Interaction between Objects in powerjava

In this paper we start from the consideration that high level interaction between entities like web services has very different properties with respect to the interaction between objects at the lower level of programming languages in the object oriented paradigm. In particular, web services, for security, usability and user adaptability reasons, offer different operations to different users by means of access control and keep track of the state of the interaction with each user by means of sessions. The current vision in object orientation, instead, considers attributes and operations of objects as being objective and independent from the interaction with another object, which is sessionless. To introduce these features in the interaction between objects directly in object oriented programming languages, we take inspiration from how access control is regulated by means of roles. Roles allow objects to offer different operations depending on the type of the role, of the type and identity of the player of the role, and to define session-aware interaction. We start from a definition of roles given in ontologies and knowledge representation and we discuss how this definition of roles can be introduced in Java, building our language powerJava.