Resource Access Interface

There is no single resource access interface in the SENSEI architecture, instead each resource description published by a REP includes information about the interface(s) available to access it, for example the URL and interface description. In order for Resource Users to easily access resources, a set of well-known resource interfaces have been defined for sensor, parameter, actuator and code-update resource types.

How to connect to these URLs using REST is described in the Connecting a Resource User section. A short example of how a response looks like is this:

<rdf:RDF>
   <nmib:Location mo:direction="" mo:hasTimeStamp="" 
         mo:latitude="" mo:line="24" mo:longitude="" 
         mo:nextStationDistance="" mo:nextStationID="" 
         mo:nextStationName="" 
         rdf:about="http://www.resource-provider-456.com/resources#location"/>
</rdf:RDF>

All responses are in the XML-RDF format so that the Semantic Query Analyser can work with them. How a Resource User gets this reference is by either querying an SQR or an RD. (see [[RuRli| the RLI Interface). Ofcourse another way would be to browse an RD directly (/rd url) and to read all resources available, but this works only on small sites.

The URL is provided by the Rep-Locator entry of the Resource Directory Description.

A resource may have one or more such urls, and even publish URL behind company proxies.

<REP-Locator>
http://195.178.44.184/rephandler/gps/358278005846910
</REP-Locator>

It is up to the client to detect if it will use IPv6 or IPv4 addresses and to select the best connected resource.

The whole RD entry looks like this:

<Resource-Description>
−
<Resource-ID>
urn:sensei:ericsson.com:EnvironmentalSensors:busgps:358278005846910
</Resource-ID>
<Name>Bus Location Sensors in Belgrade</Name>
<Storage-ID>6</Storage-ID>
<Expiration-Time>11-01-01T00:00:00+00:00</Expiration-Time>
<Tag>Bus</Tag>
<Tag>GPS</Tag>
<Tag>Sensor</Tag>
<Tag>Belgrade</Tag>
<Tag>24</Tag>
<Tag>358278005846910</Tag>
−
<Rai-Description>
<RAI-ID>tempID</RAI-ID>
<Description>GET returns sensor values (RDF)</Description>
−
<REP-Locator>
http://195.178.44.184/rephandler/gps/358278005846910
</REP-Locator>
</Rai-Description>
</Resource-Description>