The Good, the Bad, and the Ugly of Service-Oriented Architecture
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by Tom Fuller
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Overview

The focus of this article is to use a combination of online research and hands-on experience to explain the practicality of SOA as the foundation of application enterprise architectures. The rest of this article will cover three aspects of SOA:

The Good: In this section, I have used what I believe to be the most obvious immediate return on investment items for any enterprise. The upside on these items is substantial and in most cases immediate.

The Bad: All of the items in this section will create some minor headaches when attempting to deliver services that can be reused and remain long lived. The cost is most likely higher than a typical non-SOA approach, but with strong guidelines much of the cost will be a one-time-only issue.

The Ugly: These items are the ones that will likely make any project manager uneasy about the timelines and costs associated with an enterprise SOA. Many of these issues don’t have good answers for them yet and will likely continue to evolve as the technologies being used to deliver services evolve.

Service-oriented Architecture vs. Web Services

Too often discussions about service-oriented architectures inadvertently progress into a best practices discussion on web services development. This article will use many of the existing limitations of web service development to explain the costs associated with delivering service-oriented architectures. Web services are by no means the only technological mechanism for delivering an enterprise SOA. There are code libraries, shared components, and EAI solutions. With that said, web services are the most popular approach and are seen used much more often due to their implicitly interoperable transport mechanisms.

Other Reuse Strategies

It is worth taking a moment to walk the SOA timeline. At the root of SOA is code reuse and there have been a number of mechanisms used over the past 30 years for reusing code. It all began with cumbersome error-prone cut and paste techniques. This eventually progressed into code libraries and code includes. These techniques were foundational for many different development platforms until the introduction of object orientation.

Object orientation soon progressed into an underlying design concept and the packaging and deployment mechanism that followed was dubbed component oriented. These components were used to package and deploy reusable code. However, that still required multiple versions of the code and the next step was to use proprietary channels for remotely invoking those components from a single location.

What seems to be the final obstacle in the evolution of code reuse emerges. We now have a standards-based approach for remote invocation of reusable code. This, above all other reasons, is why web services over HTTP are the most common technologies found enabling service orientation in today’s enterprises.


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User Comments

Title: Project   
Name: Dude MaN (for protection)
Date: 2007-10-11 10:07:28 AM
Comment:
hey i am doing a report on the pro and cons on Architecture can u help me.
Title: RE: Great article, but Moore's Law?   
Name: Tom Fuller
Date: 2005-09-01 10:00:55 PM
Comment:
Just realized I was cut off when I posted my response. Sorry for taking so long to notice......

I think we'll see in the future that if the services that are intended to stand the test of time are delivered as tightly coupled portions of a business application then those services will in the long run lose any level of autonomy (which would be another one of those tenets).

This has been at the heart of almost every discussion I've had with people about SOA lately and I plan to write another article in the upcoming weeks titled "SOA Design Strategies: Adhering to the 4 Tenets". This will go into detail on these very issues we are discussing.

Thanks again for taking a look at my article and I appreciate your criticism.
Title: RE: Great article, but Moore's Law?   
Name: Tom Fuller
Date: 2005-08-30 10:05:45 PM
Comment:
Thank you for the feedback. I have to admit the loose application of Moore's Law in the article has come under some crticism. What I will say is that I did not intend to say poor design was justified through my use of Moore's law in the article. I really wanted to use it more as a high level comparison to show that there is little to no doubt that the capabilities of our hardware and infrastructure will only continue to increase. It is that increase that could neutralize any of these minor performance concerns with SOAP based transports and message serialization. This does not mean that you can completely dismiss performance concerns today but SOA will continue to focus on delivering loosley coupled systems that can last longer than the applications we delivered in the past. That in my mind means we should consider the potential capabilities of the network and the hardware that these systems will depend on.

The rest of your comments seem to focus on the design issues surrounding service orientation and they are certainly valid. It is too often the case that common layered architectures fall into the trap of future proofing everything that is built because of the constant pains associated with versioning. This comes back to an issue of agility in your software delivery process. I know this is easier said than done but, the fact remains, if there was no concern that services could be delivered outside of the natural release schedule of an application then you could avoid this "Field of Dreams" approach you talk about.

You have also made a very powerful statement below and that was, "some sort of agreement on what the service is all about should be reached". This covers two of the critically important tenets of SO. You are talking about boundaries being explicit here and that services exchange contracts and schema not objects and types. I think we'll see in the future that if the services that are intended to stand the test of time are delivered as ti
Title: Great article, but Moore's Law?   
Name: TravelMonkey
Date: 2005-08-29 12:25:20 AM
Comment:
Tom,

A great article overall!

However, I was a bit dismayed by the fact that you seem to use Moore's Law (or a variant thereof) as a scapegoat to allow for poor performance today. I may be stretching what you said a bit, but you seem to imply that somewhat adequate performance from SOA is OK today, because Moore's Law will take effect and in 18 months things will be better.

Has Moore's Law been extended to include networks now? I have not done the math, but I would say it's a reach to say that it has held true for our bandwidth.

At any rate, I would advocate creating the best performing design and code you can today, and leave Moore's Law as a nice theory, not an excuse if you can't make good performing code. SOA doesn't NEED to be poorly performing, though I think poorly written web services have doomed it with that stigma at times, to some purists. I think an "outside the firewall" scenario does allow for some "slop" in the code, as one expects slower performance out in the cloud due to network latencies beyond our control. However, for an intranet app, the SOA needs to scream. Internal users are far less forgiving of slow performance.

I also don't think SOA implies poor performance--I think poor design implies poor performance. Spend some of the expense of SOA on ensuring your design meets good performance standards from the beginning; you'll save money in the long run by making apps that perform today.

I think another potential money pit that needs to be examined is to ensure that you don't get bitten by the "Field of Dreams" scenario. You know--"If you build it, they will come." I don't feel that SOA is about that. Make sure service consumers are in place (a real need is identified) and that some form of contract is in place. I'm not necessarily advodating contract-first, but some sort of agreement on what the service is all about should be reached.

Your article is a great overall view of SOA, I think. Well done.

--
TravelMonkey
Title: Nice article   
Name: asp.net user
Date: 2005-08-25 2:50:40 PM
Comment:
Hi,
Really nice condeptual article. Can you give real time example where some company is already using SOA.

Thanks

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