Brocade Communications Systems ServerIron ADX 12.4.00 Service Manual download pdf (Page 11)

ServerIron ADX OpenScript Guide 1

53-1002445-01

Chapter

Overview of OpenScript

The Application Delivery environment requires more than simple CLI commands for managing

Application traffic. Often, an operator wants to make packet forwarding decisions based on

real-time events such as layer-3, layer-4, layer-7 data or server metrics such as current server load

statistics. These situations require a more dynamically programmable environment than

traditionally offered through built-in CLI commands.

In essence, the operators prefer programming the Application Forwarding Behavior rather than

statically provisioning it. The flexibility of programming the data-plane at layer-7 is invaluable in

dynamic data center environments as new applications come online.

The CLI-based interface of ServerIron ADX currently consists of a list of policy, rule, and

configuration commands that can be used to configure the application delivery switch for such

tasks as real server configuration, load-balancing metrics, as well as for traffic redirection and

transformation operations.

What is OpenScript

Brocade OpenScript provides data plane scripting functionality to manipulate traffic in

real-time.The Brocade OpenScript engine provides a programming framework and protocol level

APIs that allow you to create Perl scripts to customize the traffic handling capabilities of a

ServerIron ADX. With this capability, you do not have to depend on Brocade to add needed

functionality to suit the needs of your network.

OpenScript is available beginning with ServerIron ADX version 12.4.00. No separate license is

required and version 12.4.00 is available to all customers with an active service contract.

Why OpenScript uses Perl

Perl was chosen for OpenScript for the following primary reasons:

• Performance

• Extensibility

• Ubiquity

Performance

Because of the need to compile and interpret the program, scripting is an inherently slow process

in regards to performance. Consequently, scripting is often implemented as a multipass process.

This is preferable to the large overhead associated with the single pass execution model used with

command-based languages such as TCL that parse and execute each program statement on the

fly. In a multipass Scripting Engine such as Perl, the initial phase involves scanning and parsing the

input script to generate an intermediate byte code representation. The final run phase executes the

generated byte code by invoking underlying machine operations associated with each node in the

parsed byte code tree.

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Brocade Communications Systems ServerIron ADX 12.4.00 Service Manual Page 11