JAP Hybrid 10

• ORM (Object-Relational Mapping) helps define communication mechanisms using a Query Language based on the OO paradigm for database interaction and query execution
• ORM is a programming technique to convert data between relational databases and object-oriented programming languages.
• ORM maps results directly to Java objects
• The mapping happens automatically based on properties in the ORM configuration XML file
• ORMs support various databases like Oracle, Microsoft SQL Server, DB2, Sybase, MySQL, PostgreSQL, and Apache Derby

JDBC Revision

• JDBC: Java Database Connectivity, a free open-source API
• Contains methods to connect to database servers and perform SQL commands (DML)
• Function: Opens a database connection using a JDBC driver, sends SQL queries, and receives results

JDBC limitations

• Complexity
• Programming overhead
• Lack of encapsulation
• DBMS specificity
• Limited facilities for Object-Oriented languages when persisting data in RDBMS, causing model mismatches
• ORM bridges the gap between object and relational models.

ORM Principles

• It maps the results to corresponding Java objects
• Mapping to objects is automatic, based on properties from the ORM configuration XML file

ORM Advantages

• Better Architecture: It implements effective design patterns for clean separation of concerns.
• Performance: Implies in better performance in the main DB operations such as simple insert, update or delete
• Caching: Improves performance of data access operations. Hibernate supports multiple transactions, locking, and versioning

Hibernate and MySQL

• Relational databases organize data into tables with relations
• SQL (Structured Query Language) is used to create, modify, and extract data
• RDBMS (Relational Data Base Management Systems) uses SQL to manage databases.

Hibernate

• Hibernate ORM is a free software distributed under GNU license
• Acts as an object-relational mapping tool for the Java programming language
• Provides a framework for mapping an object-oriented domain model to a relational database
• Framework handles object-relational impedance mismatch problems by high-level object handling functions
• Popular solution for implementing ORM, allowing mapping of classes to entities persisted in different databases.

MySQL

• MySQL is an open-source relational database management system (RDBMS) distributed under the GNU General Public License
• Also available under proprietary licenses, now managed by Oracle

Maven Project and Hibernate configuration

• Maven (Apache Software Foundation) builds automation tool used for Java project management
• Maven manages builds, reporting, and documentation from a central project object model (POM)
• Libraries from several Maven artefacts, including hibernate.
• Select "New Project" > Maven Project;
• In the "Categories", select "org.apache.archetypes maven.archetype.quickstart"
• Define a "Group Id" and an "Artefact Id“
• Open the "pom.xml" file and allow MySql and Hibernate drivers

Configuration files

• Three XML files
• XML file must be placed in your project folder
• hibernate.cfg.xml: Hibernate configuration
• The data access info (username and password) must be defined
• Located in the resources folder
• The file is related to the Hibernate map that you need to do for each entity used by ORM solution
• Employee.java: Our application will use one single class, can be defined as Java object
• A Java object that doesn't extend or implement some specialized classes and interfaces respectively required by the EJB framework
• All normal Java objects are POJO
• Employee.hbm.xml: This class must be mapped by hibernate
• Create the database and a table for tests, for instance:
• Consider your installed MySql, simply create a database and a table for tests
• Implement methods for adding, listing, updating, and deleting.

UML Architecture

• Software system built at its highest level with quality and design in mind

General Architecture Review

• Software team is tied to many practical concerns such as the structure of the development team
• The needs of the business
• Development cycle
• Intent of the structure itself

Software architecture views

• Provides a basic design of the system, functions, and element relations

Use Case View

• Shows the functionality of the system as perceived by external actors
• Reveals the requirements of the system
• Capture the static aspects of this view in the use case diagrams using UML

Design View

• Functionality inside the system in terms of static structure and dynamic behavior
• Captures the vocabulary of the problem space and solution space
• Represents the static aspects of this view in class and object diagrams using UML

Implementation View

• Represents the organization of the core components and files
• Primarily addresses the configuration management of the system’s releases
• Expresses its static aspects in component diagrams, and the dynamic aspects are captured in interaction diagrams, state chart diagrams, and activity diagrams using UML

Process View

• Demonstrates the concurrency of the system
• Incorporates the threads and processes synchronizing mechanisms
• Addresses the system's scalability, throughput, and performance
• its static and dynamic aspects expressed the same way as the design view

Deployment View

• Shows the deployment of the system in terms of physical architecture
• Includes the nodes, which form the system hardware topology where the system will be executed
• Addressing the distribution, delivery, and installation of the parts that build the physical system

UML-Diagrams

• UML diagrams into structural diagrams, behavioral diagrams, are classified as hierarchy diagrams

Structural Diagrams

• Depict a static view or structure of a system
• Embrace class diagrams, composite structure diagrams, component diagrams, deployment diagrams, object diagrams, and package diagrams
• Presents and outline for the system describing the elements to be present that are to be modeled
  • Class Diagram: Depicts the static structure of the system. Displays the system's class, attributes, and methods.
  • Composite Structure Diagram: Shows parts within the class. Displays the relationship between the parts and their configuration that ascertain the behavior of the class
  • Object Diagram: Describes the static structure of a system at a particular point in time
  • Component Diagram: Portrays the organization of the physical components within the system
  • Deployment Diagram: Presents the system's software and its hardware by telling what the existing physical components are and what software components are running on them
  • Package Diagram: Illustrates how the packages and their elements are organized

Behavioral Diagrams

• Portray a dynamic view of a system. Include use case diagrams, state diagrams, and activity diagrams
• State Machine Diagram: Portrays the system's behavior utilizing finite state transitions
• Activity Diagram: Models the flow of control from one activity to the other
• Use Case Diagram: Represents the functionality of a system by utilizing actors and use cases

Interaction Diagrams

• Subclass of behavioral diagrams that emphasize object interactions and the flow between various use case elements of the system
  • Sequence Diagram: Shows the interactions between the objects in terms of messages exchanged over time
  • Communication Diagram: Shows the interchange of sequence messages between the objects
  • Timing Diagram: Used to depict the object's behavior over a specific period of time
  • Interaction Overview diagram: Mixture of activity and sequence diagram