Development of a NetworkAware Application

1
Development of a Network-Aware Application

• Daniel Peck

2
Background

• A network-aware application attempts to adjust
  its resource demands in response to network
  performance variations. In other words, the
  application adjusts to the networking environment
  by trading off the volume, quality and the time
  needed for the data to be transferred. The
  application will reduce its demands on the
  network if there is a drop in bandwidth and
  increase its demands if there are additional
  resources.

3
Purpose

• The underlying aim of this project is to develop
  a Network-Aware Application that focuses on an
  important part of network-awareness.
• Compressed Data Transmission
• Has the ability to compress data before sending
  it out with the potential to reduce network
  transmission time and reduce total elapsed time.

4
Why is this useful?

• Compression can reduce the transmission time by
  reducing the amount of data to be transferred.

5
Can the Application benefit from data compression?

• Yes, but it depends on the tradeoff between the
  reduction of network transmission time and the
  increase of local processing.

6
Architecture
7
Application Pseudo Code

• // Control loop
• repeat
• compressedDataTransmission( data )
• until (all data is sent out)
• compressedDataTransmission ( data )
• compressionSpeed getSpeed()
• compressionRatio getRatio()
• currentBandwidth getBandwidth()
• if ( compressedTransfer(data,
  currentBandwidth,
• compressionSpeed,
  compressionRatio ) )
• compress(data, compressiondata)
• send( compressiondata )
• else
• send (data )

8
Compression Module

• GZip
• Gzip is a standard compression utility commonly
  used on Unix OS platforms.
• Does not consider domain specific information and
  uses a simple, bitwise algorithm to compress
  files.
• Works in stream mode ( time compression starts,
  not all data has to be available)

9
Implementation

• Client and server to be written in Java 1.4.
• Socket, ServerSocket, java nio package.

10
Network Module

• Monitors the network performance and provides
  necessary information for the application such a
  available bandwidth.
• What is Available Bandwidth?
• How do me measure it?

11
What is Available Bandwidth?

• End to end path with n links L1,L2, , Ln
• Their capacities are B1,B2, , Bn
• Traffic loads on these links are C1,C2,,Cn
• Bottleneck link Lb(1lt b lt n ) where
  Bb min(B1, B2,,Bn)
• Tight Link Lt(1lt t lt n ) where
  Bt - Ct min(B1 C1 , B2 C2 ,, Bn - Cn )

12
What is Available Bandwidth?

• The unused bandwidth on the tight link, Bt Ct,
  is also the available bandwidth on the path.
• In other words, the link with the smallest
  residual bandwidth.

13
How to Measure Available Bandwidth

• IGI
• IGI is a tool that uses active probing to measure
  available bandwidth between two points on the
  Internet.

14
Network Module cont..
15
Network Module cont..
16
Network Module cont..
17
Network Module cont..
18
Compression Decision Module

• Makes final decision whether compression is
  beneficial.
• uncompressedTime bufferSize / bandwidth
• compressionSize bufferSize / cRatio
• sendTime compressionSize / bandwidth
• compressionTime bufferSize / cSpeed
• totalTime compressionTime sendTime

19
Decompression Module

• Use a simple application layer protocol that
  tells the client whether or not to decompress the
  chunk or not.
• "filename!isCompressed!totalChunk!filelength!
  chunkNumber!isCompressed!bufferSize!

20
Conclusion

• On schedule.
• Working prototype is finished and ready to be
  tested.