ZapThink » Event-Driven SOA

REST-Based SOA: an Iconoclastic Approach

Jason Bloomberg — Thu, 04 Aug 2011 17:30:20 +0000

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.

Photo courtesy Flickr Commons.

ZapThink Announces Service-Oriented Architecture (SOA) Events in Sydney, Australia

admin — Tue, 20 Oct 2009 00:10:00 +0000

ZapThink Announces Service-Oriented Architecture (SOA) Events in Sydney, Australia

SOA Certification and Training, Networking, and Governance Events January 2010

BALTIMORE, MD October 21, 2009 — ZapThink today announces the opening of registration for three separate Service-Oriented Architecture (SOA) and Enteprise Architecture (EA) training, certification, and networking events in Sydney, Australia, running from January 11, 2010 to January 19, 2010.

“Companies are tired of all the hype surrounding Web Services and SOAs, and are finding it difficult to learn what they really need to know from vendor-centric conferences and training,” said Ronald Schmelzer, senior analyst with ZapThink, LLC. “IT professionals want to learn from their peers about what it really takes to put together a well-designed SOA, and desire third-party credentials to assert their SOA knowledge. The Licensed ZapThink Analyst boot camps give Enterprise Architecture practitioners the SOA education and credentials they’ve been waiting for.”

Courses, certification, and networking offered include:

In the four-day SOA training course, attendees will get hands-on experience and expertise in how to implement the latest SOA best practices and methods. Learn about Service modeling, Service domains, SOA infrastructure planning, SOA testing, SOA Quality, Governance, and Management, developing a SOA Roadmap, SOA ROI and Business Planning, SOA Key Performance Indicators (KPI) and metrics, SOA security and performance optimization, SOA policy management, Composite Services and Business Process, Service-Oriented Business Applications (SOBA), and Mashups. Hear about notable SOA security case studies and get hands-on guidance in making SOA work. And, once you complete this course you will become a credentialed Licensed ZapThink Architect.

The ZapThink LZA SOA training and certification program offers the following benefits:

An annual credential that allows ZapThink to endorse individual enterprise architects as having specific SOA skills
Posting onto an LZA Directory that enables companies to research and locate architects to assist with their SOA-specific needs
Opportunity to contribute to ZapThink’s online research and content
Participation in exclusive annual LZA-only conferences, events and activities.

Increasingly, individuals like are looking to get the backing of a qualified third-party organization that can endorse their existing SOA skills as well as enable continuous improvement, enhanced networking with those looking for architecture resources, or enhance their current SOA-enabled careers. Through its LZA program, ZapThink is filling the unmet need for knowledge and credentials in this area.

For more information and to register for the events, visit http://bit.ly/ctIJ. Early bird discounts are available for a limited time. Seats are limited to only 45 people per LZA boot camp, and ZapThink expects certain boot camp dates and locations to sell out.

ZapThink Announces Service-Oriented Architecture (SOA) Training in Washington, DC

admin — Tue, 20 Oct 2009 00:10:00 +0000

ZapThink Announces Service-Oriented Architecture (SOA) Training in Washington, DC

Licensed ZapThink Architect (LZA) Boot Camp to Run February 1-4, 2010

BALTIMORE, MD October 14, 2009 — ZapThink today announces the opening of registration for its four-day Licensed ZapThink Architect (LZA) Boot Camp, providing in-depth, hands-on training and certification on Service-Oriented Architecture (SOA) and taught by notable SOA expert Jason Bloomberg. The LZA SOA Boot Camp will run from February 1-4, 2010 in Washington, DC (http://bit.ly/vw7WQ).

In this four-day SOA training course, attendees will get hands-on experience and expertise in how to implement the latest SOA best practices and methods. Learn about Service modeling, Service domains, SOA infrastructure planning, SOA testing, SOA Quality, Governance, and Management, developing a SOA Roadmap, SOA ROI and Business Planning, SOA Key Performance Indicators (KPI) and metrics, SOA security and performance optimization, SOA policy management, Composite Services and Business Process, Service-Oriented Business Applications (SOBA), and Mashups. Hear about notable SOA security case studies and get hands-on guidance in making SOA work. And, once you complete this course you will become a credentialed Licensed ZapThink Architect.

The ZapThink LZA SOA training and certification program in Washington, DC offers the following benefits:

An annual credential that allows ZapThink to endorse individual enterprise architects as having specific SOA skills
Posting onto an LZA Directory that enables companies to research and locate architects to assist with their SOA-specific needs
Opportunity to contribute to ZapThink’s online research and content
Participation in exclusive annual LZA-only conferences, events and activities.

The LZA Washington, DC SOA Boot Camp will be held from February 1-4, 2010. Register at http://bit.ly/vw7WQ.

For more information and to register for an LZA Boot camp, visit http://bit.ly/vw7WQ. Early bird discounts are available for a limited time. Seats are limited to only 45 people per LZA boot camp, and ZapThink expects certain boot camp dates and locations to sell out.

ZapThink Announces Service-Oriented Architecture (SOA) Training in London

admin — Tue, 06 Oct 2009 00:10:00 +0000

ZapThink today announces the opening of registration for its four-day Licensed ZapThink Architect (LZA) Boot Camp, providing in-depth, hands-on training and certification on Service-Oriented Architecture (SOA) and taught by notable SOA expert Jason Bloomberg. The LZA SOA Boot Camp will run from December 8-11, 2009 in London (http://bit.ly/180Csy).

The ZapThink LZA SOA training and certification program in London offers the following benefits:

An annual credential that allows ZapThink to endorse individual enterprise architects as having specific SOA skills
Posting onto an LZA Directory that enables companies to research and locate architects to assist with their SOA-specific needs
Opportunity to contribute to ZapThink’s online research and content
Participation in exclusive annual LZA-only conferences, events and activities.

The LZA London SOA Boot Camp will be held from December 8-11, 2009. Register at: http://bit.ly/OYJdN

For more information and to register for an LZA Boot camp, visit http://bit.ly/OYJdN . Early bird discounts are available for a limited time. Seats are limited to only 45 people per LZA boot camp, and ZapThink expects certain boot camp dates and locations to sell out.

Summa and ZapThink SOA Events

admin — Tue, 06 Oct 2009 00:10:00 +0000

Summa is sponsoring two upcoming ZapThink SOA events.

The first event is a networking and panel discussion of SOA Experts (including Jason Bloomberg, David Linthicum, Summa’s own Jason Armstrong and others.) It is October 1 in Washington DC (Tyson’s Corner). More details are here:

The second event is in Pittsburgh on October 22nd – focused on SOA and modernization featuring project case studies from CMU ahd Highmark. More detail and registration information are here.

ZapThink Announces Service-Oriented Architecture (SOA) Training in Boston, MA

admin — Tue, 29 Sep 2009 00:09:00 +0000

The ZapThink LZA SOA training and certification program in Boston offers the following benefits:

* An annual credential that allows ZapThink to endorse individual enterprise architects as having specific SOA skills
* Posting onto an LZA Directory that enables companies to research and locate architects to assist with their SOA-specific needs
* Opportunity to contribute to ZapThink’s online research and content
* Participation in exclusive annual LZA-only conferences, events and activities.

The LZA Boston SOA Boot Camp will be held from October 26-29, 2009. Register at www.//bit.ly/izbIZ.

For more information and to register for an LZA Boot camp, visit http://www.//bit.ly/izbIZ. Early bird discounts are available for a limited time. Seats are limited to only 45 people per LZA boot camp, and ZapThink expects certain boot camp dates and locations to sell out.

Are Your Business Analysts Ready for BI and MDM? Plus, a SOA Event Discount

admin — Fri, 25 Sep 2009 00:09:00 +0000

Discount for ZapForum DC: SOA & EA Networking Event: IT Business Edge readers in the Washington, D.C. area can receive a 50 percent off discount for ZapThink’s SOA and EA Networking event. Several big-name SOA analysts will be there, including David Linthicum, JP Morgenthal, Tim “The SOA Chief” Vibbert, James Kobielus of Forrester, and, of course, ZapThink analysts Jason Bloomberg and Ronald Schmelzer, who claims he’s the “Life of the SOA Party.” If you can go and check the facts on that claim, I’d appreciate it! The event is 5:30-8:30 at the Gordon Biersch Tysons Corner, October 1. To receive your discount, just use ITBEDISC for half off the regular $29 registration.

SOAは死んだのか？ ZapThinkフォーラムレポート（米・ボストン）

admin — Fri, 28 Aug 2009 00:08:00 +0000

2009年7月23日、米ボストン周辺にてSOA、EAコンサルタントのためのイベント「ZapThinkフォーラム」が開催された。今回は、「SOAはもう死んだのか？」をテーマに熱い議論が繰り広げられた。本稿では、その概要をお伝えする。
ビールを片手にSOAを語り合う

　 2009年7月23日、米ボストン周辺のSOA、EAコンサルタント達が、恒例のZapThinkフォーラムに参加すべく「M.J.O’Conner’s Irish Pub」の一室に集合した。このフォーラムは、SOA、Web Service、EAなどのコンサルティングに携わる人々の相互交流を目的としたもの。一般的なフォーラムと違って飲食店において立食形式で行われるほか、一方的な講義形式ではなく参加者全員が同じ立場で意見交換できるなど独特の工夫が凝らされている。普段は演壇の上でしか見たことのないような著名人とビールを片手に話せる環境が魅力的なイベントだ。

ZapThink Announces Service-Oriented Architecture (SOA) Training in Dubai

admin — Mon, 17 Aug 2009 00:08:00 +0000

ZapThink Announces Service-Oriented Architecture (SOA) Training in Dubai
Licensed ZapThink Architect (LZA) Boot Camp to Run November 2-5, 2009

BALTIMORE, MD August 17, 2009 — ZapThink today announces the opening of registration for its four-day Licensed ZapThink Architect (LZA) Boot Camp, providing in-depth, hands-on training and certification on Service-Oriented Architecture (SOA) and taught by notable SOA expert Jason Bloomberg. The LZA SOA Boot Camp will run from November 2-5, 2009 in Dubai, U.A.E. (http://).

In this four-day SOA training course (http://), attendees will get hands-on experience and expertise in how to implement the latest SOA best practices and methods. Learn about Service modeling, Service domains, SOA infrastructure planning, SOA testing, SOA Quality, Governance, and Management, developing a SOA Roadmap, SOA ROI and Business Planning, SOA Key Performance Indicators (KPI) and metrics, SOA security and performance optimization, SOA policy management, Composite Services and Business Process, Service-Oriented Business Applications (SOBA), and Mashups. Hear about notable SOA security case studies and get hands-on guidance in making SOA work. And, once you complete this course you will become a credentialed Licensed ZapThink Architect.

The ZapThink LZA SOA training and certification program in Dubai offers the following benefits:

An annual credential that allows ZapThink to endorse individual enterprise architects as having specific SOA skills
Posting onto an LZA Directory that enables companies to research and locate architects to assist with their SOA-specific needs
Opportunity to contribute to ZapThink’s online research and content
Participation in exclusive annual LZA-only conferences, events and activities.

The LZA Dubai SOA Boot Camp will be held from November 2-5, 2009. Register at: http://bit.ly/aheCZ

For more information and to register for an LZA Boot camp, visit http://bit.ly/aheCZ . Early bird discounts are available for a limited time. Seats are limited to only 45 people per LZA boot camp, and ZapThink expects certain boot camp dates and locations to sell out.

ZapThink Hosts Practical Service-Oriented Architecture (SOA) and Enterprise Architecture (EA) event in Washington, DC

admin — Thu, 13 Aug 2009 00:08:00 +0000

ZapThink Hosts Practical Service-Oriented Architecture (SOA) and Enterprise Architecture (EA) event in Washington, DC
Focus on Cost-Effective Legacy Modernization & Data Management

BALTIMORE, MD, August 11, 2009 — ZapThink announces today the availability of its upcoming Practical Service-Oriented Architecture (SOA) and Enterprise Architecture (EA) morning seminar event, running on October 2, 2009 in Washington, DC. The event features speakers, best practices, case studies, and lessons learned on how to implement cost-effective legacy modernization and data management strategies in the context of the latest enterprise architecture initiatives. The Practical SOA event series is targeted at companies and individuals looking for practical business case studies and value propositions for SOA, those who want to learn the latest best practices for making SOA a success, those looking to hear from successful architects about their SOA efforts, want to learn from peers about what it takes to put together a successful SOA, and/or want to take their SOA efforts to the next level.

“Companies are looking for practical solutions to their SOA and EA challenges,” said Ronald Schmelzer, Managing Partner with ZapThink, LLC. “Practical SOA events give Enterprise Architecture practitioners, consulting firms, and vendors, the best practices and practical implementation knowledge they are seeking by hearing from other architects and getting hands-on instruction on particular SOA and EA challenges.”

Sponsors and presenters at the upcoming Practical SOA & EA event in Washington, DC on October 2, 2009 include:

Dan Finerty, DataDirect
Jason Bloomberg, ZapThink

At the morning event, which runs from 8AM to 12noon PT, attendees will hear about the following topics:

Make SOA work in the context of legacy systems
Learn how to involve the mainframe in the context of SOA
Learn about methods for dealing with “legacy” data and composing heterogeneous data in a SOA environment
Returning Value with a Data Service Layer
Legacy, Data, and the Cloud

For more information and to register for this Practical SOA event, visit http://bit.ly/2Ty0ZU. Cost is just $29 to attend. Seats are limited and ZapThink expects Practical SOA events to sell out.