This sections describes the interactions between the GSA subsystems. In addition to the interac- tions listed here, the GSA console will interact with most of the subsystem, collecting status information for display, and forwarding commands to appropriate subsystems.
2.1 User Interface to Catalogue
The User Interface will submit queries to the catalogue system. Query results will be returned to the User Interface for display.
The User Interface will send requests for preview data. The result of the request will be a data stream containing a FITS file to be displayed to the user.
2.2 User Interface to Data Retrieval Subsystem
The User Interface sends a list of data supersets with indication of types of data to retrieve, an optional list of data processing to be done on data supersets, and the delivery media type. The request may also include authentication information for retrieving proprietary data.
The User Interface monitors progress of data requests submitted by a user, as reported in the Data Retrieval subsystem database tables.
2.3 User Interface to Data Processing Subsystem
The User Interface uses the Data Processing subsystem, and in particular the data processing cat- alogues to get information about data supersets. This information includes:
• The list of data processing recipe instances available for data supersets.
• Detailed information about the recipe instances.
• The list of calibration files appropriate for a dataset.
• The member datasets for associated data supersets.
2.4 User Interface to ADS
The User Interface subsystem will use NASA’s ADS system to get detailed information about publications.
2.5 User Interface to Gemini Observing Tool
The GSA user interfaces will use the Gemini Observing tool to display observing programs to GSA users. This should also allow observing programs from the archive to be modified and re- introduced into the observing process.
2.6 User Interface to External Catalogues
The user interface will allow links to external catalogue web interfaces from the object detail web page described in Chapter 3. This will allow linking object information extracted from external catalogues back to the source of the information.
Subsystem Interactions
2.7 Data Ingest Subsystem to Catalogue Subsystem
The Data Ingest subsystem will add datasets to the database tables in the catalogue subsystem as new datasets are detected, and will update the tables in the Catalogue subsystem when the meta- data for existing datasets is modified.
2.8 Data Ingest Subsystem to Bulk Data Storage Subsystem
The Data Ingest subsystem will use the Bulk Data Storage subsystem to keep track of the loca- tions of files on archive media. This will be used when cross-checking the datasets in the cata- logue against the datasets available on archive media.
The Data Ingest subsystem will also be able to extract meta-data from the files stored in the Bulk Data Storage subsystem, although this is intended as a backup to the primary source of meta- data.
2.9 Data Ingest Subsystem to Data Processing Subsystem
The Data Ingest subsystem will queue Data Processing Discovery Agents (see Chapter 5, section 4.3 on page 89) for each new or modified dataset.
2.10 Data Ingest Subsystem to Meta-Data Store
The Data Ingest subsystem will examine the meta-data stores described in [3] to determine if any datasets have been added or modified.
2.11 Data Retrieval Subsystem to Data Processing Subsystem
The Data Retrieval subsystem will use the Data Processing subsystem for the following tasks:
• To do any data processing necessary to for a user data request.
• As a source of information to identify the appropriate calibration data supersets associated with data supersets in a user data request.
• To do the packaging associated with processing a request.
• To get release dates for data processing needed for a user data request.
2.12 Data Retrieval Subsystem to Media Creation Subsystem
The Data Retrieval subsystem uses the Media Creation subsystem to create media to be delivered to users.
2.13 Data Retrieval Subsystem to Catalogue Subsystem
The Data Retrieval subsystem uses the Catalogue subsystem to get release dates associated with data supersets.
2.14 Data Processing Subsystem to Catalogue Subsystem
Recipe instances executed by the Data Processing subsystem will insert various types of data into the catalogues. These types of data will include:
User interactions
• Data superset descriptors derived from the data.
• Source attributes derived from the data.
• Object attributes derived from the data.
2.15 Data Processing Subsystem to Media Creation Subsystem
The Data Processing subsystem will use the Media Creation subsystem to write data to remova- ble media for user requests, and/or to become a part of the archive data store.
2.16 Data Processing Subsystem to Bulk Data Storage Subsystem
The Data Processing subsystem will retrieve data from the Bulk Data Storage subsystem when it is needed as input to recipe instances.
2.17 Data Processing Subsystem to External Catalogues
The recipes running in the Data Processing subsystem will access external catalogues to extract information about objects in the “field of view” of Gemini observations. This information will be inserted into the Gemini object catalogue tables.
2.18 Bulk Data Storage Subsystem to Archive Media
The Bulk Data storage subsystem will read archive media received from Gemini, and copy the data to on-line media. The Bulk Data storage subsystem will also be able to access archive media in a jukebox as an alternative source of data in the event of a failure of an on-line storage system.
2.19 Bulk Data Storage Subsystem to Media Creation Subsystem
The Bulk Data Storage Subsystem will use the Media Creation Subsystem to create new archive media when it becomes necessary to migrate to new media types.