Service oriented architecture for scientific analysis at W7-X. An example of a field line tracer

•We briefly overview available web-service protocols, and explain why SOAP standards are chosen.•We explain the basics of the SOAP technology and give both the usage and development patterns with corresponding examples.•We develop a new W7-X field line tracing service.•The service can calculate Poincaré maps, connection lengths, magnetic coordinates, heat fluxes, etc. with a realistic device geometry.•With the tracer service, we model the influence of 1/1 error field on the W7-X divertor heat loads.

Service oriented architecture based on web-services is a universal method of combining software components. SOAP web-services chosen for W7-X are characterized by strong standards and readily available tools. In this paper the SOAP technology is explained and is illustrated with a new service for field line tracing.The field line tracing package consists of a C++ library and a web-service interface. It features a flexible structure and can handle a realistic machine geometry. The following problems can be solved: getting a field line; making Poincaré maps; calculating flux surface characteristics; calculating heat fluxes to the wall; constructing magnetic coordinates, etc. The service is applied to estimate W7-X divertor loads with an 1/1 error field.