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April 16, 2002

The Open-Minded Server

An enterprise-class application server

By Ganesh Variar

Continued from Page 1

You can develop EAServer components using Sybase PowerBuilder and PowerJ. EAServer lets you use Java servlets, Java Server Pages, or PowerDynamo Web sites to dynamically create HTML pages and interactive HTML forms. PowerDynamo, a tool that ships along with EAServer, is used to develop thin-client Web applications. EAServer can host PowerDynamo Web sites natively.

Value-Adding Features

EAServer provides easier manageability through sophisticated tuning and administration features such as instance pooling, transaction management, thread pooling, and property sheets. Through instance pooling, EAServer can maintain a cache of component instances and bind them to client sessions as needed. With EAServer's transaction management feature, you can specify a transaction coordinator (Shared Connection, Microsoft DTC, or OTS/XA Transactions) and define a component's transactional semantics as part of the component interface. The server provides various options for performance tuning, such as object and page caching. Connection caching allows EAServer components to share pools of preallocated connections with a remote database server, avoiding the overhead imposed when each instance of a component creates a separate connection.

For applications with thousands of clients, you can define an EAServer cluster with several redundant servers to run the application's components. EAServer can use load balancing, which optimizes performance for your EAServer cluster by adjusting the load across the servers, based on load metrics and a distribution policy or on a random algorithm. You can configure components to allow automatic failover that is transparent to client applications. In-memory failover support makes it possible for a pair of servers to maintain component state locally, sparing the overhead of using a remote database to store component state. These features are extremely important for an enterprise-level application server.

EAServer message service supports the Java Message Service 1.0.2 specification to provide asynchronous messaging capabilities. EAServer also supports asynchronous processing. This feature can be useful if you need to perform an operation, such as a complex calculation, in the background without client interaction. EAServer hosts Web applications and functions as a Web server. You can install a redirector plug-in on the Web server host that allows you to send client requests directly to the Web server. EAServer provides declarative, role-based security to restrict client connections and the components that can be invoked by a specific client session. It also supports identity-based security to restrict intercomponent calls.

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Future Direction

At the time of writing, a new version of the software, EAServer 4.1, was due to be released. It introduces an XML/Java binding tool and provides adapters for Siebel, PeopleSoft, and SAP R/3. Overall, I found EAServer to be robust, flexible, and easy to learn. This product should help consolidate Sybase's position as an emerging player in the Internet software market. If you're a Sybase shop, EAServer should definitely be first on your list. On the other hand, even if you're not an avid admirer of Sybase products, the breadth of support that EAServer provides should help place it high on your list.

Ganesh Variar [ganesh_variar@yahoo.com] is a lead analyst at Regence BlueCross/BlueShield of Oregon.