Supermarket operation support system - Software Development Case Studies in Java - page 364

proxy :
LocalProxy

server :
BasicServer

dbm :
VolatileDB

employee :
Employee

User : Counter UI

btConnect
_action
Perfomed

connect
(code,
password)

authenticate
(code,
password)

getEmployee
(code)
employee
getPassword

employee employee

Figure 14.12 Connect scenario

obtained through the DBManager interface from the database, then the
provided password is compared with the one stored in the database.

14.5.3 Implementation

The interface MarketProxy defines all the operations that are available to the
counter terminal.

package Counter;
public interface MarketProxy {
// connect() and disconnect () implement the login/logout
// scenario
public String connect( long employee, String password)
throws Exception;

public void disconnect();
// define the current customer and get its name
public String getCustomer( long code) throws Exception;
// information about a product consists of name and price
public String getName( long item) throws Exception ;
public double getPrice( long item) throws Exception ;
// notify that the given quantity of a product has been
// bought
public void buy( long item, long quantity) throws Exception;
// terminate the transaction and produces the sum of the
// check
public void endTransaction() throws Exception;

}