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Deciding to outsource your IT infrastructure has a strong business case. In the outsourcing model, you focus on your core competencies and leave the headaches about IT maintenance and costs to the application service providers (ASPs) such as USinternetworking (USi) Inc., Corio Inc., or Exodus Communications Inc. Although this business model has been in practice for a while in many companies, it has truly come of age with the Internet and open networking.
Enabling technologies such as virtual private networks (VPNs) for secure networking, remote connectivity software by Citrix Systems Inc., and Web-enabled applications promise to make remote applications processing a distinct possibility. Numerous ASPs are building impressive infrastructures and delivering services for this burgeoning market. But can the ASPs deliver?
Some of the ASPs can deliver, but others cannot. The key to a successful outsourcing solution is to build a partnership with an ASP that is capable of delivering results. The foundation of this partnership is the service level agreement (SLA). The SLA should address critical goals for your outsourcing solution (See Table 1)
In the article, I will examine each of these goals, identify what you should expect from the ASP, and briefly look at the technical implementations that ASPs need to provide service at the expected levels.
Performance
Network latency is a good measure of network performance, and you should use it as a metric in the SLA. If you have dedicated data pipes to the ASP, you can request for example, that network latency from hub to hub remain between 60 to 80 milliseconds. The ASP's network infrastructure is also a good indication of its capabilities. The major ASPs will use network "peering" to connect to the major ISPs to greatly enhance performance. Peering means that the network provider will set up private connections to major ISPs such as UUNET, MCI Worldcom, or Cable & Wireless. This peering enables a direct route for network traffic and avoids bottlenecks at both the metropolitan access points and network access points, which are the more traditional pathways to the Internet.An application transaction's response time is a good measure of applicationlevel performance as well. You can think of a transaction as a unit of work that varies from application to application. For example, you can break up ERP application transactions into the time it takes to open up a window, retrieve data, and update that window. (In PeopleSoft, you refer to the window as a panel; SAP calls the window a transaction; and in Web-based applications, you call it a page or Java applet.)
Measuring the response times for these transactions can give you a good indication of how the application is performing end to end. This response time will tell you about the performance of the network, application servers, database, and operating system. When drafting the SLA, both you and the ASP should agree on the application transactions and set thresholds.
Scalability
Scalability tells you how the application and infrastructure will scale as demands on the system grow and you add new users to the system. You need to consider the scalability of the architecture and maintenance (such as data backup, software distribution, and system upgrades).Software distribution becomes a necessity every time you add a new user to the system or you apply an upgrade to the software. Web-based architectures follow the "zero administration" paradigm and require no software distribution, but client/server systems need client software placed on each user's desktop. Client distribution can be a major undertaking in a global system.
Citrix MetaFrame provides a popular alternative for remote connectivity to ASP infrastructures. Citrix lets multiple users remotely access applications installed on NT servers or Sun-based systems. Citrix MetaFrame sends a bitmapped image to the Citrix client installed on the remote desktop. The product runs on varying bandwidth and performs well even across WANs and dial-up connections. Citrix MetaFrame performance is comparable to Web-based access and facilitates the "zero administration" paradigm because software distribution (apart from the Citrix client) is not required.
During an application's life cycle, data volumes will grow. You must conduct a capacity plan to understand the nature of this growth at the very beginning of the system implementation because this growth will impact your database performance. The backup window will take longer, which may affect the guaranteed system availability. Furthermore, the database size will influence your choice of storage media. A large database may require solid state storage media, such as an EMC disk.
Optimal application architectures will depend on the type of package you implement. Most ERP systems such as PeopleSoft and SAP give you the option of implementing three-tier (the most scalable) or two-tier architectures.
  
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