= IPP to PSPS interface: {{{ippToPsps}}} =

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{{{ippToPsps}}} is the interface between IPP and PSPS. In short, {{{ippToPsps}}} creates FITS files from IPP data, then publishes them to a datastore in the form of ''batches''. On the PSPS side, the DXLayer polls the datastore, collects batches when they become available, then converts the contents to {{{csv}}} files before sending them on to SQL Server loader software, which ''merges'' them into the PSPS database. Ultimately there will be feedback from PSPS regarding errors in the received data, to which {{{ippToPsps}}} will need to respond.

It is intended that the binary tables in the FITS files generated by {{{ippToPsps}}} match the PSPS database schemas perfectly, the consequence being that any alterations to the PSPS database schema will only affect {{{ippToPsps}}} code, and not the DXLayer. A certain amount of data validation will be performed by {{{ippToPsps}}} before publication, more validation occurring at the loading and merge stages on the PSPS side.

The outputs of {{{ippToPsps}}} are referred to as 'batches', and are detailed below.

||'''Batch name''' || '''PSPS name''' || '''Description''' || '''IPP Source''' ||
|| Initialisation || IN || Metadata for the other batches eg filter ID, survey ID etc || generated from XML config ||
|| Detection || P2 || Single exposure detections || generated from one {{{smf}}} file per exposure plus associated DVO database ||
|| Difference || ? || difference image detections|| generated from one {{{cmf}}} file per skycell per exposure ||
|| Stack || ST || stack image detections || generated from... ||

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= Configuration =

Due to the potential for changes in both input and output for {{{ippToPsps}}}, the code is heavily configurable. Configuration files are in an XML format as this affords the most flexibility (human and machine readable, expandable, self-describing etc). {{{ippToPsps}}} is pointed to a config directory, under which subdirectories for each batch type hold the various XML config files.

== Table shapes ==

All FITS tables mirror PSPS database tables. Since the PSPS schema will probably remain in a state of flux for some time, rather than hard-coding table descriptions, instead {{{ippToPsps}}} reads table shapes from an XML config. This config can be regenerated from the master PSPS schema using a Perl script ({{{pspsSchema2xml.pl}}}) in the scripts directory. The same script also generates C header files for each batch-type. These headers contains enums for each PSPS table and are used by the code at runtime. This helps minimise code changes.

== Initialisation data ==

The table shapes of the initialisation batch are handled as above. The actual initialisation data (lists of filters etc), which is liable to change, is held in a config and used by {{{ippToPsps}}} to populate the tables in the FITS file. This data is also used when generating other batch types, detections for example, as look-up tables for setting survey ID etc.

== IPP to PSPS mappings ==

Most data to be loaded into the FITS tables comes from IPP {{{smf}}} or {{{cmf}}} files. For many columns, there is a direct mapping between these files and the PSPS database column. These mappings are detailed in a config.

= Architecture =

== ippToPsps ==

{{{ippToPsps}}} is a C program within the IPP build. When given the correct arguments it will generate a single FITS for the specified product (above). The program is run from a Perl script, which itself generates a list of exposure IDs based on arguments provided by the user (label etc). An instance of {{{ippToPsps}}} is run per exposure ID. Upon completion, the calling script bundles the resultant FITS files up as a ''batch'', then publishes it to the datastore, ready for collection by the DXLayer.

== DXLayer ==

The DXLayer polls the datastore waiting for new batches. Upon receipt of a new batch, the FITS files are converted to a csv format, suitable for ingest by the ODM.

== ODM Loader ==

Performs validation on incoming data based on metadata previously loaded as an initialisation batch (see above). If validation is successful, new batches are merged into the PSPS database. One basic requirement of the ODM is that all detections in a detection batch have unique object IDS. Object IDs are assigned by the IPP DVO to each detection on a chip. The number is formulated from the Ra and Dec of the detection.

= Notes about the different batch types =

== Detections ==

The input for the detection batch is one IPP camera-stage {{{smf}}} file for a given exposure, as well as an associated DVO database from which to retrieve object, and other, IDs. One FITS file is generated for each exposure. The extensions are:

1 '''{{{Primary}}}''' extension[[BR]]
1 '''{{{FrameMeta}}}''' extension[[BR]]
1 '''{{{ImageMeta}}}''' extension per chip[[BR]]
1 '''{{{Detection}}}''' extension per chip[[BR]]
1 '''{{{SkinnyObject}}}''' extension per chip[[BR]]
1 '''{{{ObjectCalColor}}}''' extension per chip[[BR]]

So, 242 extensions in all, including the obligatory primary header. The 'object ID' is featured in the last three tables, and must remain unique across the exposure (it is generated within DVO). In the merged PSPS database, the primary key on the detections table is both the object ID and detection ID, meaning the the same object can appear in multiple, overlapping exposures as they will have different detection IDs.

== Diffs ==

The input for difference batches is a set of {{{cmf}}} files, one for each skycell covered by a particular exposure. A FITS output file is generated with the following extensions:


= Unresolved fields =

Below are tables detailing which fields in the PSPS FITS files are still not populated by {{{ippToPsps}}}.

== Unresolved fields for camera stage detections ==







|| '''PSPS field''' || '''PSPS type''' || '''PSPS Description''' || '''Comments''' ||
||'''{{{FrameMeta}}}'''||||||||
||cameraID||SHORT||camera identifier|| 1? ||
||cameraConfigID|| SHORT ||camera configuration identifier|| ||
||analysisVer||STRING||IPP software analysis release|| need from smf? ||
||p1Recp||STRING||IPP phase 1 MD5 Checksum|| need from smf? ||
||p2Recip||STRING||IPP phase 2 MD5 Checksum|| need from smf? ||
||p3Recip||STRING||IPP phase 3 MD5 Checksum|| need from smf?||
||numPhotoRef||LONG||number of photometric reference sources|| ||
||calibModNum||SHORT||calibration modification number|| for future ||
||dataRelease||BYTE||Data release|| for future ||
||'''{{{ImageMeta}}}'''||||||||
||photoCalID||LONG||photometry reduction code identifier|| will use IPP dvo.photcodes in PSPS init batch||
||bias||FLOAT||detector bias level (unit = ADU)|| need from smf?||
||biasScat||FLOAT||scatter in bias level (unit = ADU)|| need from smf? ||
||numPhotoRef||LONG||number of photometric reference sources|| ||
||psfModelID||LONG||PSF model identifier|| need from smf? ||
||momentTheta||FLOAT||model PSF parameters at chip center (unit = deg)|| have major/minor, but angle?||
||detectorID||SHORT|| identifier for actual CCD chip|| ||
||qaFlags||LONG||Q/A flags for this OTA|| need from DVO? ||
||calibModNum||SHORT||calibration modification number||for future ||
||dataRelease||BYTE||Data release|| for future||
||'''{{{Detection}}}'''||||||||
||psfLikelihood||FLOAT||PSF likelihood|| need in smf||
||momentWidMajor||FLOAT|| PSF width in major axis from moments (unit = arcsec)|| MOMENT_XX/XY/YY in psf table||
||momentWidMinor||FLOAT||PSF width in minot axis from moments (unit = arcsec)|| MOMENT_XX/XY/YY in psf table ||
||momentTheta||FLOAT||PSF orientation angle from moments (unit = deg)|| MOMENT_XX/XY/YY in psf table ||
||crLikelihood||FLOAT||Likelihood the source is a cosmic ray|| need from smf? ||
||infoFlag||LONG||flag indicating provenance information|| ||
||historyModeNum||SHORT||modification number in the O-D association history||for future||
||dataRelease||BYTE||Data release when this detection was originally taken. Recalibrations do not affect this value.||for future||
||'''{{{SkinnyObject}}}'''||||||||
||projectionCellID|| LONG||projection cell identifier at discovery time|| ??? ||
||'''{{{ObjectCalColor}}}'''||||||||
||calColor||FLOAT|| color adopted for magnitude calculation (unit = mag)|| ||
||calColorErr||FLOAT|| error in calibrating color (unit = mag)|| ||



= Links =

[http://datastore.ipp.ifa.hawaii.edu/PSPS_test Datastore test area for PSPS]