The first theme deals with language primitives for services and their interactions that are developed on two different abstraction levels, an architectural design level and a programming abstraction level for service computing. Ontologies and a categorical approach are used to develop a declarative modelling language for services whereas process calculi will provide the adequate programming-level primitives. UML extensions are developed to provide visual representation of the declarative modelling primitives. These theme 1 research activities are broken down into three work packages.

• WP1 - Modelling in Service-Oriented Architectures - focus on foundations for service description, interaction and composition, at the level of architectural specification.
  
• WP2 - Core - focus on the development of core calculi for service-oriented computing, accounting for different interaction and composition architectures, like message-driven or data-driven.
  
• WP5 - Combining services - is to extend the core calculi developed in WP2 and to establish a solid mathematical basis for quality of service, service level agreements, workflow-like transactions with compensation, and dynamic reconfiguration.

Theme 1 deliverables:

• Th0.1.a: SENSORIA Languages and Calculi for Modelling Services
• Th0.1.b: From Architectural to Behavioural Specifications
• Th0.1c: A Formal Support to Business and Architectural Design for Service-Oriented Systems
  
• Th0.2.a: Advanced Calculi for Services
• Th0.2.b: Assessing Core Calculi and their Extensions
• Th0.2.c: Assessing Session-Oriented Core Calculi for SOC
• Th0.2.d: Formal Approaches to Negotiation and Planning