Introduction
The web service is intended to enable Member States to expose their dissemination database, using Web Service technologies, in SDMX-ML format. In order to facilitate the adoption and integration of this web service, it was developed in both Java and .NET platforms, this article referring to the latter. In this way, an National Statistical Institute (NSI) dissemination environment is able to support modern data transmission schemes that facilitate access by data consumers.
The ultimate goal of this web service is to enable NSIs to adopt the SDMX Reference Infrastructure, thus increasing the interoperability and visibility of their dissemination environment and thereby reducing the burden for distributing data to potential Data Consumers.
Components
The following components comprise the Web Service part of the NSI:
- Web Service Provider
- Data Retriever
- Structure Retriever
- NSI Auth Module
- SdmxSource
- Estat SdmxSource Extension
This web service is responsible for exposing data that is stored in the dissemination database, according to the metadata stored in the Mapping Store database (see Mapping Assistant tool). Thus, from the NSI Web Service perspective, these two databases are considered as actors in its use. These metadata are also required by the Data Retriever, which is responsible for querying the Dissemination database according to an SDMX-ML Query targeted to data of the aforementioned Data Structure Definition (DSD. The Structure Retriever module is responsible for retrieving structural metadata from the Mapping Store database. The Structure Retriever implements the SdmxSource interfaces for structure retrieval. By using the plug-in mechanism different implementations of this structure retrieval interfaces may be used. It uses the NSI Auth module for retrieving the dataflow authorization rules per user.
Moreover, the components of the Web Service make use of the SdmxSource component, (aka SDMX Common API) which provides an API and an implementation for representing SDMX information based in the SDMX Information Model as well as for parsing and writing SDMX-ML messages. In addition, there is also the Eurostat SdmxSource Extension module which adds further features required by the SDMX Reference Infrastructure that are not included in the SdmxSource. For instance it includes parsing and writing of custom requests for available codes in a DDB.