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This example describes a way to develop client / server
applications. To provide advanced features, in this example, we had a
mechanism of notification.
There are three main ada units in this bank example. The "bank" that
manages the client accounts, a "manager" which loads the accounts from
a small database and provides some utilities and clients which modify
their accounts and transfer money from their account to the account of
someone else. This is always the same executable for the different
clients, but of course, they don't get the same partition id in order
to differentiate them.
To proove this, the bank server notifies a customer when its account
has been granted with money by another customer.
--
To play with this example, you can do the following :
% gnatdist simcity
Open (at least) 3 sessions.
[On session 1, starts the scenario, load "example" database and print
the account status]
% bank_server
Menu :
Create
Load
Print
Quit
Save
Request : l
=> Load
Filename : example
Menu :
Create
Load
Print
Quit
Save
Request : p
=> Print
Customer : poor
Password : xxxx
Customer : 25
Customer : middle
Password : yyyy
Customer : 250
Customer : rich
Password : zzzz
Customer : 2500
Menu :
Create
Load
Print
Quit
Save
[On session 2, start the poor client]
% bank_client
Customer : poor
Password : xxxx
Balance : 25
Menu :
Balance
Deposit
Transfer
Withdraw
Request :
[On session 3, start the rich client and transfer money from rich to poor]
% bank_client
Customer : rich
Password : zzzz
Balance : 2500
Menu :
Balance
Deposit
Transfer
Withdraw
Request : t
=> Transfer
Amount : 1000
Customer : poor
Balance : 1500
Menu :
Balance
Deposit
Transfer
Withdraw
[and then you will realize that on session 2, poor has been notified
of the donation]
=> Receive 1000 from rich
|
