Geofabric – Australian Bureau of Meteorology

LISAsoft assisted the Bureau of Meteorology (the Bureau) to configure a range of standards based web services based on the Australian Hydrological Geospatial Fabric (Geofabric).

The Geofabric is a suite of products that describe important hydrological features such as rivers, water bodies, aquifers and monitoring points. By detailing the spatial relationships between these hydro-features and how they are connected, models can be developed to show how water is stored, transported and used through the landscape.

The project was broken down into the follow stages:

Analyse User Requirements

LISAsoft first analysed Geofabric use cases provided by the Bureau, and categorised how the use cases could be addressed by WFS Simple, WFS Complex, WMS or WPS web services.

Review Geofabric Information Model

LISAsoft reviewed and updated the Geofabric application schema and ported the six Geofabric  products from ESRI Geodatabase format to the Postgres open source database.

Geofabric Web Services

LISAsoft deployed and tested Geofabric features within GeoServer to provide WFS 1.1, WFS 1.0 and WMS services.

Performance

The rich information model provided by the Geofabric requires the use of Complex Features functionality. This Complex Schema functionality is still only recently implemented in the GeoServer WFS code, and LISAsoft identified and recommended areas for performance improvements. Note there is adifference between general mapping (requiring high performance maps), and data modelling (requiring data integrity). For this project, high performance general mapping was addressed by Geofabric’s WMS and WFS 1.0 interfaces, while data integrity was addressed by the WFS 1.1 Complex Schema interface.

WFS Clients

LISAsoft highlighted the immature support amongst WFS clients for Complex Schemas, which, in the short term, will hinder the usefulness of a Geofabric WFS 1.1 interface to stakeholders.  LISAsoft partially addressed this by additionally configuring GeoServer to publish Geofabric data via WFS 1.0 (with GML Simple Feature format), as well as via images in the WMS format. The GML simple feature format is more widely supported, but it loses some of the relationships between different attributes.

Processing Queries

LISAsoft provided recommendations on how to address more detailed analytical analysis, which included the use of Web Processing Services (WPS).

Deployment Options

LISAsoft provided the Bureau with a report covering options for deploying the Geofabric Services into a production environment. The report covered the application stack of software required, server specifications, configuration considerations and scaling options. Various deployments into both cloud and internal infrastructure were compared and recommendations provided.

The Geofabric project completed on time and budget and has validated the application schema approach taken by the Bureau. The User Analysis work and the outcomes of the implementation pilot provided valuable lessons and have been used by the Bureau and the greater community of industry partners interested in the Geofabric datasets. The Bureau is now moving towards making Geofabric web services publicly accessible.

Geofabric Technology Overview

Web Feature Service (WFS)

The OGC® Web Feature Service Interface Standard (WFS) defines web interface operations for querying and editing vector geographic features, such as roads or lake outlines

Web Feature Service 1.0 (Simple Features)

Version 1.0 of the WFS specification supports Simple Features. Simple features contain a list of properties that each have one piece of simple information such as a string or number. Conceptually, a Simple Feature can be thought of as a row in a spreadsheet, or a flat table. Typically, WFS simple features map directly from a database table to a “flat” XML representation, where every column of the table maps to an XML element that contains no further structure.

There are many GIS clients, both Open Source and Proprietary, which support the WFS 1.0 interface.

Web Feature Service 1.1 (Complex Features)

Version 1.1 of the WFS specification additionally supports Complex Features. Conceptually, Complex Features can be thought of as a representation of data from a relational database, which has multiple tables and where a field in one table references another table. Therefore, a Complex Feature can contain a multi-level hierarchy of features, such as a feature within another feature. In particular, it can describe the complex Geofabric data structures without losing information.

Complex Feature functionality is supported in the deployed web server, but is either limited or is not supported in many of the leading GIS clients.

Web Map Service (WMS)

The (OGC®) Web Map Service Interface Standard (WMS) provides a simple web interface for requesting map images and returning as map images (such as JPEG, PNG).

Web Processing Service (WPS)

A Web Processing Service (WPS) provides an OGC standards based interface for accessing algorithms from a web query. A WPS may offer calculations as simple as subtracting one set of spatially referenced numbers from another (e.g., determining the difference in influenza cases between two different seasons), or as complicated as a global climate change model.

A WPS was not included with the Geofabric project, but could be included to address future advanced Geofabric use cases.