Microservices Expo Authors: Roger Strukhoff, Liz McMillan, Elizabeth White, Ruxit Blog, Derek Weeks

Related Topics: Microservices Expo, Containers Expo Blog

Microservices Expo: Article

REST-Based SOA: an Iconoclastic Approach

Architecture that actually works is more important than following a dogmatic approach

At ZapThink we’re proud to be iconoclasts. After all, building agile architectures requires critical appraisal—and frequent dismissal—of traditionally held beliefs. We know this role places us among the heretics who dare challenge established dogma.

In fact, the whole notion of agility has long suffered this battle between iconoclasm and dogmatism. As we discuss in our Licensed ZapThink Architect course, the Agile Manifesto embodies an iconoclastic approach to software development dogma – and yet, so many people have become dogmatic about the Agile Manifesto itself, entirely missing its point!

ZapThink once more jumped into this iconoclasm-masquerading-as-dogma fray with our recent ZapFlash, How I Became a REST “Convert.” We explained how you can implement SOA following REST principles, and how such an approach introduces important simplifications and efficiencies as compared to a Web Services-based approach.

Get out the torches and pitchforks! ZapThink is at it again! Not only are we flying in the face of established SOA dogma, we’re taking on REST dogma as well! Never mind that the original vision for the REST movement was inherently iconoclastic. In fact, it’s no wonder that RESTafarians use religious metaphors in their discussions (although Rastafarianism is a far cry indeed from the Catholic metaphors we’re leveraging in this ZapFlash).

To quote our beloved Agile Manifesto, we want to favor responding to change over following a plan—even if that plan is how SOA or even REST is “supposed to be done.” The goal is stuff that actually addresses the business problem, not some adherence to official dogma (another Agile principle, in case you didn’t notice). Therefore, it came as no surprise to us when an organization contacted us and let us know that they are taking the REST-based SOA approach we discussed in the ZapFlash, and that it actually works.

The Iconoclastic REST-based SOA of the US Coast Guard
We recently spoke with the US Coast Guard (USCG) about their SPEAR (Semper Paratus: Enterprise Architecture Realization) initiative. The SPEAR approach to SOA centers on document-centric, event-driven, loosely coupled, asynchronous, message-based Business Services. Now, there’s nothing particularly iconoclastic about event-driven SOA—after all, we debunked that notion back in 2004—but their story doesn’t end there. Another central characteristic of their SOA approach is their document-centricity. While it’s true that document style interfaces are the norm for Web Services, the USCG takes the notion to a new level.

In the Web Services world, when a WSDL file specifies a document style interface, then the constraints on the input and output messages fall into one or more schema definitions, instead of the SOAP message structure itself. As far as SOAP is concerned, the body of the SOAP message contains a payload consisting of whatever document you like. The advantage of the document style over the tightly coupled remote procedure call (RPC) style is it allows for flexible versioning of Services: many changes to a Service do not force a new contract version.

However, as anyone who has monkeyed with Web Services can attest, the operations of a Service still cause issues, even when it’s a document style interface. We can’t seem to get away from Web Services’ tightly coupled RPC heritage. And furthermore, XML schemas are strongly typed, which introduces a further undesirable level of tight coupling.

To resolve such issues, REST moves the operations out of any formal contract, instead relying upon the GET, POST, PUT and DELETE operations best known from HTTP. Even so, there’s no requirement in REST that resources are necessarily documents. True, URLs that point to documents are a common and familiar pattern, but URLs could as easily point to abstracted method calls as well.

SPEAR takes document-centricity to the next level. For SPEAR, the document is the interface. It has meaning both for human and machine consumption. It’s self-describing and removes the need for defining a specific, formal contract. Instead, the USCG provides a basic header/body document structure. The header contains elements like requester, type, ID, timestamps, and status (request, response, publication or error, for example). The body contains different parts depending upon the type of Service. Request/response Services, for example, include elements like request, response, publication, and exception. As a result, SPEAR’s Service contracts (if you even decide to call them that) consist of a simple document structure and core REST operations—nothing more.

Maintaining State the Service-Oriented Way
For example, take a straightforward request/response Service that executes a simple database query. The Service simply populates the response field in the request document and returns the entire document to the requester. As a result, the document still contains the timestamped request. The ESB can now publish the document or put it on a queue, and the document itself acts as its own cache.

This approach to state is a simple example of a new trend in REST-based state management: Hypermedia as the Engine of Application State (HATEOAS). With HATEOAS, documents and the hyperlinks they contain represent all the state information a distributed environment requires. Want to know the next step in a process? Simply follow the appropriate link.

In the case of SPEAR, the USCG has established an internal standard URI representation: domain://provider:context/resource. For example, service://uscg.mda.vesselCrew:test/sla. The domain represents a taxonomy of resource types, including system://, organization://, geography://, and service://. The provider component represents the address to the provider of the resource. The context (squeezed in where ports go in a URL), represents the business context like :test, :dev, :stage, etc.

The ESB then resolves URIs to the physical endpoint references, acting as a routing engine that delivers the Business Service abstraction. Any hyperlink to such a URI, therefore, points to a document that contains all the state information the system requires, and furthermore, the architecture offers late binding to Services as a key feature. There is no build time mapping to any particular resource. Instead of using strongly typed schemas, they rely upon dynamic, loose typing in the documents. Such an approach is decidedly not Web Services-friendly.

It’s also important to note that state maintenance in the Web Services world has always been problematic. There are basically three ways to main state information in interactions among inherently stateless Services: rely upon the Service consumer to maintain a correlation ID (either not broadly adopted or relies upon an underlying protocol like HTTP cookies); rely upon the underlying execution environment (vendor dependent); or place state information into the message. Unfortunately, Web Services offer no standard way of accomplishing the latter task, requiring SOA teams to customize their SOAP headers—which is usually a deal killer.

The SPEAR approach, however, includes state information in the message, because, of course, the message is the document. As a result, they are taking a fully Service-oriented approach to maintaining state. They are able to do so in spite of leveraging an ESB because they selected the Fiorano ESB, which has long maintained state in a fully message-centric manner, instead of spawning threads to keep track of state as in other vendors’ ESBs.

Asynchronicity as the General Case
For many years, Gartner believed that SOA interactions were inherently synchronous, request/response—casting SOA as little more than next-gen client/server—until TIBCO twisted their arm into admitting that yes, SOA could be event driven. Nevertheless, SOA has always allowed for asynchronous as well as synchronous Service exchange patterns. (The whole Gartner event-driven SOA kerfuffle led to the SOA 2.0 fiasco, lest we forget.) In fact, ZapThink pointed out the importance of asynchronous behavior as early as 2002.

In the SPEAR architecture, the listener acts as the handler, retaining messages at their last stop. The senders simply fire and forget. Messages are sent to the Fiorano bus, not the destination, allowing for dynamic routing of messages as well as publish/subscribe. In this way the ESB routes, filters, and enforces policy via the URIs themselves.

Publish/subscribe is a broadcast push exchange pattern: many consumers can subscribe to the same topic, and the ESB pushes messages to subscribers as appropriate. Even when a single consumer queries a resource, the ESB follows a push pattern, putting documents onto a queue for the consumer to pick up. As a result, SPEAR can support different consumer behaviors, depending upon the use case. If the consumer is accessing Services via unreliable network connections, or simply requires low message volumes and can tolerate some latency, then the consumer can simply poll the Service. In other cases, when latency is an issue or when there are higher message volumes, the ESB can perform a true push to the consumer via a JMS interface.

OK, hold on just one minute. JMS? I thought we were talking about REST, you know, over HTTP. How can JMS fit into this picture?

Yes, the USCG is being iconoclastic once again. The ESB is abstracting the endpoint, while at the same time providing a push-based messaging infrastructure. If the consumer wants the resource to push a real-time stream of large messages to it, then the URI should resolve to a JMS endpoint. If not, or if the consumer doesn’t support JMS (typically when it’s running over HTTP) then the resource will resolve to an HTTP endpoint.

The ZapThink Take
Is the USCG implementing “pure” SOA or “pure” REST? I’m not even going to dignify those questions with a response, because the whole notion of a “pure” architectural approach is inherently dogmatic. What the USCG has done is implement an architecture that actually works for them—that is, it delivers loosely coupled, abstracted Business Services with the flexibility and performance they require. And remember, actually working trumps following a pre-determined set of best practices every time—especially when those best practices don’t actually solve the problems at hand.

There are two important morals here. First, REST-based SOA is alive and well, and offers straightforward solutions to many of the knottier problems that Web Services-based SOA has suffered from. But even more importantly, the success the USCG has achieved shows that any architectural approach is nothing more than a loose collection of best practices. It’s up to the architect to know which best practices are best for solving their particular problems. Avoid a dogmatic approach, and select the right tool for the job, even if that brands you as an iconoclast.

More Stories By Jason Bloomberg

Jason Bloomberg is the leading expert on architecting agility for the enterprise. As president of Intellyx, Mr. Bloomberg brings his years of thought leadership in the areas of Cloud Computing, Enterprise Architecture, and Service-Oriented Architecture to a global clientele of business executives, architects, software vendors, and Cloud service providers looking to achieve technology-enabled business agility across their organizations and for their customers. His latest book, The Agile Architecture Revolution (John Wiley & Sons, 2013), sets the stage for Mr. Bloomberg’s groundbreaking Agile Architecture vision.

Mr. Bloomberg is perhaps best known for his twelve years at ZapThink, where he created and delivered the Licensed ZapThink Architect (LZA) SOA course and associated credential, certifying over 1,700 professionals worldwide. He is one of the original Managing Partners of ZapThink LLC, the leading SOA advisory and analysis firm, which was acquired by Dovel Technologies in 2011. He now runs the successor to the LZA program, the Bloomberg Agile Architecture Course, around the world.

Mr. Bloomberg is a frequent conference speaker and prolific writer. He has published over 500 articles, spoken at over 300 conferences, Webinars, and other events, and has been quoted in the press over 1,400 times as the leading expert on agile approaches to architecture in the enterprise.

Mr. Bloomberg’s previous book, Service Orient or Be Doomed! How Service Orientation Will Change Your Business (John Wiley & Sons, 2006, coauthored with Ron Schmelzer), is recognized as the leading business book on Service Orientation. He also co-authored the books XML and Web Services Unleashed (SAMS Publishing, 2002), and Web Page Scripting Techniques (Hayden Books, 1996).

Prior to ZapThink, Mr. Bloomberg built a diverse background in eBusiness technology management and industry analysis, including serving as a senior analyst in IDC’s eBusiness Advisory group, as well as holding eBusiness management positions at USWeb/CKS (later marchFIRST) and WaveBend Solutions (now Hitachi Consulting).

@MicroservicesExpo Stories
As we enter the final week before the 19th International Cloud Expo | @ThingsExpo in Santa Clara, CA, it's time for me to reflect on six big topics that will be important during the show. Hybrid Cloud This general-purpose term seems to provide a comfort zone for many enterprise IT managers. It sounds reassuring to be able to work with one of the major public-cloud providers like AWS or Microsoft Azure while still maintaining an on-site presence.
19th Cloud Expo, taking place November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud strategy. Meanwhile, 94% of enterpri...
Without lifecycle traceability and visibility across the tool chain, stakeholders from Planning-to-Ops have limited insight and answers to who, what, when, why and how across the DevOps lifecycle. This impacts the ability to deliver high quality software at the needed velocity to drive positive business outcomes. In his general session at @DevOpsSummit at 19th Cloud Expo, Eric Robertson, General Manager at CollabNet, will discuss how customers are able to achieve a level of transparency that e...
In his general session at 19th Cloud Expo, Manish Dixit, VP of Product and Engineering at Dice, will discuss how Dice leverages data insights and tools to help both tech professionals and recruiters better understand how skills relate to each other and which skills are in high demand using interactive visualizations and salary indicator tools to maximize earning potential. Manish Dixit is VP of Product and Engineering at Dice. As the leader of the Product, Engineering and Data Sciences team a...
As software becomes more and more complex, we, as software developers, have been splitting up our code into smaller and smaller components. This is also true for the environment in which we run our code: going from bare metal, to VMs to the modern-day Cloud Native world of containers, schedulers and microservices. While we have figured out how to run containerized applications in the cloud using schedulers, we've yet to come up with a good solution to bridge the gap between getting your conta...
SYS-CON Events announced today that 910Telecom will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Housed in the classic Denver Gas & Electric Building, 910 15th St., 910Telecom is a carrier-neutral telecom hotel located in the heart of Denver. Adjacent to CenturyLink, AT&T, and Denver Main, 910Telecom offers connectivity to all major carriers, Internet service providers, Internet backbones and ...
DevOps theory promotes a culture of continuous improvement built on collaboration, empowerment, systems thinking, and feedback loops. But how do you collaborate effectively across the traditional silos? How can you make decisions without system-wide visibility? How can you see the whole system when it is spread across teams and locations? How do you close feedback loops across teams and activities delivering complex multi-tier, cloud, container, serverless, and/or API-based services?
Today every business relies on software to drive the innovation necessary for a competitive edge in the Application Economy. This is why collaboration between development and operations, or DevOps, has become IT’s number one priority. Whether you are in Dev or Ops, understanding how to implement a DevOps strategy can deliver faster development cycles, improved software quality, reduced deployment times and overall better experiences for your customers.
DevOps is being widely accepted (if not fully adopted) as essential in enterprise IT. But as Enterprise DevOps gains maturity, expands scope, and increases velocity, the need for data-driven decisions across teams becomes more acute. DevOps teams in any modern business must wrangle the ‘digital exhaust’ from the delivery toolchain, "pervasive" and "cognitive" computing, APIs and services, mobile devices and applications, the Internet of Things, and now even blockchain. In this power panel at @...
This is a no-hype, pragmatic post about why I think you should consider architecting your next project the way SOA and/or microservices suggest. No matter if it’s a greenfield approach or if you’re in dire need of refactoring. Please note: considering still keeps open the option of not taking that approach. After reading this, you will have a better idea about whether building multiple small components instead of a single, large component makes sense for your project. This post assumes that you...
What do dependency resolution, situational awareness, and superheroes have in common? Meet Chris Corriere, a DevOps/Software Engineer at Autotrader, speaking on creative ways to maximize usage of all of the above. Mark Miller, Community Advocate and senior storyteller at Sonatype, caught up with Chris to learn more about what his team is up to.
@DevOpsSummit has been named the ‘Top DevOps Influencer' by iTrend. iTrend processes millions of conversations, tweets, interactions, news articles, press releases, blog posts - and extract meaning form them and analyzes mobile and desktop software platforms used to communicate, various metadata (such as geo location), and automation tools. In overall placement, @DevOpsSummit ranked as the number one ‘DevOps Influencer' followed by @CloudExpo at third, and @MicroservicesE at 24th.
JetBlue Airways uses virtual environments to reduce software development costs, centralize performance testing, and create a climate for continuous integration and real-time monitoring of mobile applications. The next BriefingsDirect Voice of the Customer performance engineering case study discussion examines how JetBlue Airways in New York uses virtual environments to reduce software development costs, centralize performance testing, and create a climate for continuous integration and real-tim...
At its core DevOps is all about collaboration. The lines of communication must be opened and it takes some effort to ensure that they stay that way. It’s easy to pay lip service to trends and talk about implementing new methodologies, but without action, real benefits cannot be realized. Success requires planning, advocates empowered to effect change, and, of course, the right tooling. To bring about a cultural shift it’s important to share challenges. In simple terms, ensuring that everyone k...
SYS-CON Events announced today that SoftNet Solutions will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. SoftNet Solutions specializes in Enterprise Solutions for Hadoop and Big Data. It offers customers the most open, robust, and value-conscious portfolio of solutions, services, and tools for the shortest route to success with Big Data. The unique differentiator is the ability to architect and ...
A completely new computing platform is on the horizon. They’re called Microservers by some, ARM Servers by others, and sometimes even ARM-based Servers. No matter what you call them, Microservers will have a huge impact on the data center and on server computing in general. Although few people are familiar with Microservers today, their impact will be felt very soon. This is a new category of computing platform that is available today and is predicted to have triple-digit growth rates for some ...
As the world moves toward more DevOps and Microservices, application deployment to the cloud ought to become a lot simpler. The Microservices architecture, which is the basis of many new age distributed systems such as OpenStack, NetFlix and so on, is at the heart of Cloud Foundry - a complete developer-oriented Platform as a Service (PaaS) that is IaaS agnostic and supports vCloud, OpenStack and AWS. Serverless computing is revolutionizing computing. In his session at 19th Cloud Expo, Raghav...
So you think you are a DevOps warrior, huh? Put your money (not really, it’s free) where your metrics are and prove it by taking The Ultimate DevOps Geek Quiz Challenge, sponsored by DevOps Summit. Battle through the set of tough questions created by industry thought leaders to earn your bragging rights and win some cool prizes.
SYS-CON Events announced today that Transparent Cloud Computing (T-Cloud) Consortium will exhibit at the 19th International Cloud Expo®, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. The Transparent Cloud Computing Consortium (T-Cloud Consortium) will conduct research activities into changes in the computing model as a result of collaboration between "device" and "cloud" and the creation of new value and markets through organic data proces...
More and more companies are looking to microservices as an architectural pattern for breaking apart applications into more manageable pieces so that agile teams can deliver new features quicker and more effectively. What this pattern has done more than anything to date is spark organizational transformations, setting the foundation for future application development. In practice, however, there are a number of considerations to make that go beyond simply “build, ship, and run,” which changes ho...