Principle 7: WIS 2.0 will require all services that provide real-time distribution of messages to cache/store the messages for a minimum of 24-hours, and allow users to request cached messages for download

Owned by Xiaoxia Chen
Last updated: Jun 18, 2021
2 min read

WIS 2.0 will require all services that provide real-time distribution of messages to cache/store the messages for a minimum of 24-hours, and allow users to request cached messages for download

BENEFIT:  

  • Software systems that consume real-time data or notifications can recover from failure by requesting the delivery of messages that were missed while the system was offline.

Note that:

  1. From a WIS 2.0 perspective, open standard message protocols using the publish-subscribe pattern are considered to be Web services.

  2. Digital resources may be made available through multiple Web services. For example, a NC may publish SYNOPTIC reports via both downloads (e.g. a user queries the service to access data - "pull") and real-time delivery (e.g. a user subscribes to the service and data is sent when available - "push").

  3. Many Message Switching Systems (MSS) already use the channels concept to organize the distribution of data. MSS could be amended to support these new data exchange methods, thereby minimising disruption to the core business of NMHS (i.e. internal, national and international data distribution).

  4. GISCs already offer a subscription service for globally exchanged data, although none use modern messaging protocols to achieve this.

  5. As specified in the Manual on WIS (WMO-No. 1060) Part III. Functions of WIS: §3.5.5 Maintain a 24-hour cache - GISCs retain the responsibility to operate a 24-hour cache of data within their Area of Responsibility.

As specified in the Manual on WIS (WMO-No. 1060) Part I. Organization and Responsibilities, §1.7.3 - the WMO Integrated Global Data Dissemination Service (IGDDS) shall remain an important component of WIS - providing data distribution where there is no Internet connectivity using DVB-S broadcast.

During its lifetime, the GTS - a core component of WIS - has seen continual evolution; notably the establishment of managed regional networks or 'Area Meteorological Data Communication Networks' (AMDCN) using high-performance managed networks and the Internet. With such networks, all nodes on the network are visible to each other: there is no longer any need to manually route data through an intermediate chain of nodes to reach an eventual destination. Instead, the routeing of data is delegated to the underlying network infrastructure that is able to avoid the use of network segments suffering from poor performance and determine the optimal (i.e. quickest) path from the origin to destination.

The 'store and forward' data dissemination pattern, routeing data through an intermediate chain of nodes, remains central to GTS operations. Each node on the GTS operates a 'message switch' to control data flow based on the static configuration of 'routeing tables' and the unique identifier ('header') of each data package ('bulletin'). Routeing tables and bulletin headers are rendered obsolete in modern telecommunications networks.

Note that many NMHS already meet bi-lateral data sharing arrangements using direct file transfer; avoiding the need for a routeing table entry and effectively bypassing the GTS altogether (albeit often using the same underpinning telecommunications network infrastructure).