Services by Design
- By Stephen Swoyer
- November 1, 2005
The Big Idea
- Traditional software development will almost entirely be supplanted by
a virtual paradigm in which Web services are orchestrated dynamically to power
- Bring in WSDL files from Web servers, and you create pipelines of activity.
If you string enough of those routing and transformations together, pretty
soon you have an entire enterprise application infrastructure.
- Organizations automate many once-manual business processes; simplify their
app dev and maintenance by introducing modularity and effective reuse; and
optimize their business processes to ensure they align with IT.
upkeep of your application infrastructure got you down? Take a number and get
in line. Fact is, no organization relishes the beaucoup dollars and harried
human resources it pours into maintaining its application infrastructure. Given
the choice, most IT shops would gladly do away with production support, feature
or function enhancement requests, scheduled maintenance, periodic refactoring
and other budget dollar boondoggles.
That's not possible, is it? Well, that depends. Lend an ear to the technology
visionaries at BEA Systems, IBM, Oracle or at any of several other SOA religionists,
and you might find yourself singing the praises of service enablement-and of
a new generation of composite applications. (See related story, "What's a composite
If it takes hold, service enablement will fundamentally alter the enterprise
application landscape. And, at this point, anyway, few would bet against service
enablement's eventually taking hold. This is in spite of the fact that most
organizations are taking baby steps on the way to full-fledged SOA-dom. The
trend, SOA proponents claim, is clear-and the viability of the SOA vision is
itself beyond dispute. Call it SOAinevitability, of a sort.
And if service enablement truly is inevitable, it will have far-reaching ramifications
for enterprise application development. In many cases, technologists argue,
traditional applications will go the way of the slide rule, replaced by composite
applications that consist of conventional apps working in combination with Web
services and other consumable services. In the most radical articulation of
this vision, traditional software development will almost entirely be supplanted
by a virtual paradigm in which disparate Web services are orchestrated dynamically
to power composite applications.
"If you've service enabled things the right way, [composite applications] should
be merely a matter of configuration and not coding, and one look at our AquaLogic
Service Bus product will tell you how that's possible," says Bill Roth, VPof
marketing with BEA. "You bring in various WSDL files from Web servers, and you
basically create pipelines of activity...[and] if you string enough of those
routing and transformations together, pretty soon you have an entire enterprise
What's a composite app?
The SOA visions touted by BEA Systems, IBM and others don’t stop with service enablement.
SOA enthusiasts also trumpet a coming generation of composite applications— applications that are composed of multiple, independent, plugand- play services. A composite application can describe a combination of service-enabled legacy applications; Web services; standards-compliant interfaces (such as LDAP and SQL) that are exposed to internal or external consumers; or external services (such as Salesforce.com’s hosted CRM services) that are designed to be consumed by a subscriber’s internal systems. By definition, a composite application typically involves the interaction of at least two services.
One classic example is a loan approval process, which typically spawns several processes, such as one to query an external credit bureau, and another to locate and retrieve the customer’s existing financial records. In the composite model, an organization can identify the specific business processes that support the loan approval process, service enable the information systems that support these services, and choreograph the interaction of these services as part of a composite application designed (in this case, anyway) to address the loan approval process.
In a certain sense, composite applications are virtual applications, because they consist at least in part of constituent services and do not formally reside anywhere, save at the application server tier, where they are effectively managed and choreographed. Vendors seem uncomfortable with what is implied by a virtual application, maybe because it sounds too close to vaporware, and so tend to stick exclusively to the term composite.
Oh, the places you'll go
BEA isn't an entirely disinterested observer of SOA. Earlier this year, it announced
AquaLogic, a technology initiative many industry watchers described as an all-but
last-ditch effort to reinvent itself. (BEA has faced withering pressure from
IBM and Oracle in the commercial J2EE application server space, while at the
same time open-source app servers such as JBoss are also coming on strong.)
With AquaLogic, BEA sought to stake a claim to a vanguard position on the emerging
virtual application express.
But BEA's AquaLogic vision-which prescribes a heavy dose of service enablement
for the legacy application woes that bedevil almost all enterprises-isn't necessarily
a technology coup-de-main: The company's competitors have outlined similar visions,
and-in the case of IBM especially-have been talking about composite applications
for at least 2 years now.
Much of the grunt work of service-enablement involves pretty ordinary stuff:
namely, wrapping existing applications in Web services to expose them to other
service-enabled applications. Legacy applications aren't going anywhere, says
Roth and other composite app enthusiasts: They're instead being abstracted-
liquefied in BEA's parlance-by means of standards-compliant services. To the
extent that a composite application consumes these services, it is necessarily
interfacing with legacy apps, too.
In the end, says Kareem Yusuf, program director for IBM's WebSphere software
platform, composite apps aren't such a radical idea. And with SOAs fast taking
hold, Yusuf-like Roth and other SOA evangelists-argues that composite applications
are themselves inevitable. He's long espoused the idea of service choreography,
which essentially describes the managed interaction of services on the basis
of business logic and associated rules. The benefits are obvious, he maintains:
organizations automate many once-manual business processes; simplify their app
development and maintenance by introducing both modularity and effective reuse,
and optimize their business processes to ensure optimal alignment with IT.
When you think about it, he argues, it's a no-brainer.
Aha, not so fast
Although vendors and software decision makers embraced service enablement with
an uncommon gusto, enterprise codejockeys are more skeptical about SOAs. Their
skepticism starts with one of the fundamental assumptions of the composite app
vision-the inevitability of service enablement. "SOA...makes the fatal assumption
that one can create totally generic services that can be tied together like
Legos," argues Ramon Leon, a veteran programmer with an Internet software and
e-commerce development house. "In practice, this tends not to work so well for
most circumstances. The other flaw is that many of the people writing these
services do it backwards. They write the service first and then try and make
applications that use them. This predictably leads to services that don't quite
fit the application's needs."
This isn't to say that programmers are reflexively anti-SOA, however-just that
codejockeys seem to have a much more pragmatic take on service enablement than
do their executive masters. As a result, many developers see a future in which
the large-scale SOA vision of Joe Enterprise Architect gives way to a kind of
hybrid infrastructure in which some but not all applications or resources are
service enabled. Call it quasi- or best-effort- service enablement.
The point is that several foundational premises of the virtual app vision aren't
yet in place and might never come to pass. There's the inevitability of SOAs,
for starters, but there's also the emergence of enabling technologies, such
as enterprise service registries, security and policy management technologies,
and business process standardization efforts, like the still-gestating Web Services
Business Process Execution Language. (See related story, "SOA showstopper?,"
As a result, even programmers who have a charitable take on service enablement
are skeptical of the virtual application vision touted by the big application
server vendors. Take William Pietri, an application developer, author, educator
and principal with software development consultancy Scissor, who says he sees
lots of similarities between service enablement and many object-oriented design
"I like the trend toward loosely coupled systems with clear service interfaces;
it seems like object orientation writ large, and I think the benefits are similar,"
he says, noting that both the SOA paradigm and most OO programming models "aim
to encapsulate the technical craft inside a clean interface, and both aim for
loosely coupled systems joined by message passing."
Ironically, Pietri suggests, both paradigms also share some problems. "Honestly,
quite a lot of shops are still struggling to do OO design right. I'm just not
seeing developers naturally producing systems that will be easily integrated
with external apps," he argues.
Before companies can start building composite apps and start down the path to virtual app dev Nirvana, they first must service enable their IT infrastructures. And in spite of the best-laid claims of many ardent proponents, the service-oriented architecture is itself still an inchoate vision.
One reason for this is that SOA assumes a more or less portable understanding of what are, from enterprise to enterprise, often wildly different instantiations of traditional business processes. Because of this, service enablement is dependent on the maturation of technologies such as the Web Services Business Process Execution Language, the Business Process Modeling Language, and Electronic Business XML.
WSBPEL is the front-runner. It’s sponsored by a consortium of vendors that includes BEA, IBM, Microsoft, SAP and Sun Microsystems, and it’s positioned as a XML-based language, the purpose of which is to define Web services business processes. To a certain extent, some programmers allege, these vendors also hope that WSBPEL will help XML-over some of the shortcomings of the current SOA model.
“They hope that BPEL...will enable business analysts to orchestrate business processes directly,” explains Jeff Grigg, an independent programming consultant.
Jonathan House, an IT director with Amirsys, a medical technology company, sees another problem with WSBPEL: some of its proponents— companies including BEA, IBM and Sun—aren’t entirely disinterested parties. “In cases such as this, you have to follow the money, and not very far either,” he argues. “In my opinion, this is a group of vendors that are making an industry for themselves. You will notice that if you want to implement to the BPEL specification, you have to be a licensee.”
And because WSBPEL has the backing of most of the industry’s heavyweights, there’s little competitive pressure to improve it, House argues. “Since a lot of big players are behind BPEL, you will be hard-pressed to find competitors that will provide that marketplace tension that helps to improve these technologies.”
Like many veteran programmers, House also questions WSBPEL’s most optimistic assumption: that service enablement will spawn a thriving marketplace of external services providers, and that WSBEPL will help developers and business experts determine how to marshal them in support of business processes. “I’m sure that BPEL will mature in time, but who really cares if you don’t have wide vendor support?” House asks. “I honestly believe that this technology will have a significant impact in how companies deal with internal services and how customers deal with specific vendors. But outside of this space I don’t see anything taking off. After all, we’ve been talking about integrating services in this manner long before Web services showed up. If there were a compelling business case for it...we would have seen it long ago.”
Object oriented all over again
Pietri, like many programmers, confesses that he isn't altogether familiar with
the composite apps "fad." Based on what he's heard, however, Pietri sees a parallel
in the OO triumphalism of yesterday and the SOA euphoria and composite app optimism
of today. "A decade or more ago, people were talking up the future of object
orientation as one where OO enabled a component marketplace where you could
swap in one component for another. For example, if you didn't like one vendor's
graphing widget, you could buy another one and just pop it in place. In practice,
that never worked out," he points out. "It sounds like virtual applications
are a similar pitch, and I'd expect the results will be similar."
He isn't alone. Other codejockeys smell an OO antecedent in the composite application-scape,
too. "Isn't that the old, old reuse siren song?" asks Laurent Bossavit, a programmer
with app dev consultancy Exoftware. "[You] assemble apps from reusable components
instead of writing it all from scratch. Except that components are no longer
binaries, but [the] ends of Web wires."
This isn't to dismiss the composite apps vision by dint of association with
the exuberance of paradigms past. OO design is an established and vital software
development methodology, after all. It's just that some of the most optimistic
expectations of the OO design revolution haven't completely come to pass. And
if you think of composite or virtual applications as an especially optimistic
take on the SOArevolution, it's not unreasonable to suggest that a similar irrational
exuberance might be at work here, too.
That's a perspective endorsed by Matthew Fleming, an enterprise architect and
freelance developer whose clients include a prominent reseller of automotive
parts. Fleming isn't a knee-jerk SOAcritic, either. He cites the example of
a successful service-enabled e-commerce application that he helped design for
his automotive reseller client, which has a thriving mail order (via catalog)
and Web-based retail operation.
Showstopper and starter
Even so, says Fleming, the idea of a marketplace of consumable services, which
is in at least one sense a prerequisite for any composite application paradigm,
is a showstopper for many businesses.
"[Their] Web site allows third-party vendors to add products to the user's
shopping cart via a Web service. However, the business processing is definitely
handled by [the automotive reseller]. The issue with a virtual app is that businesses
want to control their own business processes and validations. They want to do
this because their customers are the ones-and ultimately the business itself-who
would suffer if such processes added unnecessary encumbrances to purchasing
a product, seeing tailored sports information or whatever."
That's one of the biggest problems with both service enablement and composite
apps, says Jeffrey Frederick, a senior development manager with software quality
assurance vendor Agitar Software. If a marketplace of consumable services is
ever to emerge, and if virtual apps are ever to thrive, businesses will first
need unprecedented proof of quality assurance, he argues.
"One of the challenges of the virtual application vision is that of collaboration
and of trust at a distance," Fredrick says. "If you are going to base your success
on a service provided by someone else, how do you begin that relationship? We
think a key part of this relationship will be a transparency into the development
process that is now almost unknown, and that quality level agreements will be
Not all SOA enthusiasm is premised on the idea of consumable external services,
however. And to the extent that businesses embrace service enablement to improve
agility and simplify the app dev process, what's not to like about composite
apps that are cobbled together from internal services?
Plenty, skeptics say.
Across the great divide
There's a real sense that business leaders and IT are at two removes from one
another. The former tend to view IT as a rogue practice that must be brought
to heel (made accountable to the business), and the latter has a Dilbert-like
take on the intelligence and efficacy of business decision-makers.
Not surprising, some programmers see SOAs and virtual apps as manifestations
of this conflict.
Executives are obsessed with controlling risk, and a paradigm in which applications
are cobbled together from ganglia of precisely delimited and reusable services
helps to mitigate risk and uncertainty. It's enough to make a pointy-headed boss
start drooling. The danger, says programmer Leon, is that business leaders can't
be trusted to pursue service enablement in an intelligent manner. "I think [the
virtual application space is] a pipe dream cooked up by people who have little
practical experience actually implementing real code for real people," he argues.
"When the business world wakes up and starts listening to developers and letting
developers guide them on what is and isn't doable-a huge cultural change not
likely to happen anytime soon-then and only then will more generic pluggable
applications become a reality."
To the extent that composite or virtual apps are sold on the idea of eliminating
a business's dependency on the vagaries of software development and software
lifecycle management, Leon and other codejockeys say, they will almost certainly
"The issue is that this has been tried before in the software world. At some
point in every software engineer's career, he or she will ask themselves: 'Why
is it that I cannot automate myself out of a job?'" Fleming says. "It seems
that after you make enough tools for a business- tools that get more abstract
and robust with each iteration-the business could expand and grow without developer
intervention. That never seems to work out in practice," he comments.
Believe in the payoff
There's another wrinkle: IT pros are sometimes nearly as clueless as business
leaders about just what service enablement means. And when you combine an SOA
mandate from clueless executives with cluelessness on the part of IT worker bees,
you've got a recipe for muddling through, says Ken Auer, a principal with agile
software development house Role Model Software. Auer speaks from experience.
"One client is insisting that everything move toward SOA," he confirms. "There
are multiple problems, however. The first being that the folks mandating it
don't necessarily know what that means, and the second is that many of the worker
bees in IT don't know what it is either."
In Auer's view, this company almost certainly has unrealistic expectations
about what service enablement means. On top of that, he says, many of the company's
existing applications are poorly architected-in many cases consisting of little
more than scripts talking to databases to present screens. So they're far from
ideal candidates for service enablement. The atmosphere, he says, is one of
general confusion. "We recently wrote an application for this client that we
were told required interfaces to nine services that were already in place. After
a little more research we found that there was really only one of the nine services
in place, and due to expediency, we were encouraged to just make the database
calls we needed and write code to fill in the details for the other eight."
Missing services or no, Auer's team delivered a service-enabled app on time.
But the company's SOAignorance is still a problem. "We were also encouraged
to provide a service for others to plug into. We asked which service and who
was going to use it and received nothing but silence."
Not all of Auer's experiences with service enablement and composite application
development have been completely Dilbert-esque, however. But even successful
composite app dev projects have entailed a setback or two, he says.
"[Another] client had a Web application that we wanted to get a service from,
and another service under development that was supposed to provide a lot of
things for us," he says. In the first case, Auer and his team had to do a lot
of bug-fixing on the first application, and its exposed service, to make it
reliable enough to use. And for the second service, Auer requested a simpler
interface, which resulted in additional delay.
Eventually, Rolemodel delivered a functional composite application. "[This]
application certainly uses two Web services very effectively to provide the
application we were chartered to write," Auer says. "We shipped in November
of last year and are in the process of our 10th deployment. Both of the Web
services we use are certainly useful to other applications, [namely] a scripture
server and an online subscription service."
Even so, Auer endorses a kind of healthy skepticism on the subjects of SOAs
and virtual applications. "The reality is that business processes change, technologies
change and needs of users change. The other reality is that the understanding
of all of these are very fuzzy-no matter how well specified people think they
are," he concludes. Best practices still apply, says Auer, and many of the bogeymen
of traditional software development-poor communication, bureaucratic fiefdoms-will
carry over, too.
And that's putting aside, too, the question of whether the majority of enterprise
programmers are themselves up to the challenge. "Many existing applications
are not factored well, and many of the developers who built them have not learned
to factor them well," Auer says. "There are many, many developers who never
learned object-oriented software development, which is really the underpinning
from any component-oriented anything," he concludes. "SOAs do not require systems
built from an object-oriented perspective, but without an object-oriented thought
process, the chance of building good services are slim."
Nevertheless, Auer allows, "the payoff can often be worth it."
The issue with a virtual app is that businesses want to control their own business processes and validations.
Composite apps in practice
The appearance of inevitability. Irrational exuberance on the part of technology
evangelists. Eager-perhaps uncritical- acceptance by business leaders.
These are some of the factors that have helped fuel the remarkable rise of
SOAs and that have encouraged some technologists to wax about a composite or
virtual application futurescape. But none of these diminish the basic attractiveness
of SOAs. To the extent that service-enablement is done intelligently- responsibly,
pragmatically- many enterprise codejockeys say they are onboard. To a lesser
extent, programmers are intrigued by the idea of virtual apps, too.
For starters, says Robert Watkins, a senior Java architect with one of Australia's
largest financial services institutions, service orientation does make sense
for many common applications. "Some technologies are particularly well suited
now to SOA. Authentication and authorization is largely solved via LDAP these
days, for example. Databases are becoming more SOA-ish through the increased
use of abstraction layers built on top of SQL," he notes.
Watkins says that both his current and previous employers are taking substantive
steps toward service enablement. "At my current organization, we are working
on making our core application expose a true SOA interface for allowing third-party
organizations to interact with us- and vice versa. At my previous employer,
we were focused mainly on creating SOA-based interfaces to our core systems
to allow other internal applications to use them better.
He also thinks composite apps are a good thing, but he's skeptical about whether
they will be feasible.
"The main reason is that the services have not become fully generic yet; you
still need a lot of glue code in the middle," he argues. "For example, I may
have an accounting service and a [point-of sale] system. In order to get transactions
raised by the POS service to register in the accounting service, there's a lot
of code to be written-you can almost guarantee that I can't simply tell the
POS, 'Hey, here's your accounting service- use that.' The reason is that there
is no generic accounting interface that a POS system could expect."
Cory Foy, a programmer with a mobile software development company, says his
employer is already a practitioner of virtual application development. The company
Foy works for designs custom mobile applications that consist mostly of canned
"We do...most of the [application] processing through Web service calls," Foy
explains. "This allows us to separate our UI from the data layer underneath
through a Web Service layer. This has worked well for us, though, of course,
[it] is slower than a direct database call," he continues. Even in this case,
however, the use of Web services processing is a reflection of business conditions,
not the result of a top-down technology mandate. Most of his company's customers
are using wireless cards for access, so speed isn't a prime concern.
Foy says he's pleased with the quality of these quasi-virtual applications.
"Our UI portion of the app is fairly stable. All of the modifications happen
dynamically based on the results of Web service calls and config files," he
says. He's far from an SOA or virtual app evangelist, however. "I don't think
[they're] fringe cases, but I do see them as specific solutions to specific
Looking for the right one
Jonathan House, an IT director with Amirsys, a medical technology company, says
he's ready for virtual apps. "We are well positioned to take advantage of virtual
applications if we ever find one that would be useful to our organization,"
he comments. "Our application interactions are segmented into specific internal
services of which there is well-defined interfaces that allow us to replace
the underlying service by simply creating a new interface implementation for
that service." But House, too, says his company's approach hasn't been dictated
by a virtual app just for the sake of it but by sound design sense. "Our approach
to decoupling our application services is not motivated by a potential move
to virtual applications, but rather from good enterprise systems integration
Based on his experiences with one of his company's service-enabled applications,
however, House is skeptical about the viability of the virtual application vision.
Even if companies like Amirsys take pains to segment their internal application
interactions into services, House says, the third-party vendors that must inevitably
provide key services- financials, inventory management, customer information
management and other key processes-will almost certainly complicate things.
They have the oldest reason in the world to do so, he points out: vendor lock-in.
"There is exactly one product that we are using that even comes close to the
virtual application concept-Salesforce.com," he says. "We have done some work
to integrate this application into our IT environment... with success," he comments.
But the promise of service portability-to plug generic, plug-and-play CRM services
into the customizations Amirsys has built-remains elusive. "There is no chance
of us switching vendors-the interface points are tightly coupled to how Salesforce.com
See Related Story: Codejockeys
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Components for SOAs and
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By Alan Radding
enablement = vendor entitlement?
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