Scaling with Other Java Application Servers

Integrated software load balancing and session management are some of the features offered by IBM WebSphere and Sun ONE application servers, as well as by Macromedia JRun. Deploying your ColdFusion applications on servers running J2EE Application Server with ColdFusion offers many features that are not inherently present in ColdFusion itself. We will discuss some of their features and look at how they can affect scaling with ColdFusion.

Java application server architecture offers the concept of application partitioning. This architecture can be highly scalable because it splits the application's components into segments. These segments can be hosted on separate servers or sets of clustered servers. Application partitions can include HTML, CFML, JSP, servlets, and EJBs. A high-traffic Web site could be split into multiple tiers where each segment or tier resides on its own server or cluster of servers. For example your web server could be on one server, your ColdFusion MX 7 application could be deployed on another server, EJBs could have their own dedicated business logic server, etc. In some J2EE applications, heavy-use EJBs can even be split from other EJBs and hosted on dedicated servers, further augmenting the performance of the application.

Load balancing and session management are two important areas of concern for any Web site that requires high performance. J2EE application servers offer strong tool sets in these areas, with many options for tweaking applications for performance. WebSphere offers server-cloning features for creating multiple copies of an object such as an application server. With the application server, cloning can be performed by either vertical or horizontal cloning. Vertical cloning refers to creating multiple clones of an application server on the same physical machine. Horizontal cloning is the practice of creating these clones for multiple physical machines. This allows the application server to span several machines, enhancing load balancing and failover.

IBM WebSphere, BEA Web Logic, and Sun ONE offer many options for load balancing, including

• Web server plug-ins. The Web server manages the load on each application server. This type of load balancing can be set to choose which machine is sent requests for applications, by server load and response times, component load and response times, or in a traditional round robin format.

• Application server load management. One application server or all application servers make decisions on load balancing among the set of clustered servers. This method can resolve requests in a fashion similar to the Web server plug-in method.

J2EE application servers offer various methods for performing session management. These methods include session-aware or sticky load balancing, which ensures that the user stays on the same server throughout the session. This is useful for maintaining state for a shopping cart application and cart checkout. Sessions can also be persistent through centralized management of the user's session. Both application servers described offer management interfaces for configuring session management across the cluster, making them viable options for preserving prior investments in J2EE architecture while moving to ColdFusion as a development platform.

NOTE

IBM has an excellent Web site for ColdFusion users who want to use WebSphere as their J2EE platform. If you're looking at or already using WebSphere as your J2EE platform, you'll want to bookmark and visit this site regularly: http://www-106.ibm.com/developerworks/websphere/partners/macromedia/.