Freenet Directory Service

1
Freenet Directory Service

• CS 524S
• Spring 2001
• Professor Marcel
• Songbai Ji and Alan Yeung
• Project Presentation

2
Contents

• Introduction to Freenet
• How Freenet works?
• Information stored in the node
• The Core
• The Keys
• Insert Request
• Data Request
• Retrieving Data
• Execution
• Proposed Ideas

3
Introduction to Freenet

• What is Freenet?
• Large-scale P2P network
• Features
• highly survivable
• private and secure
• efficient
• user-unfriendly
• It takes time!

4
How Freenet works?

• The network
• node computers running Freenet Daemon
• node stores information about itself, and
  information about some of the other nodes
• no node knows about the entire system
• no node is superior to any other

5
How Freenet works? (Cont.)

• More about nodes
• Each node holds 3 types of info
• Keys
• Reference to address of other nodes
• Optional data
• All the information is stored in a stack within
  the node
• Stack has a size limit

6
Information stored in the node
Reference
Key
Data
asc
bdf
193.123.23.78223
New item inserted here
bdf
mdf
132.456.268.21933
mff
65.31.235.232346
Data stripped
ppl
45.132.146.63598
Old item removed
Stack has size limit!
7
The Core

• A client needs a client core to handle basic
  services.
• Freenet cores can be very flexible and made to
  support different transport and presentation
  protocols.
• There are two methods that return a core
• 1. Takes only an integer of the TCP port value
  that the core should use for incoming messages as
  parameter.
• 2. Allows us to specify a set of parameters and a
  logger.

8
The Keys

• A Freenet key is used to insert or request any
  data
• Key is a funny-looking jumble of characters
• Like a 'combination lock' that lets us gain
  access to materials on Freenet.
• Here are examples of freenet keys
• SSK_at_Xdxr9gtIHEasJ1/index-20010204.html
• KSK_at_text/essay/unabomber/manifesto
• Keys begin with three letters, then an '_at_'
  character, then many characters at the end.
• No way we can access an item on Freenet without
  knowing its particular key.

9
Preparing an Insert Request

• Inserts are prepared by calling the prepare
  method of the Client object
• The method will return a RequestToken object that
  can be used to add event listeners and actually
  start the InsertRequest.
• Method includes following parameters
• htl, data, dataLength, metadata, metaLength,
  ckey, cipherName, ctBucket

10
Preparing a Data Request

• Similar to inserts, data requests are prepared by
  calling the prepare method of the Client object.
• This method will return a RequestToken to which
  you can add event listeners and actually start
  the request.
• The method includes following parameters
• htl, ck, data, metaData

11
Retrieving Data
12
Execution

• When an insert or data request executes, it will
  generate events that can be caught to read the
  status of the execution (addEventListener
  method)
• Add as many event listeners as we want.
• When we are ready to execute the request - call a
  makeRequest method.
• The request will then occur asynchronously in
  another thread - then wait and watch the events
  being produced.

13
Proposed ideas

• Updating
• The ability to change the contents of a document
  Retrieved by a Primary Key.
• Mapping
• Random death

14
Thank you

• Any Questions?