2-1 jxta concepts. 2-1 learning objectives ● this module will help you... – understand p2p...
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2-1
JXTA ConceptsJXTA Concepts
2-1
Learning Objectives
● This module will help you...– Understand P2P principles– Learn about JXTA virtual network core
building blocks– Understand the JXTA software
architecture– Gain familiarity with the JXTA shell
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Peer-to-Peer Principles
● Build complex behaviors by juxtaposing elementary ones
● Replicate information towards consumer peers
● Discover and adapt to new information sources
● Increase performance as system ages and more peers participate
● Protect data by replicating information
● Build reliability from interchangeable peers
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Peer-to-Peer Security Principles● Individual Privacy
– No centralized servers mean messages cannot be read or forged on a centralized mail server
● No central point of knowledge – Unconstrained content replication means it is
difficult to deny access since nobody knows the exact location of all copies of a content
● Web of trust – Trust based on peer behaviors and other peers'
accumulated trust level on that peer● Localized contamination
– Virus only transmitted to peer's neighbors – when a server is contaminated, all its clients are also contaminated
● Age does matter – Older peers are typically more known than newer
peers – self-protect against new intruders
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Protocols Drive Distributed Computing
Peer-to-Peer
Web-based
Client-Server
TCP/IP
HTTP
JXTA
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What is JXTA?
● An open set of XML-based protocols for creating peer-to-peer style network computing applications and services– Protocol based --> language, OS,
network, and service agnostic technology
– A virtual network overlay– Defines mechanisms, not policies– Open Source project: www.jxta.org
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JXTA Protocols
● JXTA defines XML message formats, or protocols, for communication between peers
● Protocols used to discover peers, advertise and discover resources, communicate and route messages, and provide monitoring
● Asynchronous; based on query/response model
● Can be implemented in any language
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JXTA Protocol Stack
Peer DiscoveryProtocol
Pipe BindingProtocol
Peer InfoProtocol
Peer Resolver Protocol
Peer Endpoint Protocol
Peer Rendezvous
ProtocolCoreProtocols
(Required)
StandardServicesProtocols
(Optional)
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JXTA Virtual Network
Firewall
NAT
Virtual Mapping
TCP/IP
PhysicalNetwork
HTTP
JXTA VirtualNetwork
Peer
Peer PeerPeer Peer
Peer PeerPeer
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UNIX as a Model● Provide a simple set of abstractions to
build complex systems● “Virtualized” UNIX over the Internet
In JXTAIn JXTA● Universal IDsUniversal IDs● Everything is Everything is
represented as an represented as an advertisementadvertisement
● Peergroups as resource Peergroups as resource scoping mechanismscoping mechanism
● Pipes as virtual Pipes as virtual communication channelscommunication channels
● Resolver as distributed Resolver as distributed resource locatorresource locator
In UNIXIn UNIX● IDsIDs● Everything is Everything is
represented as a filerepresented as a file● Process as resource Process as resource
scoping mechanismscoping mechanism● Pipes as communication Pipes as communication
channelschannels● Filesystem as resource Filesystem as resource
locatorlocator
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JXTA Virtual Network
● Uniform peer addressing– Peer Ids
● Dynamically configurable peer domains– Peergroups
● Uniform resource representation– Advertisements
● Universal binding– Resolver = searching for advertisements
● Virtual communication channels– Pipes
● Security and Monitoring
Building Blocks
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JXTA Software ArchitectureSample ApplicationsSample Applications
JXTA ServicesJXTA Services
JXTAApplications
JXTAServices
JXTACore
Peer GroupsPeer Groups Peer PipesPeer Pipes Peer MonitoringPeer Monitoring
Peer AdvertisementsPeer Advertisements SecuritySecurity
Any Connected Device
Peer IDsPeer IDs
SearchSearch IndexingIndexing DiscoverDiscover MembershipMembership
Instant MessagingInstant Messaging File SharingFile Sharing Resource SharingResource Sharing
Collaborative AppsCollaborative Apps AuctionsAuctions
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JXTA Shell
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What is the JXTA Shell?
● Interactive environment for the JXTA platform– Modeled after UNIX Shell– Executes within a network
● Basic commands– Discover peers/peergroups, join and
leave peergroups, create pipes, and send messages
● Environment variables– Can bind symbolic names to JXTA
objects
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JXTA Shell
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Starting the JXTA Shell
● Windows– Select Programs -> JXTA -> JXTA Shell
from the Start Menu● Other platforms
demo% cd /files/JXTA_Demo/Shell
demo% sh shell.sh
● JXTA Configuration Tool– Need to enter peer name and
username/password
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Shell Commands
● Getting helpJXTA> man
● Verify rendezvous peer connectionJXTA> rdvstatus
● Access Shell historyJXTA> history0 man1 rdvstatus
–Use up, down arrows to access commands–Use !<number> to access specific command
General Information
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Shell Commands
● Display information about current peerJXTA> whoami<Peer>my Shell</Peer><PeerId>urn:jxta:uuid-59616261646162614A78746150325033EFF0C0B7CD394BD1B9199E340B4A9E7A03</PeerId><TransportAddress>tcp://192.168.1.102:9701/</TransportAddress>...
Current Peer Information
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Peers
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Peers
● Any networked device that implements one or more JXTA protocols– PC, server, PDA, cell phone, etc.
● Operate independently, asynchronously● Spontaneously discover each other on
the network– Transient relationships– Persistent relationships (peergroups)
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JXTA Network Uniform Addressing
● A Peer is identified by:– A unique Peer ID (UUID)
– Example Peer ID: urn:jxta:uuid-59616261646162614A78746150325033EFF0 C0B7CD394BD1B9199E340B4A9E7A03
● Unique Peer IDs – Enable peers to be addressed
independently of their physical location (firewalls and NATs) in the network
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Anatomy of a JXTA ID
URI
JXTA Namespace
UUID Format
ID Value
– urn:jxta:uuid-5961626161503...F825503
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Peer Endpoints
● Network interface(s) published by peer● Example:
– TCP/IP (tcp://129.127.29.65:9700)– HTTP (http://JxtaHttpClientuuid-….)
● Used to establish point-to-point connections between two peers
● Direct connection not required– Intermediary peers can route
messages
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JXTA Peer Types● Micro peers
● Standard peers
● Super peers– Rendezvous
peer– Relay peer– Proxy peer
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Shell Commands
● Display a list of all peersJXTA> peerspeer0: name = my Shellpeer1: name = JXTA.ORG 237...
● Display peer IDsJXTA> peers -lpeer0: ID = uuid-59616261646162614A78746150325033ED194F913EA14144810D91475606A91203 name = myShell
Peers
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Shell Commands
● Initiate discovery of other peersJXTA> peers -rpeer discovery message sent
● Flush all cached peersJXTA> peers -f
Peer Discovery
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Relay Peers
● Special peers used to route messages for other peers within the physical network– Support multi-hops message transfers– JXTA messages contain self-routing information– Relay peers maintain dynamic route information– Cache messages to temporarily unavailable, or
non-reachable peers● Any peer can become a Relay peer● Primarily used for traversing firewalls and
NATs● Enable dynamic route discovery
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Relay Peers● Located outside firewalls and NATs● Provide fast network connectivity
Peer Peer
Peer
Peer
Peer
Peer Peer
Peer
PeerID
PeerID
PeerID
PeerID
PeerID
PeerID
Relay Peer
Relay Peer
Firewall NAT
TCP/IP
Physical NetworkHTTP
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Message Routing via Relay Peers
Firewall Firewall
Peer PeerPeerSuper Peer
SendMessage
ReceiveMessage
RequestMessage
A B
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Message Routing Via Relay PeersMultiple Relay Peers
Firewall Firewall
Peer PeerPeer
Super Peer
SendMessage
ReceiveMessage
RequestMessage
A B
Super Peer
RelayMessage
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Rendezvous Peers
● Rendezvous organize themselves into a “semi-consistent” network
● Rendezvous maintain index of edge peers advertisements
● Queries only propagated within Rendezvous tree structure using different walkers (DHT, multicast, sequential walk)
● Each service in a peergroup may use its own Rendezvous tree for scoping purpose
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Request Propagation via Rendezvous Network
JXTA Peer(uses R1)
JXTA Peer(uses R1)
JXTA PeerJXTA Rendezvous
JXTA Peer(uses R2)JXTA Peer
JXTA Rendezvous(knows R2 and R3)
Additionalrendezvouspeers andother peers
Additionalrendezvouspeers andother peers
JXTA PeerJXTA Rendezvous
Internet
AA
BB
CCR1R1R2R2
R3R3
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Shell Commands
● Display rendezvous statusJXTA> rdvstatusRendezvous Connection Status:_____________________________
Is Rendezvous : [false]
Rendezvous Connections :
Rendezvous name: ensd_1 Rendezvous name: dI_lab1 Rendezvous name: JXTA.ORG 235
Rendezvous Disconnections :
[None]
Rendezvous Status
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Peergroups
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Peergroups
Virtual Mapping
PhysicalNetwork
JXTA VirtualNetwork
Peer
Peer PeerPeer
Peer
PeerPeer Peer
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Peergroups
● Defined by users without requiring network administrators
● Identified by a unique “PeerGroup ID”● Enable self-organization of peers
(dynamic)● Associate a set of services:
PeerGroup services● Configurable membership policy
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Why Peergroups?
● Create secure and protected domains
● Scope peer operations– Discovery, search, communications
● Provide a “group” identity– Group peers sharing a common
interest
● Enable monitoring
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JXTA PeerJXTA Peer
JXTA Peer
JXTA PublicJXTA PublicRelay/Rendezvous Relay/Rendezvous
InternetInternet
NetPeerGroupNetPeerGroup
Public PeerGroup
Private Private PeerGroupPeerGroup
Private Private PeerGroupPeerGroup
Peergroup Scoping
JXTA Peer
FirewallFirewall
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Private Private PeerGroupPeerGroup
Private Peergroups
JXTA Peer
JXTA PublicJXTA PublicRelay/Rendezvous Relay/Rendezvous
InternetInternet
JXTA Peer
FirewallFirewall
JXTA PeerJXTA Peer
Private Private PeerGroupPeerGroup
NetPeerGroupNetPeerGroup
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Public and Private Peergroups
Private Private PeerGroupPeerGroup
JXTA Peer
JXTA PublicJXTA PublicRelay/Rendezvous Relay/Rendezvous
InternetInternet
JXTA Peer
FirewallFirewall
JXTA PeerJXTA Peer
Private Private PeerGroupPeerGroup
NetPeerGroupNetPeerGroup
Private PeerGroupPrivate PeerGroup
JXTA PeerJXTA Peer JXTA PeerJXTA Peer
FirewallFirewall
JXTA PrivateJXTA PrivateRelay/Rendezvous Relay/Rendezvous
PrivatePrivatePeerGroupPeerGroup
Public PeerGroup
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Shell Commands
● Initiate discoveryJXTA> groups -rgroup discovery message sent
● Display peergroupsJXTA> groupsgroup0: mygroupgroup1: some_other_group...
● Create a peergroupJXTA> mygroupadv = mkadv -g mygroupJXTA> mkpgrp -d mygroupadv
Discovering & Creating Peergroups
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Shell Commands
● Joining a new peergroupJXTA> mkpgrp mygroup
JXTA> join mygroup
● Changing peergroup contextJXTA> chpgrp some_other_group
group0: mygroupgroup1: some_other_group...
● Leaving current groupsJXTA> leave
Joining Peergroups
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Advertisements
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Advertisements
● Every resource in the JXTA network is represented by an advertisement– Peer advertisement– PeerGroup advertisement– Pipe advertisement– Endpoint advertisement– Module advertisement– Content advertisement– PeerInfo advertisement
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Advertisements are XML DocumentsPeerGroup Advertisement:
<?xml version="1.0"?><!DOCTYPE jxta:PGA><jxta:PGA>
<GID> urn:jxta: uuid-ABCBCDEABDBBBABEABBBABA0000001234563</GID><MSID> urn:jxta:uuid-DEFDBFEFDEDFBABAFRUDBACE000000010206</MSID><Name> My Group</Name><Desc> This group is to be used for my own testing</Desc>
</jxta:PGA>
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Peer Advertisement<?xml version="1.0"?><!DOCTYPE jxta:PA><jxta:PA xmlns:jxta="http://jxta.org">
<PID>urn:jxta:uuid-59616261646162614A78746150325033958A35814213467EBC6C88D3C138B43903
</PID><GID>
urn:jxta:jxta-NetGroup</GID><Name>
bill</Name><Svc>
<Parm><jxta:RA xmlns:jxta="http://jxta.org”>
<jxta:APA xmlns:jxta="http://jxta.org"> <EA> http://192.18.190.196:9700 </EA> <EA> tcp://192.18.190.196:9701 </EA> </jxta:APA> </Dst> </jxta:RA>
</Parm></Svc>
</jxta:PA>
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Advertisement Caching
● Peers cache advertisements (not required)● Peers publish and discover advertisements● Each advertisement is published with a
time-to-live:– Relative expiration date – Advertisements are removed from the
system when they have expired– Advertisements can be re-published
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Resolver
● All traditional “binding” operations in the JXTA network are implemented as a search for an advertisement
● Examples:– DNS (searching for Peer or PeerGroup
advertisements)– Service Location (searching for Module
advertisements) – Directory Service (searching for Peer
advertisements)– Socket Binding (searching for Pipe advertisements)– File systems (searching for Content
advertisements)
=> No Centralization Required !!
Universal Binding Mechanism
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Advertisement Discovery & Searching● Local Neighbor Discovery
– TCP/IP multicast (subnet scope)
● Rendezvous Peers– Peers which have agreed to cache a large number of
advertisements– Every peer may become a rendezvous peer– Discovery requests are forwarded between
rendezvous peers– Each peer group has its own set of rendezvous
● Invitation– JXTA Business card (Peer/PeerGroup Advertisement)
● Distributed Indexes– Shared Resource Distributed Index (SRDI)
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Shell Commands
● Make a peergroup advertisement– JXTA> grpadv = mkadv -g newgroup
JXTA> envgrpadv = PeerGroup Advertisement (class net.jxta.impl.protocol.PeerGroupAdv)...
● Display an advertisementJXTA> cat grpadv
<?xml version="1.0"?><!DOCTYPE jxta:PGA><jxta:PGA xmlns:jxta="http://jxta.org">
<GID>urn:jxta:uuid-20810AEF6C2F4711844DA8C4AE75D32502
</GID>...
Make Advertisements
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Shell Commands
● Make an advertisement available to other peersJXTA> share grpadv
Publish Advertisements
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Shell Commands
● Search for an advertisement– JXTA> search -rJXTA Advertisement search message sent
● Search for a specific advertisementJXTA> search -aName -vChat*
JXTA Advertisement adv0 (Search criteria: Attribute="Name" Value="Chat*")JXTA>cat adv0<?xml version="1.0"?><!DOCTYPE jxta:MCA><jxta:MCA xmlns:jxta="http://jxta.org">
...<Name>
ChatService</Name>
...
Search for Advertisements
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Pipes and Messages
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JXTA Pipes
● Non-localized communication channel between two or more peers– Asynchronous and unreliable– Unique “Pipe ID”– Pipe Advertisement– “Data-Typed” stream (XML schemas)– Input and output pipe endpoint
(channel access point)– Dynamic peer binding
Virtual Communication Channel
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Pipe Communication Abstraction Layer Input Input
PipePipe
Input Input PipePipe
ServiceServiceAA
JXTA Virtual Network
PeerGroup
Pipe
PipeEndpoint
Physical Network
Pipe Binding
Peer
HTTP
Peer
Peer
Peer Peer
Peer
NATPeer
Peer
PeerID
PeerID
PeerID
PeerID
PeerIDPeerID PeerID
PeerID
ServiceServiceAA
ServiceServiceCC
OutputOutput PiPipepeOutput Output
PipePipe
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Pipe Types● Point-to-Point Pipe
– Connects exactly two peer endpoints together
● Propagate Pipe– Connects one output
pipe to multiple input pipes
Additional pipe types (e.g., secure, Additional pipe types (e.g., secure, streaming, reliable) can be created streaming, reliable) can be created
from the core types.from the core types.
AA BB
AA
BB
CC
DD
Send
Receive
Send
Receive
Receive
Receive
EE
Receive
Input Pipe
Output Pipe
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Pipe Communication Model
● Connect services independently of their peer locations
● Dynamic binding (at pipe creation or for every message sent)
● Asynchronous (connect & disconnect mode)● Build highly-available services (transparent
fail-over by reconnecting pipe endpoints)● Pipeline multiple services to form complex
service
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Messages
● Object sent between JXTA peers– Message = basic unit of data exchange
● Ordered sequence of named/typed contents called Elements
● Each message contains its own routing information
● XML and binary representations used
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Shell Commands
● Create pipe advertisementJXTA> myPipeAdv = mkadv -p
● Create input and output pipesJXTA> myInPipe = mkpipe -i myPipeAdvJXTA> myOutPipe = mkpipe -o myPipeAdv
Pipe Commands
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Shell Commands
● Create a file (myFile) containing message data – a set of arbitrary XML tags<Data> Hello, JXTA</Data>
● Import into the JXTA ShellJXTA> importfile -f myFile myData
● Create a messageJXTA> myMsg = mkmsgJXTA> put myMsg myTag myData
Message Commands
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Shell Commands
● Send a messageJXTA> send myOutPipe myMsg
● Receive a messageJXTA> newMsg = recv myInPiperecv has received a message
● Extract and display the messageJXTA> newData = get newMsg myTagJXTA> cat newData<?xml version=”1.0”?><ShellDoc>
<Item><Data>Hello, JXTA</Data>
</Item></ShellDoc>
Message Commands (continued)
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Modules and Services
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Services
● Set of functions that a provider offers● Provider peer publishes service
advertisement● Pipes used to communicate with
service● Types of services
– Peer Services– Peer Group Services
(discovery, membership, etc.)
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JXTA “Core” Peergroup Services
● Services to support a peergroup– Discovery Service– PeerInfo Service– Pipe Service– Resolver Service– Membership Service– Rendezvous Service– Endpoint Service
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JXTA Modules
● JXTA Heterogeneous network of peers needs a platform-independent service representation:– Module = platform-independent
representation of a service– Service agnostic (WSDL, SOAP, RMI,
ORB, etc)– Viral effect (joining a group ->
instantiating new services)
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Module Advertisements
● Module Class– Advertise the existence of a service
● Module Specification– Advertise how to access a service
(API, messages)● Module Implementation
– Advertise a platform-specific implementation
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Security
● Every peer has its own root certificate● Public key certificate part of each
Peer advertisement● TLS Endpoint Transport (point-to-point
secure pipe)● Credential certificate embedded in
every JXTA protocol messages● Private Groups (membership policy)
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Monitoring and Metering
● Provide generic framework to collect peer monitoring and metering information– Collect network traffic information– Service queue statistics– Accounting and billing
● Show peer info statisticsJXTA> peerinfo -l
● Show metering JXTA> monitor
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JXTA Concepts
● JXTA virtual network● JXTA software architecture● JXTA objects
– Peers– Peergroups– Advertisements– Pipes and messages– Services
● Security● Monitoring and metering
Review
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End – JXTA ConceptsEnd – JXTA Concepts
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