RPC::XML::Client(3pm) User Contributed Perl DocumentationRPC::XML::Client(3pm)NAMERPC::XML::Client - An XML-RPC client class
SYNOPSIS
require RPC::XML;
require RPC::XML::Client;
$cli = RPC::XML::Client->new('http://www.localhost.net/RPCSERV');
$resp = $cli->send_request('system.listMethods');
print ref $resp ? join(', ', @{$resp->value}) : "Error: $resp";
DESCRIPTION
This is an XML-RPC client built upon the RPC::XML data classes, and
using LWP::UserAgent and HTTP::Request for the communication layer.
This client supports the full XML-RPC specification.
METHODS
The following methods are available:
new (URI [, ARGS])
Creates a new client object that will route its requests to the URL
provided. The constructor creates a HTTP::Request object and a
LWP::UserAgent object, which are stored on the client object. When
requests are made, these objects are ready to go, with the headers
set appropriately. The return value of this method is a reference
to the new object. The "URI" argument may be a string or an object
from the URI class from CPAN.
Any additional arguments are treated as key-value pairs. Most are
attached to the object itself without change. The following are
recognized by "new" and treated specially:
parser
If this parameter is passed, the value following it is expected
to be an array reference. The contents of that array are passed
to the new method of the RPC::XML::ParserFactory-generated
object that the client object caches for its use. See the
RPC::XML::ParserFactory manual page for a list of recognized
parameters to the constructor.
useragent
This is similar to the "parser" argument above, and also
expects an array reference to follow it. The contents are
passed to the constructor of the LWP::UserAgent class when
creating that component of the client object. See the manual
page for LWP::UserAgent for supported values.
error_handler
If passed, the value must be a code reference that will be
invoked when a request results in a transport-level error. The
closure will receive a single argument, the text of the error
message from the failed communication attempt. It is expected
to return a single value (assuming it returns at all).
fault_handler
If passed, the value must be a code reference. This one is
invoked when a request results in a fault response from the
server. The closure will receive a single argument, a
RPC::XML::fault instance that can be used to retrieve the code
and text-string of the fault. It is expected to return a single
value (if it returns at all).
combined_handler
If this parameter is specified, it too must have a code
reference as a value. It is installed as the handler for both
faults and errors. Should either of the other parameters be
passed in addition to this one, they will take precedence over
this (more-specific wins out over less). As a combined handler,
the closure will get a string (non-reference) in cases of
errors, and an instance of RPC::XML::fault in cases of faults.
This allows the developer to install a simple default handler,
while later providing a more specific one by means of the
methods listed below.
message_file_thresh
If this key is passed, the value associated with it is assumed
to be a numerical limit to the size of in-memory messages. Any
out-bound request that would be larger than this when
stringified is instead written to an anonynous temporary file,
and spooled from there instead. This is useful for cases in
which the request includes RPC::XML::base64 objects that are
themselves spooled from file-handles. This test is independent
of compression, so even if compression of a request would drop
it below this threshhold, it will be spooled anyway. The file
itself is created via File::Temp with UNLINK=>1, so once it is
freed the disk space is immediately freed.
message_temp_dir
If a message is to be spooled to a temporary file, this key can
define a specific directory in which to open those files. If
this is not given, then the "tmpdir" method from the File::Spec
package is used, instead.
See the section on the effects of callbacks on return values,
below.
uri ([URI])
Returns the URI that the invoking object is set to communicate with
for requests. If a string or "URI" class object is passed as an
argument, then the URI is set to the new value. In either case, the
pre-existing value is returned.
useragent
Returns the LWP::UserAgent object instance stored on the client
object. It is not possible to assign a new such object, though
direct access to it should allow for any header modifications or
other needed operations.
request
Returns the HTTP::Request object. As with the above, it is not
allowed to assign a new object, but access to this value should
allow for any needed operations.
simple_request (ARGS)
This is a somewhat friendlier wrapper around the next routine
("send_request") that returns Perl-level data rather than an object
reference. The arguments may be the same as one would pass to the
RPC::XML::request constructor, or there may be a single request
object as an argument. The return value will be a native Perl
value. If the return value is "undef", an error has occurred and
"simple_request" has placed the error message in the global
variable "$RPC::XML::ERROR".
send_request (ARGS)
Sends a request to the server and attempts to parse the returned
data. The argument may be an object of the RPC::XML::request class,
or it may be the arguments to the constructor for the request
class. The return value will be either an error string or a data-
type object. If the error encountered was a run-time error within
the RPC request itself, then the call will return a
"RPC::XML::fault" value rather than an error string.
If the return value from "send_request" is not a reference, then it
can only mean an error on the client-side (a local problem with the
arguments and/or syntax, or a transport problem). All data-type
classes now support a method called "is_fault" that may be easily
used to determine if the "successful" return value is actually a
"RPC::XML::fault" without the need to use "UNIVERSAL::ISA".
error_handler ([CODEREF])
fault_handler ([CODEREF])
combined_handler ([CODEREF])
These accessor methods get (and possibly set, if CODEREF is passed)
the specified callback/handler. The return value is always the
current handler, even when setting a new one (allowing for later
restoration, if desired).
credentials (REALM, USERNAME, PASSWORD)
This sets the username and password for a given authentication
realm at the location associated with the current request URL.
Needed if the RPC location is protected by Basic Authentication.
Note that changing the target URL of the client object to a
different (protected) location would require calling this with new
credentials for the new realm (even if the value of $realm is
identical at both locations).
timeout ([INTEGER])
Get or set the current time-out value on the underlying
LWP::UserAgent object that this object uses for sending requests.
This is just a proxy through to the method of the same name in the
LWP::UserAgent class. The return value is the current time-out
value (prior to change, if a new value is given).
message_file_thresh
message_temp_dir
These methods may be used to retrieve or alter the values of the
given keys as defined earlier for the "new" method.
Support for Content Compression
The RPC::XML::Server class supports compression of requests and
responses via the Compress::Zlib module available from CPAN.
Accordingly, this class also supports compression. The methods used for
communicating compression support should be compatible with the server
and client classes from the XMLRPC::Lite class that is a part of the
SOAP::Lite package (also available from CPAN).
Compression support is enabled (or not) behind the scenes; if the Perl
installation has Compress::Zlib, then RPC::XML::Client can deal with
compressed responses. However, since outgoing messages are sent before
a client generally has the chance to see if a server supports
compression, these are not compressed by default.
compress_requests(BOOL)
If a client is communicating with a server that is known to support
compressed messages, this method can be used to tell the client
object to compress any outgoing messages that are longer than the
threshhold setting in bytes.
compress_thresh([MIN_LIMIT])
With no arguments, returns the current compression threshhold;
messages smaller than this number of bytes will not be compressed,
regardless of the above method setting. If a number is passed, this
is set to the new lower-limit. The default value is 4096 (4k).
Callbacks and Return Values
If a callback is installed for errors or faults, it will be called
before either of "send_request" or "simple_request" return. If the
callback calls die or otherwise interrupts execution, then there is no
need to worry about the effect on return values. Otherwise, the return
value of the callback becomes the return value of the original method
("send_request" or "simple_request"). Thus, all callbacks are expected,
if they return at all, to return exactly one value. It is recommended
that any callback return values conform to the expected return values.
That is, an error callback would return a string, a fault callback
would return the fault object.
DIAGNOSTICS
All methods return some type of reference on success, or an error
string on failure. Non-reference return values should always be
interpreted as errors, except in the case of "simple_request".
CAVEATS
This began as a reference implementation in which clarity of process
and readability of the code took precedence over general efficiency. It
is now being maintained as production code, but may still have parts
that could be written more efficiently.
BUGS
Please report any bugs or feature requests to "bug-rpc-xml at
rt.cpan.org", or through the web interface at
<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=RPC-XML>. I will be
notified, and then you'll automatically be notified of progress on your
bug as I make changes.
SUPPORT
· RT: CPAN's request tracker
<http://rt.cpan.org/NoAuth/Bugs.html?Dist=RPC-XML>
· AnnoCPAN: Annotated CPAN documentation
<http://annocpan.org/dist/RPC-XML>
· CPAN Ratings
<http://cpanratings.perl.org/d/RPC-XML>
· Search CPAN
<http://search.cpan.org/dist/RPC-XML>
· Source code on GitHub
<http://github.com/rjray/rpc-xml>
COPYRIGHT & LICENSE
This file and the code within are copyright (c) 2009 by Randy J. Ray.
Copying and distribution are permitted under the terms of the Artistic
License 2.0
(<http://www.opensource.org/licenses/artistic-license-2.0.php>) or the
GNU LGPL 2.1 (<http://www.opensource.org/licenses/lgpl-2.1.php>).
CREDITS
The XML-RPC standard is Copyright (c) 1998-2001, UserLand Software,
Inc. See <http://www.xmlrpc.com> for more information about the XML-
RPC specification.
SEE ALSO
RPC::XML, RPC::XML::Server
AUTHOR
Randy J. Ray "<rjray@blackperl.com>"
perl v5.10.0 2009-12-07 RPC::XML::Client(3pm)
