Pick Up Your Web Pace With Novell Content Exchange
Articles and Tips: article
01 Jan 2001
Editor's Note: Lest you walk away from this article asking, "Are you talking to me?" we thought we'd better explain something. When we say "you" in this article, we mean anyone who works for a company with a web site that sells or conveys information about products or services. Regardless of your company's specific line of business, if your company's web site publishes large or limited volumes of web content, we're talking to you.
If you work for a company that publishes content to the web, you are probably aware that meeting web users' expectations is tough. On one hand, users want a snazzy site. On the other hand, they want snappy response--literally. Snap your fingers 20 to 25 times: That's about how long users are willing to wait for a web page to download. (See "You Want It When?" )
Unfortunately, snazzy page designs replete with photos, sound, animation, and video clips can slow content delivery. Ironically, if your site's pizzazz manages--as you hope--to attract new users but attracts them in a sudden burst, this also can slow performance to an unacceptable level. (See "Cases in Point.")
However, flashy content alone cannot be held accountable for less-than-adequate response times. In fact, poor web site performance has several culprits. For example, too much traffic on too few web servers certainly contributes to poor response times. Excessive traffic may also cause users' browsers to "time out," ultimately preventing users from accessing your company's web site altogether. Similarly, overloaded web servers that have to retrieve content from backend databases or have to encrypt sessions using Secure Sockets Layer (SSL) may leave users drumming their fingers.
A NEW APPROACH TO THE SAME OLD PROBLEM
To solve your web problems, you can simply add more web servers to accommodate the growing numbers of users and applications. But get real. "Who's going to pay for all that hardware?" asks Martin Marshall, an analyst at Zona Research (which is an Internet research and reporting firm). "You're talking some big bucks there." (See "The Price Is Right?")
Expense aside, the just-add-more-servers strategy is an ineffective and impractical way to prepare for sudden Internet crowds. After all, as Marshall points out, "How will you ever know how much is enough?"
In lieu of (or in addition to) adding more web servers, you can purchase and install a caching appliance, such as a Novell Internet Caching System (ICS) appliance. A Novell ICS appliance operating in web-acceleration mode accepts requests from web users' browsers and checks to see whether or not the requested data is in cache. If the data is in cache, the appliance returns the data directly--without burdening the web server with requests. This arrangement clearly takes a load off your company's web servers and, thus, certainly improves response times.
However, front-ending web servers with one or more caching appliances does nothing to avoid the other usual suspects of poor performance. After clearing your company's web site, content still has a long way to travel before reaching its destination. En route from your company's web site to users' desktops, web content may encounter several performance pitfalls, including poorly planned intersections between backbone providers' networks. (For more information, see "Measuring To Tailor Your Company's Web Site for Performance.")
One way to clear many of the performance-inhibiting obstacles on the Internet is to push content closer to your users. To store content at the Internet's edge, some content publishers are contracting with companies (such as Akamai and Mirror Image) that own and operate content distribution networks (CDNs).
CDNs are hierarchies of worldwide caches that first retrieve and then store much of the content users request. In this way, a local CDN server--rather than a remote web server--can respond to subsequent requests for the same content. The point, of course, is to skirt unreliable Internet routes and thus improve response times.
CDNs sound great and, in fact, provide an effective way to deliver content over private lines. However, CDNs have a couple of drawbacks. For example, CDNs do nothing to give your company's web site a boost over the critical first foot of the Internet (that is, from your company's web servers on to the Internet or to the CDN). Also, the URLs associated with content that should be distributed over a CDN must be translated into a CDN-specific format. (See the "Accelerating the CDN Exchange" section.)
If you don't like the idea of translating URLs, what other options do you have? What else can you do to deliver exciting content to users quickly and consistently, regardless of the number of users that hit your company's web site? Actually, you have several options, but perhaps none so simple and effective as the service options based on Novell Content Exchange. Leading web-hosting providers are now offering these services through partnerships with Novell.
WHAT IS NOVELL CONTENT EXCHANGE?
Novell Content Exchange is a fully managed web site acceleration service. Did you catch that? Novell Content Exchange is a service--not a product. Novell sells its Content Exchange service to web-hosting providers. These web-hosting providers, in turn, sell their particular version of the service to companies, such as yours, that publish content to the web. In other words, you can purchase a Novell Content Exchange service not from Novell but from web-hosting providers that have partnered with Novell.
For example, GlobalCenter Inc., a Global Crossing subsidiary and a leading Internet Service Provider (ISP), is the first of Novell's hosting provider partners to offer a Novell Content Exchange service. GlobalCenter calls its implementation of the service Content Acceleration Exchange. GlobalCenter's Content Acceleration Exchange is already available throughout the United States and Europe and will be available in the Asia-Pacific region later this year. (For more information about GlobalCenter's Content Acceleration Exchange, visit www.globalcenter.net/cae.)
GlobalCenter's Content Acceleration Exchange and other providers' services that are based on Novell Content Exchange work by storing your company's web site content--as is--in local and global Novell Content Exchange arrays and, optionally, in CDN caches that are closer to users. As a result, Novell Content Exchange significantly reduces the load on your company's web servers and also avoids unreliable Internet routes. (SeeFigure 1.)
If this process sounds confusing, don't worry about it. This article later explains in detail how and why Novell Content Exchange works. For now, just know this: The net effect of using Novell Content Exchange is that web users, even large crowds of them, can consistently download pages from your company's web site at rates that meet users' expectations.
"Novell Content Exchange was designed to handle multiple gigabits per second of Internet traffic," says Ari Newman, Net content director of network operations at Novell. As a result, Novell Content Exchange "is well suited for content publishers with large [web] sites pushing significant bandwidth." However, Newman adds, "that's not to say that the service doesn't perform well for smaller [web] sites as well."
Novell Content Exchange currently includes the following components that are specifically designed to improve your company's web site availability and response times:
Novell Content Exchange caching arrays
CDN transformation modules
COOL, EASY CACHE
The core of Novell Content Exchange is Novell ICS, a proxy caching appliance technology that Novell licenses to partner original equipment manufacturers (OEMs) such as Dell and Compaq. (For more information about Novell ICS, see "Cache In on the Web With Novell ICS Appliances,"Novell Connection, April 2000, pp. 6-19.)
Within each of a web-hosting provider's data centers, Novell installs a fully redundant cluster of Novell ICS appliances. Newman declines to specify which make and model appliance Novell is using for Content Exchange, saying only that "it's the latest and greatest." Whatever the specific model, however, the ICS appliances Novell uses for Novell Content Exchange will always run the latest version of Novell ICS software (which is currently Novell ICS 1.3).
Each Content Exchange cluster of Novell ICS caching appliances is linked together and managed through a redundant array of Layer 4 switches. The cluster is then linked to the hosting provider's Internet backbone through redundant router connections. Finally, each Novell Content Exchange array is linked with other Content Exchange arrays throughout the world.
Take a Load Off
The Novell Content Exchange array located within the same data center that is hosting your web site--that is, the local array--is logically positioned between your company's web site and the Internet. Novell configures this local array to operate in web-acceleration mode so that the array checks its collective cache when a users' web browser makes a request for data. If the requested data is in cache, the array responds directly, without having to retrieve the data from your company's web server. (SeeFigure 1.)
So how much of your company's total web site data is cacheable? The specific answer to this question will naturally vary. However, www.caching.com/caching101.htm.)
Apparently, 35 percent represents the low end of the potential caching spectrum. It is not uncommon for 55 percent of requested web content to be successfully cached, as the results from a recent Cache-Off sponsored by the Measurement Factory reveal. (Measurement Factory is an independent development and consulting company that provides performance testing and benchmarking services.) At a Cache-Off held in September 2000--the third Cache-Off of its kind--a Novell ICS appliance achieved a hit rate of 56 percent of 58 percent maximum. Seven of the 13 ICS appliances entered in this Cache-Off achieved a hit rate of 50 percent or higher. (Of the 14 vendors that participated in this Cache-Off, the following six vendors entered products based on Novell ICS: IBM, Compaq, Dell, Microbits, and Stratacache. For more information about this Cache-Off, visit www.measurement-factory.com/results/public/cacheoff/N03/report.by-alph.html.)
In real life, Novell configures Novell Content Exchange arrays so that their storage space is sufficient to hold the entire cacheable portion of your company's web site data. This means that if 58 percent of your web site's data were cacheable, then Novell Content Exchange would cache that 58 percent.
In such a case, Novell Content Exchange would respond to at least 58 percent of the requests for data that your company's web server would otherwise have to process. In other words, Novell Content Exchange really takes a load off of your company's web server.
In fact, Novell recently tested a customer's web site accelerated by Novell ICS. (Novell was willing to share statistics regarding this particular customer case, but asked Novell Connection not to identify the customer, which is a large, well-known corporation. This customer felt uncomfortable publishing detailed statistics about its web site.) In this test case, Novell ICS achieved a hit rate of 84 percent. By caching 84 percent of the web site's total data, Novell ICS offloaded 84 percent of the requests that the web servers would otherwise have to process. Not surprisingly, web server CPU utilization dropped from an average of 57.9 percent (with periodic peaks of 100 percent) to an average of 21.1 percent (with periodic peaks of only 37 percent).
Taking a load off web servers suggests that your company may not need as many web servers as it has now. For example, Novell ICS effectively reduced by 80 percent the number of servers at the aforementioned Novell ICS-accelerated web site. (Incidentally, Keynote Systems Inc., an e-commerce benchmarking and web performance reporting agency, reports 100 percent availability on this same web site.) Thus, regardless of the number of users your company's web site attracts, Novell Content Exchange scales to accommodate those users, sparing your company from having to purchase additional web servers--now or ever.
In addition to taking a load off web servers, the local Novell Content Exchange array accelerates your company's web site by processing requests for data very quickly. Recent independent tests reveal that Novell ICS appliances can process more requests per second than competing caching solutions. According to the results from the September 2000 Cache-Off, Novell ICS can process as many as 3,310 requests per second. The Dell-200x4 ICS appliance achieved this impressive throughput, the highest peak throughput of all of the caching products entered in this Cache-Off. Second place in this Peak Throughput category went to the Compaq-C2500 ICS appliance, which processed 2,400 requests per second. (See www.measurement-factory.com/results/public/cacheoff/N03.)
Of course, these numbers reflect the capabilities of only a single Novell ICS appliance and, therefore, do not reflect the full power of a Novell Content Exchange array. After all, each Novell Content Exchange array has more than ten Novell ICS appliances. Consequently, each array is capable of handling tens of thousands of requests per second.
Pushing It to the Edge
Despite your best efforts to accelerate your company's web site locally, if an Internet router or connection goes down between the local Novell Content Exchange array and your users, your company's web site response times will suffer, right? If you are using Novell Content Exchange arrays, probably wrong.
Recall that Novell installs Novell Content Exchange arrays at each of a web-hosting provider's data centers. Novell configures the local array serving your company's web site to push cached content to other Novell Content Exchange arrays closer to users. Thus, if 58 percent of your company's web data is cacheable, 58 percent of your company's web data will be cached in both local and global arrays.
Consider the results of caching data at strategic points throughout the world: Suppose a user lived in New Jersey and entered the URL for your company's web site, which was housed in a data center in California. Further suppose that other users had already requested this URL and three or four layers of links that appeared on the associated page.
In this case, the local Novell Content Exchange array--as well as strategic global arrays--might already have in cache the cacheable portion of your company's web sites total data. The result? The global Novell Content Exchange array closest to the user--in this case New York--would respond to 58 percent of the total data requested by the New Jersey user. As a result, 58 percent of the data requested by the New Jersey user would not have to make the journey from California to New Jersey and would thus skirt several performance-degrading obstacles.
ACCELERATING THE CDN EXCHANGE
If your company is using Novell Content Exchange services, you have the option to use a CDN in addition to Novell Content Exchange global arrays. The advantage of using a CDN is that CDNs typically have thousands of points of presence on the Internet (as opposed to the dozen or so data centers a web-hosting provider may have). For example, Akamai has 4,200 servers in about 50 countries worldwide. The sheer number of CDN servers increases the likelihood of being able to get your company's web content closer to users.
Unfortunately, to use CDNs, you have to transform the URLs associated with CDN-bound content (which is typically static) into a CDN-specific format. The method you use to transform URLs into a CDN-specific format depends on which CDN you use. For example, for some CDNs, you may have to run a CDN utility on your web server. In some cases, you have to down the server when you run this utility, which you may have to run every time you change the CDN-bound content on your company's web site.
Methods from other CDNs do not require you to down your server. Instead, some such methods transparently convert URLs into the appropriate CDN-specific format as those URLs are requested. Unfortunately, this type of URL transformation usually requires significant processing power and can slow web server response times.
With Novell Content Exchange, you don't have to bother with these transformation methods to use a CDN. Novell has formed partnerships with several leading CDN providers--namely Akamai, Mirror Image, and Digital Island--and has written CDN transformation modules for each of these partner's respective networks. Novell Content Exchange CDN transformation modules run within the Content Exchange arrays and automatically transform URLs into a format that the CDN you are using will recognize. (SeeFigure 2.) Thus, with Novell Content Exchange, you relieve your company's web servers of the processing load (and hassle) of typical CDN preparation processes. (For a glimpse at the interaction between Novell Content Exchange arrays and CDN servers, see "To the Edge and Back.")
The web-hosting providers that offer Novell Content Exchange services may support one or more of the CDNs with which Novell has formed partnerships. GlobalCenter, for example, currently supports Akamai and plans to support additional CDNs, according to Alene Ipsaro, GlobalCenter's vice president of Global Product Marketing.
Which CDNs a web-hosting provider supports and how it makes use of those CDNs will vary. For example, a web-hosting provider that supports more than one CDN may either enable customers to choose a particular CDN or may automatically switch between CDNs on the fly, depending on the optimal route.
ROOM TO SPARE
Services such as the CDN transformation modules point to a capability unique to Novell Content Exchange in general and to Novell ICS in particular. The Novell ICS platform on which Novell Content Exchange is based has an "extremely efficient engine," says Jason Werner, Novell product manager. Results of recent tests that Novell conducted at a customer's web site support this claim. (This test is the same case study mentioned earlier, and again, the customer in this case asked to remain unnamed.) Novell found that a Novell ICS appliance used at this customer's web site consumes between only 1 percent and 15 percent of its processing power.
Because the ICS engine is so efficient, it has "a lot more CPU headroom," Werner adds. In a 1999 interview with Novell Connection, Drew Major, Novell chief scientist and vice president, discussed the implications of this CPU headroom. "Quite frankly," says Major, "in the future, you will find that the value of Novell ICS will be in the services we build on top of the high-performance platform we already have." Major adds that Novell ICS will "always win the performance benchmarks, but over time, [its] services will become significantly more important and, in many respects, more valuable to consumers than the performance of our cache."
The bottom line is that Novell ICS--and by extension Novell Content Exchange--has the potential to offer far more than caching services alone. In fact, the first release of Novell Content Exchange provides evidence of Novell's drive to build performance-enhancing services that will run on top of the highly efficient caching engine.
For example, in its first release, Novell Content Exchange includes not only the CDN transformation modules but also an SSL enabler. This SSL enabler is software that runs within the Novell Content Exchange arrays and handles all SSL encryption, taking that processing load off of your company's web server.
This processing load can be significant. According to Marshall, SSL encryption "is a huge problem" that can slow a web site "by a factor of 100." In fact, Marshall reports that Zona Research has seen instances of web servers processing at a rate of 453 requests per second drop to only three requests per second when handling SSL encryption. In contrast, Novell Content Exchange handles SSL encryption while maintaining its top performance potential, thus enabling you to offer secure exchanges without slowing your company's web site.
ALL THAT SNAZZ--IN A SNAP
The goal of any content publisher is to attract and retain users. To achieve that feat these days, you need to deliver snazzy page views in a snap--or at least 20 snaps. Novell Content Exchange offers an easy way for you to do just that.
With Novell Content Exchange, you can accelerate your company's web site--without having to change your company's web site infrastructure. Because it is based on Novell ICS, Novell Content Exchange takes a load off your web servers, picking up the pace over that critical first foot of the Internet. With Novell Content Exchange, the cacheable portion of your company's web site data is stored not only in local arrays but also in global arrays. Web content is not only safe but also is stored closer to users for even speedier delivery.
Furthermore, because Novell ICS has such an efficient caching engine, Novell Content Exchange offers additional performance-enhancing services, including the CDN transformation modules and the SSL enabler, and will undoubtedly offer more services in the future. The CDN transformation modules enable you to reap all of the benefits of a CDN, without the hassle and inconvenience (not to mention the processing load) associated with traditional methods of preparing content for delivery over CDNs.
Perhaps the best news is this: To accelerate your company's web site by using a Novell Content Exchange service, you only need to contact a web-hosting provider that has partnered with Novell. Days or weeks later (depending on whether or not your company's web site is already hosted by this provider), your company's web site will perform better than ever.
Your company's users, in the interim, will experience no loss of service. On the contrary, users will notice only that on one day, they checked your company's web site and waited perhaps a bit longer than they'd like. Days later, after your company started using Novell Content Exchange, users downloaded page views at a rate that either met or exceeded their expectations. In other words, with Novell Content Exchange, speedy delivery of snazzy web content is a snap.
For more information about Novell Content Exchange and partners that are using it, visit www.novell.com/products/contentexchange.
Linda Kennard works for Niche Associates, an agency that specializes in writing and editing technical documents. Niche Associates is located in Sandy, Utah.
To the Edge and Back
If you choose to use a content distribution network (CDN) as part of your Novell Content Exchange service, Novell Content Exchange automatically transforms the appropriate URLs into the CDN-specific format. An overview of the interaction between Novell Content Exchange and a CDN may help clarify how Novell Content Exchange CDN transformation services work:
A user requests Object A from your company's web site, which is fronted by Novell Content Exchange. As the proxy for your company's web site, Novell Content Exchange receives the request.
In this case, Object A is not yet in cache, so Novell Content Exchange passes the request through to your company's web server.
The web server returns Object A to Novell Content Exchange.
Based on the URL, the CDN transformation module identifies Object A as having content that should be migrated to the CDN.
Novell Content Exchange rebuilds Object A, replacing the appropriate embedded URLs with the equivalent CDN links.
Novell Content Exchange stores the new object in cache and will handle all subsequent requests for Object A until its copy of Object A expires.
Novell Content Exchange also responds to the user, redirecting the user's browser to the CDN for additional URLs associated with Object A.
The user's browser requests additional URLs associated with Object A from the CDN, which accepts and processes those requests from the neaest CDN server.
In this case, the CDN server has not yet cached Object A. The CDN server requests a copy of Object A from Novell Content Exchange.
Novell Content Exchange returns the transformed Object A to the CDN server.
The CDN handles all subsequent requests by the same or other users for Object A until the CDN's copy of Object A expires.
Novell Connection, January 2001, p. 16
* Originally published in Novell Connection Magazine
The origin of this information may be internal or external to Novell. While Novell makes all reasonable efforts to verify this information, Novell does not make explicit or implied claims to its validity.