A better approach would be to use:-

rule "system will execute 'tc' command"
 when
    Server(message>8388608)
 then
     System.out.println("The network is so crowd that it needs repairing.");
  Runtime.getRuntime().exec("tc");#execute the "tc" command
end

This assumes you insert Server facts into working memory and they have a "getMessage" property.

Normally you'd use eval when you are unable to leverage DRL. Their use is normally discouraged. Also, your usage is incorrect; please read the documentation.

With kind regards,

Mike

2011/4/12 ÕÔ»Û <zhaoh@hpnl.ac.cn>
hello,everyone!I wrote a rule with Drools,but the error told me that the field Server.Message is not visible, I can't find how it happens. Please help me, I am almost exhausted with it. thank you.
the rules are as follows:
 
package com.sample
import com.sample.Server;
 
rule "system will execute 'tc' command"
 when
    eval(Server.Message>8388608)
 then
     System.out.println("The network is so crowd that it needs repairing.");
  Runtime.getRuntime().exec("tc");#execute the "tc" command
end
 
rule "caution"
    when
        eval(Server.Message==8388608)
    then
        System.out.println("caution!The network maybe will get blocked very soon.");
end
 
rule "fluent network"
  when
  eval(Server.Message<8388608)#conditions
 then
  System.out.println("the current network is very good");#actions
end






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