mPulse

Tuesday, August 25, 2009

Effective Web Performance: Measurement-First or CDN-First?

A hallway conversation this morning brought up a very interesting point about the relationship between Web performance measurements and Content Delivery Networks (CDNs). When choosing between a Web performance measurement solution and a CDN, which service should come first?

Companies facing dire and obvious Web performance issues will want immediate results, leading them to fall into the CDN-First camp. Deploying a CDN will have a positive effect on response times, increase user satisfaction, and may even increase customer conversions, in the short term.

In six months, deeper questions may start to be asked. A core question that will need to be answered by CDN-First organizations will be "Are we using the CDN effectively and efficiently?".

A company that makes the leap to CDN deployment without assessing the overall performance environment of their Web site may be faced with a situation where they can't tell if they need more, less, or different CDN strategies in order to continue to succeed.

As a result of the buyers remorse that can result from the leap directly to a CDN, I highly recommend the Measurement-First approach when selecting a CDN.

To help you become an advocate for the Measurement-First approach, come to the table during the CDN discussions and ask three questions. The answers will allow your organization to make the best and most appropriate CDN decision.

1. Is the CDN necessary?


In most cases, the answer to this is a resounding yes. But what can happen with a sudden shift to the CDN is that a organization overlooks those things that they can do themselves to gain some initial performance improvements.

Baselining the existing site before deploying a CDN will allow items and elements that need to be improved to be clearly identified. In some cases, an organization can fix some of these on their own to improve performance before investing in a CDN. In other cases, measuring the performance of a site may clearly indicate that third-party content is responsible for the performance issues, which would likely not be fixed by a CDN deployment.

Measurement-First policy helps clearly identify the geographies that have the worst performance before deploying the CDN. If performance in the US is acceptable, while performance in Europe or Asia-Pacific is intolerable, then the CDN deployment may initially be targeted to respond to the greatest pain first.

Understanding the current performance of your existing site can reduce the cost of the initial deployment and maximize the the long term effectiveness of the deployment.

2. Which CDN is best for us?


For a complex modern Web site, content comes in many different shapes, sizes, and formats. The thing is, so do CDNs. As I've discussed before, understanding what the CDNs vying for your business do and do well is as critical as the process of vetting their effectiveness compared to delivering the site yourself. The performance boost given to you site by a CDN may vary by region, leading your team to select one CDN for Europe and another for the Asia-Pacific region.

CDN performance can also vary based on the content you are asking them to accelerate. One CDN may be good at streaming media, while another may be better at static content (JS, CSS, Images, etc.), while yet another is better at accelerating the delivery of dynamic content.

Choose your CDN(s) based on what you need them to deliver. In some cases, one size does not fit all.

3. Is the CDN delivering?


This may look like a question for after the purchase has been completed and the solution deployed, but you will never know if the solution is working effectively unless you have a baseline of your performance before the deployment, and from your origin servers after deployment.

Measuring the performance of the CDNs under all conditions and from all perspectives (Datacenter, Last Mile, and from within the Browser) doesn't stop with the selection of a CDN(s). It becomes even more critical once the CDN solution(s) is rolled into production in order to ensure that the level of service that was promised during the sales cycle is delivered once you become a customer.

Constantly validate the performance of the CDN-accelerated site with the performance of the non-accelerated origin site. Have regular meetings with, and channels of communication into, your CDN(s) to discuss not only existing performance, but how changes you and/or the CDN provider are planning may affect performance in the future.

Takeaway


CDNs are a critical component for any Web business that wants to scale and deliver services to a national or global audience. But selecting a CDN should come after you have a very strong understanding of the current performance of your own Web site.

After you have measured and identified the items you can do to improve your own performance, your team will have greater insight into the areas of your site where the services of a CDN(s) can have the greatest impact.

The Measurement-First approach to selecting a CDN will ensure that you select a set of services that exactly meets the unique performance challenges of your site.

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