Christopher Bladon

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JXTA versus Jini
Christopher Bladon Senior Java Architect Sun Java
Centre, Sun Microsystems Zürich, Sweden
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My presentation, tall and proud

• Debian Linux
• Windows-Free
• No slide animations transitions
• No marketing
• My brain

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JXTA no infrastructure decentralised
Midlets
CICS
.Nyet
J2EE
Required Infrastructure
TPF
Grid
Jini/Rio
Hello World
Client/ Server
JXTA
Decentralisation
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There is no silver bullet

• Jini simple services
• Service facade for devices
• Rio quality of service
• Delivering services on the network
• JXTA push services and data to client
• Collaboration and document sharing
• J2EE load-balanced, components
• Business processes

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The more peers, the better

• Moves data and services close to the user
• Probabilistically better availability
• More routing possibilities
• Less configuration

JXTA peers
Performance
J2EE clients
Users
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Quick Comparison
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Peer-to-peer is cool!

• No infrastructure
• Interesting problems
• Simpler and lighter nodes
• Self-healing mentality
• Dynamic structure
• Promotes sharing
• Reliability by redundancy
• Collaborative development

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JXTA Abstractions

• Uniform Peer ID (addressing)
• Peer-groups
• Advertisements (peers, groups, content, services)
• Resolver
• Pipes

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JXTA Aspects

• Discover, Join, Query, Subscribe, Work
• Colony of Bees (without a queen)
• Replicate data resilience
• Replicate services resilience performance
• Unmanaged fault-tolerance
• Dynamic config and re-config
• Groups - Virtual network (NAT Firewalls)

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Tons of cool stuff!

• 100 p2p
• No centralised servers or admin
• Multilingual (prog. Language)
• Security is built-in
• Messages contain the route back
• Through NAT and Firewalls
• Peers authorise other peers
• No polling, link-sensing, neighbour detection

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JXTA Protocols

• PDP discover adverts on other peers
• PVP cache and forward discoveries
• PRP generic querying of peers
• PIP query peers for info status
• PEP query peers for routing info
• PMP group membership
• PBP binding to pipes

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The obligitory stack picture
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Firewalls, NAT no problem
Intranet Network 1
Network 2
Peer A
Peer Z
Subnet
Peer B
Peer C
NAT
Firewall
Peer D
Internet
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It's secure!

• 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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Some not so cool stuff

• Community's Anti-P2P mentality
• Complex, low-level programming
• No patterns
• Mediocre documentation
• Java ref-impl is not cooked fully
• Security and Trust is not cooked fully
• P2P model is probabilistic

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Rio/Jini (rio.jini.org)

• Dynamic service delivery
• 90 opaque layer on Jini
• RMI Events
• Jini Service Beans (JSBs)
• Quality of Service Provisioning
• Watches
• Deployment Operation Strings

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Rio/Jini Components

• Look-up Service
• Transaction monitor (2-phase)
• JavaSpaces
• Webster
• Cybernode
• Provisioner
• OpMon
• Service Viewer

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Cool stuff 'bout Rio/Jini

• Simple component model events
• SpaceCommands
• Flexible QoS heterogeneous compute env
• Great tools
• Paradigm similar to J2EE easier

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Problems with Rio/Jini

• Reliance on RMI
• Somewhat complex infrastructure
• Confusion Jini versus J2EE
• No security yet (next release)

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Problems in the enterprise

• Redundant Data distributed replicated
• Bladon Theorem 1 the faster data changes, the
  less it can be redundant.
• Centralised versus redundant services
• Propagating and reloading changed classes
• Transactions
• Modelling Entities and Sessions

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How would you implement

• Chat Whiteboard
• File (MP3) search and download
• Auction
• Car Chip upgrades
• Pet Store

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Conclusions

• Rio's vision is independent of Jini use any
  service platform incl. JXTA
• Rio/Jini doesn't scramble your brain like JXTA
• Rio/Jini and JXTA support collaborative
  development instead of isolated
• Rio/Jini and JXTA are not just for devices
  enterprise computing!!!!

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Christopher Bladon Senior Java Architect Sun Java
Centre, Sun Microsystems Züri, Schwyz