Level: Introductory Stephen B. Morris (stephenbjm@yahoo.com), CTO, Omey Communications
10 Jul 2007 Web 2.0 repositories can help you create a flexible software
architecture, which can easily be plugged into Web 2.0 communities and
extranets. Creating a fluid system that also works in accordance with requirements for
modifiability, performance, security, scalability, and reusability can be
challenging. In this article, learn techniques to help ensure your Enterprise Web 2.0 architecture meets your
quality requirements.
The drive to automate
Companies need to control costs while at the same time providing more services.
As a result, they're driven to automate enterprise operations. IT administration
budgets are under pressure, and even this business-critical area is now being
outsourced. Service density is increasing, and the level of interconnection
between services is also growing.
With increasingly wide geographic dispersion, most organizations are finding they have an
unexpected need for Enterprise Web 2.0. This service, or set of services, can make it easier
to aggregate key content, provide for collaboration between geographically
separate groups, and achieve business-critical aims, such as multiteam design and
development efforts, contract bidding, and corporate reorganizations.
In this article, you look at the architectural aspects of Enterprise Web 2.0 deployment and
explore a management-centric approach. You will also find out ways to make Web 2.0 architecture more reliable than its
predecessors by simplifying the major components. Learn about additional techniques, such as adding
manageability and inversion of control, to provide complex and dynamic component
relationships, helping both users and system administrators. Web 2.0 users see
business services, and Web 2.0 IT administrators see manageable technology elements,
giving each group a clear view of the enterprise.
Software architecture
quality attributes
Successful enterprise architectures must have a range of quality attributes. It
helps to define these attributes up front. The attribute set then forms a
blueprint that guides the phases of analysis, design, coding, deployment,
maintenance, update, and so on. The architecture lives on as a vision of what the
end result should be. Typical quality attributes include (but are not limited to)
the following:
- Modifiability. Ease with which the underlying software can be modified
- Availability. Extent to which the architecture makes possible defined levels
of uptime (for example, no more than 5 minutes of downtime per year)
- Performance. Architecture's measurable service levels
- Security. Architecture's defined security benchmark
- Scalability. Extent to which the architecture can grow in both user levels
and number of services supplied
- Reusability. Ability to incorporate the architecture in part or whole into a
new architecture
Architectures aren't abstract entities—you can visualize them in different
ways, including the system's physical environment, the module decomposition view,
the process view, the client-server view, the code view, and the layered view.
Each view shows one or more of the required quality attributes.
An additional quality attribute is manageability: the extent to which an
architecture simplifies automated management. The elements of Enterprise Web 2.0
provide a compelling platform for manageability.
Enterprise Web 2.0
elements
Enterprise Web 2.0 promises a range of capabilities not present in Web 1.0. This
article discusses key Web 2.0 capabilities, including:
- Content aggregation
- Community support
- Collaborative self-publishing
- Asynchronous content update
- Rich clients (enhanced browsers)
- Loose business process interaction and manipulation
Products that fulfill some or all of these are already available, including
IBM® WebSphere® Portal software and Sun
Java™ System Portal Server.
You can see these Web 2.0 capabilities in Figure 1.
Figure 1. Enterprise Web 2.0
capabilities in action
The left side of Figure 1 illustrates a community of users. This is a
loose collection of users who come together for a short- or long-term effort.
Community members can collaborate together using their rich-client tools. These
tools let users incorporate multiple streams of data and perform online content
editing from a range of intranet (and possibly external) data sources. This
client-editing capability requires a new generation of browser technology.
The middle of Figure 1 illustrates much of the software that makes Web 2.0 a
reality. Aggregation facilities combine content from Web sites, databases, and
other sources. This data is then presented to the rich clients, which combine the
supplied content as compound data: data that can include any and all
formats, such as audio, video, and so on.
Another important data source (not shown in Figure 1) is semantic search data.
This function is included in the aggregation function in Figure 1; its purpose is
to present only data that is semantically relevant. Rich clients request such data
and render it as part of their compound documents.
Rich-client documents can be saved to a persistent medium as new documents or as
part of the data from which they originated. The area of data origination is
illustrated at right in Figure 1. It's important to understand that Enterprise Web
2.0 data sources aren't necessarily static databases—data can come from
traditional databases; static or dynamic Web pages; and business processes, such
as Business Process Execution Language (BPEL) servers.
Portlets can form the basis of Web 2.0 client facilities. This format is
particularly useful for asynchronous updates—another feature of the middle part
of Figure 1. Asynchronous updates let data changes propagate to the clients in a
Web 2.0 environment.
The Enterprise Web 2.0 architecture includes at least three physical or logical
layers. Where does manageability fit into this picture?
Manageability as an architectural quality attribute
For an architecture to be manageable, it must be able to provide:
- Automation of the operation of key elements
- Ease in configuration of key elements
- Fault resistance
- Ease in measuring performance
- Alignment of services with defined metrics
- System security
Given that the Enterprise Web 2.0 clients are collaborating, aggregating content,
and manipulating complex documents, a robust platform is required. Supporting
manageability helps you provide such a platform. Consider what providing
manageability means in Figure 1.
The elements at the right in Figure 1 operate in optimal fashion when they're
managed: Web/BPEL servers and database engines need to be properly configured,
balanced, and monitored for good performance. If you measure performance, then
it's easier to know when to upgrade or add new hardware. If service-level
agreements exist (for example, no more than 20 minutes of downtime per year), then
it's important to continuously collect data on uptime. If any private data is
stored in the systems at right in Figure 1, then the more easily you can secure
it, the better.
Providing manageability may require multiple additional complex systems. The
"how" of manageability isn't as important as "why." It makes sense to try to make
management facilities as usable as possible.
In the next section, we look at Web 2.0 elements and the enhancements provided by
embracing manageability.
Content and software
repositories
In Web 2.0, repositories come in two flavors: content (data) and software
facilities. In Figure 1, data repositories are on the right. Software repositories
provide a means for storing the tools and middleware that form the Web 2.0
computing infrastructure. Software repositories are optional elements and aren't
shown in Figure 1; they provide a means for deploying the Web 2.0 tools.
Web 2.0 communities in
the enterprise
The community concept is perhaps the most novel element of Web 2.0. Such
communities reflect an organization's ability to help groups of disparate and
geographically dispersed users come together for a project, collaborate, produce a
deliverable, and then disband. How does manageability affect the community
concept?
Community management operations include the creation, addition, and deletion of
users; and, at some later date, the deletion of the community. Some important
communities, once formed, might never be destroyed (for example, a community like
HR-updates-to-staff). A manageable architecture simplifies these management
operations.
Fault resistance in a community relates more to the handling of downstream faults
(faults in a data source). A possible fault condition could be a community that
becomes too large to fulfill its original purpose.
Extranets: an old
solution in a new guise
Extranets have traditionally been deployed between partner organizations that
need to share resources at a distance. For example, a software supplier may
provide code on a contract basis to another organization. One of the partners can
set up an extranet so they can share resources such as machines, software,
individual expertise, and so on.
In the context of Web 2.0, extranets may be constructed as restricted
communities. Such communities require stringent security arrangements; for
example, it may be undesirable or even illegal to share certain intranet data with
external partners. Such considerations make a strong case for Web 2.0
manageability.
Dumbing down Web 2.0
software components
Earlier, the Manageability section defined providing
manageability as a freestanding set of quality attributes. Unfortunately, this
rarely happens in system design. In enterprise architecture, management facilities are
generally added after the main design and development is complete. The late
addition of key elements generally results in solutions that are difficult to
manage. It doesn't have to be this way!
Defining manageability requirements up front along with other architectural
quality attributes provides an interesting opportunity: Management facilities can
be decoupled from other Web 2.0 artifacts. In effect, Web 2.0 software components
can be intentionally dumbed down because they don't have to contain compile-time
management software.
One open source tool that already uses this technique is the Apache Java 2
Platform, Enterprise Edition (J2EE) reference application server Geronimo. This
tool is built in such a way that components can be configured by dependency
injection to provide support for required management operations. Geronimo's
components are built to accommodate dynamic management requests. This allows for a
more flexible management model.
This also demonstrates the power of an architectural approach: The required
quality attributes act as a constant reminder to those who build the system. It
also allows for an improved separation of concerns in the finished system.
Summary
Organizations constantly strive to reduce IT costs. Outsourcing can take you
part of the way, but may make it harder for geographically dispersed groups to get
together and deliver on short-term projects. Web 2.0 (or Web 3.0 as Enterprise Web
2.0 is sometimes called) can provide an elegant solution to the needs of highly
dispersed organizations.
Software architecture quality attributes provide a powerful statement of what an
architecture seeks to achieve. Traditionally, architects have used a wide range of
views to try to ensure that the required quality attributes are achieved.
Manageability is an architectural quality attribute that receives little
attention. Augmenting the architecture of Enterprise Web 2.0 with manageability
attributes adds configurability, fault resistance, the ability to measure
performance, security enforcement, and more.
You can apply these manageability attributes to the major artifacts that form
Enterprise Web 2.0, such as repositories and communities. Providing manageability
as a key architectural quality attribute paves the way for easier deployment and
operation of Web 2.0.
Perhaps the most unexpected benefit of Enterprise Web 2.0 manageability is the
scope it provides for dumbing down constituent software elements. The Apache
Geronimo project provides a model for this technique with its support for
dependency injection and inversion of control. This approach gives you a more
flexible management model than has traditionally been the case. As a result,
you'll find that Enterprise Web 2.0 lends itself particularly well to architecture-level
manageability.
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About the author  | | | Stephen Morris is the CTO of Omey Communications in Ireland. For the past 20
years, Stephen has worked for some of the world's largest networking companies on
a wide range of software projects, including J2EE/J2SE-based network management
systems, billing applications, porting and developing SNMP entities, network
device technologies, and GSM mobile networking applications. He is the author of
Network Management, MIBs and MPLS: Principles, Design and Implementation (Prentice Hall PTR, 2003), as well as several articles on network management and other topics for InformIT and OnJava.com. |
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