illinois security lab obix protocol overview presented by lars olson

IllinoisSecurity Lab

oBIX Protocol Overview

presented by Lars Olson


2

oBIX

• oBIX = Open Building Information Exchange– XML vocabulary for control systems– OASIS working draft

• currently 0.6, 2 December 2004• some sections are not yet written

– Links for general public, technical information

• Technical committee– Representatives from Cisco, Echelon, IBM, LonMark, OASIS,

Trane, Tridium, UNC

• Subcommittees:– Technical standards– Power systems (metering, analysis, generation)– Security systems (access control, intrusion detection, CCTV

monitoring, fire detection & life safety systems)– Enterprise requirements, Roadmap


3

oBIX Data Model

• ?????

• Objects are queried as trees– How are they organized? (Depends on the

system designer?)– Is a tree appropriate?

• e.g. Motion sensors could be part of both security system and lighting system

• Then again, we could clone duplicate entries to create a tree

• Use cases?


4

About operation

• aboutReq– locale

• aboutRes– locale– serverName– serverTime– serverBootTime– vendorName– vendorUrl– productName– productUrl– productVersion– locales– services

<aboutReq><locale>en</locale>

</aboutReq>

<aboutRes><locale>en</locale><serverName>Server B</serverName><serverTime>

2004-09-02T03:20:36+05:00</serverTime>

<vendorName>Acme</vendorName><productName>My oBIX Server</productName><productVersion>1.2.34</productVersion><locales>

<locale>en</locale><locale>fr</locale>

<locales><services>

<service><id>http://obix.com/ns/sys/1.0</id>

</service><service>

<id>http://obix.com/ns/hist/1.0</id></service>

</services></aboutRes>


5

Read operation

• readReq– locale– depth– include

• id• value• status• display• facets• ext *

– id *

<readReq>

<locale>en</local>

<depth>0</depth>

<include>

<id>true</id>

<status>false</status>

<ext>

http://obix.com/ns/hist/1.0

</ext>

</include>

<id>OutsideAirTemp 1</id>

<id>OutsideAirTemp 2</id>

</readReq>

objects in the data model are

trees (no default specified?)what values should

be returned (defaults for all but

<ext> are true)

metadata about the object (I’ll

cover this later)


6

Read operation

• readRes– locale– object *

• id

• [value] (<bool>, <int>, <str>, <unit>, etc.)

• status (described later)

• display

• facets

• ext

• children– object *

– error *• id

• display

<readRes><locale>en</locale><object>

<id>OutsideAirTemp 1</id><real>75.201</real><status>

<quality>ok</quality></status><display>75.2F</display><facets>

<min>-100</min><max>300<max>

</facets></object><object>

<id>OutsideAirTemp 2</id>...

</object></readRes>


7

Write operation

• writereq– locale– write *

• id• [value], one of:

– <bool>– <int>– <real>– <enum>– <str>– <absTime>– <relTime>– <object>

» id» [value]» children

<writeReq><write>

<id>/Zone2/Lights.on</id><bool>true</bool>

</write><write>

<id>Fan.speed</id><enum>fast</enum>

</write><write>

<id>Site.streetAddress</id><object>

<children><object>

<id>street</id><str>...</str>

</object><object>

<id>city</id><str>...</str>

</object>...

</children></object>

</write></writeReq>


8

Write operation

• writeRes– locale– error *

• id• display

<writeRes><locale>en-US</locale><error>

<id>setTime

</id><display>

Mismatched types:enum != absTime

</display></error>

</writeRes>

no matching error element means

operation completed successfully


9

Subscription operations

• subscribeReq, extends readReq– locale, depth, include,

id *– lease

• subscribeRes, extends readRes– locale, object *, error *– subscriptionId– lease

<subscribeReq><locale>en</local><depth>0</depth><include>

<id>true</id><status>false</status><ext>

http://obix.com/ns/hist/1.0</ext>

</include><id>OutsideAirTemp 1</id><lease>PT5M</lease>

</subscribeReq>

<subscribeRes>[readRes elements]<subscriptionId>

OutsideAirTemp_subscr_1</subscriptionId><lease>PT2M</lease>

<subscribeRes>

<include> describes contents of both

subscribeRes and default for pollRes

suggested xsd:duration, the

server doesn’t have to follow it


10


• pollReq– locale– subscriptionId– forceAll– include

• pollRes, extends readRes– locale, object *, error *– invalid

• display

<pollReq>

<subscriptionId>

OutsideAirTemp_subscr_1

</subscriptionId>

</pollReq>

<pollRes>

<invalid>

<display>

Lease time expired

</display>

</invalid>

</pollRes>

update every item, even if no change

has occurred (default is “false”)


11


• unsubscribeReq– subscriptionId

• unsubscribeRes (empty element)

<unsubscribeReq>

<subscriptionId>

OutsideAirTemp_subscr_1

</subscriptionId>

</unsubscribeReq>

<unsubscribeRes />


12

Status element

• status– quality

• “ok” (default if not present)

• “overridden”• “disabled”• “fault”

– alarm• inAlarm• unacked

– timestamp– param *

<status>

<quality>ok</quality>

<alarm>

<inAlarm>false</inAlarm>

<unacked>false</unacked>

</alarm>

<timestamp>

2004-09-02T10:27:00

</timestamp>

<display>OK</display>

<param name="...">

xs:string

</param>

<param name="...">

xs:string

</param>

</status>

How do we describe the

fault?

How do we acknowledge the

alarm? (<writeReq>?)


13

Unit element

• unit– id– display– symbol– dimension

• kg, m, sec, K, A, mol, cd

– scale– offset

• Example shown is kilowatt, 1000 m2kg/sec3

<unit>

<id>kilowatt</id>

<display>kilowatt</display>

<symbol>kW</symbol>

<dimension>

<m>2</m>

<kg>1</kg>

<sec>-3</sec>

</dimension>

<scale>1000</scale>

</unit>


14

Facets element

• facets– min– max– resolution– precision– writable– icon– range

• declare by reference with “id=…” attribute

• or enumerate with item *– id– display

– units

<facets><min>0</min><max>100</max><resolution>0.25</resolution>

</facets>

<facets><icon>

/icons/equipment.png</icon><range>

<item><id>true</id><display>On</display>

</item><item>

<id>false</id><display>Off</display>

</item></range>

</facets>

accuracy of the value

number of decimal placesURI for image

file for user interface


15

Other protocols

• LonTalk– Not an open protocol– Can download reference for free, license agreement required

• Modbus– 48 members– Specs available for download

• OPC– 393 members, including GM, HP, Hitachi, Microsoft, Mitsubishi,

NIST, Philip Morris (?), Siemens, various universities (mostly foreign)

– Requires free registration to download specs

• ZigBee (wireless sensor net protocol)– 183 members, including Motorola, Philips, Samsung, Cisco– Requires free registration to download specs– Presentations and white papers

illinois security lab obix protocol overview presented by lars olson

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