Distributed Multimedia Systems - Distributed Operating Systems - Lecture Slides, Slides of Computer Science

Download Distributed Multimedia Systems - Distributed Operating Systems - Lecture Slides and more Slides Computer Science in PDF only on Docsity!

Distributed Multimedia Systems

Introduction

• Most multimedia is inherently time-based – the arrival time and arrival order of data packets is important
• The Internet guarantees neither when transmitting data
• We don’t just want interactive multimedia over our networks… we want it to be reliable and high-quality
• A distributed multimedia system can come to the rescue

Goal

• Simplicity in and of itself: We want and need high quality, reliable, interactive multimedia
• The general Internet structure is not sufficient to accomplish this
• A distributed multimedia system will add protocols and architectures on top of the Internet (or LAN) to guarantee quality levels, thereby satisfying our need

Definitions

• Bandwidth: data rate through a component
• Latency: time needed for a packet to travel

end to end

• Loss rate: acceptable drop-frame ratio
• Quality of service management: negotiation

and allocation of computing resources

1: Sources provide flow spec to main QOS manager throughlocal QOS managers 2: Main QOS ready to reserve resources 3: Client send request to main QOS 4: Main QOS decides if client can be served based on availableresources 5: If so, main QOS tells local QOS to allocate resources (if not,client is rejected) 6: Service begins 7: Main QOS and local QOS monitor resource usage / quality,adjust allocated resources if necessary 8: Return to step 4 if new client connects 9: Service ends, resources are freed

Controller

Features and Structure

Client

Source Source Source

QOS QOS QOS

Main QOS

Transmission Line (Internet)

How To Use

• A distributed multimedia system is a combination of source hardware, QOS manager software, and a transmission line
• Can be bought as a complete, dedicated, proprietary package – very expensive!
• Can be built using existing hardware and Internet / LAN connection lines… all that is needed beyond that is QOS management software – can be purchased or developed

Significant Points

• Distributed multimedia systems exist to guarantee quality of delivery levels
• Resource reservation is the key
• Additional clients do not degrade system – they can be refused if resources are scarce
• Quality guarantees are of paramount importance, whether used for business, entertainment, scientific or health-related applications

Summary

• Serving multimedia requires strict resource control to maintain quality
• Resources consist of bandwidth, latency, and loss rate, among others
• Source components declare the resources they need in flow specifications
• Quality of service managers negotiate and reserve resources to guarantee quality
• Source + flow spec + QOS manage + transmission lines = distributed multimedia system