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* * * ## What is SOAP? Simple Object Access Protocol (SOAP) is a protocol specification for exchanging data. SOAP is a simple XML-based protocol that allows applications to exchange information over HTTP. Simple Object Access Protocol is a protocol specification for exchanging data. It is a lightweight, simple, XML-based protocol (a subset of the Standard Generalized Markup Language) designed for exchanging structured and formatted information on the web. For more SOAP tutorials, please visit: [http://www.w3cschool.cc/soap/soap-tutorial.html](#). * * * ## SOAP4R Installation SOAP4R was developed by Hiroshi Nakamura for SOAP applications in Ruby. SOAP4R download address: [http://raa.ruby-lang.org/project/soap4r/](http://raa.ruby-lang.org/project/soap4r/). **Note:** Your Ruby environment might already have this component installed. In a Linux environment, you can also use gem to install the component with the following command: gem install soap4r --include-dependencies If you are developing in a Windows environment, you need to download the zip archive and install it by executing install.rb. * * * ## SOAP4R Services SOAP4R supports two different service types: * CGI/FastCGI-based services (SOAP::RPC::CGIStub) * Standalone services (SOAP::RPC::StandaloneServer) This tutorial will introduce how to build a standalone SOAP service. The steps are as follows: ### Step 1 - Inherit from SOAP::RPC::StandaloneServer To implement your own standalone server, you need to write a new class that is a subclass of SOAP::RPC::StandaloneServer: class MyServer<SOAP::RPC::StandaloneServer ............... end **Note:** If you want to write a FastCGI-based server, you need to inherit from the SOAP::RPC::CGIStub class. The rest of the program will remain the same. ### Step 2 - Define Handler Methods Next, we define the Web Service methods. Here we define two methods: one for adding two numbers and one for dividing two numbers: class MyServer<SOAP::RPC::StandaloneServer ............... def add(a, b)return a + b end def div(a, b)return a / b end end ### Step 3 - Publish the Handler Methods Next, we add the methods defined on the server. The initialize method is public and is used for external connections: class MyServer<SOAP::RPC::StandaloneServer def initialize(*args)add_method(receiver, methodName, *paramArg)end end Here is the description of each parameter: | Parameter | Description | | --- | --- | | **receiver** | The object containing the method. If you define the service methods in the same class, this parameter is _self_. | | **methodName** | The method name to be called by the RPC request. | | **paramArg** | Parameter names and parameter modes | To understand _inout_ and _out_ parameters, consider the following service method, which requires two input parameters: inParam and inoutParam. After execution, it returns three values: retVal, inoutParam, and outParam: def aMeth(inParam, inoutParam)retVal = inParam + inoutParam outParam = inParam . inoutParam inoutParam = inParam * inoutParam return retVal, inoutParam, outParam end The public method call is as follows: add_method(self, 'aMeth', [%w(in inParam), %w(inout inoutParam), %w(out outParam), %w(retval return)]) ### Step 4 - Start the Service Finally, we start the service by instantiating the derived class and calling the start method: myServer = MyServer.new('ServerName', 'urn:ruby:ServiceName', hostname, port)myServer.start Here is the description of the request parameters: | Parameter | Description | | --- | --- | | **ServerName** | The service name, you can choose any name you like. | | **urn:ruby:ServiceName** | Here _urn:ruby_ is fixed, but you can choose a unique _ServiceName_ for your service. | | **hostname** | Specifies the hostname. | | **port** | The web service port. | ### Example Next, we will create a standalone service using the steps above: ## Example require"soap/rpc/standaloneserver"begin class MyServer err puts err.message end After executing the above program, a local service listening on port 8080 is started, exposing two methods: add and div. You can run the service in the background: $ ruby MyServer.rb & * * * ## SOAP4R Client In Ruby, the SOAP::RPC::Driver class is used to develop SOAP clients. Let's take a detailed look at how to use the SOAP::RPC::Driver class. Calling a SOAP service requires the following information: * SOAP Service URL (SOAP Endpoint URL) * Method Namespace URI * Service method name and parameter information Next, we will create a SOAP client step by step to call the SOAP methods mentioned above: add and div: ### Step 1 - Create a SOAP Driver Instance We can call the new method by instantiating the SOAP::RPC::Driver class, as shown below: SOAP::RPC::Driver.new(endPoint, nameSpace, soapAction) Here is the description of the parameters: | Parameter | Description | | --- | --- | | **endPoint** | The URL address to connect to the SOAP service. | | **nameSpace** | The namespace for all RPCs of the SOAP::RPC::Driver object. | | **soapAction** | The value for the SOAPAction field in the HTTP header. If the string is "", it defaults to _nil_. | ### Step 2 - Add Service Methods To add SOAP service methods to the SOAP::RPC::Driver, we can call the following method on the SOAP::RPC::Driver instance: driver.add_method(name, *paramArg) Here is the description of the parameters: | Parameter | Description | | --- | --- | | **name** | The method name of the remote web service. | | **paramArg** | Specifies the parameters for the remote procedure. | ### Step 3 - Call the SOAP Service Finally, we can use the SOAP::RPC::Driver instance to call the SOAP service: result = driver.serviceMethod(paramArg...) serviceMethod is the actual method name of the SOAP service, and paramArg is the list of method parameters. ### Example Based on the steps above, we can write the following SOAP client: ## Example require'soap/rpc/driver'NAMESPACE = 'urn:ruby:calculation'URL = 'http://localhost:8080/'begin driver = SOAP::RPC::Driver.new(URL, NAMESPACE)driver.add_method('add', 'a', 'b')puts driver.add(20, 30)rescue =>err puts err.message end Above, we briefly introduced Ruby's Web Service. If you want to learn more, you can check the official documentation: (http://www.ruby-doc.org/stdlib/libdoc/soap/rdoc/index.html "Web Service with Ruby")