP
.Vb 9
\& LWP                \-\- This file.  Library version number and documentation.
\& LWP::MediaTypes    \-\- MIME types configuration (text/html etc.)
\& LWP::Debug         \-\- Debug logging module
\& LWP::Simple        \-\- Simplified procedural interface for common functions
\& HTTP::Status       \-\- HTTP status code (200 OK etc)
\& HTTP::Date         \-\- Date parsing module for HTTP date formats
\& HTTP::Negotiate    \-\- HTTP content negotiation calculation
\& File::Listing      \-\- Parse directory listings
\& HTML::Form         \-\- Processing for <form>s in HTML documents
.Ve
.SH "MORE DOCUMENTATION"
.IX Header "MORE DOCUMENTATION"
All modules contain detailed information on the interfaces they
provide.  The \fIlwpcook\fR manpage is the libwww-perl cookbook that contain
examples of typical usage of the library.  You might want to take a
look at how the scripts \f(CW\*(C`lwp\-request\*(C'\fR, \f(CW\*(C`lwp\-rget\*(C'\fR and \f(CW\*(C`lwp\-mirror\*(C'\fR
are implemented.
.SH "ENVIRONMENT"
.IX Header "ENVIRONMENT"
The following environment variables are used by \s-1LWP:\s0
.IP "\s-1HOME\s0" 4
.IX Item "HOME"
The \f(CW\*(C`LWP::MediaTypes\*(C'\fR functions will look for the \fI.media.types\fR and
\&\fI.mime.types\fR files relative to you home directory.
.IP "http_proxy" 4
.IX Item "http_proxy"
.PD 0
.IP "ftp_proxy" 4
.IX Item "ftp_proxy"
.IP "xxx_proxy" 4
.IX Item "xxx_proxy"
.IP "no_proxy" 4
.IX Item "no_proxy"
.PD
These environment variables can be set to enable communication through
a proxy server.  See the description of the \f(CW\*(C`env_proxy\*(C'\fR method in
LWP::UserAgent.
.IP "\s-1PERL_LWP_USE_HTTP_10\s0" 4
.IX Item "PERL_LWP_USE_HTTP_10"
Enable the old \s-1HTTP/1\s0.0 protocol driver instead of the new \s-1HTTP/1\s0.1
driver.  You might want to set this to a \s-1TRUE\s0 value if you discover
that your old \s-1LWP\s0 applications fails after you installed \s-1LWP\-5\s0.60 or
better.
.IP "\s-1PERL_HTTP_URI_CLASS\s0" 4
.IX Item "PERL_HTTP_URI_CLASS"
Used to decide what \s-1URI\s0 objects to instantiate.  The default is \f(CW\*(C`URI\*(C'\fR.
You might want to set it to \f(CW\*(C`URI::URL\*(C'\fR for compatibility with old times.
.SH "AUTHORS"
.IX Header "AUTHORS"
\&\s-1LWP\s0 was made possible by contributions from Adam Newby, Albert
Dvornik, Alexandre Duret-Lutz, Andreas Gustafsson, Andreas Ko\*:nig,
Andrew Pimlott, Andy Lester, Ben Coleman, Benjamin Low, Ben Low, Ben
Tilly, Blair Zajac, Bob Dalgleish, BooK, Brad Hughes, Brian
J. Murrell, Brian McCauley, Charles C. Fu, Charles Lane, Chris Nandor,
Christian Gilmore, Chris W. Unger, Craig Macdonald, Dale Couch, Dan
Kubb, Dave Dunkin, Dave W. Smith, David Coppit, David Dick, David
D. Kilzer, Doug MacEachern, Edward Avis, erik, Gary Shea, Gisle Aas,
Graham Barr, Gurusamy Sarathy, Hans de Graaff, Harald Joerg, Harry
Bochner, Hugo, Ilya Zakharevich, \s-1INOUE\s0 Yoshinari, Ivan Panchenko, Jack
Shirazi, James Tillman, Jan Dubois, Jared Rhine, Jim Stern, Joao
Lopes, John Klar, Johnny Lee, Josh Kronengold, Josh Rai, Joshua
Chamas, Joshua Hoblitt, Kartik Subbarao, Keiichiro Nagano, Ken
Williams, \s-1KONISHI\s0 Katsuhiro, Lee T Lindley, Liam Quinn, Marc Hedlund,
Marc Langheinrich, Mark D. Anderson, Marko Asplund, Mark Stosberg,
Markus B Kru\*:ger, Markus Laker, Martijn Koster, Martin Thurn, Matthew
Eldridge, Matthew.van.Eerde, Matt Sergeant, Michael A. Chase, Michael
Quaranta, Michael Thompson, Mike Schilli, Moshe Kaminsky, Nathan
Torkington, Nicolai Langfeldt, Norton Allen, Olly Betts, Paul
J. Schinder, peterm, Philip GuentherDaniel Buenzli, Pon Hwa Lin,
Radoslaw Zielinski, Radu Greab, Randal L. Schwartz, Richard Chen,
Robin Barker, Roy Fielding, Sander van Zoest, Sean M. Burke,
shildreth, Slaven Rezic, Steve A Fink, Steve Hay, Steven Butler,
Steve_Kilbane, Takanori Ugai, Thomas Lotterer, Tim Bunce, Tom Hughes,
Tony Finch, Ville Skytta\*:, Ward Vandewege, William York, Yale Huang,
and Yitzchak Scott-Thoennes.
.PP
\&\s-1LWP\s0 owes a lot in motivation, design, and code, to the libwww-perl
library for Perl4 by Roy Fielding, which included work from Alberto
Accomazzi, James Casey, Brooks Cutter, Martijn Koster, Oscar
Nierstrasz, Mel Melchner, Gertjan van Oosten, Jared Rhine, Jack
Shirazi, Gene Spafford, Marc VanHeyningen, Steven E. Brenner, Marion
Hakanson, Waldemar Kebsch, Tony Sanders, and Larry Wall; see the
libwww\-perl\-0.40 library for details.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
.Vb 2
\&  Copyright 1995\-2005, Gisle Aas
\&  Copyright 1995, Martijn Koster
.Ve
.PP
This library is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.
.SH "AVAILABILITY"
.IX Header "AVAILABILITY"
The latest version of this library is likely to be available from \s-1CPAN\s0
as well as:
.PP
.Vb 1
\& http://www.linpro.no/lwp/
.Ve
.PP
The best place to discuss this code is on the <[e-mail]>
mailing list.