Guide: When and how to use REST
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In recent years, there has been a federal push for a national health IT infrastructure, but a nationwide standard for health information exchange has remained elusive, hindering efforts. SearchSOA.com recently spoke with Gerald Beuchelt, project software systems engineer at The MITRE Corporation, about how RESTful services might play a role in creating a nationally-recognized health information exchange, charting the way for a REST architecture in health IT.
In particular, Beuchelt gave insight into hData, a REST-based standards framework for health information exchange (HIE) that has already gone through its first round of standardization. The hData project began back in 2009 when MITRE, a federally funded research and development nonprofit, conceived of the idea in response to government needs. According to Beuchelt, HIE standards at the time were complex, and the health IT industry recognized it had a problem. From the beginning, hData reflected a departure from the way HIE had been approached in the past, Beuchelt said, noting:
We got to the problem and consciously said, 'Let's start with a clean slate, and [think about] how we would really rebuild all this, having learned a lot of things from our adventures with SOAP and SOA.' One of the things we came up with is that we probably want to use a RESTful approach instead of a fairly XML-centric, SOAP approach.
Beuchelt said hData began as a clean slate, taking into account lessons learned from 'adventures with SOAP and SOA.'
According to Beuchelt, health IT has gone through a number of changes with regards to the exchange paradigm over the past few decades:
In the '80s, it was very much message oriented. But such message architecture is not necessarily the most effective for interoperability, and it also does not necessarily address all use cases that you would like to address. [Then,] one of the things that came up in the late '90s and early 2000s was the creation of the CDA -- clinical document architecture. It is effectively an XML framework for writing complex medical notes. … But one of the issues that the industry was facing with the CDA specification was that it was a very, very complex XML. … A service exchange paradigm allows you to create a much more agile way of passing things around.
The potential of service-oriented architecture (SOA) as a paradigm for exchanging health information wasn't recognized until the mid-2000s, he said. Since then, groups like Health Layer 7 (HL7) and the Object Management Group have been working closely together to create services that deal with specific health IT needs. For example, Beuchelt is co-chair of the SOA Working Group, an HL7 group that works to enable HL7 standards to be fully usable within systems that are designed using SOA principles.
The hData work follows recent trends supporting REST. Beuchelt explained:
We saw that a lot of RESTful developers were very successful in terms of creating effective exchange solutions -- not necessarily based on formal languages like WSDL or WADL [Web Application Description Language], but by using "code by example" and good documentation of the exchange semantics and syntax that are required for a RESTful exchange.
REST is sometimes something of a Wild West, at least compared to more highly standardized approaches like WSDL. But Beuchelt and his colleagues are intent on bringing a well-described hData REST methodology. "That is the reason why we actually took hData and went forward to some standards organizations to effectively write a profile of how we want to use a RESTful architecture for health-IT exchange," he said.