ScaleOut StateServer

asp:review

ScaleOut StateServer

Manage ASP.NET Session States

By Mike Riley

In the realm of Internet e-commerce, availability anduptime make all the difference between living and dying in the virtual world. Ifyour services are inaccessible even for a minute, your customers will beunhappy the first time it happens and furious if it happens a second time. Strikeout a third time and you not only lose that customer, but your service scredibility will be irreparably damaged.

Gone are the days of single server, single service, andforgiving customers. User expectations have exceeded beyond five 9s (an annualuptime of 99.999% of the time) and any disruption in service availability willbe a painful reminder of this new quality level. Although Microsoft hasprovided a satisfactory network load-balancing feature in Windows Server 2003 Enterpriseto mitigate service disruption, it s a straightforward and barely adequatesolution for demanding online infrastructures.

ScaleOut Software, a company consisting of a managementteam experienced in serious software products for the enterprise market, hasreleased their first product aimed squarely at this problem facing WindowsServer customers. In fact, Bill Bain, the company s founder and CEO, createdthe load-balancing solution that ultimately became the Network Load BalancingService in Windows Server 2003. As such, he knows what the service is capable(and incapable) of doing for Microsoft ASP.NET customers.

Figure 1: The StateServer Console isa simple GUI indicating the number of active licensed ScaleOut distributedservices, the number of active objects, and other related statistics.

ScaleOut StateServer is a very easy to use,straightforward application that superbly masks the complexity that it manages behindthe simple GUI. After installing ScaleOut StateServer and identifying the otherservers running the ScaleOut service, the product automatically handles thereplication of all active objects across the servers so that no server is leftin the dark about any active session. Unlike other solutions in this space,ScaleOut s heartbeat protocol doesn t burden the network with multicast pingsto the other ScaleOut deployments, which is especially helpful in large-scale Webfarms.

Although ASP.NET session objects can be maintained inother ways, such as saving the sessions off to a centralized SQL Serverdatabase cluster, the cost associated with this is formidable in both thesoftware license expense and potential downtime while requests get re-routed toa reactivated session once the server is identified to be unavailable. ScaleOut ssolution keeps active sessions distributed among the ScaleOut participants,scaling it to as many servers running the software while also recovering thesession in an instant because of the distributed active nature of the service. Thisrealization is best appreciated by SysAdmins and Web developers who have usedthe SQL Server or ASP.NET StateServer approaches; my eyes brightened when I sawhow quickly the state recovery was made after running the product on twophysical machines and one virtual machine. It was a remarkable, convincingmoment.

While existing ASP.NET projects can immediately takeadvantage of other Web farm servers running the ScaleOut solution withoutchanging a line of code, the real power of ScaleOut is amplified when using theSoss.Client.DataAccessor object to create, read, update, and delete ScaleOutobjects across the entire server base. Coupled with a sophisticated e-commerceASP.NET application, the possibilities for this newfound distributed power areas scalable as the ScaleOut server is allowed to be licensed. In fact, a newclass of solutions can be built using the simple ScaleOut API (three classes, onestructure, and one enumeration check it out online at http://www.scaleoutsoftware.com/support/stateServer/soss_APIdoc/index.html),from vastly distributed e-commerce to even grid and complex scientific applications.

This is a 1.0 product release, and, as such, it isextremely focused on doing one thing very well: managing ASP.NET session stateson Windows servers running the .NET 1.1 Framework. This is not a piece ofsoftware yet designed to run on non-Microsoft OSes (and given the fact that itis managing .NET services, it s unlikely that it ever will run on anythingelse). It s also expensive, though not nearly as expensive as other softwareand hardware alternatives. There s also the question of how long beforeMicrosoft either develops or acquires an alternative that will become thedefault way of handling such transactional uptime requirements in the future. However,for those Windows-exclusive Web farms seeking a remarkably robust, amazinglyfast, and stunningly simple to use service to dramatically improve systemavailability, ScaleOut StateServer will no doubt be a top contender in thehigh-end services space.

MikeRiley is anadvanced computing professional specializing in emerging technologies and new developmenttrends. He also is a contributing editor for asp.netPRO. Readersmay contact Mike at mailto:[email protected].

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Web Site: http://www.scaleoutsoftware.com

Price: ServerEdition, US$4,495; EnterpriseEdition, US$7,795; DataCenter Edition, US$10,995 and up.