The OGDI (Open Government Data Initiative) DataLab platform leverages by defaut the Microsoft Azure Platform, an open cloud-based runtime and hosting environment helping developers to quickly and easily create, deploy, manage and run applications and Web services across the Internet. The Azure platform allows developers to focus on their core business: applications and Web services. Developers uses their own existing skills (NET, Ruby, Python, Java, PHP, etc.) and their current tools and IDEs (Visual Studio, Eclipse, etc.) to develop these applications and Web services and deploy them to the cloud. For more information, please go to the homepage of the Microsoft Azure Platform.
OGDI DataLab exposes data through REST web services. The basic format of an OGDI DataLab service call is
Also note that if a property has a null value for a particular entity in the data set, it will be omitted entirely from the result set returned by OGDI DataLab. Your (modern) application design should take this into account and handle potentially missing properties.
By default, OGDI DataLab returns data in the Open Data Protocol (OData) format. This format extends the broadly adopted Atom Publishing Protocol and can be easily consumed by a variety of platforms, including Microsoft .NET, Java, Ruby, PHP, and Python. Refer to the code samples on the Data Browser page for examples.
OGDI DataLab can also return data in the RDF (Resource Description Framework) format. RDF is a graph model for describing formally web resources and their associated metadata. Developed by W3C, RDF is a base language for semantic Web. To return data in RDF format, simply append the format=rdf parameter to your query:
Many of the data sets in OGDI DataLab also include geospatial data, which is returned in the KML (Keyhole Markup Language)format. This format is compatible with popular desktop and Web-based mapping technologies including Google Earth, Google Maps, ou encore Yahoo! Maps. To return geospatial data in KML format, append the format=kml parameter to your query. For example, to retrieve geospatial points in KML format for crime incidents in DC that occurred during the police department's evening shift:
Note that if the data set that you are using does not include any geospatial data, a KML query to OGDI DataLab will return an empty result set.
OGDI DataLab and the underlying Azure Table Storage service support paging through large sets of query results. The documentation for Query Timeout and Pagination in the Azure Table Storage service provides a complete description of how OGDI DataLab and the underlying Azure platform support paging. You can also refer to the "C#/ASP.NET Paging" sample on the OGDI DataLab’s Data Browser page here, which demonstrates how to perform paged queries using the WCF Data Services client library.
Developers using Microsoft Visual Studio 2010 (and above) can use WCF Data Services to access data from OGDI DataLab through easy-to-use .NET classes. Within Visual Studio, this is accomplished by using the Add Service Reference feature (see .NET samples on the OGDI DataLab’s Data Browser page here). To make accessing OGDI DataLab data easier from their language of choice, developers can refer to the various libraries listed on the OData web sites. Java developers can use for example ODataJClient. Conversely, PHP developers can take advantage of the OData SDK for PHP.