3 Use Cases, Scenario, and Example
- Contents
3.1 Scope of this Chapter
In order to present a common theme throughout this User Guide a common set of use cases, a common scenario, and a common set of examples are used. This chapter specifies the use cases, scenario, and the example SDMX structural metadata used.
3.2 Use Cases
SDMX supports many use cases.
Use Case System Processing
Activity
Structural Metadata Requirements Data Reporting Extract data from the source (database, file, spreadsheet) Access to DSD. Write an SDMX-ML or SDMX-EDI data set Access to DSD and possibly code transformations and aggregations. Validate the data set Access to the DSD or an XML schema derived from it. Load data into a database Access to DSD and possibly code transformations. Report reference metadata Extract metadata from a database Access to MSD. Write metadata set Access to MSD. Validate metadata set Access to MSD or schema derived from it. Load reference metadata into a database (often called a metadata repository) Read SDMX-ML metadata. Access to MSD and possibly code transformations. Write metadata to database Access to MSD. Report data by means of the “pull” method Access to DSD Place the file at a URL location Publish the existence of the dataset by means of an SDMX Registration Provision Agreement in an SDMX Registry. Database Administration (automatic generation of database tables) Create database tables Access to DSD Load database Access to DSD Enable database to be compatible with SDMX Web
Services
Accept and process and SDMX structure query Access to SDMX structural metadata such as DSD, MSD, Dataflow, Metadata flow, Data Provider, Provision Agreement, Constraint, Category Scheme. Accept and process an SDMX data query Access to DSD. Write SDMX data set Access to DSD. Data Discovery Locate data source Category Scheme and links to Dataflow, Provision Agreement and data Registration Data and Metadata Query and Visualisation Query an SDMX structural repository. Access to SDMX structural metadata. Create an SDMX query from the user selections Access to DSD. Access a metadata repository to extract referential metadata pertaining to the data. Access to code lists and concepts. Transform the SDMX data and referential metadata into tables, graphs, charts etc Access to DSD and metadata code lists and concepts. 3.3 Scenario
3.3.1 Web Dissemination Use Case
The use of web dissemination is the prime use case for this User Guide and the chapters in this guide follow this process flow. However, the topic of each chapter is relevant to more than this single use case of SDMX. For instance, a Data Structure Definition is relevant to all use cases concerning data, and an SDMX Registry is relevant to virtually all use cases. The reason for choosing web dissemination of data and related metadata is twofold:
- this single use case uses many of the SDMX constructs
- it is an increasingly popular use of SDMX as it enables organizations to build a self-updating dissemination system
Figure 1: Process flow of an SDMX Web Data Dissemination System
Process Description 1 Retrieve the DSD from a structural metadata source (e.g. an SDMX Registry), and create database tables. 2 Read an SDMX data set file and load the data into the database 3 Data discovery system continually synchronises its metadata with the structural metadata source. A user makes a data selection from choices built from the information held in an SDMX Registry (structural metadata such as category scheme, dataflow, DSD, data provider, provision agreements and data registration) 4 These choices are logical choices, built from the dimension selections. 5 The logical choice is formatted as an SDMX data query. This is passed to the Data Base which responds with an SDMX data set. 6 Reference metadata relevant to the data returned is retrieved from a metadata repository. 7 The data and metadata are passed to a visualization tool to display the data in tables, charts, graphs, maps etc. Often a download is offered in various formats. The download options often include also the DSD or MSD. 3.3.2 Structural Metadata
The following structural metadata and provisioning metadata is used in the scenario.
Figure 2: Structural and Provisioning Metadata Used in the Scenario
The content of these metadata is described in the chapters that follow.