Introducing OData: Data Access for the Web, Cloud, Devices, and More
[This article was contributed by the SQL Azure team.]
David Chappell recently completed a whitepaper on OData that I encourage you to take a look at. You can view it here, or download a PDF version. David does an outstanding job providing an overview of OData, the problems it solves, practical usage scenarios, and a look at the protocol itself. If you’re quitting work for the day, stop here and read David’s whitepaper. If you have a few more minutes to spare, then continue reading. :)
Many of our partners have started using OData in their commercial releases. Two notable recent ones are SAP, who are making it an integral part of their Netweaver offering to extend SAP data to devices and social applications. You can read more about it here.
EastBanc is also utilizing OData and SQL Azure to share real-time data from Washington metro area transit systems to share up to date schedules for trains and buses. A case study on that is here.
If you’re not already familiar with the Open Data Protocol (OData), it’s a Web protocol for querying and updating data that provides a way to unlock your data and free it from silos that exist in applications today. OData does this by applying and building upon Web technologies such as HTTP, Atom Publishing Protocol (AtomPub) and JSON to provide access to information from a variety of applications, services, and stores. The protocol emerged from experiences implementing AtomPub clients and servers in a variety of products over the past several years. OData is being used to expose and access information from a variety of sources including, but not limited to, relational databases, file systems, content management systems and traditional Web sites.
At this point you may be asking – why talk about OData on the SQL Azure blog? Because OData is an open protocol and what I like to call “the language of data on the web”. Let’s take an example of a web service that does a lookup of an employee. The tricky thing here is that this turns into multiple service calls, or methods with multiple input parameters to get results with different input and output criteria, like:
One Service Powering Multiple Experiences
In addition to powering mobile experiences, the openness of the OData protocol can power multiple user experiences. In the videos below we show how to utilize OData to access SQL Azure cloud data on both Android and Windows Phone 7 devices. OData is also natively supported in PowerPivot, making complex BI attainable today with SQL Azure cloud databases – again using the same OData service that can power an Android, iOS, Windows Phone, and web experience.
Things get even more interesting for BI when you consider Windows Azure DataMarket, our one-stop shop for accessing public domain and commercial data-sets – all consistently accessible via OData. Joining that data with your application’s data can create some interesting new insights. Is there a relationship between retail sales and weather? Hmm…DataMarket has weather data available from WeatherBug.