Intel IXA SDK ACE Programming Framework - Department of ...

ACEs and Support Structures
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For more information on crosscalls, see Chapter 11, “Communication Within an
Application.”
For detailed reference information on OMS functions, see the IXA SDK Reference.
ACEs and Support Structures
The primary processing element on an IXA application is the ACE. An application
can contain multiple ACEs to perform different processing operations, can start and
stop ACEs at run time, and can change how packets flow from ports, through ACEs,
and out of ports.
The IXA SDK defines system ACEs to represent the physical network interfaces and
the Linux TCP/IP stack, and library ACEs to perform typical network processing
tasks. You define additional ACEs to process packets as needed by your application.
Creating ACEs
To define and create an ACE, you must first create the ACE single object executable.
To do this:
1. Define the ACE’s initialization phase in a C source file. This file must contain a
definition for the initialization function ix_init. This function definition must, at
least, allocate an ACE structure (ix_ace) and call ix_ace_init, which creates the
ACE object. The function should also create and initialize any other structures
that belong to the ACE, such as targets and sets. The file must also define a corresponding
termination function (ix_fini) that cleans up the created structures.
2. Define the ACE’s action phase in a C source file. The action code must contain
definitions for the ACE’s action functions, which implement the handling and
disposition of classified packets.
3. Define the crosscall interfaces for interobject communication in an IXA IDL source
file, compile it with the tao_idl compiler. This results in additional C source files
for the ACE. See “Supporting Languages” on page 23.
4. Define the ACE’s classification phase in an NCL source file. See “Supporting
Languages” on page 23.
5. Compile and link the initialization, action, and classification code into a single
executable. (See Chapter 3, “Compiling and Testing Applications.”)
An application’s manager program can create and initialize the application’s ACEs
by calling Resolver functions in the OMS. To do this, it must first create a CAP
channel through which to communicate with the Resolver. In the manager program:
1. Create a CAP channel to the OMS using the ASL function ix_cap_init.
2. Open a Resolver session by passing the CAP to the OMS function ix_res_open.
3. Create the ACE using the function ix_res_create_ace, passing the Resolver
session handle, the name of the ACE, and the path to the ACE executable in the
development file system.
You can also create ACEs from the command line or a script using the utility ixace.
This utility creates a Resolver session and calls the ix_res_create_ace function.
22 Elements of an Application
Revision 3.3, August 2001