White Paper: 1) Architecture Objectives: The primary objective of this architecture is to meet the. 2) Architecture Explanation

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1 White Paper: 1) Architecture Objectives: The primary objective of this architecture is to meet the following requirements (SLAs). Scalability and High Availability Modularity and Maintainability Extensibility Portability of technologies in each tier Portability of databases Portability of Application Servers Rapid Application Development 2) Architecture Explanation This architecture is based on Java/JEE technologies with the following stack of technologies/frameworks. But the frameworks in each tier of the architecture can be replaced with other compliant/similar frameworks without affecting the other tiers. JSF 2.x with RichFaces 4.x (including AJAX) for Presentation Tier EJB 3.x for Business Tier JPA 2.x with any ORM for Persistence Layer JCA/JMS for Integration with External Systems(This is for future expansion when required to connect with other external systems) The following diagram illustrates various tiers used in the application architecture. Figure1: Architecture Diagram

2 The application developed as per the above architecture is as per the JEE standards. So, it can be deployed in all JEE compliant application servers which support clustering and load balancing. These tiers make the application modular, extensible and maintainable along with the ability to be deployed in clustered and load balanced environments. Presentation Tier: All the presentation logic is encapsulated in this tier. This allows the business tier to remain unaffected to the changes in the presentation tier. This also gives the freedom in using the technology of our choice for the presentation without affecting the business tier. And also, separating the presentation from business gives the ability to support multiple client types; ex. Mobile Clients, Desktop Clients and Web Service clients. The above architecture allows usage of any of the (and any other applicable framework) frameworks to be used for the Presentation Tier. Pure JSPs with/without Servlets Pure Servlets with/without JSPs Struts (This is what we have used in the CPSIA project) JSF (This will be used in the Material Traceability Project) Flex, etc. Business Tier: The application/business functionality is implemented in this tier. The separation of business logic from presentation logic allows the business tier to be used/accessed by multiple types of clients (Ex. Web, Mobile, Desktop, and Web Services). The architecture above allows usage of the following technologies for implementing the business tier. POJOs (This is what we have used in the CPSIA project) RMI EJB (This will be used in the Material Traceability Project) Spring Web Services Integration Tier: This is the layer where the application interacts with external systems such as RDBMS, ERP, etc. Mechanisms used to integrate with RDBMs are separated from mechanisms used to interact with ERP systems such as SAP or Mainframes, etc. To make it uniform to access any database, we have a choice of the following technologies. JDBC (This is what we have used in the CPSIA project) JPA with Hibernate (This will be used in the Material Traceability Project) To make it uniform to access any other external systems (other than the RDBMS) such as ERP (ex, SAP or Mainframes), the above architecture allows using JCA.

3 JMS allows asynchronous integration with various Messaging Middleware Systems. 3) Deployment Architecture: Following is the deployment architecture used in the application. Figure2: Deployment Architecture. The proposed deployment architecture makes use of clustering and load balancing techniques. The load balancer distributes the concurrent client requests across various nodes in the Web Cluster. This is a technique used to handle concurrent user requests. The clustering of nodes (Web Server and Application) guarantees the high availability as if one node goes down, the load balancer stops sending the requests to the dead node and will send the requests any other available node. As a result, we are avoiding single point of failure situations. Session Replication: The above architecture encourages applications to be developed for allowing the Session Replication. As a result, if a node goes down while in the middle of a request processing, the load balancer can forward the request to another available node in the cluster. If session replication is enabled, the new node can handle the request without even knowing there is a dead node in the cluster. Caching is one of the important aspects of this architecture which contributes towards good performance. Caching is one of the techniques by which we reduce the round trips to servers or enterprise resources such as Databases or external systems. This reduced server round trips are one of the several techniques to keep the response times under the desired minimum. Cloud Based Deployment: applications designed and developed for JEE compliant servers can be easily deployed in closed based environments. This allows us to control the costs on hardware by managing the hardware affectively between peak and off peak hours. Separate Web Server and Application Servers: There are definitely benefits by separating the web and application layers. If the Web layer and Business Layers are deployed on different physical

4 machines, it allows the Web Servers not to worry about the traffic from Desktop and Mobile clients to the Business Tier. 4) Benefits of Architecture: In this section we describe how the architecture proposed above meets the objects set. Scalability and High Availability: Since this architecture is based on JEE standards, any application built using this architecture can be deployed in a clustered and load balanced environment which can addresses the concerns around scalability and high availability. The increasing number of concurrent users can be easily accommodated with the clustering and high availability is guaranteed with the fault tolerant load balancing mechanism. Modularity: Since the architecture is using the layered concept, it is highly modular and maintainable. Extensibility: Using this architecture, we can support multiple types of clients. Currently, the architecture above is for a web based client. We can easily extent it for mobile based clients and desktop based clients as well. The only difference to the architecture (in case if we have to support Desktop and Mobile Clients), there will be separate Presentation Tier for each of those client types. Portability of technologies in each tier: The architecture is designed such a way that each tier can use a technology of choice. The following shows the choice of various technologies/frameworks for each of the tiers. Presentation Tier Business Tier Integration Tier Plain JSP & Servlets POJOs JDBC Struts RMI JPA with JSF Spring Hibernate/iBatis/Eclipse Link Flex EJB JMS and any other possible Web Services JCA Portability of Databases: Any application developed using the above architecture when JPA is used as the Persistence Layer technology specification, it enjoys the portability across multiple database engines without modifying any code. The usage of SQL Dialects along with the JPQL (Java Persistence Query Language) makes it possible to swap databases without changing any code. Portability of Application Servers: This architecture is based on JEE standards and no application server specific APIs are used. So, it is guaranteed to work on any JEE compliant application server without making any source code changes.

5 Rapid Application Development: The various frameworks used in the architecture above are allowing faster development by eliminating the need for writing the boiler plate code repetitively. For example, the usage of annotations in all the three tiers (Presentation, Business and Persistence) reduces the amount of coding the developers have to write. It is providing the developer with a way to avoid time spending in metadata configurations. With this architectural framework, it takes less than 10 minutes to implement a typical Create/Maintain use case with lots of functionality other than just saving and retrieving the data to and from a data base. 5) Acronyms Used AJAX API EJB ERP JCA JEE JMS JPA JSF JSP ORM POJO RDBMS RMI SAP SLA XML Acronyms Used Asynchronous JavaScript And XML Application Programming Interface Enterprise JavaBeans Enterprise Resource Planning Java Connector Architecture Java Enterprise Edition Java Messaging Service Java Persistence API JavaServer Faces JavaServer Pages Object Relational Mapping Plain Old Java Object Relational Database Management System Remote Method Invocation Systems, Applications and Products Service Level Agreement Extensible Markup Language