Domain Logic Patterns  Transaction Script  Domain Model  Table Module  Service Layer

Transaction Script  Organizes business logic by procedures where each procedure handles a single request form the presentation

TS: How It Works  Each business transaction corresponds to one transaction script  Business transaction: Book a hotel room  Tasks: check room availability, calculate rates, update the database – all handled in one BookARoom script.  Transaction scripts access the database directly  Don’t call any logic in the presentation layer  Organization  Each script is a procedure  Related scripts are enclosed in one class  Each script is in one class.

TS: Architecture TransactionScript businessTransaction1() businessTransaction2() businessTransaction3() Gateway findDataForBusinessTransaction1(sql_query) insertRecordsForBusinessTransaction1(sql_insert, items) updateRecordsForBusinessTransaction2(sql_update, items) … sql_query= “ SELECT * FROM table 1…” sql_insert = “INSERT into tablei…” sql_update = “ UPDATE tablei …” sql_delete = “DELETE FROM …” DB

TS: When to use it  When the domain logic is very simple  When transactions do not have a lot of overlap in functionality

Example Revenue Recognition  A contract is signed for one product  The revenue of a contract may not be recognized right away.  Different types of product may have different revenue recognition schedule  Three types of product  Word Processor: revenue recognized right away  Spreadsheet: 1/3 today, 1/3 in 60 days, 1/3 in 90 days.  Database: 1/3 today, 1/3 in 30 days, 1/3 in 60 days. Product Name type Contract date _signed revenue RevenueRecognition Amount date 1 1 * *

TS: Example RecognitionService calcRecognitions(contract#) recognizedRevenue(contract#, date) createContract(id, revenue, prod_id, date) … DatabaseGateway findContract(contract#) findRecognitionsFor(contract#, date) insertRecognition(contract#, revenue, date) … Sql_findContract = “ SELECT * FROM Contract WHERE id = ?” Sql_findRecogns = “select* from recog Where cid=? and date<?” Sql_insertContract = “INSERT into contract…” DB

createContract() Sequence Diagram: test cases :RecognitionService:DatabaseGateway :Tester insertContract() INSERT into contract … :Database calcRecognitions() insertRecognition() INSERT iinto Recog… recognizedRevenue() findRecognitionsFor() SELECT * FROM … insertRecognition() INSERT iinto Recog… insertRecognition()

TS: Example class Gateway { static String findRecogns = “SELECT * FROM revenueRecognition WHERE contract = ? And date <= ?”; static String findContract = “SELECT * FROM contract c, product p WHERE c.id = ? And c.pid = p.id”; public ResultSet findRecognitionsFor(int contrno, Date d) { PreparedStatement s = db.prepareStatement(findRecongs); s.setInt(1, contrno); s.setDate(2, d); ResultSet result = s.executeQuery(); return result; } public ResultSet findContract(int contrno) { PreparedStatement s = db.prepareStatement(findContract); s.setInt(1, contrno); ResultSet result = s.executeQuery(); return result; }

TS: Example class RecognitionService { private Gateway gw = new Gateway(); public Money recognizedRevenue(int contrno, Date d) { Money Result = Money.dollar(0); ResultSet rs = gw.findRecognitionsFor(contrno, d); while (rs.next()) { result = result.add(rs.getBigDecimal(“amount”)); } return result; } public void calculateRevenueRecognitions(int contrno) { ResultSet contrs = gw.findContract(contrno); totalRevenue = contrs.getBigDecimal(“revenue”); dates = contrs.getDate(“date_signed”); type = contrs.getChar(“type”); if (type == ‘S’) { db.insertRecognition(contrno, totalRevenue/3, date); db.insertRecognition(contrno, totalRevenue/3, date+60); db.insertRecognition(contrno, totalRevenue/3, date+90); } else if (type = ‘W’) { db.insertRecognition(contrno, totalRevenue, date); } else if (type == ‘D’ {... }...

Domain Model  An object model of the domain that incorporates both behavior and data

DM: Revenue Recognition Product Name type Contract date _signed revenue RevenueRecognition Amount date 1 1 * * recognizedRevenue(date) calculateRecognitions() calcRecognitions(contrct) RecognitionStrategy Complete RecognitionStrategy * 1 Three-way RecognitionStrategy calcRecognitions(contrct) isRecognizableBy(date) DB

DM: Example class RevenueRecognition { private Money amount; private Date date; public RevenueRecognition(Money amnt, Date d) {...} public Money getAmount() { return amount; } public boolean isRecognizableBy(Date date) { return this.date.before(date) || this.date.equals(date); }... } class Contract { private List revenueRecognitions = new ArrayList(); public Money recognizedRevenue(Date date) { Money result = Money.dollar(0); Iterator it = revenueRecognitions.iterator(); while (it.hasNext()} { RevenueRecognition r = (RevenueRecognition)it.next(); if (r.isRecognizableBy(date)) result = result.add(r.getAmount()); } return result; }...

DM: Example class RevenueRecognition { private Money amount; private Date date; public RevenueRecognition(Money amnt, Date d) {...} public Money getAmount() { return amount; } public boolean isRecognizableBy(Date date) { return this.date.before(date) || this.date.equals(date); }... } class Contract { private List revenueRecognitions = new ArrayList(); public Money recognizedRevenue(Date date) { Money result = Money.dollar(0); Iterator it = revenueRecognitions.iterator(); while (it.hasNext()} { RevenueRecognition r = (RevenueRecognition)it.next(); if (r.isRecognizableBy(date)) result = result.add(r.getAmount()); } return result; }...

DM: Example class Contract { private Product product; private Money amount; private Date dateSigned; private long id; public Contract(Product p, Money amnt, Date d) {...} public void addRecognition(RevenueRecognition rr) { revenueRecognitions.add(rr); } public Date getDateSigned() { return dateSigned; } public void calcRecognitions() { product.calcRecognitions(this); }... } interface RecognitionStrategy { public void calcRevenueRecognitions(Contract c); }

DM: Example class CompleteRecognitionStrategy implements... { public void calcRevenueRecognitions(Contract c) { c.addRecognition(new RevenueRecognition( c.getAmount(), c.getDateSigned()); } class ThreeWayRecognitionStrategy implements... { private int firstRecognitionOffset; private int secondRecognitionOffset; public ThreeWayRecognitionStrategy(int offset1, int offset2) { this.firstRecognitionOffset = offset1; this.secondRecognitionOffset = offset2; } public void calcRevenueRecognitions(Contract c) { c.addRecognition(new RevenueRecognition( c.getAmount()/3, c.getDateSigned()); c.addRecognition(new RevenueRecognition( c.getAmount()/3, c.getDateSigned()+offset1); c.addRecognition(new RevenueRecognition( c.getAmount()/3, c.getDateSigned()+offset2); }... }

DM: Example class Product { private String name; private RecognitionStrategy recogStrategy; public Product(String name, RecognitionStrategy rs) { this.name = name; this.recogStrategy = rs; } public void calcRecognitions(Contract c) { recogStrategy.calcRecognitions(c); } public static Product newWordProcessor(String name) { return new Product(name, new CompleteRecognitionStrategy()); } public static Product newSpreadsheet(String name) { return new Product(name, new ThreeWayRecognitionStrategy(60, 90)); } public static Product newDatabase(String name) { return new Product(name, new ThreeWayRecognitionStrategy(30, 60)); }

DM: Example class Tester { public static void main(String[] args) { Product word = Product.newWordProcessor(“IntelWord”); Product calc = Product.newSpreadsheet(“calc II”); Product db = Product.newDatabse(“DB IV”); Date today = System.today(); Contract c1 = new Contract(word, , today); c1.calcRecognitions(); Contract c2 = new Contract(calc, 24000, today); c2.calcRecognitions(); // sequence diagram – next slide Contract c3 = new Contract(db, , today); c3.calcRecognitions(); System.out.println(c1.recognizedRevenue(today + 10)); System.out.println(c2.recognizedRevenue(today + 70)); System.out.println(c3.recognizedRevenue(today + 80)); }

product:Product c2.:Contract calcRecognitions() calcRecognitions(c2) DM: Sequence Diagram: c2.calcRecognitions() rr1:RevenueRecognition recogStrategy:RecognitionStrategy (amount/3, date) calcRecognitions(c2) Mount = getAmount() date = getDateSigned() addRecognition(rr1) rr2:RevenueRecognition rr3:RevenueRecognition addRecognition(rr2) addRecognition(rr3) (amount/3, date + 60) (amount/3, date + 90) :Tester

c2.:Contract recognizedRevenue(date) isRecognizableBy(date) DM: Sequence Diagram: c2.recognizedRevenue() rr[0]:RevenueRecognitionrr[1]:RevenueRecognitionrr[2]:RevenueRecognition :Tester getAmount() isRecognizableBy(date) getAmount() isRecognizableBy(date) return result

Table Module  A single instance that handles the business logic for all rows in a database table or view  Each module is responsible for all the CRUD operations on the corresponding table.  No other modules are supposed to CRUD directly on the table  Each module also includes business logic that is tightly related to the table.

TM: Architecture Table_1 TableModule_1 CRUD operations on Table_1 Business Logic related to Table_1 Attributes Table_2 TableModule_2 CRUD operations on Table_2 Business Logic related to Table_2 Attributes Table_n TableModule_n CRUD operations on Table_n Business Logic related to Table_n Attributes Database

TM: Example - Tables Product Contract RevenueRecognition Id: Number dateSigned: Date revenue: Number prod_id: Number (FK) Id:Number name: String type: String Id: Number amount: Number date: Date c_id: Number (FK)

TM: Example - Modules Product ContractRevenueRecognition Insert(cid, revenue, prod_id, date) calculateRecognitions(c_id) getProductType(prod_id) Insert(c_id, amount, date) recognizedRevenue(c_id, date) DB

:Product :Contract getContract(id) getProductID() TM: Sequence Diagram: calcRecognitions() :RevenueRecognition :Tester contract:ResultSet getProductType(pid) calcRecognitions(cid) insert(cid, revenue/3, date) insert(cid, revenue/3, date+60) insert(cid, revenue/3 date+90) getRevenue() getDateSigned() return result DB SELECT INSERT

recognizedRevenue(c_id, date) getAmount() TM: Sequence Diagram: recognizedRevenue() :RevenueRecognition:Tester recognitions:ResultSet :Contract getRecognitions(c_id, date) getAmount() return result DB SELECT

Service Layer  Defines an application’s boundary with a layer of services that establishes a set of available operations and coordinates the application’s response in each operation.  Two type of business logic  Domain logic: pure logic of the business domain  E.g., calculating revenue recognitions of a contract  Application logic: application responsibilities  E.g., notifying administrators and integrated applications, of revenue recognition calculations

TM: Example - Modules Domain Model Service Layer Data Loader DB User Interfaces Integration Gateways

SL: Architecture  Domain logic: Domain model layer  Application logic: Service layer  Service layer:  Operation Scripts – A set of classes that implement application logic but delegate to domain model classes for domain logic.  Clients interact with the operation scripts  Operation scripts for a subject area are encapsulated in a class named SubjectService.

SL: Services and Operations  Determined by the needs of clients  Derived from use case models  Data validation  CRUD operations on domain objects  Notification of people or other integrated applications  All responses must be coordinated and transacted automatically by the service layer

SL: When to Use It  When there are many different kinds of clients  When the response may involve application logic that needs to be transacted across multiple transactional resources

SL: Example  Revenue Recognition  New requirements: once revenue recognitions are calculated, it must  a notification to contract administrators  Publish a message to notify other integrated applications

SL: Example RecognitionService calcRevenueRecogs(contr#) recognizedRevenue(contr#, date) ApplicationService Gateway send (toAddr, subj, body) get Gateway(): Gateway getIntegrationGateway(): IntegrationGateway IntegrationGateway publishRevenueRecogs(contract) ContractProductRevenueRecognition Domain Model

SL: Example class RecognitionService extends ApplicationService { public void calcRevenueRecogs(contractNo) { Transaction trans = Transaction.getNewTransaction(); trans.begin(); // delegate to domain objects Contract contract = Contract.getContract(contractNo); contract.calcRecognitions(); Contract c2 = new Contract(calc, 24000, today); // interact with transactional sources get Gateway().send (contract.getAdmin (), “RE: contract revenue recognitions”, contract.getId() +”Recognitions calculated”); getIntegrationGateway().publishRevenueRecogs(contract); trans.commit(); }

Domain Logic: Summary  Transaction Script  One script per user request/action  Good for simple, no-overlapping business logic  Domain Model  A set of interrelated objects for business logic  Good for application with complex business logic  Table Module  A module for the CRUD operations and business logic for a table in DB  Compromise between Transaction Script and Domain Model  Service Layer  Application logic is separated into a new layer from domain logic  Good for applications that have complex application logic – interacting with multiple transactional resources