Zend_XmlRpc_Client
Introdución
Zend Framework provee soporte para consumo remoto para servicios XML-RPC
como un cliente en el paquete Zend_XmlRpc_Client
. Su mejor característica es la conversión automática de tipos
entre PHP y XML-RPC, un servidor de objeto proxy, y acceso a
capacidades de instrospección del servidor.
Method Calls
El constructor de Zend_XmlRpc_Client recibe la
URL del servidor XML-RPC como su primer parámetro.
La nueva instacia devuelta puede ser usada para llamar cualquier número de métodos remotos en el punto final.
Para llamar un método remoto con el cliente XML-RPC, instáncealo
y usa el método de instancia call() . El código de ejemplo a continuación utiliza una demostración en el servidor XML-RPC en el sitio web de Zend Framework
. Puede utilizarlo para probar o explorar los componentes
Zend_XmlRpc.
XML-RPC Method Call
call('test.sayHello');
// hello
]]>
El valor XML-RPC devuelto desde la llamada al método remoto automáticamente será convertida al tipo nativo PHP equivalente
. En el ejemplo anterior, es devuelto un string PHP
y está listo para ser usado inmediatamente.
El primer parámetro del método call() recibe el nombre del método remoto que llamar. Si el método remoto requiere algún parámetro, éste puede ser enviado por el suministro de un segundo, parámetro opcional a call() con un array de
valores para pasar el método remoto:
XML-RPC Method Call with Parameters
call('test.sayHello', array($arg1, $arg2));
// $result es un tipo nativo PHP
]]>
si el método remoto no requiere parámetros, este parámetro opcional
podrá ser excluido o se puede pasar un array()
vacío. El array de parámeters para el método repoto puede contener tipos nativos PHPs, objetos Zend_XmlRpc_Value
, o una combinación de estos.
El método call() convertirá automáticamente la respuesta
XML-RPC y devolverá su tipo nativo PHP equivalente. Un objeto
Zend_XmlRpc_Response para el valor devuelto también estará
disponible para llamar el método getLastResponse()
después de la llamada.
Tipos y Conversiones
Algunas llamadas a métodos remoto requieren parámetros. Éstos son
dados al método call() de Zend_XmlRpc_Client
como un array en el segundo parámetro. Cada parámetro puede ser dado
como un tipo nativo PHP, que será convertido automáticamente,
o como un objeto que representa un tipo específico de XML-RPC
(uno de los objetos Zend_XmlRpc_Value).
Tipos Nativos PHP como Parámetro
Los parámetros pueden ser pasados a call() como variables
PHP nativas, ya sea un string,
integer, float,
boolean, array, o un
object. En este caso, cada tipo PHP nativo será
autodetectado y convertido en uno de los tipos XML-RPC
de acuerdo con esta tabla:
Tipos de Conversión entre PHP y XML-RPC
Tipo Nativo PHP
Tipo XML-RPC
integer
int
double
double
boolean
boolean
string
string
array
array
array asociativo
struct
object
array
¿A qué tipo se convierten los arrays Vacios?
Pasar un array vacío a un método XML-RPC es problemático,
as it could represent either an array or a struct.
Zend_XmlRpc_Client detects such conditions and
makes a request to the server's
system.methodSignature method to determine the
appropriate XML-RPC type to cast to.
However, this in itself can lead to issues. First off,
servers that do not support
system.methodSignature will log failed
requests, and Zend_XmlRpc_Client will resort to
casting the value to an XML-RPC array type. Additionally,
this means that any call with array arguments will result in
an additional call to the remote server.
To disable the lookup entirely, you can call the
setSkipSystemLookup() method prior to making
your XML-RPC call:
setSkipSystemLookup(true);
$result = $client->call('foo.bar', array(array()));
]]>
Zend_XmlRpc_Value Objects as Parameters
Parameters may also be created as Zend_XmlRpc_Value
instances to specify an exact XML-RPC type. The primary reasons
for doing this are:
When you want to make sure the correct parameter
type is passed to the procedure (i.e. the
procedure requires an integer and you may get it
from a database as a string)
When the procedure requires base64 or
dateTime.iso8601 type (which doesn't exists as a
PHP native type)
When auto-conversion may fail (i.e. you want to
pass an empty XML-RPC struct as a parameter. Empty
structs are represented as empty arrays in PHP
but, if you give an empty array as a parameter it
will be auto-converted to an XML-RPC array since
it's not an associative array)
There are two ways to create a Zend_XmlRpc_Value
object: instantiate one of the Zend_XmlRpc_Value
subclasses directly, or use the static factory method
Zend_XmlRpc_Value::getXmlRpcValue().
Zend_XmlRpc_Value Objects for XML-RPC Types
XML-RPC Type
Zend_XmlRpc_Value Constant
Zend_XmlRpc_Value Object
int
Zend_XmlRpc_Value::XMLRPC_TYPE_INTEGER
Zend_XmlRpc_Value_Integer
double
Zend_XmlRpc_Value::XMLRPC_TYPE_DOUBLE
Zend_XmlRpc_Value_Double
boolean
Zend_XmlRpc_Value::XMLRPC_TYPE_BOOLEAN
Zend_XmlRpc_Value_Boolean
string
Zend_XmlRpc_Value::XMLRPC_TYPE_STRING
Zend_XmlRpc_Value_String
base64
Zend_XmlRpc_Value::XMLRPC_TYPE_BASE64
Zend_XmlRpc_Value_Base64
dateTime.iso8601
Zend_XmlRpc_Value::XMLRPC_TYPE_DATETIME
Zend_XmlRpc_Value_DateTime
array
Zend_XmlRpc_Value::XMLRPC_TYPE_ARRAY
Zend_XmlRpc_Value_Array
struct
Zend_XmlRpc_Value::XMLRPC_TYPE_STRUCT
Zend_XmlRpc_Value_Struct
Automatic Conversion
When building a new Zend_XmlRpc_Value
object, its value is set by a PHP type. The PHP type
will be converted to the specified type using
PHP casting. For example, if a string is given as a
value to the Zend_XmlRpc_Value_Integer
object, it will be converted using
(int)$value.
Server Proxy Object
Another way to call remote methods with the XML-RPC client is to
use the server proxy. This is a PHP object that proxies a remote
XML-RPC namespace, making it work as close to a native PHP object
as possible.
To instantiate a server proxy, call the getProxy()
instance method of Zend_XmlRpc_Client. This will
return an instance of Zend_XmlRpc_Client_ServerProxy.
Any method call on the server proxy object will be forwarded to
the remote, and parameters may be passed like any other PHP
method.
Proxy the Default Namespace
getProxy(); // Proxy the default namespace
$hello = $server->test->sayHello(1, 2); // test.Hello(1, 2) returns "hello"
]]>
The getProxy() method receives an optional argument
specifying which namespace of the remote server to proxy. If it
does not receive a namespace, the default namespace will be
proxied. In the next example, the test namespace
will be proxied:
Proxy Any Namespace
getProxy('test'); // Proxy the "test" namespace
$hello = $test->sayHello(1, 2); // test.Hello(1,2) returns "hello"
]]>
If the remote server supports nested namespaces of any depth,
these can also be used through the server proxy. For example, if
the server in the example above had a method
test.foo.bar(), it could be called as
$test->foo->bar().
Error Handling
Two kinds of errors can occur during an XML-RPC method call: HTTP
errors and XML-RPC faults. The Zend_XmlRpc_Client
recognizes each and provides the ability to detect and trap them
independently.
HTTP Errors
If any HTTP error occurs, such as the remote HTTP server
returns a 404 Not Found, a
Zend_XmlRpc_Client_HttpException will be thrown.
Handling HTTP Errors
call('bar', array($arg1, $arg2));
} catch (Zend_XmlRpc_Client_HttpException $e) {
// $e->getCode() returns 404
// $e->getMessage() returns "Not Found"
}
]]>
Regardless of how the XML-RPC client is used, the
Zend_XmlRpc_Client_HttpException will be thrown
whenever an HTTP error occurs.
XML-RPC Faults
An XML-RPC fault is analogous to a PHP exception. It is a
special type returned from an XML-RPC method call that has
both an error code and an error message. XML-RPC faults are
handled differently depending on the context of how the
Zend_XmlRpc_Client is used.
When the call() method or the server
proxy object is used, an XML-RPC fault will result in a
Zend_XmlRpc_Client_FaultException being thrown.
The code and message of the exception will map directly to
their respective values in the original XML-RPC fault
response.
Handling XML-RPC Faults
call('badMethod');
} catch (Zend_XmlRpc_Client_FaultException $e) {
// $e->getCode() returns 1
// $e->getMessage() returns "Unknown method"
}
]]>
Cuando el método call() es usado para realizar la
petición, Zend_XmlRpc_Client_FaultException será
lanzado como error. Un objeto Zend_XmlRpc_Response conteniendo
el error estará disponible llamando a
getLastResponse().
Cuando el método doRequest() sea usado para realizar una
petición, no lanzará una excepción. En vez de eso, devolverá un objeto
Zend_XmlRpc_Response que contendrá el error.
Esto puede comprobarse con
isFault() método instancia de
Zend_XmlRpc_Response.
Server Introspection
Some XML-RPC servers support the de facto introspection methods under the XML-RPC
system. namespace. Zend_XmlRpc_Client provides special
support for servers with these capabilities.
A Zend_XmlRpc_Client_ServerIntrospection instance may be retrieved by calling
the getIntrospector() method of Zend_XmlRpcClient. It can
then be used to perform introspection operations on the server.
From Request to Response
Under the hood, the call() instance method of Zend_XmlRpc_Client
builds a request object (Zend_XmlRpc_Request) and sends it to another method,
doRequest(), that returns a response object (Zend_XmlRpc_Response).
The doRequest() method is also available for use directly:
Processing Request to Response
setMethod('test.sayHello');
$request->setParams(array('foo', 'bar'));
$client->doRequest($request);
// $server->getLastRequest() returns instanceof Zend_XmlRpc_Request
// $server->getLastResponse() returns instanceof Zend_XmlRpc_Response
]]>
Whenever an XML-RPC method call is made by the client through any
means, either the call() method,
doRequest() method, or server proxy, the last request
object and its resultant response object will always be available
through the methods getLastRequest() and
getLastResponse() respectively.
HTTP Client and Testing
In all of the prior examples, an HTTP client was never specified.
When this is the case, a new instance of
Zend_Http_Client will be created with its default
options and used by Zend_XmlRpc_Client automatically.
The HTTP client can be retrieved at any time with the
getHttpClient() method. For most cases, the default
HTTP client will be sufficient. However, the
setHttpClient() method allows for a different HTTP
client instance to be injected.
The setHttpClient() is particularly useful for unit testing. When combined
with the Zend_Http_Client_Adapter_Test, remote services can be mocked
out for testing. See the unit tests for Zend_XmlRpc_Client for examples
of how to do this.