secretLately I've been seeing quite a few links to a white paper popping up in my alerts and feed-reader. Regardless of who's linking to it, it generally reads as promising to reveal some grand secret about how web application acceleration is an epic failure. I finally gave in and clicked on a link and ended up directed to download a white-paper, the description for which essentially distilled "web application acceleration" down to "caching". And then promised to tell me why caching wasn't a good way to accelerate web applications.

I didn't download the white paper primarily because equating "web application acceleration" to "caching" is exceedingly shortsighted and intimated that the actual content of the paper was most likely equally astigmatic.

While caching is certainly one mechanism used by web application acceleration solutions, it's not the only one. (I also found it ironic (hence the title) to see a paper denigrating the use of caches being promoted by a vendor for whose technology caching, albeit at the byte and object level, is an underlying foundation. Oh, none of us with these kinds of solutions call it that because it needs a snazzy marketing name, but that's the core of what it really is. Anyone who claims otherwise is just (desperately) trying to sell you something. Go ahead, ask me about how we implement that particular technology. Part of the answer is "caching at the byte and network level". I could continue this parenthetical aside further and say that what these guys are accelerating in the end is applications, so technically they're a (web) application acceleration solution, too, (So aren't they really pointing out their own faults then?) but that's probably better left as another post for another day. (Man, that was almost as bad as programming in LISP, but now I really digress.)) 

In any case, the truth is that caching is only one of the technologies used by web application acceleration to improve performance of web applications. Otherwise we'd call just them caches, wouldn't we?

Other technologies used by web application acceleration include:

  • Protocol optimization
    You would be amazed (or maybe you wouldn't) at the number of enhancements to protocols like TCP are available that improve the performance of web (and other applications riding on the protocol) applications. Web application acceleration solutions often implement these enhancements. 
  • Compression
    Fewer packets means faster transmission and one of the ways in which you turn big fat web application messages into fewer packets is to compress them. This is especially true for HTML and XML and other web application formats like JSON which are text-based and are therefore highly compressable. Sometimes the answer to improving performance is not to compress, and web application acceleration solutions need to be intelligent enough to determine when to use this technology.
  • Linearization of PDF documents
    Waiting for a PDF to load is one of the most painful experiences on the web. Technology that linearizes PDF documents and allows you to start reading page one while pages two through, well, whatever reduces the pain of that transfer. It still takes as long, but at least you aren't wasting your time waiting for it load.
  • Leveraging the browser cache
    Caching often implies a server-side technology but let's not forget that there's a cache in every browser. Unfortunately, it's often not leveraged to its fullest potential. Web application acceleration technology improves the use of the browser cache to improve performance, because the fastest way to load content is to get it locally if it's fresh and available.
  • Content spooling
    How fast a server can dish out content to a client is highly dependent upon the size of the network pipe (usually not a problem), number of concurrent users, number of open connections, distribution of resources being requested, and the total load and memory utilization on the server. Web application acceleration solutions, at least good ones, suck the content from the server as fast as possible and then serve it up to the browser. This reduces the number of open connections and concurrent users which reduces the load and resource consumption on the server and thus improves the speed at which the server can dish out content. Which makes the application faster.
  • SSL acceleration
    It's forever been true that encryption and decryption is slow, and can be dramatically improved through the use of hardware assisted acceleration. Web application acceleration solutions generally employ this technique to improve the performance of secure web applications delivered via SSL.

I could go on about how web application acceleration solutions further leverage technology like TCP multiplexing to improve performance by eliminating the overhead associated with the constant opening and closing of TCP sessions, which in turns makes servers more efficient which in turn makes them faster resulting in ... faster application delivery. But I think that's enough for one day.

The truth is that web application acceleration technologies comprise more than just caching and employ multiple techniques that improve the efficiency of servers and the performance of applications whether they are delivered over the LAN, the WAN, or the Internet.

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