Ruby Web Service Application – SOAP4R

SOAP4R is a Ruby library that enables interaction with SOAP services. It allows you to create SOAP clients and servers in Ruby. As of my knowledge cutoff in September 2021, SOAP4R is not actively maintained, and many developers are moving towards RESTful services due to their simplicity and scalability.

However, if you still need to work with SOAP services, below is a basic example of how you can use SOAP4R.

Firstly, you need to install the gem:

gem install soap4r

Creating a SOAP client

Here's how you can create a basic SOAP client with SOAP4R:

require 'soap/wsdlDriver'

wsdl_url = 'http://www.example.com/service?wsdl'
client = SOAP::WSDLDriverFactory.new(wsdl_url).create_rpc_driver

# Assuming the service has a 'sayHello' operation
result = client.sayHello('Alice')
puts result  # Outputs the result of the 'sayHello' operation

In this example, we're creating a SOAP client that connects to a web service using its WSDL file. We then call an operation sayHello on the service and print the result.

Creating a SOAP server

Creating a SOAP server with SOAP4R is more complex. Below is a basic example:

require 'soap/rpc/standaloneServer'

class MyServer < SOAP::RPC::StandaloneServer
  def initialize(*args)
    super
    add_method(self, 'sayHello', 'name')
  end

  def sayHello(name)
    "Hello, #{name}!"
  end
end

server = MyServer.new('MyServer', 'urn:mySoapServer', 'localhost', 8080)
server.start

In this example, we're creating a SOAP server that listens on port 8080. The server has one operation sayHello that returns a greeting.

These are very basic examples of how to use SOAP4R. When working with real SOAP services, you'll need to handle more complex data types, error handling, and possibly security features like WS-Security. Also, remember that SOAP4R is not actively maintained, so you may encounter issues or lack of support for newer SOAP features.

Building web services with SOAP4R in Ruby: SOAP4R is a library for working with SOAP in Ruby.
```
require 'soap/wsdlDriver'
```

Creating a SOAP server in Ruby: Build a SOAP server using SOAP4R.

require 'soap/rpc/standaloneServer'

class MyService < SOAP::RPC::StandaloneServer
  def initialize(*args)
    super
    add_method(self, 'add', 'a', 'b')
  end

  def add(a, b)
    a + b
  end
end

server = MyService.new('MyService', 'urn:my-service', 'localhost', 8080)
trap('INT') { server.shutdown }
server.start

Ruby SOAP client example with SOAP4R: Create a SOAP client to consume a SOAP service.

require 'soap/wsdlDriver'

wsdl_url = 'http://example.com/my-service?wsdl'
client = SOAP::WSDLDriverFactory.new(wsdl_url).create_rpc_driver

result = client.add(3, 5)

Working with SOAP headers in Ruby: Include headers in SOAP requests.

header = SOAP::SOAPHeader.new('urn:my-header')
header_item = SOAP::SOAPElement.new('item').add('value')
header.add(header_item)

client.add(3, 5, header)

Handling SOAP faults in Ruby with SOAP4R: Manage SOAP faults in Ruby SOAP requests.

begin
  result = client.add(3, 'invalid')
rescue SOAP::FaultError => e
  puts "SOAP Fault: #{e.message}"
end

Ruby SOAP4R WSDL usage: SOAP4R uses WSDL to define the structure of SOAP services.

wsdl_url = 'http://example.com/my-service?wsdl'
client = SOAP::WSDLDriverFactory.new(wsdl_url).create_rpc_driver

Ruby SOAP4R authentication: Implement authentication for SOAP requests.
```
client.headerhandler << MyAuthHeader.new('username', 'password')
```

Ruby SOAP4R complex types: Define and use complex types in SOAP requests and responses.

class MyRequest
  attr_accessor :param1, :param2
end

request = MyRequest.new
request.param1 = 3
request.param2 = 'value'

result = client.my_method(request)

Ruby SOAP4R custom serializers: Customize serialization for specific types.

class MySerializer < SOAP::SOAPBasetype
  def initialize(value)
    @value = value
  end

  def to_s
    @value.to_s
  end
end

client.custom_method(MySerializer.new('custom_value'))

Debugging SOAP requests and responses in Ruby: Print or log SOAP requests and responses for debugging.
```
client.wiredump_dev = STDOUT
```