1. Introduction

Goal of the Tutorial

This tutorial aims to teach you how to use SOAP (Simple Object Access Protocol) RPCs (Remote Procedure Calls) to execute methods on servers remotely.

Learning Outcomes

By the end of this tutorial, you will be able to:
- Understand the concept of SOAP RPCs and how they work
- Implement SOAP RPCs in your web development projects
- Debug and troubleshoot common issues with SOAP RPCs

Prerequisites

Before you start with this tutorial, it's good to have:
- Basic understanding of web development concepts
- Familiarity with XML and HTTP
- Basic programming knowledge, preferably in a language such as Java or .NET as they commonly use SOAP APIs

2. Step-by-Step Guide

SOAP and RPCs

SOAP is a protocol for exchanging structured information in web services using XML. It relies on HTTP for its transport protocol. RPC is a protocol that one program can use to request service from a program located in another computer on a network.

SOAP RPCs

SOAP RPCs allow for method calls between computers on a network through SOAP messages. The method request is sent as a SOAP message over HTTP, and the method response is sent back as a SOAP message over HTTP.

3. Code Examples

Example 1: Simple SOAP RPC

Let's start with a simple SOAP RPC example. Here, we're calling a method to get the current date from a remote server:

POST /InStock HTTP/1.1
Host: www.example.com
Content-Type: text/xml; charset="utf-8"
Content-Length: nnnn
SOAPAction: "http://www.example.com/GetDate"

<?xml version="1.0"?>
<soap:Envelope 
  xmlns:soap="http://www.w3.org/2001/12/soap-envelope" 
  soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding">

  <soap:Body xmlns:m="http://www.example.com/stock">
    <m:GetDate/>
  </soap:Body>
</soap:Envelope>

In the above example:
- We're making a POST request to the /InStock endpoint on www.example.com
- We specify the SOAPAction as http://www.example.com/GetDate
- In the SOAP body, we define the method we want to call: GetDate

4. Summary

In this tutorial, we've covered:
- The basics of SOAP and RPCs
- How to make a SOAP RPC
- A simple example of a SOAP RPC

Next, you should practice with more complex examples, perhaps calling methods that require parameters.

5. Practice Exercises

1. Exercise 1: Write a SOAP RPC to call a method that returns the current stock price for a given symbol.
2. Exercise 2: Write a SOAP RPC to call a method that adds a new book to a library. The method should take parameters for the book title and author.

Remember, practice is the key to mastering any new concept. Happy coding!