1. peer-to-peer and agent-based computing
JXTA

2. peer-to-peer and agent-based computing
Project JXTA
Conceived by Bill Joy (SUN Microsystems)
Also the creator of “vi”
Designed by small number of experts from academia and industry
Stands for juxtaposed, i.e., side-by-side
a recognition that P2P is juxtaposed to client-server or Web- based computing, which is today’s traditional distributed computing model
“A network programming and computing platform”
Features:
Interoperability (different services)
Platform and language independence
Ubiquity (anything can be a peer)
Open standards (XML, HTTP, TCP/IP)
Open source (Java source available)
peer-to-peer and agent-based computing

3. peer-to-peer and agent-based computing
JXTA design constraints
Interoperability
Software vendors tend to create specific code for their services e.g. file sharing, instant messaging etc
Incompatible systems, duplication of effort
JXTA give peers common language to talk
Platform independence – JXTA technology is designed to be independent of:
Programming languages e.g. C or Java
System platforms e.g. Microsoft Windows and UNIX
Networking platforms (such as TCP/IP or Bluetooth)
Ubiquity
Implementable on every device with a digital heartbeat e.g. PDAs, phones, sensors, etc.
Avoid specific binding to platforms
future proof e.g. such technologies should be extended to new platforms e.g. mobile phones etc e.g. using J2ME
i.e. none of them able to interoperate with one another.
in creating software and system primitives commonly used by all P2P systems.
Platform independence:
These set of criteria solve a number of development issues including code duplication and incompatibility. For example, many P2P systems today offer services through APIs that are tied to a particular operating system using a specific networking protocol i.e. one system might use C++ APIs on Windows over TCP/IP, while another uses a C API hosted on UNIX systems over TCP/IP but also requiring HTTP. A P2P developer is then forced to choose which set of APIs to use and consequently, which set of P2P customers to target. Further, if the developer wants target both communities then they may have to develop the services twice, one for each platform (or develop a bridge system between them).
peer-to-peer and agent-based computing

4. peer-to-peer and agent-based computing
JXTA implementations
JXTA Platform Current Implementations
Java 2 Platform Standard Edition (J2SE) – the reference implementation
Java 2 Platform Micro Edition (J2ME) – for cell phones, PDAs, and controllers
PersonalJavaTM technology – for PDAs
C, PERL, Python, Ruby, Mon (C#), Smalltalk
JXTA Transport Current Implementations
TCP
HTTP
BEEP
Reliable Multicast
i.e. none of them able to interoperate with one another.
in creating software and system primitives commonly used by all P2P systems.
Platform independence:
These set of criteria solve a number of development issues including code duplication and incompatibility. For example, many P2P systems today offer services through APIs that are tied to a particular operating system using a specific networking protocol i.e. one system might use C++ APIs on Windows over TCP/IP, while another uses a C API hosted on UNIX systems over TCP/IP but also requiring HTTP. A P2P developer is then forced to choose which set of APIs to use and consequently, which set of P2P customers to target. Further, if the developer wants target both communities then they may have to develop the services twice, one for each platform (or develop a bridge system between them).
peer-to-peer and agent-based computing

5. peer-to-peer and agent-based computing
Project JXTA
Goals/Purpose
enable a wide range of distributed computing applications by developing a common set of general purpose P2P protocols
achieve platform independence: any language, any OS, any hardware
overcome the limitations found in many of today's P2P applications
enable peers to be any device that has a digital heartbeat (desktop computers, servers, PDAs, cell phones, and other connected devices)
peer-to-peer and agent-based computing

6. peer-to-peer and agent-based computing
Project JXTA
In other words:
Interoperability (different services)
Platform and language independence
Ubiquity (anything can be a peer)
Open standards (XML, HTTP, TCP/IP)
Open source (Java source available)
peer-to-peer and agent-based computing

7. Project JXTA: Technology (Cont’d)
Based on XML, Java, and key concepts of UNIX operating system
Transmitted information packaged as messages. Messages define an XML envelop to transfer any kind of data
Java is not required: JXTA protocols can be implemented in C, C++, Perl, or any other programming language
peer-to-peer and agent-based computing

8. Project JXTA Technology (Cont’d)
Set of simple, open peer-to-peer protocols:
Any digital device that can be connected may communicate, collaborate and share resources
JXTA peers create virtual, ad-hoc networks on top of existing networks, hiding details
peer-to-peer and agent-based computing

9. Project JXTA Architecture
JXTA Community Applications
Sun Applications
JXTA Applications
JXTA Shell Peer Commands
JXTA Community Services
Sun JXTA Services
JXTA Services
JXTA Core
Security
Peer Groups
Peer Pipes
Peer Monitoring
Any Peer on the Web (Desktop, cell phone, PDA, Server)
peer-to-peer and agent-based computing

10. peer-to-peer and agent-based computing
JXTA terms
Peer
Peer: A JXTA node.
Peer
JXTA Group: a group is a set of JXTA nodes who share a common interest
A Rendezvous Peer: a meeting place e.g. gateway for JXTA groups
Peer
Peer
Peer
Peer
peer-to-peer and agent-based computing

11. Project JXTA Architecture (Cont’d)
Core layer:
Peer groups – create, delete, join, advertise, discover, communication, security, sharing.
Peer pipes – transfer of data, content and code in protocol-independent way.
Peer monitoring – access control, priority setting, traffic metering, bandwidth balancing.
Service layer:
Expand core and facilitate application development
Mechanisms for indexing, searching, resource sharing
Application layer:
Built using peer services as well as the core layer
ing, auctioning, storage systems
peer-to-peer and agent-based computing

12. JXTA technology concepts
Lightweight specification:
Security is not specified (many ways to do it…)
Focus on mechanisms, rather than policies
Entity:
A peer, a service, an advertisement, a pipe…
Identifiers:
Every entity has an identifier
Uses UUID, a 128-bit datum
Within a local run-time environment, each entity has a unique identifier.
peer-to-peer and agent-based computing

13. JXTA technology concepts (Cont’d)
Resource:
A peer, a peer group, a pipe, or a service
Advertisements:
XML structured document
Names, describes and publishes a resource
JXTA defines a basic set of advertisements
Other kinds of adverts via XML schemas
Peer:
Any entity that speaks the protocols of a peer
A PDA, a sensor, a PC, a human user
No need to speak all 6 protocols!
peer-to-peer and agent-based computing

14. JXTA technology concepts (Cont’d)
Messages:
Asynchronous, unreliable, and unidirectional transport
Datagrams with envelope and stack of protocol headers with bodies
Peer groups:
Virtual entity that speaks the set of protocols of a group of peers.
Collection of cooperating peers providing a common set of services
Spontaneous, not prescribed nor mandatory
Protocol available to discover peer groups
World Peer Group includes all JXTA peers
peer-to-peer and agent-based computing

15. JXTA technology concepts (Cont’d)
Pipes:
Communication channels to send/receive messages
Unidirectional, hence input and output pipes
Virtual: a pipe’s endpoint may be connected to more than one peer endpoint
Pipe Binding Protocol binds pipe at run-time
Different protocols can be used within a pipe to transfer data
peer-to-peer and agent-based computing

16. peer-to-peer and agent-based computing
Virtual JXTA
JXTA Virtual Network overlay
JXTA Groups
JXTA Virtual Pipes
peer-to-peer and agent-based computing

17. peer-to-peer and agent-based computing
JXTA Virtual Mapping
Peer
Peer
JXTA
Virtual
Network
Peer
Peer
Peer
Peer
Peer
Peer
Virtual Mapping
Firewall
NAT
Bluetooth
TCP/IP
NAT
Physical
Network
Firewall
Http
Firewall
NAT
peer-to-peer and agent-based computing

18. peer-to-peer and agent-based computing
JXTA Groups
Virtual entity - speak a set of peer group protocols
Collection of cooperating peers providing a common set of services e.g. file sharing peer group, a CPU sharing peer group.
Peer group boundaries define search scope
Can be used to create a monitoring environment
Can be password protected and implement local security policies
One special group, called the World Peer Group (the default peer group a peer joins) that includes all JXTA peers.
At least one rendezvous for a group – groups are the scoping environment for a rendezvous
FS Frank
Peer
Peer
Peer
Peer
FS Fred
Peer
Peer
Peer
Peer
peer-to-peer and agent-based computing

19. peer-to-peer and agent-based computing
JXTA Groups
Provide the grouping of services/users to provide:
Scope for searching
Security
Monitoring
And accountability etc.
Provide a similar concept to VO’s in Grid computing except:
VOs are more flexible
More fine-grained sharing rules
Low-level services
e.g. Job submission and file transfer vs services and pipe comms.
peer-to-peer and agent-based computing

20. peer-to-peer and agent-based computing
JXTA Pipes
Peer 1 2 3 4
A JXTA Pipe
Firewall
Actual Route
Output Pipe
Input Pipe
Virtual Communication Channels
Switchable e.g. TCP/IP, HTTP, Bluetooth
NOT point to point
Pipe endpoints  input pipe (the receiving end) and the output pipe (the sending end).
Asynchronous and unidirectional
Messages flow from the output pipe into the input pipes.
Support the transfer of any object, including binary code, data strings, and Java technology-based objects
Two Types:
(End) Point to (End) Point
Propagate (multicast)
Peer
Peer
Peer
Peer
Peer
Point to Point
Propagate
Peer
peer-to-peer and agent-based computing

21. peer-to-peer and agent-based computing
JXTA Scenario RV 1 3 4 7 6 2 5
New
Node 2. 1. 3. 4. . 5.
Rendezvous node (RV) accepts connection for nodes 1-7 and stores advertisements locally
New node contacts Rendezvous using a discovery mechanism e.g. Unicast/multicast (PDP)
RV authenticates New Node and adds the New Node to the group (RVP)
New Nodes performs a file search query by contacting the RV find a match locally or propagates this query to all other members in the group. The file is found on node 6 (PDP)
New Node and node 6 communicate directly through a JXTA pipe. This connection is virtual and may actually traverse (route) through the RV node and node 7
peer-to-peer and agent-based computing

22. peer-to-peer and agent-based computing
JXTA: Protocols
A set of 6 defined protocols:
Peer Endpoint Protocol (PEP)
Rendezvous Protocol (RVP)
Peer Resolver Protocol (PRP)
Peer Discovery Protocol (PDP)
Peer Information Protocol (PIP)
Pipe Binding Protocol (PBP)
Protocols can be implemented in any
programming language for any system
peer-to-peer and agent-based computing

23. peer-to-peer and agent-based computing
JXTA: Protocol Stack
Peer Discovery
Protocol
Peer Discovery
Protocol
Via Peer Resolver Protocol
Peer Information
Protocol
Peer Information
Protocol
Via Peer Resolver Protocol
Pipe Binding
Protocol
Pipe Binding
Protocol
Via Peer Resolver Protocol
Peer Resolver
Protocol
Peer Resolver
Protocol
Via Enpoint Routing Protocol
Rendezvous
Protocol
Rendezvous
Protocol
Via Enpoint Routing Protocol
Peer Endpoint
Protocol
Peer Endpoint
Protocol
Via installed Network Transports
Network Transport
Via Installed Network Transports
Network Transport
peer-to-peer and agent-based computing

24. peer-to-peer and agent-based computing
Peer Discovery
Peer Discovery
Protocol
A peer uses the PDP to discover a JXTA resource
resources are described by advertisements e.g. can be services, pipes, peers, peer groups, or any other advertisements
Note that the first word (peer) is the subject & not necessarily the object
Using this protocol, peers can advertise their own resources, and discover the resources from other peers
Peer resources are published using XML-based advertisements
Peer Information
Protocol
Pipe Binding
Protocol
Two levels of discovery:
Joining a JXTA network
Multicast
Unicast
Discovering JXTA resource within a JXTA network.
Without the PDP, a P2P client would be useless, unable to find and use the resources offered by other peers.
peer-to-peer and agent-based computing

25. peer-to-peer and agent-based computing
Finding information about peers
Peer Discovery
Protocol
allows peers to learn about the capabilities and status of other peers e.g. uptime, traffic load, capabilities, state etc
e.g. one can send a ping message to see if a peer is alive.
also query a peer’s properties where each property as a name and a value string
useful for implementing monitoring
Peer Information
Protocol
Pipe Binding
Protocol
Without the PDP, a P2P client would be useless, unable to find and use the resources offered by other peers.
peer-to-peer and agent-based computing

26. peer-to-peer and agent-based computing
Binding pipes
Peer Discovery
Protocol
Allows a peer to establish a virtual communication channel (i.e. a pipe) between peers
Allows the binding of the two or more ends of the pipe endpoints forming the connection
A peer binds a pipe advertisement to a pipe endpoint thus indicating here messages actually go over the pipe
Bind occurs during the open operation, whereas unbind occurs during the close operation.
Peer Information
Protocol
Pipe Binding
Protocol
Peer 1 2 3 4
A JXTA Pipe
Firewall
Actual Route
Output Pipe
Input Pipe
Without the PDP, a P2P client would be useless, unable to find and use the resources offered by other peers.
peer-to-peer and agent-based computing

27. peer-to-peer and agent-based computing
“The” Resolver
Enables a peer to implement high-level search capabilities
Allows a peer to send and receive generic queries to find or search for peers, peer groups, pipes, and other information
Peer Resolver
Protocol
Rendezvous
Protocol
Peer Endpoint
Protocol
peer-to-peer and agent-based computing

28. peer-to-peer and agent-based computing
Rendezvous
Peer Resolver
Protocol
Allows a Peer to send messages to all the listeners of the service
The rendezvous protocol defines how a peer can subscribe or be a subscriber to a propagation service allowing larger communities to form
A rendezvous nodes’ scope is a peer group
e.g. the rendezvous protocol is used by the peer resolver protocol and by the pipe binding protocol in order to propagate messages.
Rendezvous
Protocol
Peer Endpoint
Protocol
peer-to-peer and agent-based computing

29. peer-to-peer and agent-based computing
Routing those messages
Peer Resolver
Protocol
allows a peer to find information about the available routes for sending a message to destination peer
i.e. pipes are often not directly connected to each other
allows the implementation of routing algorithms into JXTA
Peers implementing the endpoint routing protocol respond to queries with available route information giving a list of gateways along the route.
Rendezvous
Protocol
Peer Endpoint
Protocol
peer-to-peer and agent-based computing

30. JXTA: security considerations
No security mechanisms in place yet…
Security is a big challenge:
Peers can be clients and servers
Anonymity of peers
peer-to-peer and agent-based computing

31. JXTA: potential applications
Search the entire web and all its connected devices (not just servers) for needed information
Save files and information to distributed locations on the network
Connect game systems so that multiple people in multiple locations
Participate in auctions among selected groups of individuals
Collaborate on projects from anywhere using any connected device
Share compute services, such as processor cycles or storage systems, regardless of where the systems or the users are located
peer-to-peer and agent-based computing

32. peer-to-peer and agent-based computing
JXTA Search Overview
Started in June 2000 by Infrasearch as an idea to distribute queries to network peers best capable of answering them.
Now it is the default searching methodology for the JXTA framework in the form of JXTA Search.
Communication via an XML protocol called Query Routing Protocol (QRP).
Network components: providers, consumers, hubs
Capable of providing both wide and deep search
deep search shows the most benefits
Design goals:
Simplicity, structure, extensibility, scalability
peer-to-peer and agent-based computing

33. peer-to-peer and agent-based computing
JXTA Search Benefits
Speed of update:
especially noticeable in deep search, where large data in databases are accessed directly without a need to create a central index.
Access:
in crawling based approach many companies are resilient to grant access to web crawlers. In distributed approach the companies can serve the data as they feel appropriate.
Efficiency:
no need to create a centrally placed and maintained index for the whole web.
peer-to-peer and agent-based computing

34. JXTA Search Architecture
Each JXTA peer can run instances of
Provider,
Consumer, and
Registration services on top of its JXTA core.
Each peer interacts with the JXTA Search Hub Services, which is also running on top of the JXTA core.
peer-to-peer and agent-based computing

35. JXTA Search Architecture (Cont’d)
Registration
Consumer
Provider
JXTA Peer
Hub
Each peer within the network interacts with the hub using its appropriate service
peer-to-peer and agent-based computing

36. peer-to-peer and agent-based computing
Collaboration
Over 25 companies developing JXTA projects
Core (7 projects)
security, juxta-c, juxtaperl, pocketjxta
Services (20 projects)
search, juxtaspaces, p2p- , juxta-grid, payment, monitoring
Applications (12 projects)
shell, jnushare, dfwbase, brando
Other projects (5)
demos, tutorials, etc.
peer-to-peer and agent-based computing

37. peer-to-peer and agent-based computing
JXTA: myJXTA
Peer interface
Windows
Unix/Linux
Basic P2P services
Search
Chat
Download
peer-to-peer and agent-based computing

38. peer-to-peer and agent-based computing
Reading list
JXTA Project.
Gnutella.
Books:
Free downloadable book available at
JXTA: P2P Computing with Java, Sing Li, 2002
JXTA, Brendon J. Wilson, 2002
JXTA: Java P2P Programming, Daniel Brookshire et al, 2002
Mastering JXTA Development, Joe Gradecki, 2002
Java P2P Unleashed, Robert Flenner et al, 2002
JXTA in a Nutshell, Scott Oaks et al, 2002
peer-to-peer and agent-based computing