CS 580 Client-Server Spring Semester, 2004 Databases & Architecture
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Doc 11, Databases & Architecture Slide # 2

Databases & Architecture

Doc 11, Databases & Architecture Slide # 3

• Find Office hours for instructor X
• Find office hours of any graduate advisor
• Find office hours of any undergraduate advisor
• Find office hours of any TA
• Who has office hours at time X
• What times are there no office hours
• Add office hours
• Modify office hours

Doc 11, Databases & Architecture Slide # 4

Doc 11, Databases & Architecture Slide # 5

public class DatabaseConnector {
   private String databaseUrl;
   private String user;
   private String password;
   private ArrayList connectionPool;
   private static DatabaseConnector instance =
      DatabaseConnector(“filename”);
   public static DatabaseConnector instance() {
      return instance;
   }
   private DatabaseConnector(String filename) {
      read file for database info
      set private fields
   }
   public ResultSet executeQuery( String sql ) {
      return getStatement().executeQuery( sql);
   }
   public Statement getStatement() {
      return getConnection().createStatement();
   }

   private Connection getConnection() { return a connection}
   
   etc
}

Doc 11, Databases & Architecture Slide # 6

Table Data Gateway

Doc 11, Databases & Architecture Slide # 7

public class OfficeHoursGateway {
   private static    String addOfficeHoursSql =
         “INSERT 
           INTO officeHours ( startTime, endTime, day, facultyId )
           VALUES ( ? , ?, ‘?’, ?)”;
   Private static String officeHoursSql =
         “SELECT startTime, endTime, day
           FROM officeHours 
           WHERE facultyId = ?”;
   public ResultSet officeHoursFor(int facultyId,) {
      Statement hoursStatement = 
         DatabaseConnector.instance().prepareStatement(officeHoursSql);
      hoursStatement.setObject( 1, facultyId);
      return hoursStatement.executeQuery();
   }
   public int setOfficeHoursFor(int facultyId, Time start, Time end, String day) {
   
      Statement addOfficeHours = 
         DatabaseConnector.instance().prepareStatement(addOfficeHoursSql);
      addOfficeHours.setObject(1, start);
      addOfficeHours.setObject(2, end);
      addOfficeHours.setObject(3, day);
      addOfficeHours.setObject(4, facutlyId);
      return addOfficeHours.executeQuery();
   }

Doc 11, Databases & Architecture Slide # 8

Transaction Script + Table Gateway

public class OfficeHoursServer {
   private OfficeHoursGateway officeHours;
   private FacultyGateway faculty;
   etc.
   public Vector officeHoursFor(String facultyName) {
      int facultyId = faculty.idFor(facultyName,);
      ResultSet officeHoursRows = officeHours.officeHoursFor( facultyId);
      Vector officeHours = new Vector();
      while (officeHoursRows.next() ) {
            Dictionary officeHour = new Dictionary();
            officeHour.put( “start”, officeHoursRows.getObject( “start”));
            officeHour.put( “end”, officeHoursRows.getObject( “end”));
            officeHour.put( “day”, officeHoursRows.getObject( “day”));
            officeHours.add( officeHour);
      }
      officeHoursRows.close();
      return officeHours;
   }
   etc.
}
Doc 11, Databases & Architecture Slide # 9

Active Record

• Class for each table
• An object represents one row in the table

Doc 11, Databases & Architecture Slide # 10

public class Facutly {
   String name;
   String phoneNumber;
   int id;
   etc.
   private final static String findByNameSql =
      “SELECT *
        FROM faculty
       WHERE name = ‘?’”;
   public static Faculty findByName(String name ) {
         Statement find = 
            dabaseConnnector.prepareStatement(findByNameSql);
         find.setObject( 1, name);
         ResultSet facultyRow = find.executeQuery();
         return load(facultyRow);
   }
   public static Faculty load( ResultSet facultyRow) {
      create faculty object.      
      get data out of Resultset.
      Put data into faculty object.
      Return faculty object.
   }

Doc 11, Databases & Architecture Slide # 11

   public boolean hasOfficeHoursAt(Time anHour) {
      Iterator hours = officeHours().iterator();
      while (hours.hasNext() ) {
         OfficeHour officeHour = (OfficeHour) hours.next();
         if (officeHour.contains( anHour) ) return true;
      }
      return false;
   }
   public ArrayList officeHours() {
      if( officeHours = nil ) {
         officeHours = OfficeHour.findFor( id );
      }
      return officeHours;
   }
      
Doc 11, Databases & Architecture Slide # 12

Domain Model + Active Record

         
public class OfficeHoursServer {
   public Vector officeHoursFor(String facultyName) {
      Faculty X = Faculty.findByName (facultyName,);
      ArrayList officeHours = X.officeHours();
      
      Convert contents of officeHOurs to XML-RPC acceptable types
      return vector of valid XML-RPC types;
   }
   etc.
}

Doc 11, Databases & Architecture Slide # 13

Object-Relational Mapping Layers

• JDO – Java Data Object
• Smalltalk GLORP – Generic Lightweight Object-Relational Persistence

Doc 11, Databases & Architecture Slide # 14

Object Databases

• Gemstone ( http://www.gemstone.com/)
• Objectivity ( http://www.objectivity.com/)
• Matisse ( http://www.matisse.com/)
• OmniBase ( http://www.gorisek.com/homepage/index.html)
• Versant ( http://www.versant.com/index)
• ObjectStore ( http://www.objectstore.net/index.ssp)
• Zope Object Database ( http://zope.org/Wikis/ZODB/FrontPage)

Doc 11, Databases & Architecture Slide # 15

database :=OmniBase createOn: 'examples'.

[OmniBase root
   at: 'restaurantTypes'
   put: Set newPersistent
] evaluateAndCommitIn: database newTransaction.

Server>>addType: aString
   (aString isNil or: [aString isEmpty]) ifTrue:[^false].
   [types := OmniBase root at: 'restaurantTypes'.
   types add: aString.
   types markDirty]   evaluateAndCommitIn: database newTransaction.
   ^true

Server>>types
   [^(OmniBase root at: 'restaurantTypes') asSortedCollection] 
      evaluateIn: database newTransaction.

Doc 11, Databases & Architecture Slide # 16

[OmniBase root
   at: 'restaurants'
   put: OrderedCollection newPersistent
] evaluateAndCommitIn: database newTransaction.


Server>>restaurantById: anInteger
   | restaurant |
   [restaurants :=OmniBase root at: 'restaurants'.
    restaurant :=restaurants 
      detect: [:each | each id = anInteger]
      ifNone: [Dictionary new].
    ^restaurant asDictonary
   ] evaluateIn: database newTransaction.

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