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mdf edited this page Sep 6, 2012 · 12 revisions 
How to get data for a Timestreams Visualisation.

In short:

- ask the server what time it is
- optionally ask the server for a list of existing Timestreams, or you need to know the ID of a specific Timestream
- ask for the metadata that describes the datasource currently feeding the Timestream
- ask the server for an initial data set (the last 30 readings, for example)
- repeatedly ask the server for data that has arrived since you last asked

In practical terms:

- ask the server what time it is

Method name: timestreams.ext_get_time

Arguments: username, password



timestreams.ext_get_time

USERNAME
PASSWORD



curl --noproxy localhost -d "timestreams.ext_get_timeUSERNAMEPASSWORD" http://localhost/relatedev/xmlrpc.php

returns the current server time in seconds. All queries involving a timestamp sent to the server should be relative to this timestamp to avoid time zone problems - i.e. calculate your local time offset from the server's current time, and apply this offset when telling the server when you last asked for something.



  
    
      
      1346924718
      
    
  


- get a list of Timestreams.

Method name: timestreams.ext_get_timestreams
Arguments: username, password



timestreams.ext_get_timestreams

USERNAME
PASSWORD



curl --noproxy localhost -d "timestreams.ext_get_timestreamsUSERNAMEPASSWORD" http://localhost/relatedev/xmlrpc.php

currently returns an array of all Timestreams. Realistically you would only care about timestream_id and name (the friendly name)



  
    
      
      
  
  timestream_id18
  nameadadda
  head_id21
  metadata_id26
  starttime2012-08-19 14:50:41
  endtime2012-08-19 15:12:18

  
  timestream_id17
  nametestimg
  head_id20
  metadata_id28
  starttime2012-08-28 16:11:52
  endtime2012-08-28 16:12:09


      
    
  


- ask for the metadata that describes the datasource currently feeding the Timestream

Method name: timestreams.ext_get_timestream_metadata
Arguments: username, password, timestream id



timestreams.ext_get_timestream_metadata

USERNAME
PASSWORD
17



curl --noproxy localhost -d "timestreams.ext_get_timestream_metadataUSERNAMEPASSWORD17" http://localhost/relatedev/xmlrpc.php

returns metadata about the datasource - max value, min value, information about the sensor, units etc



  
    
      
      
  metadata_id28
  tablenamewp_5_5_ts_Image_89
  measurement_typeImage
  first_record
  min_value0
  max_value100
  unitimage/png
  unit_symbolPNG
  device_details5909E86B-DF41-54E6-AD21-FD767045AB33
  other_infoTesting
  data_typeVARCHAR(200)

      
    
  


- ask the server for an initial data set (the last 30 readings, for example)

Method name: timestreams.ext_get_timestream_metadata
Arguments: username, password, timestream id, time last asked, maximum number of readings to return

Note how the initial time last asked argument is 0, indicating we want the latest 30 readings initially. 



timestreams.ext_get_timestream_data

USERNAME
PASSWORD
17
0
30



curl --noproxy localhost -d "timestreams.ext_get_timestream_dataUSERNAMEPASSWORD17134692471810" http://localhost/relatedev/xmlrpc.php

Returns an array of readings. "valid_time" is the time that this reading actually happened, so is the one to display if necessary. "value" is the actual reading - temperature reading, URL of an image etc


  
    
      
      
  
  id14
  valuehttp://robin.timestreams.wp.horizon.ac.uk/files/2012/08/wp_5_5_ts_Image_89_img13.png
  valid_time2012-08-28 16:11:23
  transaction_time2012-08-28 16:12:31

  
  id15
  valuehttp://robin.timestreams.wp.horizon.ac.uk/files/2012/08/wp_5_5_ts_Image_89_img14.png
  valid_time2012-08-28 16:11:23
  transaction_time2012-08-28 16:12:43

  
  id12
  valuehttp://robin.timestreams.wp.horizon.ac.uk/files/2012/08/wp_5_5_ts_Image_89_img11.png
  valid_time2012-08-28 16:11:12
  transaction_time2012-08-28 16:12:11

  
  id13
  valuehttp://robin.timestreams.wp.horizon.ac.uk/files/2012/08/wp_5_5_ts_Image_89_img12.png
  valid_time2012-08-28 16:11:12
  transaction_time2012-08-28 16:12:23


      
    
  

Subsequently repeat this call, but now include the time we last asked, which we should have remembered from the previous call. Timestamp is a unix timestamp in seconds, as below.



timestreams.ext_get_timestream_data

USERNAME
PASSWORD
17
1346924718
30

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