1. VSP Video Station Protocol Presented by : Mittelman Dana Ben-Hamo Revital Ariel Tal Instructor : Sela Guy Presented by : Mittelman Dana Ben-Hamo Revital Ariel Tal Instructor : Sela Guy

2. Presentation Overview Introduction Top Level Design Client ’ s Modules Message Structure Server ’ s Modules Bandwidth Control Mechanism

3. Project Objective Implementation of prioritized communication protocol,in terms of bandwidth, in order to transfer multimedia stream from a video server to hosts that we call VS’s (i.e video stations).

4. Theoretical Background Client-server A network architecture in which each computer on the network is either a client or a server. Servers are powerful computers or processes dedicated to managing disk drives,printers or network traffic. Clients are PC’s or workstations on which users run applications. Clients rely on servers for resources Streaming A process of playing a file while it is still downloading. We will focus on streaming media which is a sequence of frames that are sent over the Internet and are seen by the viewer as they arrive.

5. Over Look Example This example is for one server and one client only: Client APIServer API Client VSP Protocol Server VSP Protocol API Callback request Ack UDP TCP + UDP

6. Message Structure Messages between the client and the server will run over TCP & UDP. There are two kinds of messages: Control Messages (TCP) - Made up of Header (in permanent size ) & body Data Messages (UDP).

7. Message Structure – cont. Types of massages : Application messages, include the abilities of the server & the demands of the client. Protocol codes: Hello, Bye, Allocate video channel, Free video channel Control Messages Header structure:

8. Message Structure – cont. Hello reply: is sent with the header and a body which includes the server’s abilities and if the client was registered or not. Control Messages - example Hello request: is sent with the header and a body which includes the client’s id and priority.

9. Management messages overview ClientServer listen Process reply Connect (TCP) Accept (TCP) Send Request Send Reply SRV socketCL socket Phase 1 reading Phase 2 reading 2 phase reading Analyze header Read header Read body Analyze body

10. Main modules – Client + Server Protocol Format UDP Manager Socket Client/Server Information Protocol Format Socket Client/Server Information UDP Manager Protocol Handler

11. Client’s Modules Client API Protocol Handler Protocol Format Socket Interface Servers Context UDP Manager

12. Client’s Modules – Cont. Client API : An interface holding application relevant functions for the client. Protocol Handler : Includes all of the protocol’s logic management, using the modules: UDP Handler, Socket Interface and Protocol Format. Server Information : Holds information regarding every server. The servers status (such as TCP open port, open channels) with every server that has an open session.

13. Client’s Modules – Cont. Protocol Format : Receives application and protocol data and converts into VSP message request format. Receives VSP message reply format and converts into application and protocol data. Socket Interface : Wrapper that contains all socket issues.

14. Client’s Modules – Cont. UDP Manager Video Managers Listener Thread Talker Thread synchronized queue Creates and removes all video connections Creates and destructs the Listener, Talker and synchronized queue Reads from the server and write to the synchronized queue Reads from the synchronized queue and writes to the local host

15. Server’s Modules Server API Client Handlers + VSP Layers Socket Interface Client Context Protocol Format Call Back UDP Manager Protocol Handler (dispatcher)

16. Server’s Modules – Cont. Server API : An interface holding application relevant functions for the server. Protocol Handler : Handles all client’s connections and opens a client thread for each client TCP connection. Client Handler + VSP Layer : Handles protocol’s logic management. For every client connection there will be a separate Handler and Layer. VSP Layer holds all relevant client information and opens a UDP connection for every client request.

17. Server’s Modules – Cont. Protocol Format: Receives VSP message request format and converts into application and protocol data. Receives application and protocol data and converts into VSP message reply format. Socket Interface : Wrapper that contains all socket issues. Client Information : Holds information regarding every client. The clients status (such as TCP open port, priority) for every client that has an open session.

18. Server’s Modules – Cont. UDP Manager Video Managers Listener Thread Talker Thread synchronized queue Bandwidth control mechanism

19. Bandwidth Control Mechanism We Calculated the number of bytes we need to send, by multiplying the bandwidth by the time it will take us to send it. We calculated it incrementally by sending a portion every time interval, and decreasing the bytes we sent from the total bytes we need to send. We limited the sent frames quota by limiting the “quiet” time.

20. Bandwidth Control Mechanism A frame can be larger than it’s quota by 5%, because of the following reasons: Avoid wasting a slot when we have a frame that we can send. A frame which is slightly larger then the quota can be sent immediately The bandwidth given to the client is calculated according to his priority, and the way to calculate it can be changed by the application. The protocol uses the slots made by the operating system and only chooses whether to use the current slot or not.