If you are an architect or developer working on service-oriented architecture (SOA) projects, you probably are not doing representational state transfer (REST) now, but within the next five years you probably will be.
That is how Burton Group Inc. analysts answered their own rhetorical question – REST: Is it the next big thing? – with a resounding yes at a Web conference on Tuesday. Repeating the mantra "The Web is REST. REST is the Web," Anne Thomas Manes, vice president and research director at Burton, said the only thing new about REST is that it is starting to catch on with SOA tool vendors and the open source community as well as architects and developers.
"REST is not new because REST is in fact the Web," she said. "The Web has been around for 15 years, but very few people have used it for service-oriented systems. Mostly REST is being used for visual applications, browser-based applications."
That is about to change. Looking to the future, Manes listed time frames Burton predicts for REST adoption now and in the next three, five and 10 years.
"Today, it is only innovators that are really working with REST," she said. "In three years, we should see the early adopters start to play with REST. It will probably be five years before it is adopted by the early majority. We anticipate that the late majority will probably not pick up REST for at least another 10 years."
What will drive REST adoption eventually is that it brings structure in the form of "constraints" to the sometimes chaotic world of Web services, which includes those pesky rogue services, according to Burton. This will provide a level of maturity for SOA development.
Peter Lacey, senior consultant at Burton, played devil's advocate on the Web conference, arguing the current state of Web services standards are inadequate and hamper SOA development, which needs the constraints REST development will bring. Manes did not agree that the state of Web services standards is hopeless, but she did advocate the transition to REST for SOA.
So what does this mean to IT departments in general, and enterprise architects and developers in particular? Manes said where they end up on the adoption curve depends on the skills of the architects and developers and their willingness to think outside the box of object-oriented programming.
She explained that the basic concept of REST, which starts with sending out GET commands sent via HTTP to URIs to retrieve data is simple enough. But she noted that even long-time REST advocates admit having trouble thinking of applications in terms of REST.
Borrowing a verb from Robert A. Heinlein's fictional Martian language in the 1961 novel "Stranger in a Strange Land," she said, "The basic concepts are easy, but truly groking REST takes time."
To illustrate the difference between an object-oriented approach and REST, she used the example of writing a program to turn a building's lights on and off, keeping in mind that in REST the power is in sending a command to a URI.
"A REST application to turn on and off the lights in your building will require you to design a URI for every light bulb and then you send it on/off messages," she explained. "It's not like I have a single service that manages all my light bulbs. It's a very different approach to designing a system. And it's going to be really hard for developers to get their hands around it."
Frameworks and tools for designing and building such REST applications are coming from major vendors, especially IBM and Microsoft, which are making major investments in the technology, she said. It is also coming from the open source community. The new version 2.0 of Ruby on Rails "will make it easier to do REST Web services," Manes said. A major vendor commitment was confirmed this past week by Jerry Cuomo, IBM Fellow and WebSphere CTO, who said in an interview at IBM's Impact 2007 conference in Orlando, that Big Blue also sees REST as the next big thing.
However, the problem for early adopters is that most of the tools developers will use for future REST development are still on the drawing boards, and current tooling is not ready for REST, Manes said. "Web services toolkits that say they do REST don't always [do it as advertised]," she said. "They do POX (plain old XML)."
But architects and developers will not have long to wait before REST is "baked into frameworks," she said. "You're going to see some very interesting frameworks come down the line in the not too distant future," she predicted.
In the next three years, an IT organization's willingness to be patient with early versions of REST tools and to make the mind-leap from object-oriented programming will determine where they land on the adoption curve, Manes said.
"The first thing you have to figure out is whether or not you're ready for REST," she told her audience. "What's your developer skill set? Are they going to be comfortable working with XML? Are they going to be comfortable working with raw HTTP? Are they comfortable working with open source projects, experimental frameworks or incubation projects? Are they open to letting go of their object-oriented mindset? Are they willing to relinquish the productivity frameworks that are inherent in the current vendor tooling and start working in a more raw framework environment?"
Any architect or IT manager answering yes to all of the above is a REST innovator in Manes book.
"If you're ready for REST I suggest you jump on board right away and get ahead of the curve," she said. "You'll have to train your developers in REST principles. You'll probably want to adopt one of the new frameworks or help build one yourself to help your developers implement RESTful applications. You definitely need to provide guidance to your people. What you want to do is work to the point where REST becomes the default for all your distributed applications."
Those who are not ready to take the leap into REST need not be too concerned, she said, stressing that the advent of REST as the programming model for SOA is a matter of "when, not if.".
"If you're not ready for REST, if your organization is not ready to jump into the innovator stage that's okay," she reassured her audience. "You're not going to get hurt. It's perfectly reasonable to wait two to three years for the frameworks to mature to the point where they are actually going to help you with this process. For the time being, you probably should continue to use SOAP and WS-* to build your distributed services."
The frameworks and tools are coming she reiterated and the REST adoption curve is rising.