XML appliances speed Web services

XML is becoming the lingua franca for Web services. However, XML's flexibility places significant demands on network infrastructure, consuming as much as 80% of server processing power to perform CPU-intensive tasks such as transformation, compression and XML Web services security.

XML acceleration is emerging as a critical technology to offload XML processing from applications, especially in the form of hardware-based appliances. Along with processing XML data, XML acceleration helps implement secure data exchange and delivers quality of service (QoS).

An acceleration appliance typically consists of an off-the-shelf motherboard and an off-the-shelf operating system. The appliances perform operations such as parsing, validating, transforming and compressing XML faster than application servers because they are tuned for specific tasks and can use the operating system and hardware far more efficiently.

The appliances generally are deployed in a three-tier architecture in a data center. They typically sit behind firewalls, between load balancers and application servers or a device that combines application server and Web server functions. Load balancers distribute the load between acceleration appliances just as they distribute it between Web servers or application servers. Application servers are the main producers and consumers of XML data and benefit most from the acceleration these appliances provide.

Pick a direction

XML traffic can be viewed as inbound or outbound. Inbound XML acceleration uncompresses, decrypts, validates and routes for QoS. XML appliances process HTTP or Simple Object Access Protocol headers or XML content, and use configuration information to decide how to transform, validate or uncompress content.

Inbound load balancers are configured to select the appropriate data to be switched to the acceleration appliance. For example, an HTTP header on its way from the load balancer to the application server indicates to the appliance that the data is compressed. The appliance can be configured to uncompress the data, relieving the application server from executing CPU-intensive uncompressing function.