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o all observations related to FOI o all observations for specific observable properties in a specific area and time
range o all observations for specific observable properties in a specific area and time
range produced by a call of procedures o all observations whose attributes fulfil specific conditions for example quality
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search for “procedures” o all procedures e.g. sensor types, models in a specific area
o all procedures that have specific properties described by their SensorML document
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search for “services” o all services that deal with a procedure
As examples, the following sequence diagrams show the typical chain of service operation calls for two selected query types:
1. The search target for the first sequence is an observation according to the Observation Measurements model see section 7.2. To keep this example simple it is assumed that
the user wants to find observations without using procedure information as selection criteria.
2. The second sequence shows how to discover procedures. The user wants to discover a procedure that is similar or identical to a known procedure.
10.2.3.1 Discovery of Observations
The first sequence diagram Figure 10-1 shows how a user may discover observations and retrieve their attribute values. It is divided into three parts:
1. The user starts to discover a Feature of Interest FOI within an area by sending a search request to the catalogue using a bounding box as a spatial condition. Additional
conditions, such as the type of the FOI may be added here. The catalogue returns a list of feature instances that fulfil the search conditions. This list contains the IDs of the feature
instances together with a set of core attributes e.g. according to the Dublin core schema. If additional attributes are required, the user can retrieve the complete meta-information
entry that is available in the catalogue by issuing a getMetaInformation operation request for a selected FOI instance. Finally, the user decides which FOIs they want to move
further along in the discovery process.
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Figure 10-1: Discovery of Observations
2. The user continues by searching in the catalogue for the SOS instance that provides observations for the selected FOIs. Typically they add one or more observable
properties and a time range, for which the SOS should provide observations as an additional condition. The user sends a search request to the catalogue to find an SOS
service instance and retrieves a list of SOS instances that meet the search conditions. Again the user can get additional meta-information about the services instances by
issuing a getMetaInformation operation request to the catalogue. If the meta-information
entry of the catalogue doesn‟t contain the full set of capabilities provided by an SOS
SANY D2.3.4 Specification of the Sensor Service Architecture V3 Doc.V3.1
Copyright © 2007-2009 SANY Consortium Page 177 of 233
instance or if the catalogue information is not sufficiently current for the user‟s purpose, they may retrieve the capabilities directly from the SOS instance by issuing a
getCapabilities operation request to the SOS instance. The capabilities document of the
SOS instance usually provides more detailed information about the service such as possible result models and the procedures used to get the values of an observation. Based
on this information the user now selects one or more SOS instances from which they want to get observations.
3. The user gets the observations by issuing a getObservation operation request to the SOS instance. It is important to note that the user does not get the observations from the
catalogue. The user finally decides which observations will be used in the application. Possible criteria for this decision are contained in the attributes of the observation, such
as quality attributes.
Depending on prior knowledge the user may skip parts of the sequence. As an example, the user may directly start with step 2, the search for an SOS instance, without having previously
searched an FOI in step 1. In this case the user may replace the ID of the FOI with a condition for the spatial context in the search SOS request to the catalogue.
10.2.3.2 Discovery of Procedures
