1. ONTOLOGICAL MIDDLEWARE Enabling Semantically-aware Networking Ben Tagger and Dirk Trossen (presenting)

2. The Role of Middleware (simplified!) User/ App Core Architecture publishScope publishData subscribeScope subscribeItem and so on … Middleware current proposed 2

3. What we hope to achieve… Provide middleware that matches and builds on our goal of information centricity. Enhance the usability of the core architecture. Exploit the functionality of the core architecture. Separate user-space and network-level data/metadata requirements. Incorporate formal modelling of metadata. Promote collaboration and discussion within the group! 3

4. The Principal Design Challenge Understand the (meta)data flow through our system (the blue bit). What data/metadata can be provided to the middleware? i.e., what does the user know? What data/metadata is required at the network level? What does the network need to know? Core Architecture Meta(data) 4

5. Exploring the Design Space At the extreme left, we have a flat mapping of metamodels. (+) Distinct separation of middleware/ network metadata. (-) Removes the possibility of network optimisations. At the extreme right, we have an exact mapping of metamodels. (+) All metadata is preserved at the network level – enables optimisations. (-) Replicating metadata that may not be required. Must compromise on expressiveness of metamodel. ✔ We are looking for the optimum design. 5

6. Separation of Metadata The metadata of publications exists between layers. User-interesting metadata exists at the middleware level. Network-interesting metadata exists at the network level. Some metadata will be of interest to both parties. Questions: What metadata should be placed at which level? How is metadata modelled within the middleware? How is metadata modelled within the network? We have some answers… 6

7. Design Overview video publish Content QoSSecurityOther… Stock Ontologies Annotations User/App Network Ontological Metamodel Rendezvous Metamodel Presentations annotate Key Points: publications are annotated with ontological concepts. ontologies can be built on any relevant topic and easily integrated. If we wish to include a new feature, we need only build a new ontology. 7

8. Benefits of the Design 1 Formal Metamodelling All metadata is placed within a structure. We can demonstrate the correctness of a metamodel. And we can demonstrate the incorrectness! Consistency is passed down to the Network level (Network metamodel is built by the middleware). Formal Publication Every publication has a formal definition. Every bit of data in our network has a meaning. “The what is more important than ….” Advanced Subscriptions subscribe to publications using expressive queries. “give me all the photos uploaded in the last 2 days within ½ mile of me” “give me videos that feature Madonna and in high definition.” The capabilities of the queries depend on the expressiveness of the publications. The more you put in, the more you get out… 8

9. Benefits of the Design 2 Metadata Management Thorough analysis of metadata; what metadata exists? Separation of metadata; what metadata goes where? Leverages the Current Metamodel Puts only the right semantics at the Network layer. Opens the possibility to optimise operations while enhancing functionality. Decouples Data and Metadata Modularity of transport/signalling mechanisms. Middleware contains no data. It’s all in the network layer (where it belongs!) 9

10. Challenges Expressiveness vs Complexity tradeoff We do not advocate an entirely ontology-based design! Strength of the architecture allows for choosing different level of realisations, depending on the desired tradeoff For each area, we have to determine this tradeoff, e.g., in QoS Demonstrate the strength Simplify network-level operations is only one area Other, more user-level areas are candidates But these are mainly not in the scope of PURSUIT Demonstrate the inherent architecture advantage Prove our ‘impedance mismatch’ claim Need metrics to determine efforts for middleware development More than just complexity 10

11. Thanks, Questions and Discussion 11