Package org.epics.archiverappliance.retrieval.mimeresponses

Class MatlabResponse

java.lang.Object

org.epics.archiverappliance.retrieval.mimeresponses.MatlabResponse

All Implemented Interfaces:

EventConsumer, MimeResponse

public class MatlabResponse
extends Object
implements MimeResponse

Generate a ".mat" matlab file The response contains two objects, a header and a data object. The header object is indexed by the string header and is a MLStructure with fields for pvname, start and end times etc. The data object is indexed by the string data and is a MLStructure with these fields.

1. epochSeconds - contains Java epoch seconds as a 1x1 uint64 array. The times are in UTC; so any conversion to local time needs to happen at the client.
2. values - contains the values for the samples. All scalars come as a 1x1 double array. Waveforms come as a 1xelementcount double array where elementcount is the EPICS element count of the waveform.
3. nanos - contains the nano second value of the EPICS record processing timestamp as a 1x1 uint64 array. Some installations embed the beam code/pulse id into this field; however, this is done at the IOC side and as far as this code are concerned, this is the nanoseconds.
4. isDST - contains booleans that indicate if the time indicated by epochSeconds was in daylight savings time in the timezone of the server. This is an attempt to get around the deficiencies in Matlab w.r.t timezones.

If needed, we can add separate fields for status and severity. Owing to the column-major nature, this response consumes a lot of memory. If we are serving large datasets using Matlab responses, we should increase the heap size for the retrieval war to large values.

Author:

mshankar

Field Summary

Fields inherited from interface org.epics.archiverappliance.retrieval.mimeresponses.MimeResponse

ACCESS_CONTROL_ALLOW_ORIGIN, CONTENT_TYPE, PROXIED_HEADERS

Constructor Summary

Constructors

Constructor	Description
MatlabResponse()

Method Summary

Modifier and Type	Method	Description
void	close()
void	consumeEvent(Event e)
HashMap<String,String>	getExtraHeaders()	Get extra headers that are to be added to the response.
void	processingPV(BasicContext retrievalContext, String pv, Timestamp start, Timestamp end, EventStreamDesc streamDesc)	Called when we swich to a new PV.
void	setOutputStream(OutputStream os)
void	swicthingToStream(EventStream strm)

Methods inherited from class java.lang.Object

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

Constructor Detail

MatlabResponse

public MatlabResponse()

Method Detail

consumeEvent

public void consumeEvent(Event e)
                  throws Exception

Specified by:

consumeEvent in interface EventConsumer

Throws:

Exception

setOutputStream

public void setOutputStream(OutputStream os)

Specified by:

setOutputStream in interface MimeResponse

processingPV

public void processingPV(BasicContext retrievalContext,
                         String pv,
                         Timestamp start,
                         Timestamp end,
                         EventStreamDesc streamDesc)

Description copied from interface: MimeResponse

Called when we swich to a new PV.

Specified by:

processingPV in interface MimeResponse

pv - The name of PV

start - Timestamp

end - Timestamp

streamDesc - Could be null if we have no data in first store we hit.

swicthingToStream

public void swicthingToStream(EventStream strm)

Specified by:

swicthingToStream in interface MimeResponse

close

public void close()

Specified by:

close in interface MimeResponse

getExtraHeaders

public HashMap<String,String> getExtraHeaders()

Description copied from interface: MimeResponse

Get extra headers that are to be added to the response. For this to work correctly in a clustered environment, you'll need to add the header to the set of proxiedHeaders below

Specified by:

getExtraHeaders in interface MimeResponse

Returns:

HashMap ExtraHeaders