Source: wp-includes/class-wp-http-ixr-client.php
Since: 3.1.0
Extends: IXR_Client

Purpose

WordPress’s XML-RPC client implementation that uses the WordPress HTTP API (wp_remote_post()) instead of the parent IXR_Client‘s raw socket/cURL calls. This ensures XML-RPC requests benefit from WordPress’s proxy support, SSL certificate handling, timeout management, and HTTP API filters.

Used internally for pingbacks, trackbacks, and any XML-RPC communication between WordPress sites.

Class Definition

#[AllowDynamicProperties]
class WP_HTTP_IXR_Client extends IXR_Client

Properties

Inherited from IXR_Client: $server, $port, $path, $useragent, $timeout, $headers, $debug, $message.

Constructor

public function __construct( string $server, string|false $path = false, int|false $port = false, int $timeout = 15 )

Two modes:

1. URL mode ($path === false): Parses $server as a full URL via parse_url(). Extracts scheme, host, port, path, and query. If path is empty, defaults to '/'. Query string is appended to path.

2. Component mode ($path provided): Sets scheme to 'http', uses $server as hostname, $path as-is, $port as-is.

URL mode ($path === false): Parses $server as a full URL via parse_url(). Extracts scheme, host, port, path, and query. If path is empty, defaults to '/'. Query string is appended to path.

Methods

query( ...$args )

Component mode ($path provided): Sets scheme to 'http', uses $server as hostname, $path as-is, $port as-is.

URL mode ($path === false): Parses $server as a full URL via parse_url(). Extracts scheme, host, port, path, and query. If path is empty, defaults to '/'. Query string is appended to path.

Component mode ($path provided): Sets scheme to 'http', uses $server as hostname, $path as-is, $port as-is.

1. Build XML-RPC request: Shifts the method name from $args, creates an IXR_Request object, serializes to XML via $request->getXml().

2. Construct URL: "{$this->scheme}://{$this->server}{$port}{$this->path}"

3. Build request args:

   php

   $args = [
       'headers'    => ['Content-Type' => 'text/xml'],
       'user-agent' => $this->useragent,
       'body'       => $xml,
   ];
   

4. Merge custom headers: Iterates $this->headers and adds them to $args['headers']. Comment references Trac ticket #8145.

5. Filter headers:

   php

   $args['headers'] = apply_filters( 'wp_http_ixr_client_headers', $args['headers'] );
   

   @since 4.4.0 — Filters the headers collection to be sent to the XML-RPC server.

6. Set timeout: If $this->timeout !== false, sets $args['timeout'].

7. Debug output: If $this->debug is truthy, echoes the raw XML request in a <pre> tag.

8. Send via WordPress HTTP API: $response = wp_remote_post( $url, $args )

9. Error handling — three failure modes:

   • WP_Error: Sets $this->error = new IXR_Error( -32300, "transport error: {$errno} {$errorstr}" )
   • Non-200 status: Sets $this->error = new IXR_Error( -32301, "transport error - HTTP status code was not 200 ({$code})" )
   • XML parse failure: Sets $this->error = new IXR_Error( -32700, 'parse error. not well formed' )

10. Parse response: Creates IXR_Message from response body, calls ->parse(). If message type is 'fault', sets error from fault code/string.

11. Returns true on success — parsed response accessible via $this->message.

Error Codes

Hooks

Streaming Relevance

Sets $this->useragent to 'The Incutio XML-RPC PHP Library' and $this->timeout to the provided value (default 15 seconds).

• WP_Error: Sets $this->error = new IXR_Error( -32300, "transport error: {$errno} {$errorstr}" )
• Non-200 status: Sets $this->error = new IXR_Error( -32301, "transport error - HTTP status code was not 200 ({$code})" )
• XML parse failure: Sets $this->error = new IXR_Error( -32700, 'parse error. not well formed' )

@since 3.1.0
@since 5.5.0 — Formalized the existing ...$args parameter by adding it to the function signature.

Usage Context

Build XML-RPC request: Shifts the method name from $args, creates an IXR_Request object, serializes to XML via $request->getXml().

• WP_Error: Sets $this->error = new IXR_Error( -32300, "transport error: {$errno} {$errorstr}" )
• Non-200 status: Sets $this->error = new IXR_Error( -32301, "transport error - HTTP status code was not 200 ({$code})" )
• XML parse failure: Sets $this->error = new IXR_Error( -32700, 'parse error. not well formed' )

Construct URL: "{$this->scheme}://{$this->server}{$port}{$this->path}"