neval

Network Eval (neval)

nsdci/dcicommon/neval.c

Introduction

The Network Eval API (neval) is used to evaluate a script on a remote host. No result is returned.

TCL API

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neval.send

Sends a script or command to a remote host. No result is returned. neval.send host port pass script ?timeout?

Argument
Description

host
String. The IP address of the remote client.

port
String. The port configured for neval on the remote client.

pass
String. The neval password configured on the remote client.

script
String. The script or command to evaluate.

?timeout?
Integer. The time in seconds to wait brefore timing out.

Result
Description

NULL
Success. The script was sent.

TCL_ERROR
Failure. An error occurred. See the server log for more information.

Configuration

Client:

    ns_section "ns/server/$server/module/dci/neval"
        ns_param address $address
        ns_param port $nevalPort
        ns_param password $encryptedPassword ; # ns_crypt $password t2
        ns_param allowed 127.0.0.1

Usage

In the tool Control Port to send a command to the frontend server (See Topology for more detail):

    % telnet 127.0.0.1 8900
    Trying 127.0.0.1...
    Connected to localhost.
    Escape character is '^]'.
    login: 
    Password:

    Welcome to tool running at /usr/local/aolserver/bin/nsd (pid 6930)
    AOLserver/4.5.0 (aolserver4_5) for osx built on Jan  4 2007 at 17:11:28
    CVS Tag: $Name:  $
    tool:nscp 1> neval.send 127.0.0.1 9600 neval "ns_log notice foo"

    tool:nscp 2> exit

    Goodbye!
    Connection closed by foreign host.

Looking at the tool server log you will see the following log entry:

    [07/Jan/2007:18:10:43][6930.25205760][-nscp:4-] Notice: neval: send to 127.0.0.1:9600: {ns_log notice foo}

Looking in the frontend server log you will the connection as well as the result of the command since it was a log notice:

    [07/Jan/2007:18:10:43][6928.25189376][-socks-] Notice: neval: connected to 127.0.0.1
    [07/Jan/2007:18:10:43][6928.25189376][-socks-] Notice: neval: queued 127.0.0.1
    [07/Jan/2007:18:10:43][6928.25208832][-neval-] Notice: recv from 127.0.0.1: {ns_log notice foo}
    [07/Jan/2007:18:10:43][6928.25208832][-neval-] Notice: foo

Best Practices