A new production process based on a loosely coupled architecture:
Peter J. Trevelyan, The U.K. Met office, Exeter, United Kingdom; and A. Radford, G. Mallin, J. Tandy, and B. Wright
The Met Office relies heavily on visualisation and production systems, comprised of a number of applications that form the production chain. For the sake of efficiency the systems are closely coupled and often optimised to create a specific type of product. As a consequence the production chain is inflexible i.e. changes tend to be difficult and costly to make. For example:- changes in data formats/feeds have to be propagated across all applications and significant changes to the look and feel of a product e.g. adding a high resolution map background are costly as it will often mean making programmatic changes to applications.
A number of new technologies enable software to be divided up into “Services” that can exchange information and interoperate. These services can be configured or chained flexibly i.e. production paths can share data and functions, by using standard interfaces. The key to the future is in identifying these “Services”, i.e. deciding what applications can be re-used and “wrapped” as a “Service” and identifying new applications that are needed to fill the gaps. The key objective is to create a set of modules that are loosely coupled and flexibly orchestrated, thereby reducing duplication (and therefore cost) by only having one service per business function.
The new production strategy being developed will be based on the “Service Orientated Architecture” (S.O.A) pattern providing a sound architectural basis for defining a loosely coupled production chain based upon collaborating “Services”. In order for these “Services” to connect and communicate a new set of standards are needed and the OGC (Open Geospatial Consortium) have gone a long way in achieving this.
The OGC have developed a number of services that enable the transfer of features, maps, grids etc in a standard way across a network using Internet protocols. Thus a lot of the hard work in creating catalogues, interface definitions and the metadata description has already been done. The Geography Markup Language (GML) utilises XML to express geospatial data and serves as a modelling language for geographic systems as well as an open interchange format for geographic data. The key OGC web services are:-
• The Web Coverage Service (WCS), which supports electronic interchange of geospatial data as "coverages" – that is, digital geospatial information representing space-varying phenomena. A WCS provides access to potentially detailed and rich sets of geospatial information, in forms that are useful for client-side rendering, multi-valued coverages, and input into scientific models and other clients.
• The OGC Web Map Service (WMS), which allows a client to overlay map images for display served from multiple Web Map Services on the Internet.
• The OGC Web Feature Service (WFS), which allows a client to retrieve and update geospatial data encoded in Geography Markup Language (GML) from multiple Web Feature Services.
The final link will be the creation of a registry that stores information about customers, delivery channels, products and, importantly, a definition of the “Services” needed to create them.
This talk will report on the lessons learned from our prototype product generation system and in particular:- • How well the OGC interfaces worked; • The scalability of the S.O.A architecture; • The success or failure of coordination and orchestration by using an “Enterprise Service Bus”; • The ease in which a product could be changed without making changes to any application; • Future plans.
Extended Abstract (436K)
Session 9A, Internet Applications and Cyberinfrastructure
Thursday, 18 January 2007, 1:15 PM-3:00 PM, 216AB
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