Booking SystemTzu-Han Wu 15524883Yi-Chi Chiang 54641046Han-Yang Ou 59283702

Motivation◦ Avoid over-booking

Features◦ Show seats status in real-time◦ Multi-server processing in distributed environment◦ Fully replication◦ Load balancing◦ Add servers dynamically

Implementation◦ JAVA RMI◦ Mutual exclusion: altered Ricart-Agrawala algorithm

Introduction – Booking System

Client 1

Client 3

Client 2

Server 1Server 2

New Server

S1

S2

M

S3

N

Notify new server

Send other servers info and status of seats

Notify other servers new server coming

At the same time, the other server may send seat status update messages

The new server should compare the version and decide to update or ignore the messages

ID: 103

Connection RequestClient address

Ask appropriate server

New Client

S1

S2

M

S3

C101

C102

C202

C204

C205 C306

C301

C003

C001

C005

N

Reply address of S1

C103

Ask status of seatsReply status of seats

S1

S2

M

S3

C101

C102

C202

C204

C205 C306

C301

C003

C001

C005

The other server set flag 5 to trueThe other servers send OK to S2

Flag 5: True

Request Assume seat 5 is availableC204 send seat 5 request message to S2

Flag 5: false

Flag 5: false

Flag 5: false

Flag 5: false

S2 set flag 5 to trueS2 send seat request to other server

Flag 5: true

Flag 5: true

Flag 5: true

S2 sends update notification to other serversServers sends update notification to clients

Release

S1

S2

M

S3

C101

C102

C202

C204

C205 C306

C301

C003

C001

C005

Assume seat 7 is occupied by C202

Flag 7: true

Flag 7: true

Flag 7: true

Flag 7: true

C202 sends release message to S2S2 sets flag 7 to false

Flag 7: false

S2 sends update notification to other serversServers send update notifications to clients

Flag 7: false

Flag 7: false

Flag 7: false

Other servers set their flag 7 to false

CommitmentS2 sends seat 2 update notifications messages to other serversS2 sends seat 3 update notifications messages to other serversServers send seat 2 update notifications to clients

S1

S2

M

S3

C101

C102

C202

C204

C205 C306

C301

C003

C001

C005

Assume C205 has requested seat 2 and 3

Flag 2: true

Flag 2: true

Flag 2: trueFlag 3: true

Flag 3: true

Flag 3: true

Flag 2: trueFlag 3: true

C205 sends commit message to S2Servers send seat 3 update notifications to clients

5 clients 10 clients 15 clients 20 clients0

20

40

60

80

100

120

3 servers2 servers1 server

ms

Performance Measurement