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E-mail over low bandwidth networks. Indika Wasala Sasanka Usgoda Arachchi Dr. Gihan Dias. Contents. Objective Research Problem Previous Work at UoM Other Related work Current Project Future Work References. Objective. To optimize email communication over Low Bandwidth networks.

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e mail over low bandwidth networks

E-mail over low bandwidth networks

Indika Wasala

Sasanka Usgoda Arachchi

Dr. Gihan Dias

contents
Contents
  • Objective
  • Research Problem
  • Previous Work at UoM
  • Other Related work
  • Current Project
  • Future Work
  • References
objective
Objective
  • To optimize email communication over Low Bandwidth networks.
problem
Problem
  • Dialup internet connections in rural areas.
  • ADSL connections with shared bandwidth.
  • Expensive Leased Lines.
  • CDMA/GPRS connections.
  • Download delays
    • Large attachments
previous work at uom
Previous work at UoM
  • On-the-fly Inter-proxy Data Compression for Web Access - Pradeepa Gurusinghe, Gihan Dias, Vishaka Nanayakkara
  • A Market-Based Approach to Control Web Bandwidth Usage - Chamara Dissanayake, Gihan Dias
  • Dynamic Bandwidth Negotiation among Web Proxies - Sumith Gamage, Gihan Dias
other related work
Other Related Work
  • draft-ietf-lemonade-compress-04
    • COMPRESS extension
    • IMAP Connection is compressed effectively and efficiently.
      • to reduce the bandwidth usage of IMAP
    • Commands
      • CAPABILITY
        • Response COMPRESS=DEFLATE
      • COMPRESS DEFLATE
        • Response OK DEFLATE active
current project
Current Project

E-mail over low bandwidth networks

solution
Solution
  • IMAP proxy server

and

proxy client

to

optimize email communication over low bandwidth connection.

email server

email client

IMAP Proxy

client

Legacy email

client

IMAP Server

IMAP Proxy

server

Low bandwidth network

scope
Scope

email client

  • IMAP Proxy client functions
    • Defining filter rule set
    • Assignment of priorities to emails.
    • Compression of IMAP requests
    • Decompression of IMAP responses
    • Sending decompressed responses to client
    • Sending compressed requests to server

IMAP Proxy

client

Legacy email

client

scope cont
Scope cont..

email server

  • IMAP Proxy Server functions
    • Email filtering
    • Selecting a pre-fetch model
    • Compression of IMAP responses
      • Different compressors for different content-types
    • Decompression of IMAP requests and sending to IMAP server.
    • Spam filtering

IMAP Server

IMAP Proxy

server

solution components
Solution Components
  • Mail server : qmail (www.qmail.org)
  • IMAP Server : binc imap (www.bincimap.org)
  • IMAP proxy : imapproxy (www.imapproxy.org)
  • All are open source components.
proxy client configuration
Proxy Client Configuration
  • Filtering Rules
    • Configured in proxy client
    • Using a simple UI
    • Using config file
    • <header field:”matching string”> <priority> <image compression on/off>
      • from:”x@xyz.com” 1 0
proxy client configuration contd
Proxy Client Configuration contd..
  • Priorities and Pre-fetching
    • Priority 1 : Pre-fetch whole message
    • Priority 2 : Pre-fetch first 1 KB of the message
    • Priority 3 : Pre-fetch only the header information including attachment type if there are any.
    • Priority 4 : Delete messages
pre fetching
Pre-fetching
  • Static
    • Pre-fetch at night or when the link is idle
  • Dynamic
    • While previous message / first part of message is being read
imap proxy server operation

Client Connects

Process Client

Is Link idle

?

Requests

Get All unseen UIDs

and put them into a

list

IMAP Proxy server Operation

NO

YES

imap proxy server operation contd

Download user rule

configuration into

proxy server

For each UID in list get

#

Format of a rule

header and check whether

Assign default priority

From

:

x

@

xyz

.

com

1 0

any match is found in rules

=

3

config

.

Check Priority

IMAP Proxy server Operation Contd..

NO

YES

imap proxy server operation contd1
IMAP Proxy server Operation Contd..
  • Priority = 1
    • Check for compression bit for images
    • Compress or leave image in original form
    • Compress text/html part
    • Send whole email to proxy client
imap proxy server operation contd2
IMAP Proxy server Operation Contd..
  • Priority = 2
    • Check for compression bit for images
    • Compress or leave image in original form
    • Store attachments
    • Generate a URLs for attachments
    • Append URLs to the end of email
    • Get 1st KB of the email
    • Append a URL to next KB
    • Compress and send to proxy client
imap proxy server operation contd3
IMAP Proxy server Operation Contd..
  • Priority = 3
    • Check for compression bit for images
    • Compress or leave image in original form
    • Leave any other attachment in original form
    • Compress email header
    • Send header to proxy client
imap proxy server operation contd4
IMAP Proxy server Operation Contd..
  • Priority = 4
    • Delete email
    • Remove UID from the list
imap proxy client operation

Client Connects

toproxy client

uncompreses pre

fetched

email headers

Email box will be

populated with the

headers of pre

-

fetched

emails

Client fetches an email

Checks the priority

of the requested

email

IMAP Proxy client operation
imap proxy client operation contd
IMAP Proxy client operation contd..
  • Priority = 1
    • Uncompress and Send pre-fetched mail to email client
    • Check priority of next email
    • If 3 start fetching next email from server
    • If priority is 1 or 2 check priority of next email
imap proxy client operation contd1
IMAP Proxy client operation contd..
  • Priority = 2
    • Uncompress and Send pre-fetched part to email client
    • Start fetching next part from the server
    • If end of mail check priority of next email
    • If 3 start fetching next email from server
    • If priority is 1 or 2 check priority of next email
imap proxy client operation contd2
IMAP Proxy client operation contd..
  • Priority = 3
    • If it was pre-fetched, uncompress and send to email client
    • If not fetch from server, uncompress and send to email client
    • Check priority of next email
    • If 3 start fetching next email from server
    • If priority is 1 or 2 check priority of next email
future work
Future Work
  • Caching of attachments
    • For future reuse
  • Different compression algorithms for different content types
references
References
  • RFC 3501 - Internet Message Access Protocol - Version 4rev1
  • RFC 2683 - IMAP4 Implementation Recommendations
  • RFC 3516 - IMAP4 Binary Content Extension
  • Arnt Gulbrandsen, draft-ietf-lemonade-compress-04
  • Bruce Zenel, A general purpose proxy filtering mechanism applied to the mobile environment
  • Pradeepa Gurusinghe, Vishaka Nanayakkara, Gihan Dias, On-the-fly Inter-proxy Data Compression for Web Access
  • Chamara Disanayake & Gihan Dias,A Market-Based Approach to Control Web Bandwidth Usage
  • Qmail manual, www.lifewithqmail.org/lwq.html
  • Binc IMAP, www.bincimap.org
  • 8bitMIME - http://en.wikipedia.org/wiki/8BITMIME
  • MIME - http://en.wikipedia.org/wiki/MIME
  • Zlib - http://www.zlib.net/manual.html