# 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

    $client = new Zend_XmlRpc_Client('http://framework.zend.com/xmlrpc');

    echo $client->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

    $client = new Zend_XmlRpc_Client('http://framework.zend.com/xmlrpc');

    $arg1 = 1.1;
    $arg2 = 'foo';

    $result = $client->call('test.sayHello', array($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:

    $client->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

    $client = new Zend_XmlRpc_Client('http://framework.zend.com/xmlrpc');

    $server = $client->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

    $client = new Zend_XmlRpc_Client('http://framework.zend.com/xmlrpc');

    $test  = $client->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

    $client = new Zend_XmlRpc_Client('http://foo/404');

    try {

        $client->call('bar', array($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

    $client = new Zend_XmlRpc_Client('http://framework.zend.com/xmlrpc');

    try {

        $client->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

    $client = new Zend_XmlRpc_Client('http://framework.zend.com/xmlrpc');

    $request = new Zend_XmlRpc_Request();
    $request->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.