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Sample Application

Sample Application. Multi Layered Architecture (n-tier): Graphical User Interface (GUI): Forms, components, controls The Visual Designer in Visual Studio Application: Model Controllers Database. Architecture. So far we have had our “user interface” in the Main method

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Sample Application

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  1. Sample Application • Multi Layered Architecture (n-tier): • Graphical User Interface (GUI): • Forms, components, controls • The Visual Designer in Visual Studio • Application: • Model • Controllers • Database UCN Technology: Computer Science

  2. Architecture • So far we have had our “user interface” in the Main method • This won’t do with reel users! • Normally one will use what is known as a layered (or n tier) architecture, for instance: • UI • Controller • Model • Database Application Until now we have focused on the application layer UCN Technology: Computer Science

  3. Architecture First, we are going to focus on the UI layer Application UCN Technology: Computer Science

  4. Banking4 – An existing Project View Code (Banking4) UCN Technology: Computer Science

  5. Banking4 with GUI (Banking5) View Code (Banking5) UCN Technology: Computer Science

  6. How to Create a GUI for an Existing Project • Firstly you must have a working project with model and controller, for instance Banking4. • First step is to create a new solution in Visual Studio: It must be a “Windows Form Application” Give it a good name. And choose a location for it. UCN Technology: Computer Science

  7. How to Create a GUI for an Existing Project Toolbox. Here you find GUI components New Form in VS Properties. Here you can edit components. For instance give the form a good name UCN Technology: Computer Science

  8. How to Create a GUI for an Existing Project • Right click on the solution. Choose ‘Add’ and ‘Existing Project’. • Locate the project you want to add the GUI to: Here is the project file for ‘Banking4’ Choose that. UCN Technology: Computer Science

  9. How to Create a GUI for an Existing Project • Now ‘Banking4’ shows in the Solution Explorer in Visual Studio: UCN Technology: Computer Science

  10. How to Create a GUI for an Existing Project • Next we want to make the project (‘Banking4’) known to our GUI project: • You must use the namespace of Banking4: • Right click on the form and choose ‘View Code’ • Type this using: But the compiler doesn’t recognises it? Right click on ‘References’ for the GUI project in the Solution Explorer and choose ‘Add Reference’ UCN Technology: Computer Science

  11. How to Create a GUI for an Existing Project Choose the project tab. ...and ‘OK’ Choose the project you want – Banking4 Now the compiler recognises ‘Banking4’ namespace and we are ready. UCN Technology: Computer Science

  12. Using the Existing Project • Right click on the form, choose ‘View Code’, and now we can write code, for instance get an instance of the controller: namespace Bank4WithGUI { public partial class Form1 : Form { private BankCtrmyBank = BankCtr.GetInstance(); public Form1() { InitializeComponent(); } } } Now myBank can be used in the form, and we are able to communicate with the Banking4 application. UCN Technology: Computer Science

  13. Adding Components and Controls to the Form • Drag- and-drop. You may change the properties of components Button ToolStrip TextBox Label UCN Technology: Computer Science

  14. Adding Code //--- public Form1() //Constructor { CreateTestData();//mymethod InitializeComponent(); } //--- private void CreateTestData() { Customer c = new Customer(1, "Peter Thomsen"); myBank.AddCustomer(c); myBank.AddCustomer(new Customer(2, "Ib Helmer")); BankAccount acc1 = new BankAccount(1, 8, 100); BankAccount acc2 = new BankAccount(2, 0.25, 0); BankAccount acc3 = new BankAccount(3, 5, 1000); c = myBank.GetCustomer(1); c.AddAccount(acc1); c.AddAccount(acc2); c.AddAccount(acc3); c = myBank.GetCustomer(2); c.AddAccount(acc2); } • Test data is added by the constructor. • New method added by me. UCN Technology: Computer Science

  15. Getting some Action //--- private void button1_Click(object sender, EventArgs e) { } private void button1_Click(object sender, EventArgs e) { string input = this.textBox1.Text; intcustNo = Convert.ToInt32(input); //no error handling Customer c = myBank.GetCustomer(custNo); this.textBox2.Text = c.Name; } • Double click on the Find Customer Button and you get an empty event handler method for the button. This method is executed when the button is clicked. • Type in the code for the actions that you want. UCN Technology: Computer Science

  16. Getting some Action • Components are objects and may used like any other objects. private void button1_Click(object sender, EventArgs e) { string input = this.textBox1.Text; intcustNo = Convert.ToInt32(input); //no error handling Customer c = myBank.GetCustomer(custNo); this.textBox2.Text = c.Name; } • Use ‘this’ and the IntelliSense to find variable names of components and properties of components. UCN Technology: Computer Science

  17. Error Handling - Exceptions • If, what is entered here, not is a valid and existing customer number; some exception (NumberFormat or NullPointer) will make the program crash. private void button1_Click(object sender, EventArgs e) { string input = this.textBox1.Text; intcustNo = Convert.ToInt32(input); //no error handling Customer c = myBank.GetCustomer(custNo); this.textBox2.Text = c.Name; } UCN Technology: Computer Science

  18. Error Handling - Exceptions private void button1_Click(object sender, EventArgs e) { string inString = textBox1.Text; try { intcustNo = Convert.ToInt32(inString); c = bankCtr.GetCustomer(custNo); textBox2.Text = c.Name; } catch (Exception excep) { MessageBox.Show("Customer number must be an integer"); } } • We want to catch and handle that exception. • That is done by enclosing the code in a try-block. • After that we have a catch-block where we handle the exception. UCN Technology: Computer Science

  19. Adding a Database • So far we have create some test data and kept them in memory. • This won’t do for real application! • Normally one will use what is known as a layered (or n tier) architecture, for instance: • UI • Controller • Model • Database • And the databasewill be some kind of SQLserver. Application Now we focus on adding a database UCN Technology: Computer Science

  20. A Side: Creating the Database • First we define our database tables (this is done using SQL Server Management Studio, but can also be done from Visual Studio (not Express): • One table per domain object: • Customer • (Bank)Account • View the database in SQL Server Management Studio • SQL scripts for creating the database and inserting test data can be found here. The 1- n association from Customer to BankAccount is implemented in the database by including custNo as a foreign key in Account UCN Technology: Computer Science

  21. Adding a Database - Architecture • We will add a database to the Banking Project. • Architecture: • The Controller is responsible for communication with the database connection classes (DBLayer). • The DBLayer encapsulates the code for accessing the database and stores and builds objects. • The DBLayer takes the role of containers. View Code SQL Server UCN Technology: Computer Science

  22. Architecture – in Visual Studio • One Solution – 5 projects, each project having its own namespace. • Architecture: • Model: (old Banking4). The controller is put in its own project: Controller. • Banking5 is the old GUI. • The DBLayer has classes for accessing the database and storing and building objects. • BankingWithFullMonty is the main project with the new start-up form UCN Technology: Computer Science

  23. DBLayer • We use a SQL Server Database. • The Class AccessDbSQLClient is responsible for opening and closing the connection and for creating a Command object that can be passed to the SQL Server. • The class CustomerDBSQLClient is responsible for retrieving and storing Customer objects in the database. View Code UCN Technology: Computer Science

  24. The Controller //public void AddCustomer(Customer c) //{ // customers.Add(c); //} public void AddCustomer(Customer c) { CustomerDBSQLClient.CreateCustomer(c.CustNo, c.Name); } //public List<Customer> Customers //{ // get { return customers; } //} public List<Customer> Customers { get { return CustomerDBSQLClient.GetCustomers(); } } • Old implementation using lists is changed • Instead we use calls to the database. UCN Technology: Computer Science

  25. The Controller //public Customer GetCustomer(int no) //{ // //if customer not found, null is returned // Customer c = null; // inti = 0; // bool found = false; // while (!found && i < customers.Count) // { // c = customers[i]; // if (c.CustNo == no) // found = true; // else // i++; // } // return c; //} public Customer GetCustomer(int no) { return CustomerDBSQLClient.FindCustomerByNo(no); } • Complex search loops are replaced by calls to the database. UCN Technology: Computer Science

  26. class CustomerDBSQLClient public static Customer FindCustomerByNo(intcustNo) { string sql = @"select * from Customer where custNo = " +custNo; dbCmd = AccessDbSQLClient.GetDbCommand(sql); IDataReaderdbReader; dbReader = dbCmd.ExecuteReader(); Customer c; if (dbReader.Read()) c = new Customer(Convert.ToInt32(dbReader["custNo"].ToString()), dbReader["name"].ToString()); else c = null; dbReader.Close(); AccessDbSQLClient.Close(); return c; } The SQL Statement is build Command object with this SQL statement is build The command is sent to the SQL Server and executed The result is returned in a reader object – The Customer object is build from the reader DB Connection is closed Eventually the Customer object is returned. UCN Technology: Computer Science

  27. Exercises • Make the “Show total bal” button work (some refactoring may be necessary). • Add some more interesting functionality to the application (you may use some of the methods in the controller). • Refactor the application, so that the different layers (tiers) becomecomponents (.dll). UCN Technology: Computer Science

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