Welcome!

@CloudExpo Authors: Liz McMillan, Ed Featherston, Elizabeth White, Roger Strukhoff, Dana Gardner

Related Topics: Microservices Expo, Java IoT, Linux Containers, Open Source Cloud, @CloudExpo, SDN Journal

Microservices Expo: Article

Beyond REST and SOA: Introducing Agent-Oriented Architecture

Dynamic coupling represents a paradigm shift in how to build and utilize APIs

A question we commonly get at EnterpriseWeb is whether our platform follows REST or not. Representational State Transfer (REST) is an architectural style for distributed hypermedia systems such as the World Wide Web, and is perhaps best known for providing a lightweight, uniform Web-style application programming interface (API) to server-based resources. One the one hand, EnterpriseWeb can both consume and expose any type of interface, including tightly coupled APIs, Web Services, as well as RESTful APIs, and the platform has no requirement that customers must build distributed hypermedia systems. It would be easy to conclude, therefore, that while EnterpriseWeb supports REST, it is not truly RESTful.

Such a conclusion, however, would neglect the broader architectural context for EnterpriseWeb. The platform builds on top of and extends REST as the foundation for the dynamic, enterprise-class architectural style we call Agent-Oriented Architecture (AOA). EnterpriseWeb's intelligent agent, SmartAlex, leverages RESTful constraints as part of the core functionality of the EnterpriseWeb platform. The resulting AOA pattern essentially reinvents application functionality and enterprise integration, heralding a new paradigm for distributed computing.

The Limitations of REST
One of the primary challenges to the successful application of REST is understanding how to extend REST to distributed hypermedia systems in general, beyond the straightforward interactions between browsers and Web servers. To help clarify this point, Figure 1 below illustrates a simple RESTful architecture. In this example, the client is a browser, and it sends GETs and PUTs or other RESTful queries to URIs that resolve to resources on a server, which responds by sending the appropriate representation back to the client. In addition, REST allows for a cache intermediating between client and server that might resolve queries on behalf of the server for scalability purposes.

Figure 1: Simple RESTful Architecture

As an architectural style, however, the point of REST isn't the uniform interface that the HTTP verbs enable. REST is really about hypermedia, where hypermedia are the engine of application state - the HATEOAS constraint essential to building hypermedia systems. In figure 1, we're representing HATEOAS by the interactions between human users and their browsers as people click links on Web pages, thus advancing the application state. The RESTful client (in other words, the browser) maintains application state for each user by showing them the Web page (or other representation) they requested when they followed a given hyperlink.

However, software clients that do not necessarily have user interfaces may be problematic for REST, but they are a familiar part of the Service-Oriented Architecture (SOA) architectural style, where we call such clients Service consumers. Combining REST and SOA into the combined architectural style we call REST-Based SOA introduces the notion of an intermediary that presents a Service endpoint and resolves interactions with that endpoint into underlying interactions with various legacy systems. The SOA intermediary in this case exposes RESTful endpoints as URIs that accept GETs, PUTs, etc. from Service consumers, which can be any software client. See figure 2 below for an illustration of the REST-Based SOA pattern.

Figure 2: REST-Based SOA

Note that adding SOA to REST augments the role of the intermediary. Pure REST allows for simple caching and proxy behavior, while SOA calls for policy-based routing and transformation operations that provide the Service abstraction. SOA also reinforces the notion that the Service consumer can be any piece of software, regardless of whether it has a user interface.

Even with REST-based SOA, however, we still have problems with implementing HATEOAS: coding our clients so that they are able to gather the metadata they need by following hyperlinks. In other words, how do we apply REST to any hypermedia system, where instead of a browser we have any piece of software as a client? How do we code the software client to know how to follow hyperlinks, where it doesn't know what the hyperlinks are ahead of time or what representations they're supposed to interact with? Humans simply click hyperlinks until they get the representation they want, even if they don't know beforehand how to find it. How do we teach software to automate this process and gather all the metadata it needs by following a sequence of hyperlinks?

Introducing Agent-Oriented Architecture
The answer to these questions is to cast an intelligent agent in the role of SOA intermediary in the REST-Based SOA pattern in Figure 2. Intelligent software agents (or simply intelligent agents when we know we're talking about software) are autonomous programs that have the authority to determine what action is appropriate based upon the requests made of them. In this new, Agent-Oriented architectural pattern, the agent interacts with any resource as a RESTful client, where the agent must be able to automatically follow hyperlinks to gather all the information it requires in order to respond appropriately to any request from the client.

In other words, when following this newly coined AOA architectural style, software clients do not have to comply with HATEOAS (they may, but such compliance is optional). Instead, the agent alone must follow the HATEOAS constraint as it interacts with resources. To achieve this behavior, we must underspecify the intelligent agent. In other words, the agent can't know ahead of time what it's supposed to do to respond to any particular request. Instead, it must be able to process any request on demand by fetching related resources that provide the appropriate metadata, data, or code it needs to properly respond to that request with a custom response, for each interaction in real time. Figure 3 below illustrates the basic AOA pattern.

Figure 3: Agent-Oriented Architecture

For each request from any client, regardless of whether it has a user interface, the agent constructs a custom response based on latest and most relevant information available. In fact, requests to the agent can come from anywhere (i.e., they follow an event-driven pattern). The agent's underspecification means that it doesn't know ahead of time what behavior it must exhibit, but it does know how to find the information it needs in order to determine that behavior - and it does that by following hyperlinks, as per HATEOAS. In other words, the goal-oriented agent resolves URIs recursively in order to gather and execute the information it needs - a particularly concise example of fully automated HATEOAS in action.

The Benefits of AOA

An earlier Loosely-Coupled newsletter explained that if you follow REST, you're unable to accept out-of-band metadata or business context outside of the hypermedia. Agent-Oriented Architecture, however, solves these problems, because the agent is free to fetch whatever it needs to complete the request, since it treats all entities - metadata, data, code, etc. - as resources. In other words, the agent serves as a RESTful client, even when the software client does not. What was out-of-band for REST isn't out-of-band for AOA. Everything is on the table.

The true power of AOA, though, lies in how it resolves the fundamental challenge of static APIs. Whether they be Web Services, RESTful APIs, or some other type of loosely-coupled interface, every approach to software integration today suffers from the fact that interactions tend to break when API contract metadata change.

By adding an intelligent agent to the mix, we're able to resolve differences in interaction context between disparate software endpoints dynamically and in real time. Far more than a traditional broker, which must rely on static transformation logic to resolve endpoint differences, the agent must be able to interpret metadata, as well as policies, rules, and the underlying data themselves to create real time interactions that maintain the business context - an example of dynamic coupling, a central principle to AOA.

Dynamic coupling, therefore, represents a paradigm shift in how to build and utilize APIs. Up to this point in time, the focus of both SOA and REST has been on building loosely-coupled interfaces: static, contracted interfaces specified by WSDL and various policy metadata when those interfaces are Web Services, or Internet Media Types and related metadata for RESTful interactions. Neither approach deals well with change. AOA, in contrast, relies upon dynamic coupling that responds automatically to change, since the agent interprets current metadata for every interaction in real time.

Icons by http://dryicons.com

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).

@CloudExpo Stories
“We're a global managed hosting provider. Our core customer set is a U.S.-based customer that is looking to go global,” explained Adam Rogers, Managing Director at ANEXIA, in this SYS-CON.tv interview at 18th Cloud Expo, held June 7-9, 2016, at the Javits Center in New York City, NY.
SYS-CON Events announced today that SoftLayer, an IBM Company, has been named “Gold Sponsor” of SYS-CON's 18th Cloud Expo, which will take place on June 7-9, 2016, at the Javits Center in New York, New York. SoftLayer, an IBM Company, provides cloud infrastructure as a service from a growing number of data centers and network points of presence around the world. SoftLayer’s customers range from Web startups to global enterprises.
The vision of a connected smart home is becoming reality with the application of integrated wireless technologies in devices and appliances. The use of standardized and TCP/IP networked wireless technologies in line-powered and battery operated sensors and controls has led to the adoption of radios in the 2.4GHz band, including Wi-Fi, BT/BLE and 802.15.4 applied ZigBee and Thread. This is driving the need for robust wireless coexistence for multiple radios to ensure throughput performance and th...
SYS-CON Events announced today that Secure Channels 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 bedrock of Secure Channels Technology is a uniquely modified and enhanced process based on superencipherment. Superencipherment is the process of encrypting an already encrypted message one or more times, either using the same or a different algorithm.
SYS-CON Events announced today that Commvault, a global leader in enterprise data protection and information management, has been named “Bronze Sponsor” of SYS-CON's 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Commvault is a leading provider of data protection and information management solutions, helping companies worldwide activate their data to drive more value and business insight and to transform moder...
Let’s face it, embracing new storage technologies, capabilities and upgrading to new hardware often adds complexity and increases costs. In his session at 18th Cloud Expo, Seth Oxenhorn, Vice President of Business Development & Alliances at FalconStor, discussed how a truly heterogeneous software-defined storage approach can add value to legacy platforms and heterogeneous environments. The result reduces complexity, significantly lowers cost, and provides IT organizations with improved efficienc...
Fifty billion connected devices and still no winning protocols standards. HTTP, WebSockets, MQTT, and CoAP seem to be leading in the IoT protocol race at the moment but many more protocols are getting introduced on a regular basis. Each protocol has its pros and cons depending on the nature of the communications. Does there really need to be only one protocol to rule them all? Of course not. In his session at @ThingsExpo, Chris Matthieu, co-founder and CTO of Octoblu, walk you through how Oct...
SYS-CON Events announced today that CDS Global Cloud, an Infrastructure as a Service provider, 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. CDS Global Cloud is an IaaS (Infrastructure as a Service) provider specializing in solutions for e-commerce, internet gaming, online education and other internet applications. With a growing number of data centers and network points around the world, ...
DevOps at Cloud Expo – being held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA – announces that its Call for Papers is open. Born out of proven success in agile development, cloud computing, and process automation, DevOps is a macro trend you cannot afford to miss. From showcase success stories from early adopters and web-scale businesses, DevOps is expanding to organizations of all sizes, including the world's largest enterprises – and delivering real results. Am...
SYS-CON Events announced today that LeaseWeb USA, a cloud Infrastructure-as-a-Service (IaaS) provider, 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. LeaseWeb is one of the world's largest hosting brands. The company helps customers define, develop and deploy IT infrastructure tailored to their exact business needs, by combining various kinds cloud solutions.
"We have several customers now running private clouds. They're not as large as they should be but it's getting there. The adoption challenge has been pretty simple. Look at the world today of virtualization vs cloud," stated Nara Rajagopalan, CEO of Accelerite, in this SYS-CON.tv interview at 18th Cloud Expo, held June 7-9, 2016, at the Javits Center in New York City, NY.
Big Data has been changing the world. IoT fuels the further transformation recently. How are Big Data and IoT related? In his session at @BigDataExpo, Tony Shan, a renowned visionary and thought leader, will explore the interplay of Big Data and IoT. He will anatomize Big Data and IoT separately in terms of what, which, why, where, when, who, how and how much. He will then analyze the relationship between IoT and Big Data, specifically the drilldown of how the 4Vs of Big Data (Volume, Variety,...
In his general session at 18th Cloud Expo, Lee Atchison, Principal Cloud Architect and Advocate at New Relic, discussed cloud as a ‘better data center’ and how it adds new capacity (faster) and improves application availability (redundancy). The cloud is a ‘Dynamic Tool for Dynamic Apps’ and resource allocation is an integral part of your application architecture, so use only the resources you need and allocate /de-allocate resources on the fly.
Creating replica copies to tolerate a certain number of failures is easy, but very expensive at cloud-scale. Conventional RAID has lower overhead, but it is limited in the number of failures it can tolerate. And the management is like herding cats (overseeing capacity, rebuilds, migrations, and degraded performance). Download Slide Deck: ▸ Here In his general session at 18th Cloud Expo, Scott Cleland, Senior Director of Product Marketing for the HGST Cloud Infrastructure Business Unit, discusse...
SYS-CON Events announced today that Interface Masters Technologies, a leader in Network Visibility and Uptime 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. Interface Masters Technologies is a leading vendor in the network monitoring and high speed networking markets. Based in the heart of Silicon Valley, Interface Masters' expertise lies in Gigabit, 10 Gigabit and 40 Gigabit Eth...
Vidyo, Inc., has joined the Alliance for Open Media. The Alliance for Open Media is a non-profit organization working to define and develop media technologies that address the need for an open standard for video compression and delivery over the web. As a member of the Alliance, Vidyo will collaborate with industry leaders in pursuit of an open and royalty-free AOMedia Video codec, AV1. Vidyo’s contributions to the organization will bring to bear its long history of expertise in codec technolo...
There is little doubt that Big Data solutions will have an increasing role in the Enterprise IT mainstream over time. Big Data at Cloud Expo - to be held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA - has announced its Call for Papers is open. Cloud computing is being adopted in one form or another by 94% of enterprises today. Tens of billions of new devices are being connected to The Internet of Things. And Big Data is driving this bus. An exponential increase is...
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...
A strange thing is happening along the way to the Internet of Things, namely far too many devices to work with and manage. It has become clear that we'll need much higher efficiency user experiences that can allow us to more easily and scalably work with the thousands of devices that will soon be in each of our lives. Enter the conversational interface revolution, combining bots we can literally talk with, gesture to, and even direct with our thoughts, with embedded artificial intelligence, wh...
SYS-CON Events announced today that Tintri Inc., a leading producer of VM-aware storage (VAS) for virtualization and cloud environments, 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. Tintri VM-aware storage is the simplest for virtualized applications and cloud. Organizations including GE, Toyota, United Healthcare, NASA and 6 of the Fortune 15 have said “No to LUNs.” With Tintri they mana...