# Implementing a Provider Object

The Provider interface is relatively easy to implement. It only has one method, invoke(), that needs to be implemented. In addition it has three simple requirements:

* An implementation must have the @WebServiceProvider annotation.

* An implementation must have a default public constructor.

* An implementation must implement a typed version of the Provider interface. In other words, you cannot implement a Provider<T> interface. You must implement a version of the interface that uses a concrete data type. For example, you can implement an instance of a Provider<SAXSource> .

The complexity of implementing the Provider interface surrounds handling the request messages and building the proper responses.

### In this section

* [Working with messages](https://help.qlik.com/talend/en-US/esb-service-developer-guide/7.3/working-with-messages)