EXPRESS and the 3-tier Architecture

We can picture a mapping between the way EXPRESS does things and the 3-tier architecture. This mapping depends on what type of system EXPRESS is providing an interface for.

EXPRESS can provide RESTful Semantic Web Services as an interface for systems that have complex business logic or for systems that have datasets and want to provide them with simple access. In addition to dividing systems into complex business logic systems and dataset access systems, we can divide them into legacy systems (non-web or non-Semantic) and Semantic systems (based on Semantic technologies like OWL or RDF and have Semantic metadata).

So in total we have 4 categories of systems that EXPRESS can be used to provide RESTful Semantic Web Services:

1. Legacy systems with complex business logic
2. Legacy systems providing dataset access
3. Semantic systems with complex business logic
4. Semantic systems providing dataset access

The mapping between EXPRESS and the 3-tier architecture can be viewed as follows

1. Legacy systems with complex business logic

• Presentation Tier = Semantic Interface
• Application Tier = Business Logic
• Data Tier = Database

2. Legacy systems providing dataset access

• Presentation Tier = Semantic Interface
• Application Tier = CRUD to SQL mappings.
• Data Tier = Database

3. Semantic systems with complex business logic

• Presentation Tier = Semantic Interface
• Application Tier = business logic.
• Data Tier = Triple store or some semantic

4. Semantic systems providing dataset access

• Presentation Tier = Semantic Interface
• Application Tier = CRUD to SQL mappings.
• Data Tier = Triple store or another Semantic database

This mapping raises an important question, if we have two systems one with complex business logic and the other providing only dataset access, and both have similar OWL files how do we show that the complex business one does more than the other.