Rolling with changes

Warp 2063e appliance coordinates with Web servers, Oracle databases to cache dynamic content

See correction below

There are many Web acceleration appliances around, which perform functions from caching to SSL off-loading. The Warp Solutions 2063e Application Acceleration Appliance is a caching appliance that attempts to address the issue of dynamic content. Early caching devices were very good at caching static data, but they had no way of handling dynamic content. The 2063e not only can handle dynamic content but also work directly with Oracle databases to ensure that content is updated as necessary.

The 2063e consists of a 2u (3.5-inch) Intel-based, rack-mount PC with dual 2.8GHz Xeon hyperthreading processors, 4GB of RAM, two 10/100/1000 NICs and one 10/100 NIC, two 34GB Ultra 160 SCSI drives, and redundant power supplies.

Many caching appliances run either as a router, sitting between the Internet and the Web server, or as a proxy, with all traffic directed first to the appliance rather than to the Web server. The 2063e operates differently, using a server plug-in on each Web server to identify which content should be served from the 2063e and which from the Web server. By default, the 2063e caches all the content requested from the Web server; the plug-in connects to a rules file on the appliance that specifies when cached content should be expired and refreshed.

The plug-in architecture means that there is no need to change DNS settings for the network or the Web servers, and there would be no network impact if the 2063e should fail. The plug-in supports Apache 1.3.x on Solaris, Linux, or BSD; Microsoft IIS 4.x and 5.x on Windows NT and Windows 2000; and Netscape Enterprise 3.x and 4.x and iPlanet 6.x Web servers on Solaris. There is also a proxy mode that supports Web servers that aren’t supported via a plug-in or other types of servers such as application servers. Non-supported Web servers can still handle dynamic caching, but the 2063e must be set up in proxy mode, which requires reconfiguring the network.

In addition to allowing you to set rules to govern the expiration of cached content, the 2063e can track changes in back-end Oracle databases and respond accordingly. The database bridge is an Oracle script that creates a set of tables that flag changes in the database content. The script runs from the Warp appliance, at regular intervals you specify, and doesn't require any additional software installs.

Setting up and testing the 2063e is a fairly involved process. First, the basic IP configuration is done through a serial terminal, then the rest of the setup and administration can be performed through the Web interface (or via the command line interface). The Web interface is accessed via the IP address of the Warp 2063e with a port number of 8000, and a separate log-in and password from the command line log-in.

The next step is to use a supplied Windows or Linux application to create a rules file for identifying content that needs to be flushed from the cache and refreshed. The rules editor makes it simple to create the rules file. The rules file is an XML document, which can also be created manually or with a script. Once you have created the rules file and uploaded it to the 2063e, you install the plug-in on the Web server and edit a configuration file on the Web server to reflect the IP address of the 2063e.

The 2063e can preserve content that has been invalidated until the new version is available. It can also rewrite embedded personalized links on cached pages with the current user value so that personalized content is presented properly. As long as the content is specified in the URL (e.g., http://www.xyz.com/content/catalog.asp?search=gadget), that content will be cached and can be delivered to anyone else who wants that specific search.

In addition to a refresh of content triggered by the rules file or the database bridge, a refresh can be triggered by a refresh request from a client browser or by the amount of time lapsed since last access.

To test the database bridge functionality, we configured an Oracle database and set up a small Web site that pulled catalog items from the database. The 2063e currently supports only Oracle databases, although Warp Solutions can add support for any JDBC-compliant database if a customer requests it. The database bridge utility creates two tables and a stored procedure, which identifies changes in the database and sends a message to the 2063e when it’s necessary to update the cached data.

We ran a load-testing application against the Web server, then turned on the 2063e and reran the tests. Depending on the number of simulated clients, response times with the 2063e were one-half to one-fifth of times without it and throughput increased by an average of 321 percent.

These numbers will vary considerably, depending on the application and network bottlenecks. However, the benefits of caching are well-established; the real issue is whether the 2063e can work well with dynamic content in addition to the usual static content that all caching products can handle. In our tests, changing data in the database produced the update in cached data that it should have, and changes to content defined in the rules file also triggered refreshes of the cache.

Whether the 2063e will produce dramatic results in your application will depend on the type of data served. For example, on a data search portal or a very large catalog application with mostly unique searches, the 2063e will provide much less of an advantage than with applications that have dynamic data that is requested by many users. According to Warp Solutions, performance increases of up to 600 percent have been noted by some of its customers.

The 2063e can be deployed in an active/active failover configuration and supports a load balanced configuration as well. SSL support is included. The 2063e also includes SNMP capability so that enterprise monitoring applications can gather performance data from it.

The biggest limitation to the current version of the 2063e is that it supports only Oracle databases. The next version, due in April, will be database-agnostic. If you’re using an Oracle database and a supported Web server, and if your Web site’s dynamic data is amenable to caching, the 2063e is well worth investigating.

Correction

In this article, we misreported the name of the product reviewed. It is Warp 2063.

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