Zend_XmlRpc_Server
Introduction
Zend_XmlRpc_Server is intended as a fully-featured XML-RPC
server,
following the specifications
outlined at www.xmlrpc.com. Additionally, it implements the
system.multicall() method, allowing boxcarring of requests.
Basic Usage
An example of the most basic use case:
setClass('My_Service_Class');
echo $server->handle();
]]>
Server Structure
Zend_XmlRpc_Server is composed of a variety of components,
ranging from the server itself to request, response, and fault objects.
To bootstrap Zend_XmlRpc_Server, the developer must attach one or
more classes or functions to the server, via the
setClass() and addFunction() methods.
Once done, you may either pass a Zend_XmlRpc_Request
object to Zend_XmlRpc_Server::handle(), or it will
instantiate a Zend_XmlRpc_Request_Http object if none
is provided -- thus grabbing the request from
php://input.
Zend_XmlRpc_Server::handle() then attempts to
dispatch to the appropriate handler based on the method
requested. It then returns either a
Zend_XmlRpc_Response-based object or a
Zend_XmlRpc_Server_Faultobject. These objects both have
__toString() methods that create valid XML-RPC XML
responses, allowing them to be directly echoed.
Conventions
Zend_XmlRpc_Server allows the developer to attach functions and
class method calls as dispatchable XML-RPC methods. Via
Zend_Server_Reflection, it does introspection on all attached
methods, using the function and method docblocks to determine the
method help text and method signatures.
XML-RPC types do not necessarily map one-to-one to PHP types.
However, the code will do its best to guess the appropriate type
based on the values listed in @param and @return lines. Some XML-RPC
types have no immediate PHP equivalent, however, and should be
hinted using the XML-RPC type in the PHPDoc. These include:
dateTime.iso8601, a string formatted as
YYYYMMDDTHH:mm:ss
base64, base64 encoded data
struct, any associative array
An example of how to hint follows:
PhpDocumentor does no validation of the types specified for params
or return values, so this will have no impact on your API
documentation. Providing the hinting is necessary, however, when the
server is validating the parameters provided to the method call.
It is perfectly valid to specify multiple types for both params and
return values; the XML-RPC specification even suggests that
system.methodSignature should return an array of all possible method
signatures (i.e., all possible combinations of param and return
values). You may do so just as you normally would with
PhpDocumentor, using the '|' operator:
One note, however: allowing multiple signatures can lead to
confusion for developers using the services; generally speaking, an
XML-RPC method should only have a single signature.
Utilizing Namespaces
XML-RPC has a concept of namespacing; basically, it allows grouping
XML-RPC methods by dot-delimited namespaces. This helps prevent
naming collisions between methods served by different classes. As an
example, the XML-RPC server is expected to server several methods in
the 'system' namespace:
system.listMethods
system.methodHelp
system.methodSignature
Internally, these map to the methods of the same name in
Zend_XmlRpc_Server.
If you want to add namespaces to the methods you serve, simply
provide a namespace to the appropriate method when attaching a
function or class:
setClass('My_Service_Class', 'myservice');
// Function 'somefunc' will be accessible as funcs.somefunc
$server->addFunction('somefunc', 'funcs');
]]>
Custom Request Objects
Most of the time, you'll simply use the default request type included with
Zend_XmlRpc_Server,
Zend_XmlRpc_Request_Http. However, there may be times when you
need XML-RPC to be available via the CLI, a GUI, or other environment, or want to log
incoming requests. To do so, you may create a custom request object that extends
Zend_XmlRpc_Request. The most important thing to remember is to
ensure that the getMethod() and getParams() methods are implemented
so that the XML-RPC server can retrieve that information in order to
dispatch the request.
Custom Responses
Similar to request objects, Zend_XmlRpc_Server can return custom
response objects; by default, a Zend_XmlRpc_Response_Http object
is returned, which sends an appropriate Content-Type HTTP header for
use with XML-RPC. Possible uses of a custom object would be to log
responses, or to send responses back to STDOUT.
To use a custom response class, use
Zend_XmlRpc_Server::setResponseClass() prior to calling
handle().
Handling Exceptions via Faults
Zend_XmlRpc_Server catches Exceptions generated by a dispatched
method, and generates an XML-RPC fault response when such an
exception is caught. By default, however, the exception messages and
codes are not used in a fault response. This is an intentional
decision to protect your code; many exceptions expose more
information about the code or environment than a developer would
necessarily intend (a prime example includes database abstraction or
access layer exceptions).
Exception classes can be whitelisted to be used as fault responses,
however. To do so, simply utilize
Zend_XmlRpc_Server_Fault::attachFaultException() to pass an
exception class to whitelist:
If you utilize an exception class that your other project exceptions
inherit, you can then whitelist a whole family of exceptions at a
time. Zend_XmlRpc_Server_Exceptions are always whitelisted, to
allow reporting specific internal errors (undefined methods, etc.).
Any exception not specifically whitelisted will generate a fault
response with a code of '404' and a message of 'Unknown error'.
Caching Server Definitions Between Requests
Attaching many classes to an XML-RPC server instance can utilize a
lot of resources; each class must introspect using the Reflection
API (via Zend_Server_Reflection), which in turn generates a list
of all possible method signatures to provide to the server class.
To reduce this performance hit somewhat, Zend_XmlRpc_Server_Cache
can be used to cache the server definition between requests. When
combined with __autoload(), this can greatly increase performance.
An sample usage follows:
setClass('My_Services_Glue', 'glue'); // glue. namespace
$server->setClass('My_Services_Paste', 'paste'); // paste. namespace
$server->setClass('My_Services_Tape', 'tape'); // tape. namespace
Zend_XmlRpc_Server_Cache::save($cacheFile, $server);
}
echo $server->handle();
]]>
The above example attempts to retrieve a server definition from
xmlrpc.cache in the same directory as the script. If unsuccessful,
it loads the service classes it needs, attaches them to the server
instance, and then attempts to create a new cache file with the
server definition.
Usage Examples
Below are several usage examples, showing the full spectrum of
options available to developers. Usage examples will each build
on the previous example provided.
Basic Usage
The example below attaches a function as a dispatchable XML-RPC
method and handles incoming calls.
addFunction('md5Value');
echo $server->handle();
]]>
Attaching a class
The example below illustrates attaching a class' public methods
as dispatchable XML-RPC methods.
setClass('Services_Comb');
echo $server->handle();
]]>
Attaching several classes using namespaces
The example below illustrates attaching several classes, each
with their own namespace.
setClass('Services_Comb', 'comb'); // methods called as comb.*
$server->setClass('Services_Brush', 'brush'); // methods called as brush.*
$server->setClass('Services_Pick', 'pick'); // methods called as pick.*
echo $server->handle();
]]>
Specifying exceptions to use as valid fault responses
The example below allows any Services_Exception-derived class to
report its code and message in the fault response.
setClass('Services_Comb', 'comb'); // methods called as comb.*
$server->setClass('Services_Brush', 'brush'); // methods called as brush.*
$server->setClass('Services_Pick', 'pick'); // methods called as pick.*
echo $server->handle();
]]>
Utilizing a custom request object
The example below instantiates a custom request object and
passes it to the server to handle.
setClass('Services_Comb', 'comb'); // methods called as comb.*
$server->setClass('Services_Brush', 'brush'); // methods called as brush.*
$server->setClass('Services_Pick', 'pick'); // methods called as pick.*
// Create a request object
$request = new Services_Request();
echo $server->handle($request);
]]>
Utilizing a custom response object
The example below illustrates specifying a custom response class
for the returned response.
setClass('Services_Comb', 'comb'); // methods called as comb.*
$server->setClass('Services_Brush', 'brush'); // methods called as brush.*
$server->setClass('Services_Pick', 'pick'); // methods called as pick.*
// Create a request object
$request = new Services_Request();
// Utilize a custom response
$server->setResponseClass('Services_Response');
echo $server->handle($request);
]]>
Cache server definitions between requests
The example below illustrates caching server definitions
between requests.
setClass('Services_Comb', 'comb'); // methods called as comb.*
$server->setClass('Services_Brush', 'brush'); // methods called as brush.*
$server->setClass('Services_Pick', 'pick'); // methods called as pick.*
// Save cache
Zend_XmlRpc_Server_Cache::save($cacheFile, $server);
}
// Create a request object
$request = new Services_Request();
// Utilize a custom response
$server->setResponseClass('Services_Response');
echo $server->handle($request);
]]>