The Nexus Architectural Model (NAM) is the core architectural model employed by Nexus to create business applications. The model ensures secure, scalable, and robust software performance.

It is based upon the recommended Microsoft n-tier design for the .Net platform. It is a fully object oriented model that employs inheritance and polymorphism to create entity mapped code modules.

NAM provides a number of advantages over typical none-tier based architectures:

• Isolation of presentation, business logic and data services
• Portability of application across differing database platforms
• Scalability and extensibility is maximised
• Security management is transparent
• Adaptable to changes in technology
• Low level system documentation is producible
• 'Plug and play' modularity is built in
• Adaptable to differing client types

NAM has been in use at Nexus for over four years.

NAM is based upon the principle of tier separation. This means that a system is broken down into specific units that provide services to other units. Typically a NAM system will have three separate layers, plus database storage:

• Presentation Tier
• Business Tier
• Data Tier
• Data Storage

The tiers may only communicate with each other through their assigned order. This tier isolation enforces modularity and promotes disciplined development practices.

Presentation tier

This tier is responsible for compiling resource media to send to the client and brokering client requests to the business layer. The output that the tier provides can be adapted to suit the particular client, e.g., desktop application, 5th generation browsers, 4th generation browsers, mobile devices, XML readers.

The tier has been fitted with adaptive functions that ensure the dispensed mark-up is formed according to the recommended W3C standards and UK accessibility laws.

The presentation tier is governed by the primary ASP.Net code-execution API. This tier makes use of pre-compiled user control resources to render its navigation systems and common user functionality. These controls are part of the Nexus Code Library (NCL) and provide 'plug and play' compatibility to all our NAM based applications.

Business tier

The business object layer concerns itself with moving data between the inputs of the presentation layer and the database operations of the data tier. It enforces specific business rules and logic and compartmentalises the orchestration of the application into a centralised, compile-protected unit. The business tier classes are all inherited from a base business class that isolates the core methods to ensure baseline performance is consistent throughout all NAM applications.

Loosely coupled to the business tier is the XML web services tier that allows the publication and exposure of the business and data services in the system across secure web protocols. This facilitates secure distributed network communication and content syndication.

Data tier

The data object layer handles the data operations between the application and all forms of data storage. It is fully modular so that if the database technology were to change, one would only have to alter the base class within the data tier to ensure compatibility.

Typically the data tier links to DBMS systems that support stored procedures because they offer greater performance than inline SQL; they support transactions, and promote modularity.

NAM typically performs best when using Microsoft SQL Server, however, the system supports all ODBC compliant database structures, and is capable of consuming data from none-relational data storage such as directory stores, spreadsheets, and XML.

All Nexus systems are designed using NAM and this has allowed us to create many large scale distributed applications that are dependable, scaleable and adaptable. All of our development staff are comprehensively trained in the use of NAM and its supporting technologies.

Click here to contact the Nexus team.