Communication Software Exam 5º Ingeniero de Telecomunicación January 26th Name:

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1 Duration: Marks: 2.5 hours (+ half an hour for those students sitting part III) 8 points (+ 1 point for part III, for those students sitting this part) Part II: problems Duration: 2 hours Marks: 4 points Answer two of the following three questions, each question on a separate sheet of paper. The use of books or notes is not permitted. Question 1 (2 points) (a) (1,25 points) A shop database contains the following tables: Products Product_code Supplier_ref Units_per_pack Product_info Order_details Order_date Order_ref Product_code Quantity Orders Order_ref Supplier_ref Amount Payment_method Stock Stock_ref Product_code Quantity Storage_location Suppliers Supplier_ref Name Address Tel Fax Web Sales Product_code Price Year Week Units_sold where each product is obtained from one and only one supplier and the Amount of an order is the sum of the price of all the products of that order. You may assume the existence of the functions currentdate(), currentweek() and currentyear(), that return the current date, the current week and the current year, respectively, in the required format. Now Provide SQL sentences that implement the following instructions:

2 (i) (1 point) We wish to order exactly 1 pack of each product that is out of stock (i.e. STOCK.Quantity = 0) in the warehouse (Storage_location = 'warehouse'); provide the commands to modify the database accordingly. You may assume that: 1. no more than one order can be placed with a given supplier each day so that each new Order_ref can be constructed by concatenating the current date to the end of the corresponding Supplier_ref (the SQL concatenation operator is written ), 1. the value of Payment_method for all Orders is the string 'CASH', 2. all the products to be ordered have a (non-zero) price in Euros which can change weekly (the current price can be obtained from the Sales table), 3. the default value for the Order_date column is the result of executing the function currentdate(). Hints: 1. You will need to create new rows, first in Order_details, then in Orders; do not worry about the transactional aspects of the two commands used to do so. 2. There is a variant of the command to create new rows in which, instead of simply providing the values for the new row, you provide an SQL query (in parentheses) which, when executed, returns the values for one or more new rows. 3. In the command to create new rows, if not all the columns are explicitly assigned values then when the command is executed, the remaining columns will be assigned default values (null, if the schema specifies no default value for the column). A column specification a comma-separated list of column names in square brackets placed immediately before the row values (or before the query that returns the values for one or more rows, see previous hint) can be used to avoid ambiguity with regard to which of the columns are explicitly being given values. 4. The elements of a select list (i.e. the comma-separated list following the SELECT keyword) can be SQL value expressions (i.e. they do not have to be column names). (ii) (0.15 points) An article whose Product_code is is sold; provide the command to modify the Sales table of the database accordingly. (iii) (0.1 points) Delete from the Sales table all the entries from 2005 whose price was less than 10 Euros. (b) (0,75 points) Figure 1 contains a UML diagram representing the domain model of a Spanish university department. Study the model and then answer the following questions: (i) (0.25 points) What type of UML diagram is this and to what diagram category does it belong? What does the box labelled Empleado represent? What does the text contained in this box represent? What other information could have been provided in the boxes? (ii) (0.25 points) What is the meaning of the line labelled Es autor connecting the boxes labelled Publicación and Empleado? What is the meaning of the text autores_locales placed at the Empleado-extremity of this line (i.e. where this line meets the box labelled Empleado)? What is the meaning of the annotation * that appears at the Publicación-extremity and of the annotation 1..* that appears at the Empleadoextremity of this line? What is the meaning of the absence of such an annotation at an extremity of a line connecting two boxes of the diagram (e.g. the Empleado-extremity of the line labelled Es responsable connecting Publicación and Empleado)? (iii) (0.25 points) What is the meaning of the line connecting the boxes labelled Grupo_Investigación and Línea_Investigación (don't forget to take into account the diamond shape and to explain what it means in practical terms)? What is the meaning of the lines connecting the box labelled Empleado_Universidad and the boxes labelled PDI and PAS?

3 Question 2 (2 points) Study the following code conforming to the EJB3 specification (due to Bill Burke and Richard Monson-Haefel) and then answer the questions appearing below it. In file TravelAgentRemote.java: package com.titan.travelagent; import com.titan.processpayment.creditcarddo; import javax.ejb.remote; import public interface TravelAgentRemote { public Customer findorcreatecustomer(string first, String last); public void updateaddress(address addr); public void setcruiseid(int cruise); public void setcabinid(int cabin); public TicketDO bookpassage(creditcarddo card, double price) throws IncompleteConversationalState; In file TravelAgentBean.java: package com.titan.travelagent; import com.titan.processpayment.*; import com.titan.domain.*; import javax.ejb.*; import javax.persistence.*; import javax.annotation.ejb; import public class TravelAgentBean implements TravelAgentRemote private EntityManager private ProcessPaymentLocal processpayment; private Customer customer; private Cruise cruise; private Cabin cabin; public Customer findorcreatecustomer(string first, String last) { try { Query q = entitymanager.createquery( "from Customer c where c.firstname = :first" + " and c.lastname = :last"); q.setparameter("first", first); q.setparameter("last", last); this.customer = (Customer) q.getsingleresult(); catch (NoResultException notfound) { this.customer = new Customer(); this.customer.setfirstname(first); this.customer.setlastname(last); entitymanager.persist(this.customer); return this.customer;

4 public void updateaddress(address addr) { this.customer.setaddress(addr); this.customer = entitymanager.merge(customer); public void setcabinid(int cabinid) { this.cabin = entitymanager.find(cabin.class, cabinid) ; if (cabin == null) throw new NoResultException("Cabin not found"); public void setcruiseid(int cruiseid) { this.cruise = entitymanager.find(cruise.class, cruiseid); if (cruise == null) throw new NoResultException("Cruise not public TicketDO bookpassage(creditcarddo card, double price) throws IncompleteConversationalState { if (customer == null cruise == null cabin == null) { throw new IncompleteConversationalState(); try { Reservation reservation = new Reservation( customer, cruise, cabin, price, new Date()); entitymanager.persist(reservation); processpayment.bycredit(customer, card, price); TicketDO ticket = new TicketDO(customer, cruise, cabin, price); return ticket; catch(exception e) { throw new EJBException(e); In file Customer.java: package com.titan.domain; public class Customer implements java.io.serializable { private long id; private String firstname; private nullable=false, columndefinition="integer") public long getid() { return id; public void setid(long id) { this.id = length=20, nullable=false) public String getfirstname() { return firstname; public void setfirstname(string firstname) { this.firstname = firstname; public String getlastname() { return lastname; public void setlastname(string lastname) { this.lastname = lastname;

5 (a) (0.7 points) Explain briefly the use of each of the following annotations: (see TravelAgentRemote @EJB (see TravelAgentBean (see Customer class) (b) (0.4 points) Explain briefly the role of the EntityManager class and the use of each of the following methods of this class: createquery(), persist(), merge() and find(). (c) (0.4 points) Suppose we are not generating the database tables from the Java code (nor vice versa). Provide the SQL code to create the database table corresponding to the Customer class. (d) (0.4 points) If we were to use the following code for the Customer class instead of that appearing above, what would the SQL code to create the database table corresponding to this class now public class Customer implements java.io.serializable private long id; private String firstname; private String lastname; public long getid() { return id; public void setid(long id) { this.id = id; public String getfirstname() { return firstname; public void setfirstname(string firstname) {this.firstname = firstname; public String getlastname() { return lastname; public void setlastname(string lastname) {this.lastname = lastname; (e) (0,1 point) What annotation would you use if you wanted the values of the primary key of the database table corresponding to the Customer class to be automatically-generated?

6 Question 3 (2 points) Study the following code for the service method of a Java servlet and then answer the questions appearing below it. Note that the method getproductitem is passed a list of products and a product ID and returns the product from the list having that ID or null if there is no such product on the list. public void service(httpservletrequest request, HttpServletResponse response) throws ServletException, IOException { List<Product> products = null; try { HttpSession session = object1.method1(false); if (session == null) { object2.method3(object2.encoderedirecturl("/shop/login")); Cart cart = (Cart) object3.method2("cart"); if (cart == null) { object2.method3(object2.encoderedirecturl("/shop/login")); String productidtoadd = object1.method4("buy"); String productid = (String) object1.method4("productid"); products = (Vector) object3.method2("products"); if (productidtoadd!= null) { Product item = getproductitem(products, productidtoadd); cart.add(new LineItem(item, 1, 0)); object1.method5("productpurchased", item.getname()); this.getservletcontext().getrequestdispatcher( "/catalog.jsp").method6(request, response); else if (productid!= null) { object1.method5("productitem", getproductitem(products, productid)); this.getservletcontext().getrequestdispatcher( "/productinfo.jsp").method6(request, response); else { if (products == null) { products = catalog.getproductlist(); object3.method7("products", products); this.getservletcontext().getrequestdispatcher( "/catalog.jsp").method6(request, response); catch (Exception e) { e.printstacktrace();

7 (a) (0.3 points) What are the respective roles of the request and response objects (i.e. the objects of class HttpServletRequest and HttpServletResponse) that appear as arguments of the service method)? (b) (0.1 points) The way this servlet is implemented by overriding the service method is not the usual way of implementing a servlet. What is the usual way? (c) (1.0 points) Provide the names of the objects object1, object2 and object3 and of the methods method1, method2, method3, method4, method5, method6, and method7. If you cannot remember the name of a method, instead, explain very briefly what it does. (d) (0.4 points) Explain very briefly the difference between method3 and method6. For each of the three calls to method6, state how the functionality would be affected if the call to this method of the requestdispatcher object were replaced by a call to object2.method3. (e) (0.2 points) As far as you can tell, does the application of which this code forms a part follow the MVC pattern? You must justify your answer (very briefly).