Tooling up for Components
With component-based development becoming today's hot buzzword, it is easy
to forget just how recently this "plumbing" was developed. Just ask
Countrywide Home Loans, the nation's largest independent home loan provider.
When the firm began developing a loan origination application based on Microsoft
OCX controls -- the forerunner of today's COM and DCOM component models -- it
had to invent many of the basics. This included tasks such as reading and linking
component interfaces, as well as maintaining database connectivity, all of which
are taken for granted today.
What makes component-based development attractive to users is its potential
to reduce application complexity and promote reuse. However, prior to the emergence
of specifications from Microsoft Corp., Sun Microsystems Inc., Cupertino, Calif.,
and the Framingham, Mass.-based Object Management Group (OMG), the only choices
available to application managers were inventing their own component models
or relying on tool-specific ones.
Yet the new standards are just that -- new. For example, the Enterprise JavaBeans
(EJBs) 1.0 standard supports traditional transaction models, but will not offer
"entity" beans attuned to newer, object transactional models until
an as-yet unscheduled upcoming release.
Nevertheless, the emergence of COM, Corba and various flavors of client- and
server-side JavaBeans is happening not a moment too soon. Packaged applications
are taking a larger bite out of internal development, with the market expected
to double to $100 billion in five years, according to International Data Corp.
(IDC), a Framingham, Mass.-based research firm. Theoretically, components should
make internal development a more competitive option, with tool-makers taking
notice. Most development tools now provide the ability to automatically generate
COM, Corba or Java components, or at least develop interfaces to them.
Generating a standard component is only the first step, however. What about
how the components should be bolted together? Without guidelines that define
the relationships between various parts, conflicts might occur. In automotive
manufacturing, for example, a wheel attached with a screw could be threaded
into a dashboard with the same fitting. You probably would not want to drive
such a car, however.
Translated into software terms, a component for a customer order credit limit
and product paint color could sport compatible wrappers or interfaces, and their
behaviors might not necessarily conflict. But could you imagine an application
piecing them together without additional logic?
Not surprisingly, a growing number of tools are addressing the need to provide
this elusive context. Some tools now bundle their own native repositories while
offering grudging support of third-party repositories from Microsoft, Unisys
Corp., Blue Bell, Pa., or other vendors. A few vendors, such as Select Software
Tools Inc., Irvine, Calif., offer separate component manager products that document
the components stored in those repositories. And other firms, such as Microsoft
and Sybase Inc., Emeryville, Calif., bundle front-end and middleware components
under a common umbrella.
UML-based modeling tools from Platinum Technology Inc., Oakbrook Terrace, Ill.,
Rational Software Corp., Cupertino, Calif., and Riverton Software Corp., Cambridge,
Mass., are committed to generating not just raw objects, but components that
are compatible with Microsoft, Corba or Sun standards. However, the most popular
feature is the framework, a library of generic processes for functions such
as workflow or system functions, such as mapping application functions to the
operating environment. In some cases, frameworks are even going to the "next
step" by including business templates that are almost applications in the
Been there, done that
Component-based development did not dawn with COM/DCOM or Corba. During the
heyday of two-tier client/server development, Forté Software Inc., Oakland,
Calif.; Nat Systems, Paris; Magic Software Enterprises Inc., Irvine, Calif.;
Netron Inc., Toronto; Progress Software Corp., Bedford, Mass.; Seer Technologies
Inc., Cary, N.C.; Sterling Software Inc., Dallas; and Uniface Corp., now part
of Compuware Corp., Farmington Hills, Mich., offered tools that supported multitier
development. Because component and application communication standards had yet
to exist, many of these tools devised their own formats to modularize code.
Forté, for instance, built its own format and messaging infrastructure
layered atop TCP/IP.
In most cases, these veterans are slowly embracing the new generation of DCOM/
ActiveX and Java/IIOP interfaces in order to protect their installed base. There
is also the common refrain that open systems standards take time to achieve
the robustness of their proprietary counterparts. For example, while Forté
offers the necessary interfaces, it still claims that its
proprietary format offers superior multithreading and application messaging
capabilities, and in the long run, may offer DCOM/Corba/JavaBean bridges.
Other vendors have added component-based development capabilities to tools
built initially on Case and entity-relationship modeling foundations by extending
their meta models to support component specification. Sterling's Cool:Gen product,
for example, now generates Microsoft COM components.
But there are vendors that are reticent about supporting the new generation
of de facto component standards. Netron maintains a proprietary "frames"
architecture that relies not on distributed object request brokers (ORBs), but
on traditional CICS-style transaction monitors. Like many tools on the market,
Netron provides "frameworks" consisting of groups of generic functions,
such as SQL call generation, reporting and Cobol screen painting. While Netron
has not yet generated COM or Java components, it promises to do so in the future.
Microsoft and Sybase are among the best examples of vendors trying to be almost
all things to some people. Microsoft's Visual Studio 6.0 -- which despite its
release number is actually the second release -- combines all of Microsoft's
development tools. It includes languages, an HTML application builder, a transaction
server, a distributed application "wire" analysis tool, a lightweight
version of the Rational Rose modeling tool and several component management
tools built around the Microsoft Repository. Like Microsoft Office, Visual Studio
features toolbar-level integration of a collection of separate tools that can
generate -- what else -- COM components automatically. Although data modeling
and testing are notable omissions, Visual Studio is one of the broadest component
development environments available -- that is as long as you are content working
only in a Windows environment and with COM component models.
For its part, Sun has unveiled Java Studio, which includes a visual development
tool, a UML modeler and configuration management. It also offers Java Workshop,
which provides GUI testing capabilities and will eventually include a load-testing
element. Java Studio currently supports Java- Beans, but is still working on
EJB support. Of course, you can develop and test all you want, as long as you
are working on a 100% pure Java virtual machine environment.
If the pure Microsoft or Sun solutions are too restrictive, Sybase's Enterprise
Applications Studio provides a more agnostic alternative. It consolidates its
PowerBuilder and Java tools with the Jaguar Transaction Server that supports
COM, C++ or Java components, a light version of the Riverton HOW modeling tool,
and a development copy of its mobile database (SQL Anywhere). The Sybase offering
might provide a migration path for classic PowerBuilder fat client applications,
but PowerBuilder developers will have to be patient. Jaguar will not support
PowerBuilder objects until next year.
A framework in every pot
Next to component, "framework" is probably the most overworked term
in application development today. And virtually every tool supplier claims to
At their core, frameworks are pre-built system services that allow application
components to work with operating systems, visual environments and data sources.
The goal is to avoid the need for developers to reinvent some of the basic plumbing,
a critical productivity requirement that keeps development teams focused on
what counts: business logic. Providers such as Blueprint Technologies, McLean,
Va., Persistence Software Inc., San Mateo, Calif., Riverton Software and Template
Software Inc., Dulles, Va., deliver varying combinations of services, such as
transaction state maintenance, database mappings, application logic mapping,
and partitioning and process monitoring. Riverton backs this up with a UML-oriented
modeling environment, while Blueprint Technologies relies on Rational Rose for
application models. Platinum, meanwhile, is building a framework for component
development based on the Catalysis methodology.
Most of these tools also offer business logic builders or templates. For instance,
Blueprint Technologies and Template are planning business logic frameworks for
specific vertical industry sectors. In some cases, these frameworks could morph
into packaged applications in the rough that could stand on their own or fill
the gaps not covered by popular enterprise resource planning (ERP) packages,
such as SAP's R/3.
One of the major issues when scaling up component-based applications is delivering
robust back-end services. Distributed applications require more complex back-end
services than simply connecting to a database. For instance, a simplistic view
of a distributed securities trading application would replace monolithic logic
with the following process: A trading order component would invoke a customer
credit history component, which in turn invokes credit threshold components.
However, each of these components might be based on different servers. Therefore,
there has to be a way for "disparate" components to talk to and invoke
One approach is a transaction server that coordinates the messages sent back
and forth. Providers such as Microsoft and Sybase promote their bundling of
native transaction servers with development tools. This is based on a traditional,
transaction processor monitor view of the world that regards messages as transactions,
not necessarily as objects.
The other approach is the object request broker model that involves multiple,
individual interactions between distributed
objects. Surprisingly, Scotts Valley, Calif.-based Inprise Corp., which offers
a spectrum of development tools (JBuilder, for example) and ORB middleware (like
its Visi- Broker ORB, which the firm added as part of its Visigenic acquisition),
has not yet added any integration between those products. Conversely, New York
City-based Prolifics Inc., which offers only development tools, provides interfaces
to Microsoft Transaction Server (MTS) and the Tuxedo transaction monitor from
BEA Systems Inc., Sunnyvale, Calif. Prolifics will also add support for BEA's
new M3 Object Transaction Manager.
Of course, the choice of transaction server vs. ORB as a back-end strategy
for building an engine capable of supporting high-throughput applications is
a philosophical debate. ORBs are the purer, but less mature view. Proponents
claim distributed object-oriented approaches are, in the long run, more scalable
as they avoid the use of monolithic transaction monitors or servers that limit
flexibility, and threaten potential bottlenecks and single points of failure.
Transaction processing promoters respond that their scalability and robustness
is proven. Object transaction monitors theoretically combine the best of both
worlds, but BEA's M3 product is barely a few months old.
Another approach to the problem is taking the well-worn technique of caching
inside the component itself. Persistence Software uses this method, and has
developed an application server that caches frequently used logic and data to
minimize database I/O for EJB and C++ components.
The other side of the scalability issue is deploying components. Admittedly
not a showstopper for small applications, the issue becomes more critical to
high-throughput applications as they are likely to be more complex and involve
larger populations of components. Repositories and component managers take care
of half the equation: They store and organize components, but few, if any, are
capable of deploying them at runtime. When large numbers are involved, it becomes
necessary to ensure that the right versions of the components are deployed at
the right time.
InLine Software Corp., Sterling, Va., has proposed an interim solution. A meta
data modeling tool that acts as the bridge between Java development tools and
application servers can extract EJB archive files characterizing business functions
and convert them into eXtensible Model Interchange (XMI) files, a spin-off of
the eXtensible Markup Language (XML). At runtime, XMI files are loaded into
a temporary repository. Nonetheless, InLine admits that this is not a long-term
substitute for a real, permanent repository.
Testing, however, remains the Achilles' heel of component-based development.
Automated tools still tend to focus on aggregate behaviors, such as how well
the screen navigation works and how well servers can handle the logical processing
loads. For instance, Mercury Interactive Corp., Sunnyvale, Calif., recently
added the capability to test DCOM calls on MTS. Meanwhile, Rational has consolidated
its various load and screen testing tools from SQA, Performance Awareness and
other acquisitions into the Darwin Performance Studio.
But as organizations deploy larger applications involving larger groups of
components, only careful design can prevent components from being deployed with
overlapping or conflicting functionality. Today's automated testing technologies
can test DCOM or JavaBean wrappers, as well as perform data-driven regression
tests to check the soundness of the logic under stress. However, they cannot
look under the hood to judge whether a customer component identifying a customer
might overlap with a credit history component that duplicates customer information
Testing is but one of a number of issues that impact component development.
The most effective means for scaling up component-based applications remains
a topic of debate. And, of course, the issue of how standard "standard"
components will be remains. For instance, could a developer of a back-end COM
business component be confident with generating applications in the COM-compliant
language or tool of their choice?
There is little question that components are in most developers' futures. But
for all these questions, there is currently only one sure answer. In the world
of component-based development, waiting for solutions remains a virtue.