N layer/tier Architecture

• An n layer/tier architecture includes layers as per its High level diagram or interaction with upstream and downstream systems besides three basic layers.
• Client layer(Desktop/Mobile/browser)
• User interface, client side validation, Ajax, UI rules
• RIA Design(Ajax, Jquery, CSS)
• Forms
• HTTP/HTTPS/POST
• Presentation layer(PL)
• The top most level of the application is the user interface.
• The main function of the interface is to translate tasks and results to something that the user can understand.
• User interface, UI event handlers, UI rules, NAVIGATION
• Event Based Design
• JSF/data Valuators
• Canonical object model, local POJO, SOAP, REST
• Business/Services Layer(BLL)
• This layer coordinates the application, processes, commands, makes logical decisions and evaluation and perform calculations. 
• It also moves the processed data between the two sounding layers.
• Business logic, business rules, Workflow, data validation
• Design by contract
• EJB, IOC/CDI, JAX-WS and JAX-RS
• Canonical object model
• SOAP, REST
• This layer is all about handling and executing business logic, business rules and interaction with data services.
• Data access/services layer(DAL)
• Here information is stored and typed from a database or file system.
• The information is then passed back to the logic layer for processing and then eventually back to the user.
• Interacts with operational database Like business entity media et cetera.
• CRUD data persistence
• Data access objects
• Entity driven design
• Entity beans(ORM)
• Hibernate
• Integration Tier orchestration
• Workflow
• Rules
• JMS, SOAP, JAXB, Spring
• Interact with external systems, such as interfaces, feeds and printers.