What this means is that different computers can use XML-RPC to “ask each other questions”. Using XML-RPC is just like making a function call in PHP, only the computer that executes the function could be thousands of miles away.

With the Incutio XML-RPC Library, making and receiving XML-RPC requests is almost as simple as calling native PHP functions.

The Incutio XML-RPC library (IXR) is designed primarily for ease of use. It incorporates both client and server classes, and is designed to hide as much of the workings of XML-RPC from the user as possible. A key feature of the library is automatic type conversion from PHP types to XML-RPC types and vice versa. This should enable developers to write web services with very little knowledge of the underlying XML-RPC standard.

IXR takes great pains to hide the details of the XML-RPC specification from the user. Where-ever possible, XML-RPC types are converted to PHP types (and vice versa) with no intervention needed from the web service programmer. Where this is not possible, objects are returned that allow easy access to the encapsulated data.

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Here’s a fully compliant XML-RPC client and server written in pure PHP. Only requirements are PHP, and the XML parser you’re guaranteed to have if you’re using PHP built into Apache…

The main benefit of using this XML-RPC library over others is that it uses native PHP datatypes wherever possible and doesn’t force you into OO. I’d tried other XML-RPC libraries, and they make you use objects in complex ways just to build your XML-RPC message. With this library, you can build your message using nothing but native PHP datatypes. Since PHP is a high level scripting language, it has most of the type information available to you that you need to build an XML-RPC message. That’s called “reflection”. The library is also fairly small (<500 lines).

This software is Open Source…

Find out more at Keith Devens site or get the source

Reverse Ajax refers to an Ajax design pattern that uses long-lived HTTP connections to enable low-latency communication between a web server and a browser. Basically it is a way of sending data from client to server and a mechanism for pushing server data back to the browser.

In web development, Comet is … a web application model in which a long-held HTTP request allows a web server to push data to a browser, without the browser explicitly requesting it. Comet is an umbrella term that uses multiple techniques for achieving this interaction. All methods have in common that they rely on browser-native technologies such as JavaScript, rather than on proprietary plugins. In theory, the Comet approach differs from the original model of the web, in which a browser requests a complete web page or chunks of data to update a web page.
However in practice, Comet applications typically use Ajax with long polling to detect new information on the server. The concept … is known by several other names, including Ajax Push, Reverse Ajax, Two-way-web, HTTP Streaming and HTTP server push.

XHR is a ‘wrapper’ on the http call, and has the same logic as a normal http call. Every time I fire the ‘sleep/flush’ combi in the php routine the backend sends data on the http connection and the xhr instance notices it, and it fires a statechange, but has to remain readystate 3, “polling“.

If you keep a javascript pointer on the xhr-buffer and process only the latest received string you have a continual updating frontend.

Program one, it’s easy.

But it’s also clumsy, so here’s some alternatives :

Chris Chabot wrote a php socket daemon :

This project came into existence while i was writing a new web based IRC application.

To deal with 1000′s of concurrent, always on (comet aka hanging iframe) http (server) connections, and an equal amount of IRC client connections, plus being able to interpret and parse and delegate all the messages and events, i needed a very fast, stable, flexible and easy to use ‘daemon’ library for PHP.

Chris sounds like a geek but what he programmed is a bit like the windows messaging subsystem (okay, that’s vague geek stuff, too). I read it before I made my blog-pipe reader using the php stream commands and it’s inspiring stuff. For geeks.

Then there is (as usual) your basic java applet :
caucho resin java applet

Resin’s server-push (Comet) servlet API enables streaming communication such as reverse AJAX dynamic updates for browser/JavaScript applications. The API encapsulates of the threading and communications issues between the request threads and the rest of the application.

Resin’s server-push (Comet) API lets server application push new data to the client as it becomes available. Administration and monitoring applications need to continually update the client when new information becomes available to the server.

Version 3 of Apache XML-RPC is still compliant to the XML-RPC specification. However, several vendor extensions are available, that greatly extend the power of XML-RPC:

• All primitive Java types are supported, including long, byte, short, and double.
• Calendar objects are supported. In particular, timezone settings, and milliseconds may be sent.
• DOM nodes, or JAXB objects, can be transmitted. So are objects implementing the java.io.Serializable interface.
• Both server and client can operate in a streaming mode, which preserves resources much better than the default mode, which is based on large internal byte arrays.

XML parser support

Apache XML-RPC supports SAX 1.0 and can therefore be used with any compliant XML parser. The default parser is John Wilson’s MinML parser which is included in the package. MinML is an ideal parser for XML-RPC because it is small, fast, and implements exactly the features of XML which are used by XML-RPC.

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[Daniel McLaren] just finished porting Matt Shaw‘s XML-RPC for Actionscript 2.0 code to AS3. This is a really easy way to get Flash to transfer data with an XML-RPC endpoint. Matt did a great job and the conversion wasn’t too difficult.

Nice going, Daniel.

How to operate the thing :

1. Type in the desired XML-RPC Endpoint URL.
2. Type in the specific desired XML-RPC function to call.
3. Now the interesting part… type in the params for your XML-RPC function call using JavaScript syntax for all of the XML-RPC datatypes (including arrays, structs, dates, and base64 values to an arbitrary depth).
4. Click “Execute”.

Ehr… okay… so ?

Upon completing the function call you will see three groups of information in the main tabbed display:
1. XML Request: This is the raw XML request you have just sent to the server.
2. XML Response: This is the raw XML response you have just received from the server.
3. Object Response: This is a psuedo-code representation of the objects that were returned from the server.

That’s what you want from a debug tool : feedback you can actually read in PseudoHuman Language. Nice tool.

It is a library implementing the XML-RPC protocol, written in PHP. It is also known as PHPXMLRPC.
It is designed for ease of use, flexibility and completeness. Speed and reduced memory footprint are not the main goals of the project.

…

XML-RPC for PHP was originally developed by Edd Dumbill of Useful Information Company. As of the 1.0 stable release, the project has been opened to wider involvement and moved to SourceForge.

PHPXMLRPC or derivative versions are used in many open source projects, including Ampache, Xaraya, Drupal (only up to releases 4.6.2 and 4.5.4), PostNuke, b2evolution, nucleus cms, phpmyfaq, phpPgAds, phpgroupware, egroupware, TikiWiki, Civicspace (old release only) and MailWatch for MailScanner.

Copyright and disclaimer
© Copyright 1998-2003 UserLand Software. All Rights Reserved.

XML-RPC is a Remote Procedure Calling protocol that works over the Internet.

An XML-RPC message is an HTTP-POST request. The body of the request is in XML. A procedure executes on the server and the value it returns is also formatted in XML. Procedure parameters can be scalars, numbers, strings, dates, etc.; and can also be complex record and list structures.