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Mainstream adoption and implementation of SOA is rapidly approaching critical



As Microsoft continues to release SOA-enabled platforms like Vista, Longhorn,

Office 2007, and BizTalk, the availability of services within your environment

continues to explode. Your SOA implementation can now take advantage of a wealth

of services offered not only by your diligent development efforts, but by the

underlying platforms themselves. Its an exciting time for developers, but

theres something missing: a rich, interactive user-interface that takes

advantage of the services offered by your SOA implementation.

Analysts have recently coined the term WOA (Web oriented architecture) as an

all-encompassing acronym that describes the explosion of Web 2.0 technologies

forming the foundation for deploying RIAs (rich interactive applications).

Whether youve adopted Vistas new markup language XAML or discovered the world

of AJAX with Microsofts ASP.NET AJAX, youve discovered WOA and the benefits of

pairing Web 2.0 with SOA to enable rapid development of new applications that

address the volatile business environment of todays Internet.

Its unlikely that you anticipated the resulting stress on the network,

however, and have now discovered yet another TLA: NOA (network oriented angst).

Its purely coincidental, of course, that this acronym, when spoken rapidly, is

the same sound that network administrators and developers make when discovering

the effects of the explosion of traffic and connections arising from the

combination of WOA and SOA deployments.


The introduction of WOA as the primary mechanism for building out the

client-facing portion of a SOA application has completed the end-to-end

equation. Unfortunately, the two architectural styles combined can incur serious

performance penalties that may dampen the initial excitement over this new breed

of application.

Making Your Connections

The most obvious impact on the network of deploying a WOA application is the

rate and size of requests exchanged between the browser and the server. An

application that, when developed in a page-centric paradigm, had a predictable

usage pattern suddenly balloons into a quagmire of unpredictable requests.

Instead of the user following a designated flow through the application, they

are suddenly clicking around, loading data willy nilly, while under the covers

the browser is doing its own thingupdating RSS feeds and live data while

simultaneously handling the increase in user initiated requests for more data.


This increase in requests has a deleterious effect on your application

infrastructure. The server that once managed to service thousands of concurrent

users is suddenly only able to service a fraction of its former capacity. The

network is clogged with three or four times the amount of traffic, giving the

server and intermediate delivery infrastructure that bloated sensation that

comes from handling just one more request.

The server slows down. Taxed with managing more connections, more often, the

overhead of setting up and tearing down TCP sessions combined with the actual

work of serving the requests is chewing up resources faster than a kid eats an

ice-cream. The browser, ever concerned about the server, starts sending out

concerned queries about the status of its last request. The additional TCP

retransmited begins to cause additional congestion on the network as

intermediary devices try to keep the traffic flowing as smoothly as possible.

Your network performance suddenly seems like a typical afternoon at Chicago

OHare. Congestion. Delays. Cancellations.


And then your application starts missing connections. Timeouts on the server

caused by the overload of requests and congestion on the network cause real-time

updates to simply stop updating. Requests generated by the user are suddenly

lost in the ether or take forever to return, resulting in performance problems

with your application and causing acceptance of your new WOA application to


You and the network team scramble to find the answer, and then realize that

youve all been afflicted with the same thing. Youve all got NOA.

The Cure

Luckily there are several cures for NOA, but the one best suited to your

environment, application infrastructure, and budget is heavily dependent upon a

number of factors, all of which are unique to your organization. One aspect of

the cure that is common to all organizations is that it will require

coordination between you, the server, and network administrators. This

collaboration is increasingly important in the world of WOA and SOA as the

factors that affect application performance are increasingly distributed across

disparate areas of expertise.


Performance Tuning: As is sometimes the case, a few tweaks of your

application server may solve the issues inherent with deploying Web 2.0

applications. Increase the TCP timeout value to be in-line with the rate of

requests coming from your client. Check the Connection Timeout in IIS and make

sure its set higher than the anticipated request rate. This will reduce the

number of connections that time-out due to network congestion and will further

reduce the overhead of initiating TCP connections as existing connections can be


Increase Browser Connections: Depending on your level of control over the

browser, you can manually modify the configuration imposed limits on the number

of simultaneous connections allowed by the browser. This requires a registry

edit for Internet Explorer, so if your primary users are consumers this may not

be an acceptable option. Increasing the number of connections available from the

browser will remove the delays introduced by the client waiting for an available

connection over which it can make a request.

Deploy an application delivery network solution: These network-deployed

devices are designed to efficiently manage connections for all types of

web-based applications. With a plethora of options to choose from, these devices

can not only clear up your connection problems, but provide additional benefits

such as security, acceleration, compression, and optimization of applications,

all of which will severely reduce and even eliminate the possibility of a

recurrence of NOA.

If youre already experiencing the effects of NOA, consider the options

above. If youre concerned about preventing NOA in your organization altogether,

consider deploying an application delivery network solution before you deploy

your WOA-based application to ensure a smooth deployment and to reduce the

possibility of catching a nasty case of NOA. As grandma said, an ounce of

prevention is worth a pound of cure.

Lori MacVittie

The author is Technical Marketing Manager, F5 Networks