# Contract-first development

In this section we'll work through the dev-guide-wsdl-first example available in the Talend ESB download, in the examples/talend/cxf folder. This sample web service provides a simple SOAP operation called "DoubleIt", which takes an integer in the SOAP request and provides a doubled number in the response. Both Tomcat and Talend ESB deployment options are shown below.

### In this section

* [Project Structure](https://help.qlik.com/talend/en-US/esb-developer-guide/8.0/project-structure)
* [Maven POM files](https://help.qlik.com/talend/en-US/esb-developer-guide/8.0/maven-pom-files)
* [Creating the WSDL](https://help.qlik.com/talend/en-US/esb-developer-guide/8.0/creating-wsdl)
* [Configuring Deployment Descriptors](https://help.qlik.com/talend/en-US/esb-developer-guide/8.0/configuring-deployment-descriptors)
* [Creating the Web Service Provider (WSP)](https://help.qlik.com/talend/en-US/esb-developer-guide/8.0/creating-web-service-provider-wsp)
* [Deploying the WSP](https://help.qlik.com/talend/en-US/esb-developer-guide/8.0/deploying-wsp)
* [Running the SOAP Client](https://help.qlik.com/talend/en-US/esb-developer-guide/8.0/running-soap-client)