Gatewaying in Wireless Sensor Networks

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Gatewaying in Wireless Sensor Networks
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Overview

• TinyDB
• Introduction to Zeroconf
• Bonjour
• Avahi

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TinyDB

• It is a query processing system for extracting
  information from a network of TinyOS sensors.
• Declarative SQL-like query interface. The query
  language is referred to as TinySQL.
• It manages the connectivity of motes in the
  network.
• Network is monitored via queries.
• It provides a graphical interface for
  distributing queries over motes and collecting
  data from them.
• Problem TinyDB is supported by an older release
  of TinyOS.

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Zeroconf Zero Configuration Networking

• A Zeroconf network is one that can exist without
  a central control element, and works without any
  kind of user configuration.
• Automatically creates an IP network.
• Can be accomplished on both ethernet and wireless
  local networks.

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ZEROCONF

• ZeroConf performs the following
• Automatic Interface Configuration
• Automatic Multicast Address Allocation
• Name-to-Address Translation
• Service Discovery

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Zeroconf

• DEVICE CONFIGURATION Zeroconf uses a technique
  called link local addressing.
• A device, when added to the network, randomly
  selects an IP address and assigns that address to
  itself.
• It then sends a message on the network to
  determine if another device is already using the
  address.
• If yes, the device randomly selects addresses
  till it finds one that is not in use.

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Zeroconf

• SERVICE DISCOVERY To share services a device
  must create a unique name for each of its
  services and let other devices on the network
  know about their existence.
• Zeroconf uses a variant of DNS called mDNS-SD
  (Multicast Domain Name Server-Service Discovery)
• mDNS-SD is query driven and retrieves the type,
  name of service, IP and Port address.
• Each device on the network receives the
  notification and stores the information.

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Zeroconf

• Example of a mDNS query
• Copy Room_ipp._tcp.local.PTR
• Copy Room Name of the service
• _ipp Type of service
• _tcp Networking protocol identifier
• .local. The local lookup domain

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Implementations of Zeroconf

• Bonjour (formerly known as Rendezvous) is Apples
  trade name for its implementation of the Zeroconf
  framework.
• Avahi is an implementation of the ZeroConf
  specification for Linux.

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AVAHI

• It is a system for multicast DNS service
  discovery on a local network.
• Allows programs to publish and discover services
  and hosts running on a local network with no
  specific configuration.
• It uses D-Bus for communication between user
  applications and a system daemon.

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AVAHI

• avahi-discover Shows a real-time graphical
  browse list for mDNS/DNS-SD network services
  running on the LAN using the Avahi daemon.
• avahi-publish Registers an mDNS/DNS-SD service
  or host name/address mapping using the Avahi
  daemon.
• Avahi-daemon Registers local IP addresses and
  static services using mDNS/DNS-SD.

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AVAHI

• avahi-publish-service "SENSOR" _http._tcp 9001
• avahi-discover

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NEXT STEP

• Integration into the web page.

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References

• www.tinyos.net
• http//www.zeroconf.org/
• http//www.apple.com/macosx/features/bonjour/
• www.avahi.org