th which the <code>Work</code> instance must be executed.  
 This class is provided as a convenience for easily creating 
 <code>ExecutionContext</code> instances by extending this class
 and overriding only those methods of interest.

 <p>Some reasons why it is better for <code>ExecutionContext</code> 
 to be a class rather than an interface: 
 <ul><li>There is no need for a resource adapter to implement this class. 
 It only needs to implement the context information like 
 transaction, etc.
 <li>The reso