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2 ORGANIZATION AND RESPONSIBILITIES

2.1 Organization of WIS

WMO Members implement and operate WIS, using existing centres with some additional or modified capabilities. Centres participating in WIS are categorized by three types:

• Global Information System Centres (GISCs),
• Data Collection or Production Centres (DCPCs),
• National Centres (NCs).

Refer to Manual on WIS 4 for a description of the functions of the three types of WIS Centres.

2.2 Compliance with Required WIS Functions

As required per WMO No. 49, Vol I, A.3 and Manual on WIS 2 and 4, WIS Centres shall maintain compliance with required WIS functions. The Guide to WIS contains additional guidance on practices, procedures and specifications for WIS functions, supplementing the standard and recommended practices, procedures and specifications for WIS functions set out in the Manual on WIS (WMO No. 1060).

2.3 Interaction among WIS Centres

As required per Manual on WIS 2.3, GISCs shall connect to each other by the WIS Core Network. Data,products and metadata shall flow to a GISC from DCPCs and from NCs within its area of responsibility. An illustration of likely interaction among WIS Centres is provided in Figure 1 (next page). Note: Named centres are illustrative examples and do not comprise a complete list of likely WIS Centres.

2.4 Implementation of WIS

As required per Manual on WIS 2.4, WIS is implemented in two parallel parts: continued evolution of the WMO Global Telecommunication System (GTS), and extension of WMO services through Discovery, Access and Retrieval (DAR) facilities, as well as flexible timely delivery.

2.5 Discovery, Access and Retrieval Function

2.5.1 As required per WMO No. 49, Vol I, A.3, and Manual on WIS 2.5, WIS is based on metadata catalogues describing data and products available across WMO, plus metadata describing dissemination and access options. The Discovery, Access and Retrieval (DAR) function of WIS is the primary realization of the WIS comprehensive catalogue, maintained collaboratively by all WIS Centres.

2.5.2 A typical user of WIS DAR should find available data and products using a Web browser or other Internet tool. The searcher should be able to discover available data and products by browsing the catalogue or by searching the catalogue using discovery concepts such as subject keywords, geographic extent, or temporal range.

2.5.3 A typical user of WIS DAR should first receive a list of relevant items with associated metadata such as originator, data type, generation date, use constraints, and the like. Once desired data or products have been identified, a user may request immediate retrieval ("pull") or subscription for recurring delivery ("push") if locally available, or be referred to another centre holding the item. The WIS Centre having the item should then facilitate delivery through any of a broad range of online and offline transmission options. In the case of a subscription, the WIS Centre should maintain further information to support recurring delivery.

2.6 Robustness and Reliability of Components

As required per Manual on WIS 2.6, high robustness and reliability of WIS components are essential to the operation of WIS. Indicators of performance are evaluated in the designation procedure for WIS Centres, to include assurance that data content flowing via WIS network technologies fully satisfies requirements for security, authenticity, and reliability. Some specifications of service levels are identified within the Manual on WIS and this Guide to WIS, but further specifications can be anticipated.

2.7 Collection and Dissemination Services

2.7.1 Refer to Manual on WIS 2.7 for standard and recommended practices, procedures and specifications on this topic.

2.7.2 With regard to satellite-based data and products, the WMO Integrated Global Data Dissemination Service (IGDDS) addresses: user requirements review; data concentration: inter-regional data exchange; data dissemination; data discovery; data access on request; data delivery to authorized users; and, data management, including interoperable catalogue, quality of service monitoring and user support.

2.7.3 In addition to satellite-based data and products, IGDDS should distribute a basic subset of the information intended for global exchange.

2.7.4 IGDDS calls for regional dissemination components linked in a global network for inter-regional data exchange. Each regional component should include a WIS DCPC and should ensure routine dissemination by various means including a satellite-based Digital Video Broadcast (DVB-S) service covering its region.