The scope of distribution for data within WIS shall be expressed using the following controlled vocabulary:
“GlobalExchange”, “RegionalExchange” and “OriginatingCentre”.
Data marked with RegionalExchange only needs to be in the cache of those GISCs involved in the distribution of such data.
Data marked with “OriginatingCentre” may be cached at the decision of the GISC, but are only expected to be available from the orginating centre.
Data marked with “GlobalExchange” must be cached by all GISCs. (See GISC Core Cache)
Cache file format: agreed by TT-GISC-2015
GISC Cache types
(Comment by chair TT-GISC -TOR which the TT-GISC should have afresh)
1. The Manual on WIS defines the GISC cache as a holding of 24 hours
2. The purpose of the cache is two fold:
- To support Data Discovery and Access
- To support reruns of data to centres in a GISC area of responsibility should they go offline or miss data.
3. Although defined as a 24 hour holding, this is the minimum period of retention.
- A GISC may hold some data longer if the user requirement shows this is needed
- The GISC cache must support the performance criteria of WIS by having warnings available within two minutes of their publishing into WIS.
- The period of retention of a GISC cache beyond 24 hours is at the discretion of the GISC itself
4. Thus the GISC cache has two components.
- The primary is the Core GISC Cache (See next page).
- The secondary is the cache supporting regional or just those centres in its area of responsibility.
5. GISCs exchange files, but the default file format for holdings in the Cache is the Meteorological Bulletin
Note on Meteorological Bulletins
For meteorological bulletins, the format within 24h cache should allow the full “meteorological bulletin” to be stored. Information stored should be the complete bulletin as defined in the Manual on GTS Attachment II-15 para 5.2 on accumulating messages into files. It must include all text between the TTAAii of the abbreviated heading and end with “=” (equal) at the end of the text part as shown below.