WSDL top-down bottom-up Approach
Top-down approach
WSDL document is the contract between the consumer and the service, it can be used to generate the Java code for the consumer and the service. This is the top-down approach, also known as contract first. This approach starts with the contract (the WSDL) by defining operations, messages, and so forth. When both the consumer and provider agree on the contract, you can then implement the Java classes based on that contract. Metro provides some tools (wsimport) that generate classes from a WSDL.
Bottom-up Approach
With the other approach, called bottom-up, the implementation class already exists, and all that is needed is to create the WSDL. Again, Metro provides utilities (wsgen) to generate a WSDL from existing classes. In both cases, the
code may need to be adjusted to fit the WSDL or vice versa. That is when JAX-WS comes to your aid. With a simple development model and a few annotations, Java-to-WSDL mapping can be adjusted.
Ref : Beginning of JavaEE 7
WSDL document is the contract between the consumer and the service, it can be used to generate the Java code for the consumer and the service. This is the top-down approach, also known as contract first. This approach starts with the contract (the WSDL) by defining operations, messages, and so forth. When both the consumer and provider agree on the contract, you can then implement the Java classes based on that contract. Metro provides some tools (wsimport) that generate classes from a WSDL.
Bottom-up Approach
With the other approach, called bottom-up, the implementation class already exists, and all that is needed is to create the WSDL. Again, Metro provides utilities (wsgen) to generate a WSDL from existing classes. In both cases, the
code may need to be adjusted to fit the WSDL or vice versa. That is when JAX-WS comes to your aid. With a simple development model and a few annotations, Java-to-WSDL mapping can be adjusted.
Ref : Beginning of JavaEE 7