XML-RPC

The XML- RPC implementation library you choose will do all that work for you , if you provide valid inputs .

XML- RPC is a powerful and simple message passing system that excels in the sort of application described in this article .

XML-RPC is the realization of this idea: it is nothing more than ordinary RPC, but with XML -- instead of XDR -- as the encoding format.

In RPC (and XML-RPC), encoding can only occur for a predefined set of data types.

The front-end code can only get to the underlying data by making these XML-RPC calls.

In the next article, we will take a look at a more complex and practical example of XML-RPC.

Don't let the name fool you; this really is Perl's XML-RPC library, which for historical reasons has this unexpected name.

In practice, though, XML-RPC's datatypes are often flexible enough to do complex tasks.

Also like the Perl library, PHP allows the programmer to look at the underlying XML-RPC conversation for debugging.

Using XML for messaging has become popular enough to have produced these two alternatives: XML-RPC and SOAP.

XML-RPC: Study the XML-RPC specification and its variety of implementations for RPC in a distributed computing environment.

XML-RPC is designed to be as simple as possible, while allowing complex data structures to be transmitted, processed, and returned.

XML-RPC is a simple Web service protocol that takes the pain out of building middleware.

XML-RPC has a few additional artifacts -- like the need to wrap the whole object in a one-item tuple -- but these are minor issues.

For single value datatypes, and , which respectively denote string and integer data, are the workhorses for most XML-RPC programs.

XML-RPC, SOAP, gnosis. xml. pickle, and the XML serializer libraries in various languages take a generic approach to representing mappings.

I'd say that close to 75 percent of those who are enamored with SOAP actually are enamored with simple XML-RPC.

This is the sort of information defines an API to the XML-RPC listener.

Given this brief theoretical background, let's solve a real world problem with XML-RPC middleware.

XML-RPC is built on HTTP and, like ordinary Web traffic, its stateless conversations are of the request and response variety.

More basic efforts include XML-RPC, a precursor to SOAP that was only capable of RPC, and various forms of HTTP usage without SOAP.

If it isn't, the document is well-formed, and you send an XML-RPC response message.

On the project I ve described in this article, we used XML-RPC to facilitate external scripting of our application for testing purposes.

Koi uses XML-RPC as the communications model in its client-server architecture.

The four technologies that you will examine in this column are SOAP, CORBA, XML-RPC, and good, old-fashioned low-level sockets.

We ll go over some highlights in this section to set the stage for how we used XML-RPC on our project.

We wrote a simple testing framework in Ruby and had it make XML-RPC requests to our app, which included the Marquee Java XML-RPC server.

An XML-RPC message is an HTTP-POST request with an XML body.

SOAP and XML-RPC are designed for Web services and therefore use HTTP as the transport protocol.

both FTP and XML-RPC do not have such independent presentation components.

XML-RPC only understands regular positional arguments and arguments with default values.

These developers could gain a lot from moving to a SOAP-based or XML-RPC-based communication model.

If the variable is set, the document is not well-formed, and you instead send an XML-RPC fault response.

Unfortunately, the XML-RPC specification doesn't provide any standard discovery method for listeners to transmit this information.

And one very simple, open architecture middleware protocol that works well in Web applications is XML-RPC.

In my previous article (see Resources), I introduced XML-RPC (see Resources) as an easy way to execute functions on remote machines.

XML-RPC structures are formed with key-value pairs, which should feel natural to Perl, Python, and PHP coders.

XML-RPC is truly simple, which makes it worth considering for distributed applications.

Installed, you may be surprised at how little code it takes to make an XML-RPC call.

Listing 6 shows a simple XML-RPC server that handles the requests from our XML-RPC client discussed earlier.

Based on the research of the XML-RPC and BEEP protocols, this paper presents a distributed object technology to resolve the problem.

This XML-RPC structure is represented in Perl as a hash reference.

Finally on line 9, the connection is made with the XML-RPC listener and a response object is returned.

When it came time to ship the app, we simply turned off the XML-RPC server.

JAX-RPC's dynamic invocation interface (DII) is the Call object (javax. xml. rpc. Call).

Page contains links to various XML-RPC client and server implementations.

A very common way to communicate with remote systems is via XML-RPC, a very light-weight protocol on top of HTTP.

DII defines a javax. xml. rpc. Call object instance for dynamic invocation.

These functions can be used to write XML-RPC servers and clients.

Using the fully qualified name of the WSDL's service, you construct a javax. xml. rpc. Service object.

All I need to do is create a javax. xml. rpc. namespace. QName object which represents the type.

XML-RPC defines procedure calls encoded in XML and communicated over HTTP.

This integer is then returned to the XML-RPC client.

The handle(javax. xml. rpc. handler. MessageContext msgCtx) method is invoked when your handler is required to process an in-flight message.

Listing 5 shows a simplified sample of what our XML-RPC wrapper class looked like.

An introductory XML-RPC program needs a meatier framework.

Table 1 shows the XML-RPC middleware API for this application's user accounts data store.

Consider, for example, the fact that your XML data can be sent, relatively unchanged, into an XML-RPC call with little to no overhead.

SOAP has made starts on these and XML-RPC requires that you, the programmer, handle these issues.

In JAX-RPC, the dynamic invocation object is javax. xml. rpc. Call.

In particular, I looked at RPC, XML-RPC, and SOAP, dissecting what is included with each technology.

The other important detail to remember is that XML-RPC has a finite set of datatypes.

Finally, picture an XML-RPC sender at one place of business sending an XML-RPC payload to another business.

" Enable C applications for Web services using XML-RPC" is a step-by-step guide to exposing C methods as services.

Many people have commented to us that XML-RPC can fill most of the roles that SOAP does.

Now I know you may be feeling cheated here, as this is an article about SOAP, and you are getting an XML-RPC code sample.

You can turn on debugging in the XML-RPC object to verify this.

The second benefit to CORBA (over SOAP or XML-RPC) is that its message format is binary, though this is in some ways a hindrance as well.

Listing 4 shows the sequence using the various XML-RPC calls to the remote service.

XML-RPC provides a much easier solution.

The XML-RPC fault response does the same thing.

In this case, XML-RPC let us do what we needed to do, without getting in the way.

To use a Marquee XML-RPC server, a running server instance has to know how to decode your method string.

Let's look at a concrete example of XML-RPC in action.

Table 1 is lists all the XML-RPC datatypes.

The real paydirt is occurs on Line 11 where a new XML-RPC client object is created.

For example, a short time ago, I needed to provide -- quickly -- a stub application for testing the client side of an xml-rpc-like API.

Simplicity Slightly complex compared to XML-RPC Easy to understand and develop Implementation-specific

Line 6 brings in our XML-RPC library.

Here you may discover that the things you like about SOAP aren't related to SOAP directly but, in fact, are features of XML-RPC.

One last thing to note about SOAP and XML-RPC is that they are just based on plain XML.

You can easy change the technology (for example from XML-RPC to RMI).

XML-RPC works by encoding the RPC requests into XML and sending them over a standard HTTP connection to a server or

Packages the results in an XML-RPC response and sends it back to the client

Regardless of the language in which you write an XML-RPC client, you always need to know

When you make an XML-RPC call, you ll get an XML response, which contains one

Part 2 of Using XML-RPC for Web services

Table 1: XML-RPC API for account info