Basic web services part 1

Web Service :- Every project consists of web services as a part of it . Its a way to explore the functionalities provide by any organization. We can make some logic reusable and expose them via standard xml so any underlying programming language can use it.

Mediator :- Now we need a xml technology who does the mediation process so that any technology can understand it. Such technology is WSDL.

WSDL : -  Web service description language is used as intermediate layer to show the methods provided as service. For example third party gateway as a service. Now we will see how to write services in wsdl and structure them.

Basic structure of wsdl  :-

<definitions> 

<types>

   What all data types you are using as your input and output parameters .For example think them as class level data type variables.

</types>

<message>

   define your input parameter as wrapper by grouping above data types. You can define your output parameters also.

</message>

<portType>

      <operation>

 You can have multiple operations by grouping input and output parameters

      </operation>

</portType>

<binding>

    Here you will define how your operations will communicate via wired networks either soap or http protocol

</binding>

<service>

   Here you will define the url to reach your service i mean the end point has to be defined. You can name your service here

</service>

</definitions>

Usecase :- Think we have to provide a service which passes location name as input we have to provide temperature back to them. We will start constructing WSDl for it

<?xml version="1.0" encoding="UTF-8"?>

<wsdl:definitions name="Weather" targetNamespace="http://weather.service.sample/"

xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" xmlns:tns="http://weather.service.sample/"

xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" xmlns:xsd="http://www.w3.org/2001/XMLSchema">

<wsdl:types> //Provide all inputs

<xsd:schema targetNamespace="http://weather.service.sample/">

<xsd:element name="inputCity">

<xsd:complexType>

<xsd:sequence>

<xsd:element name="value" type="xsd:string" />

</xsd:sequence>

</xsd:complexType>

</xsd:element>

</xsd:schema>

<xsd:schema targetNamespace="http://weather.service.sample/">

<xsd:element name="outPutTemp">

<xsd:complexType>

<xsd:sequence>

<xsd:element name="value" type="xsd:string" />

</xsd:sequence>

</xsd:complexType>

</xsd:element>

</xsd:schema>

</wsdl:types>

<wsdl:message name="TemperatureRequest"> // input wrapper

<wsdl:part element="tns:inputCity" name="parameters" />

</wsdl:message>

<wsdl:message name="TemperatureResponse"> //output wrapper

<wsdl:part element="tns:outPutTemp" name="parameters" />

</wsdl:message>

<wsdl:portType name="Weather"> //combination operation

<wsdl:operation name="QuerryTemperature">

<wsdl:input message="tns:TemperatureRequest" />

<wsdl:output message="tns:TemperatureResponse" />

</wsdl:operation>

</wsdl:portType>

<wsdl:binding name="WeatherSOAP" type="tns:Weather"> //binding to a operation

<soap:binding style="document"

transport="http://schemas.xmlsoap.org/soap/http" />

<wsdl:operation name="QuerryTemperature">

<soap:operation soapAction="" />

<wsdl:input>

<soap:body use="literal" />

</wsdl:input>

<wsdl:output>

<soap:body use="literal" />

</wsdl:output>

</wsdl:operation>

</wsdl:binding>

<wsdl:service name="Weather"> //Service definition

<wsdl:port binding="tns:WeatherSOAP" name="WeatherSOAP">

<soap:address location="http://localhost:9080/PracticseWebService/Weather" />

</wsdl:port>

</wsdl:service>

</wsdl:definitions>

Note :- Will see approach in second part