2. Contents Digital-SNOWTAM Trial Introduction REST Introduction
REST in the Digital-SNOWTAM Trial
Why it is used
Architecture
How it is used
Example
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3. Digital-SNOWTAM Trial Introduction

4. Demo
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5. REST Introduction

6. REST Representational State Transfer An architectural style REST
It is an architectural style. OFTEN LEAD TO REStful Web Services E.g. Amazon S3 REST API.
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7. Main definitions Resources Representations Actions – Verbs
Type of data
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8. Resources
A resource is a real thing that can be acted upon with a request
Anything that can be named can be a resource e.g. PDF, XML, SVG, HTML page, today’s weather report.
They are found using URIs (see
These are represented using URIs (see purl.org)
Anything can be a resource e.g. PDF, XML, SVG, HTML page.
A resource is a real thing that can be acted upon with a request
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9. Resources and time Resources can vary over time.
The only thing that must be static is the semantic of the mapping (name).
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10. Representations
The data transmitted to and from the resource is called a representation
Captures the current or intended state of the resource
It can be a copy of the file or a description of it
The data transmitted to and from the resource is called a representation.
It can be a copy of the file or a description of it.
The interaction of the representation on the resource is determined by the verb.
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11. Transparency
How the representation is found should be transparent to the user
It could involve the server parsing the URL, constructing a database query and returning the result
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12. Actions - Verbs
Once the representation of the resource has been returned, an action can be performed
The interaction is determined by the HTTP verbs: GET, PUT, POST and DELETE
The interaction is stateless
Once the resource has been found, an action can be performed.
These use the HTTP verbs: GET, PUT, POST and DELETE
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13. Type of data
When performing an action on a resource it is important to know what the resource is
MIME types can help here (e.g. text/xml)
The format of the request/response can be specified in a schema
When performing an action on a resource it is important to know what the resource is.
MIME types can help here (text/xml).
The format of the response can be specified in a schema. Likewise, a schema can define the format of the response.
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14. Actions GET Used to read a resource or as a query
Should be side-effect free
PUT
Replaces the target resource in its entirety
DELETE
Removes the resource
POST
Has a variety of meanings e.g. it can be used when only a subset of a resource has to be modified
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15. REST in the Digital-SNOWTAM Trial

16. Why it is used
Support the provision of AIXM 5.1 data to end-user applications
The REST interface shall enable digital users to:
Query the Digital SNOWTAM database for the list of airports contained in the database and select one of these airports;
Get the list of airport’s features for a selected airport;
Get the surface contamination records for each such feature;
Get the feature related through xlink:href;
Get the SNOWTAM text and the free text translation associated with an Airport.
Read-Only
Except for the list of Airports always returns an AIXM Basic Message which contains features
There is no AIXM message yet for list of airports
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17. Architecture
The REST implementation framework used is Struts 2 REST plug-in which in turn uses the Convention plug-in.
See for more information.
Please note the REST plug-in is only available for Struts or above.
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18. Implementation Only GET is need for the trial.
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19. Workflow In order to interrogate the database:
request the list of airports
select one airport and use the xlink:href to get the details about this airport
select a runway and use the corresponding xlink:href to get the details about this feature
The xlink:href is a URL compliant to the Digital SNOWTAM REST request structure
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20. Base URL Base: http://<server>/<app>
E.g.
Then add a Suffix:
/<REST suffix>
Will work on HTTPS
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21. Find Airports Suffix: /airportheliports[?designator=<pattern>]
There are about airports/heliports in the database so…
Optional Parameter:
The pattern is of the form [A-Z*]{1,4} where * is the wildcard character.
Pattern samples:
EB* matches any designator beginning with EB
*BBR matches any designator ending in BBR
E*R matches any designator beginning with E and ending with R
The response to this request is not AIXM5.1-compliant since AIXM5.1 doesn’t define the concept of list of airports/heliports.
Can add date&time if needed.
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22. Query an Airport Suffix:
/airportheliports/<gml:identifier>[?features=yes/no&contaminations=yes/no&date=<date&time>]
Mandatory parameter:
gml:identifier – UUID
Optional parameters:
date - <date&time> is the search date&time
features - specify if xlink:href pointing to related features must be included in the results, e.g. runways, taxiways, etc
contaminations - specify if contaminations must be included or not in the result
Use the gml identidfier from the Find Airport stage
Here are a few remarks valid for all the suffixes described below:
date is an optional parameter and <date&time> is the search date&time in the format dd/mm/yyyy hh:mm (e.g.: 11/06/ :35). In each case, the response will be limited to data valid at that date&time. If no date&time is provided, the current date and time is used.
features is an optional parameter to specify if xlink:href pointing to related features must be included in the results,e.g. runways, taxiways, apron of an airport or runway directions of a runway. Possible values are yes and no. If missing, no is assumed.
contaminations is an optional parameter to specifiy if contaminations must be included or not in the result. Possible values are yes and no. If missing, no is assumed.
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23. Examples

24. 1 – Create Contamination
Use Bromma to create a contamination
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25. 2 – Use REST to find the airport
<ResultList>
<AirportHeliportFeature designator="ESSB" id="77a0de0e-277a-4824-a561-2ba779a3658c" href="
</ResultList>
Use FireFox with text link plug in:
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26. 3 – Find SNOWTAM Text
<aixm:annotation>
<aixm:Note>
<aixm:definition>snowtam-icao</aixm:definition>
<aixm:translatedNote>
<aixm:LinguisticNote>
<aixm:note lang="eng">
SW** ESSB (SNOWTAM A)ESSB B) C)12 F)3/2/2 G)1/1/1 H)2/3/3 BRD )
</aixm:note>
</aixm:LinguisticNote>
</aixm:translatedNote>
</aixm:Note>
</aixm:annotation>
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27. 4 – Get Airport data …
<aixm:associatedRunways>
<aixm:associatedRunway id="12/30" xlink:href="
</aixm:associatedRunways>
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28. 5- Get Runway contamination
<aixm:areaContaminant>
<aixm:RunwaySectionContamination>
<aixm:observationTime> T09:00:00Z</aixm:observationTime>
<aixm:depth uom="MM">1</aixm:depth>
<aixm:frictionEstimation>MEDIUM</aixm:frictionEstimation>
<aixm:frictionDevice>BRD</aixm:frictionDevice>
<aixm:obscuredLights>NO</aixm:obscuredLights>
<aixm:layer>
<aixm:SurfaceContaminationLayer>
<aixm:layerOrder>1</aixm:layerOrder>
<aixm:type>WATER</aixm:type>
</aixm:SurfaceContaminationLayer>
</aixm:layer>
<aixm:section>2_THIRD</aixm:section>
</aixm:RunwaySectionContamination>
</aixm:areaContaminant>
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29. 6 - Time based
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30. AIXM 5.1
TEMPDELTA and a BASELINE
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