2014 Pre-MSc-IS-4 Business Logic Layer

Programme: Master of Science in Business Information Systems FHNW
Course: Pre-Master Information Systems
Topic: Business Logic Layer

Transcript

1. Andreas Martin - Page 1 Master of Science in Business Information Systems FHNW Pre-Master Information Systems 4. Business Logic Layer Andreas Martin 4. Business Logic Layer http://www.flickr.com/photos/dirk_hofmann/4200450207
2. Andreas Martin - Page 2 Business Logic Layer  Enterprise JavaBeans  Hands-on:  Hands-on 3: ENTERPRISE JAVA BEANS I  Hands-on 4: ENTERPRISE JAVA BEANS II 4. Business Logic Layer
3. The Latte Macchiato «Layering» Principle http://www.flickr.com/photos/tf28/4367660424 Presentation Layer Goal: Display of information, processing / forwarding of user interactions. Technologies: JavaServer Faces (JSF), JavaServer Pages (JSP), Servlets, etc. Business (Logic) Layer Goal: Reproduction of actions or «verbs» of the application (buy a book, print an order, deliver a book, etc.). Technologies: Enterprise Java Beans (EJBs) Persistence Layer Goal: Reproduction of database attributes, information or «nouns» in object / class attributes (Object-Relational Mapping, ORM). Technologies: Java Persistence API (JPA)
4. Enterprise JavaBeans http://www.flickr.com/photos/jcolivera/2950430514
5. Andreas Martin - Page 5 From the NOUNS to the VERBS…  Previously we used the NOUNS on persistence layer, like Books, Customers, Persons, etc…  …now we are considering the VERBS, like create a book, deliver a book, buy a book, etc.  Now it becomes obvious why we talk about Enterprise Java Beans…  …because we are going to implement the business logic. 4. Business Logic Layer
6. Andreas Martin - Page 6 Enterprise Java Bean (EJB) Container  An EJB is nothing else as a:  annotated Java object…  …, which will be deployed in a container.  The EJB Container provides:  Transaction,  persistence and  security- management  …the engineer can focus on the development of the business logic. 4. Business Logic Layer Source: http://java.sun.com/developer/onlineTraining/EJBIntro/EJBIntro.html
7. Andreas Martin - Page 7 Business Layer Java EE 7 – Typical Layering including injected POJO’s 4. Business Logic Layer Persistence Layer @EntityManager (JPA) (JPA) @Entity (JPA) Session Bean (EJB) @PersistenceContext Presentation Layer Facelets (JSF) @ManagedBean (JSF) Facelets (JSF) Users Databases @EJB / @Inject POJO @Inject
8. Andreas Martin - Page 8 Annotations of an EJB  @Stateless: A «Stateless Bean» does not have a state between method calls from outside (e.g. a client) – it does not held data in-memory.  @Stateful: A «Stateful Bean» does have a state between method calls e.g. from a client.  @Singleton: A «Singleton Bean» (or Single Session Bean) exists only once as object. 4. Business Logic Layer
9. Andreas Martin - Page 9 Simple Stateless EJB 4. Business Logic Layer Listing: A Simple Stateless EJB @Stateless public class BookEJB { @PersistenceContext(unitName = "primary") private EntityManager em; public Book findBookById(Long id) { return em.find(Book.class, id); } public Book createBook(Book book) { em.persist(book); return book; } }
10. Andreas Martin - Page 10 @Startup and @Singleton Style Dirty Java EE Testing 4. Business Logic Layer
11. Andreas Martin - Page 11 @Startup and @Singleton Style - Example 4. Business Logic Layer @Singleton @Startup public class BookStartupSingletonTest { @EJB private BookEJBLocal bookEJBLocal; @PostConstruct void init() { try { shouldCreateABook(); } catch (Exception ex) { Logger.getLogger(BookTestEJB.class.getName()).log(Level.SEVERE, null, ex); } } public void shouldCreateABook() throws Exception { Book book = new Book(); book.setTitle("Hello"); book.setPrice(12.5F); book.setDescription("Science fiction comedy book"); book.setIsbn("1-84023-742-2"); book.setNbOfPage(354); book.setIllustrations(false); book = bookEJBLocal.createBook(book); assertNotNull("ID should not be null", book.getId()); List<Book> books = bookEJBLocal.findBooks(); assertNotNull(books); } }
12. Andreas Martin - Page 12 Hands-on 3 ENTERPRISE JAVA BEANS I 4. Business Logic Layer Based on: Goncalves, 2010: Beginning Java™ EE 6 Platform with GlassFish™ 3
13. Andreas Martin - Page 13 Database Connection …will be used for the next hands-on’s  Modify the MySQL_premscis-ds.xml file:  When using a Web Project in Eclipse, it is possible to deploy a datasource using a JBoss datasource file (…-ds.xml)  This file must be placed under: Project +---src\main\webapp\WEB-INF ¦ faces-config.xml ¦ jboss-web.xml ¦ MySQL_premscis-ds.xml  Choose another student ‘number’ (DatabaseName) to avoid overwriting. 4. Business Logic Layer <?xml version="1.0" encoding="UTF-8"?> <datasources xmlns="http://www.jboss.org/ironjacamar/schema"> <datasource jta="true" jndi-name="java:jboss/datasources/MySQL_premscis" enabled="true" use-java-context="true" pool-name="MySQL_premscis"> <connection-url>jdbc:mysql://mature.iwi.wirtschaft.fhnw.ch:80/premscis</connection-url> <driver>mysql-connector-java-5.1.32-bin.jarcom.mysql.jdbc.Driver_5_1</driver> <pool></pool> <security> <user-name>premscis</user-name> <password>premscis</password> </security> </datasource> </datasources>
14. Andreas Martin - Page 14 Hands-on 3 1. Import project «Hands-on-3» and… 2. …create a «Book» entity with the following attributes (id, title, price, description, isbn, numberOfPages und illustrations) 3. Extend the «Book» entity with the following two NamedQueries: findAllBooks und findAllBooksById 4. Business Logic Layer
15. Andreas Martin - Page 15 Hands-on 3 4. Create a «BookEJB». 5. …and implement the following methods: findBooks, findBookById, createBook, deleteBook und updateBook. 6. Write a @Startup - @Singleton, which creates and retrieves a book from database. 4. Business Logic Layer @Singleton @Startup public class BookStartupSingletonTest { @EJB private BookEJB bookEJBLocal; @PostConstruct void init() { try { shouldCreateABook(); } catch (Exception ex) { ex.printStackTrace(); } } public void shouldCreateABook() throws Exception { Book book = new Book(); book.setTitle("HelloNew"); book.setPrice(12.5F); book.setDescription("Science fiction comedy book"); book.setIsbn("1-84023-742-2"); book.setNbOfPage(354); book.setIllustrations(false); book = bookEJBLocal.createBook(book); assertNotNull("ID should not be null", book.getId()); List<Book> books = bookEJBLocal.findBooks(); assertNotNull(books); }}
16. Andreas Martin - Page 16 Hands-on 4 ENTERPRISE JAVA BEANS II 4. Business Logic Layer
17. Andreas Martin - Page 17 Book EJB Customer EJB Business cases: • Create a customer including address • …CRUD… Book Lending EJB Hands-on 4  Now in «Hands-on-4» we create an EJB based application for lending books.  Primary we represent the following business use cases: the lending, retrieval and returning of books. 4. Business Logic Layer <Entity> Address <Entity> Customer <Entity> Book Lending <Entity> Book n 1 0..1 0..1 1 Business cases: • Lend a book • Return a book • Show all lendings Business cases: • Create a book • …CRUD.. 1
18. Andreas Martin - Page 18 Hands-on 4 1. Import the «Hands-on-4» project. 2. Create the following entities Customer, Address and Book. Can you read the cardinalities? What does that mean? 3. Create a BookLending entity with the following attributes: Customer, Book, LendingDate, ReturnDate, nbOfDaysToReturn and bookIsLended. 4. Business Logic Layer Book EJB Customer EJB Business cases: • Create a customer including address • …CRUD… Book Lending EJB <Entity> Address <Entity> Customer <Entity> Book Lending <Entity> Book n 1 0..1 0..1 1 Business cases: • Lend a book • Return a book • Show all lendings Business cases: • Create a book • …CRUD.. 1
19. Andreas Martin - Page 19 Hands-on 4 4. Write for the Customer and Book entity a corresponding EJB. 5. Write a Lending EJB that convers the use cases. 6. And finally write a @Startup - @Singleton and create test data. 4. Business Logic Layer Book EJB Customer EJB Business cases: • Create a customer including address • …CRUD… Book Lending EJB <Entity> Address <Entity> Customer <Entity> Book Lending <Entity> Book n 1 0..1 0..1 1 Business cases: • Lend a book • Return a book • Show all lendings Business cases: • Create a book • …CRUD.. 1
20. Andreas Martin - Page 20 Hands-on 4  Domain model:  Business logic model: 4. Business Logic Layer