org.lsst.ccs.subsystem.airwatch.main

Class RestfulClient

java.lang.Object

org.lsst.ccs.subsystem.airwatch.main.RestfulClient

public class RestfulClient
extends Object

Retrieves the data from the Lighthouse environment sensors via HTTP. The server is a Python script running on the Lighthouse PC which knows how to read the data from the LMS Express OPC DA server. Immutable.

Author:

tether

Constructor Summary

Constructors

Constructor and Description
RestfulClient(URL serverUrl, Duration connectionTimeout, Duration readTimeout) Stores the HTTP URL.

Method Summary

Modifier and Type	Method and Description
String	dumpData() Dumps the text received from the server without trying to parse it.
List<Map<String,Object>>	fetchData() Reads sensor information in JSON format and parses it.
static void	main(String[] args)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RestfulClient

public RestfulClient(URL serverUrl,
                     Duration connectionTimeout,
                     Duration readTimeout)

Stores the HTTP URL.

Parameters:

serverUrl - the URL for the sensor PC's data server.

connectionTimeout - how long to wait for a connection to complete.

readTimeout - how long to wait for data after connecting.

Method Detail

dumpData

public final String dumpData()
                      throws IOException

Dumps the text received from the server without trying to parse it.

Returns:

The text sent from the server.

Throws:

IOException - if the the server could not be found or if data could not be read from it.

fetchData

public final List<Map<String,Object>> fetchData()
                                         throws IOException

Reads sensor information in JSON format and parses it.

Returns:

A list of Map<String, Object>. In each map the value with key "location" is a string giving the name of the location such as "MAIN_NW" or "AUX". The other keys are all channel names. A numerical channel name key such as "0.3" or "3.0" denotes a particle counter channel for particles of that size or greater in microns. Anything else is the name of an analog channel such as "temp".

A value for a particle counter channel is itself a map of items appropriate for such a channel:

• density (double): The value of the particle density in particles/ft^3.
• quality (String): The OPC DA quality for the value. Should be "Good" if the value is well measured.
• time (String): The timestamp for the value in ISO format including the local offset from UTC.
• status (String): If the quality is not "Good", this is a brief description of the trouble
• limitViolation (boolean): True if and only if the value is out of bounds. Distinct from quality of measurement.
• malfunction (boolean): true if and only if a sensor malfunction occurred.
• absolute (double): The absolute particle count for the air sample, not divided by sample volume.

A value for an analog channel is itself a map. It also has the keys "quality", "time", "status", "limitViolation" and "malfunction". In addition it has:

• value (double): The sensor reading.
• lowBound (double): The lowest acceptable reading.
• highBound (double): The highest acceptable reading.

Throws:

IOException - if no data could be read or could not be parsed.

main

public static void main(String[] args)
                 throws MalformedURLException,
                        IOException

Throws:

MalformedURLException

IOException