Exploring Enterprise Service Bus[ESB]

*ESB* is yet another buzzword in the IT world currently. I am writing this post to take the snap shot at what is current status of ESBs in the market. This post has taken significant amount time for me to study the trend of ESBs and its realted Technologies, Standards, Frameworks, Patterns and ofcourse the buzzwords;). So thought i would sum it all in this post kind a one-stop-shop for the analysis of ESBs (lol).


P.S: Well most of my the knowledge on this subject is borrowed. As per the principles of DRY which states,

''Every piece of knowledge must have a single,
unambiguous, authoritative representation within a system''.

Going by the same prinicple, there are many good articles on the web, 'written' by those who have been both in the EAI era & been witness to the transformation of standards into the current platform independent standards & protocols; Some authors who follow the new breed of standards (which fall under SOA like SOAP, WSDL, WSBPEL, etc); And some authors who represent the Vendors who have some kind of implementations of ESB. All due rights are held by the respective Vendors or Groups or Authors.

So let us start from the scratch,

What Is an ESB?

An ESB is an open standards, message-based, distributed, integration solution that provides routing, invocation, and mediation services to facilitate the interactions of disparate distributed information technology resources (applications, services, information, plat-forms) in a reliable manner. That’s a lot to take in, so let’s break down the key terms in our ESB definition, as follows:

• Open Standards. Open stan-dards refers to both the ESB solution compo-nents (runtime container, messaging infrastructure, integration services, design-time notations) and the mechanisms for inte-grated resources to participate (attach, request, respond) on the bus.
• Message-Based. The communication mechanism of an ESB is messaging, using standard message notation, protocols, and transports.
• Distributed. The ESB runtime environment can be distributed across a networked envi-ronment for the purposes of quality of service, quality of protection, and economics.
• Routing, Invocation, and Mediation. Routing, invocation, and mediation are the ba-sic functions of the ESB. Routing includes address-ability and content-based routing. Invocation refers to the ability to make requests and receive responses from integration services and integrated resources. Mediation refers to all translations and transforma-tions between disparate resources including security, protocol, message notation/format and message payload (data/semantics).
• Facilitate. The ESB must coordinate the interactions of the various resources and provide transactional support.
• Reliable. The ESB must guarantee message delivery.

Source:Ebizq

If u have time and want to invest in knowing how EAI evolved over a period of time. How EAI was transformed to the new age *ESB*, then you could spend some time reading this.

What are the essentials in an ESB?

Source: Ebiz and Patricia Seybold Group.

But this doesn't mean that all the Vendors of ESB agree with the feature list. Most of them provide them in their own way. Here is list for some of the Vendors & their features.

• BEA --- Aqua Logic
• CapeClear --- ESB
• Cordys --- ESB
• Fiorano --- ESB
• Firona --- Xtended Web Services Management Suite
• HP --- Adaptive Enterprise Services
  
• IBM --- ESB
• Iona --- Atrix
• Oracle --- ESB
• PolarLake --- Integration Suite
• Progress --- SonicESB
• Tibco --- ESB
• SeeBeyond --- eInsight

Now we know what is an ESB, their features and also some of the Vendors in this arena. There are many Use-Cases around which fits perfectly for these infrastructre products, so i wouldn't be venturing into them. One thing which has been constantly lingering in my mind is the fact that every major infrastructre Vendor wants to jump into the Bandwagon of ESB or ESB-styled products and offer services on them. This is what Ronan Bradley, CEO of PolarLake had to say when i asked him about the numerous flavours of ESB sprouting in the market on his blog,


"With regard to question around ESB vendors - there are already many who either claim that they have an ESB - or in the case of IBM and more recently Tibco claim that they have been selling one for years (a claim that I find bizarre and incredible).



If the market growth continues, the number of vendors may well grow further. That is why it is important for the user to focus on what they are trying to do rather than abstract marketing driven definitions (perhaps this is stating the obvious). "

I agree with Ronan, that there is enough room for all the major vendors, but looks like there will be some tough competition from the open source world. As far as i know, currently there are 2 players in ESB, they are Mule and ServiceMix.

Not to leave our prime Open-Source player, Apache, which has finally made its plans of entering the infrastructure software development by announcing the project Synapse. Since, Apache, the Mother of Open-Source Projects has ventured into the development of an ESB, i guess the other players should take a note of it. May be it is too early to say anything about Synapse, but you definitely can't write them off. Moreover, Synapse has some highly credible industry support with Sonic Software, Blue Titan, Iona and Infravio all pitching in. If you have noticed that some of the key vendors of ESB are pitching into the development of Synapse, apart from WSO2 being the key contributor. Switching groups has already begun, if u didn't get what i mean then you should read this.


Here are some of the articles relating to ESB, which I have really enjoyed reading.

The ESB vs WS "Fabric" - a Phoney War? - By Ronan Bradley, CEO of PolarLake.

Incremental Integration & the ESB - By Ronan Bradley, CEO of PolarLake.

Following are some links to interesting articles on ESB @ Ebizq

Enterprise Service Bus Q&A Part I

Enterprise Service Bus Q&A Part II

ESB and BPEL: Changing the Rules of Integration

The Omnipotent Extensible ESB

ESB Fills Management Gaps for Web Services

Following are some links to interesting articles on ESB @ LooselyCoupled

ESB: time to grow up

All about ESB

Let me know if there are any more interesting articles on ESB.

Source: Apache, BEA, CapeClear, Cordys, Ebiz, Fiorano, Firona, Loosely Coupled, HP, IBM, Iona, Oracle, Patricia Seybold Group, PolarLake, Progres, Tibco, SeeBeyond.