j2ee - best practices

Architecture Strategies and Best Practices for Server-Side J2EE Development Darren Broemmer copyright 2002-3 Darren Broemmer Guiding Principles copyright 2002-3 Darren Broemmer Elements of Transactional, Web- Based Business Applications  Business applications share many common characteristics  This analysis forms the basis of the software architecture  From these commonalities, you can derive the software layers and component types  The reference architecture is based on a mapping of this analysis to J2EE copyright 2002-3 Darren Broemmer The Structure of Business Applications copyright 2002-3 Darren Broemmer Business Entities  The ‘things’ a business deals with  Range from high-level entities such as Customer down to lower-level entities such as Purchase Order or Line Item  Common characteristics  Behaviors  Properties  Relationships with other Entities  Rules or policies copyright 2002-3 Darren Broemmer Business Processes  The processes used to carry out the work of the business  Defined workflow  Involve business entities as participants  Need to be executed in a secure manner  Comprise units-of-work  Accessible from different clients  Internal/External clients  Browser-based applications  Wireless devices  B2B Web-Service clients copyright 2002-3 Darren Broemmer User Interaction  Providing users access to services and processes  Application presentation (i.e. HTML/XML over HTTP)  Access to business functions and services  Static and dynamic content  Screen flow, or page navigation  Forms processing  Error handling  Includes user interface, interaction with web service clients, etc. copyright 2002-3 Darren Broemmer Reference Architecture (PIM): Realization of Bus. App. Analysis copyright 2002-3 Darren Broemmer Usage of Design Patterns  Patterns provide a foundation of proven, reusable solutions  Model-View-Controller (MVC)  GoF Design Patterns  Sun’s Core J2EE Patterns  Reference architecture is largely defined by the interaction of a number of design patterns  Variations of many existing patterns as applied to J2EE copyright 2002-3 Darren Broemmer Architectural (or Large-Scale) Design Patterns  Layered Architecture  Logical software layers that isolate and modularize responsibilities  Building-block type approach that requires only knowledge of adjacent level directly below given layer  Model-View-Controller (MVC)  Proven object-oriented pattern used for applications with graphical user interfaces  Separation of concerns between content, presentation logic, and business logic  Common functions can be automated (i.e. Struts) [...]... (Model-Driven Architecture) copyright 200 2-3 Darren Broemmer Performance and Scalability  Java, the language itself, starting to approach C/ C++ performance, particularly on server side   Due to aggressive Just-In-Time (JIT) compilers Enterprise Java services, however, add another level of overhead    Must weigh the benefits vs the performance costs Example: Entity Beans not ideal for fine-grained... 200 2-3 Darren Broemmer Metadata-Driven Components  Metadata is input to automated, configurable common functions    Run-time libraries Development-time code generation Industry trend is evident     Most component architectures are defined in part by metadata (EJB, Struts, O/R mapping tools, etc.) Most UML design tools now support XMI (XML Metadata Interchange) JSR-40 – Java Metadata Interface... copyright 200 2-3 Darren Broemmer Application Exception Hierarchy copyright 200 2-3 Darren Broemmer The “Save” Template    Part of standard BusinessObject interface May or may not include actual persistence (for example, CMP Entity Beans) Typically used for the following purposes:    Property and object-level validation integrated with transaction management Manipulation of aggregated objects Pre-save... implementation classes extend VO implementation classes copyright 200 2-3 Darren Broemmer BO & VO Class Diagram copyright 200 2-3 Darren Broemmer Object Validation and Error Handling  Types of validation & implementation  Data Type (ex Characters in numeric field)   Required field checking   Reusable PropertyHandler mechanism Object-level (ex account balance > $50)   BO, VO Base class – validate... Mapped to J2EE copyright 200 2-3 Darren Broemmer Automating Common Functions  From the analysis of transactional, webbased business applications:   Common characteristics can be implemented through configurable, extendible foundation components A Business Logic Foundation (BLF) enables: Higher level of quality  Consistency  Less duplication of effort, faster development times  copyright 200 2-3 Darren... CommonException; copyright 200 2-3 Darren Broemmer Configuring Property Handlers   Can use metadata to configure property handlers and subclasses of BaseBusinessObject Defining Property Handlers  . and Best Practices for Server-Side J2EE Development Darren Broemmer copyright 200 2-3 Darren Broemmer Guiding Principles copyright 200 2-3 Darren Broemmer Elements of Transactional, Web- Based. manner  Comprise units-of-work  Accessible from different clients  Internal/External clients  Browser-based applications  Wireless devices  B2B Web-Service clients copyright 200 2-3 Darren Broemmer User. analysis to J2EE copyright 200 2-3 Darren Broemmer The Structure of Business Applications copyright 200 2-3 Darren Broemmer Business Entities  The ‘things’ a business deals with  Range from high-level