Executing tasks dynamically
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Executing tasks dynamically |
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Under certain conditions you may want to create and execute tasks on the fly. An example of such a situation might be when the command for the next task depends on the response of the previous task. Dynamic TelnetTask usually have a null start prompt value as they are not waiting on data from the telnet server. To illustrate we will use the following use case.
Use Case
| 1. | Login to system |
| 2. | Execute run.sh command |
| 3. | If response of run.sh command contains the text "Success" then logout Else execute fail.sh command and logout. |
Example
[C#]
using System;
using System.Threading;
using Jscape.Telnet;
namespace TelnetScriptExample {
public class TelnetScriptExample {
string user = "username"; // Specify user name to login
string pass = "password"; // Specify password to login
string host = "telnet.server.com"; // Specify telnet server
string prompt = "$";
public Telnet MyTelnet = null;
public TelnetScriptExample(){
MyTelnet = new Telnet(host);
// Subscribe to connection events
MyTelnet.ConnectedEvent += new Telnet.ConnectedEventHandler(OnConnected);
MyTelnet.DisconnectedEvent += new Telnet.DisconnectedEventHandler(OnDisconnected);
// Subscribe to option events
MyTelnet.DoOptionEvent += new Telnet.DoOptionEventHandler(OnDoOption);
MyTelnet.DontOptionEvent += new Telnet.DontOptionEventHandler(OnDontOption);
MyTelnet.WillOptionEvent += new Telnet.WillOptionEventHandler(OnWillOption);
MyTelnet.WontOptionEvent += new Telnet.WontOptionEventHandler(OnWontOption);
// Subscribe to data received event
MyTelnet.DataReceivedEvent += new Telnet.DataReceivedEventHandler(OnDataReceived);
// Create a TelnetScript
TelnetScript script = new TelnetScript(MyTelnet);
// Create script tasks
TelnetTask login = new TelnetTask("login:", user, "Password:");
TelnetTask password = new TelnetTask("Password:", pass, prompt);
TelnetTask sh_exec = new TelnetTask(prompt, "run.sh", prompt);
// Subscribe to task started event
script.TaskStartedEvent += new TelnetScript.TaskStartedEventHandler(OnTaskStarted);
// Subscribe to task ended event
script.TaskEndedEvent += new TelnetScript.TaskEndedEventHandler(OnTaskEnded);
// Subscribe to task failed event
script.TaskFailedEvent += new TelnetScript.TaskFailedEventHandler(OnTaskFailed);
// Add tasks to script
script.AddTask(login);
script.AddTask(password);
script.AddTask(sh_exec);
// Connect to telnet server
MyTelnet.Connect();
while(!sh_exec.IsComplete()) {
try {
Thread.Sleep(1000);
} catch(Exception e) {}
// sh_exec complete - check response
if(sh_exec.GetResponse().IndexOf("Success") != -1) {
// success - logout
MyTelnet.Disconnect();
} else {
// failure - run fail.sh (no start prompt needed) then logout
TelnetTask failTask = new TelnetTask(null, "fail.sh", prompt);
// wait for fail task to complete
while(!failTask.IsComplete()) {
try {
Thread.Sleep(1000);
} catch(Exception e) {}
}
}
// Disconnect from telnet server
MyTelnet.Disconnect();
}
}
public static void Main() {
// Create new telnet example
TelnetScriptExample telnetScriptExample = new TelnetScriptExample();
}
public virtual void OnTaskStarted(object sender, TelnetTaskStartedEventArgs e) {
}
public virtual void OnTaskEnded(object sender, TelnetTaskEndedEventArgs e) {
}
public virtual void OnTaskFailed(object sender, TelnetTaskFailedEventArgs e) {
// Write the task name and disconnect
Console.WriteLine("Task " + e.Task.Command + " failed.");
MyTelnet.Disconnect();
}
public void OnConnected(object sender, TelnetConnectedEventArgs e) {
Console.WriteLine("Connected to {0}:{1}", e.Host, e.Port);
}
public void OnDisconnected(object sender, TelnetDisconnectedEventArgs e) {
Console.WriteLine("Disconnected.");
}
public void OnDoOption(object sender, TelnetDoOptionEventArgs e) {
MyTelnet.SendWontOption(e.Option);
}
public void OnDontOption(object sender, TelnetDontOptionEventArgs e) {
MyTelnet.SendDontOption(e.Option);
}
public void OnWillOption(object sender, TelnetWillOptionEventArgs e) {
MyTelnet.SendDontOption(e.Option);
}
public void OnWontOption(object sender, TelnetWontOptionEventArgs e) {
MyTelnet.SendWontOption(e.Option);
}
public void OnDataReceived(object sender, TelnetDataReceivedEventArgs e) {
Console.Write(MyTelnet.Encoding.GetString(e.Data));
}
}
}
[Visual Basic]
Imports System
Imports System.Threading
Imports Jscape.Telnet
Public Class TelnetExample
Private WithEvents myTelnet As Telnet
Private WithEvents myScript As TelnetScript
Public Sub New()
myTelnet = New Telnet("10.0.0.1")
' Create a TelnetScript
myScript = New TelnetScript(myTelnet)
' Create script tasks
Dim login As TelnetTask = New TelnetTask("login:", "username", "Password:")
Dim password As TelnetTask = New TelnetTask("Password:", "password", "$")
Dim sh_exec As TelnetTask = New TelnetTask("$", "run.sh", "$")
Dim failTask As TelnetTask = New TelnetTask(vbNull, "fail.sh", "$")
' Add tasks to script
myScript.AddTask(login)
myScript.AddTask(password)
myScript.AddTask(sh_exec)
' Connect to telnet server
myTelnet.Connect()
While Not sh_exec.IsComplete()
Try
Thread.Sleep(1000)
Catch e As Exception
End Try
End While
' sh_exec complete - check response
If (sh_exec.GetResponse().IndexOf("Success") <> -1) Then
' success - logout
myTelnet.Disconnect()
Else
' failure - run fail.sh (no start prompt needed) then logout
myScript.AddTask(failTask)
' wait for fail task to complete
While Not failTask.IsComplete
Try
Thread.Sleep(1000)
Catch e As Exception
End Try
End While
End If
' Disconnect from telnet server
myTelnet.Disconnect()
End Sub
Public Shared Sub main()
' Create new TelnetExample instance passing telnet server hostname or IP address
Dim example As TelnetExample
example = New TelnetExample
End Sub
Private Sub OnConnected(ByVal sender As Object, ByVal e As TelnetConnectedEventArgs) Handles myTelnet.ConnectedEvent
Console.WriteLine("Connected to {0}:{1}", e.Host, e.Port)
End Sub
Private Sub OnDisconnected(ByVal sender As Object, ByVal e As TelnetDisconnectedEventArgs) Handles myTelnet.DisconnectedEvent
Console.WriteLine("Disconnected")
End Sub
Private Sub OnDoOption(ByVal sender As Object, ByVal e As TelnetDoOptionEventArgs) Handles myTelnet.DoOptionEvent
myTelnet.SendWontOption(e.Option)
End Sub
Private Sub OnDontOption(ByVal sender As Object, ByVal e As TelnetDontOptionEventArgs) Handles myTelnet.DontOptionEvent
myTelnet.SendDontOption(e.Option)
End Sub
Private Sub OnWillOption(ByVal sender As Object, ByVal e As TelnetWillOptionEventArgs) Handles myTelnet.WillOptionEvent
myTelnet.SendDontOption(e.Option)
End Sub
Private Sub OnWontOption(ByVal sender As Object, ByVal e As TelnetWontOptionEventArgs) Handles myTelnet.WontOptionEvent
myTelnet.SendWontOption(e.Option)
End Sub
Private Sub OnDataReceived(ByVal sender As Object, ByVal e As TelnetDataReceivedEventArgs) Handles myTelnet.DataReceivedEvent
Console.WriteLine(myTelnet.Encoding.GetString(e.Data))
End Sub
Private Sub OnTaskStarted(ByVal sender As Object, ByVal e As TelnetTaskStartedEventArgs) Handles myScript.TaskStartedEvent
End Sub
Private Sub OnTaskEnded(ByVal sender As Object, ByVal e As TelnetTaskEndedEventArgs) Handles myScript.TaskEndedEvent
End Sub
Private Sub OnTaskFailed(ByVal sender As Object, ByVal e As TelnetTaskFailedEventArgs) Handles myScript.TaskFailedEvent
' Write the task name and disconnect
Console.WriteLine("Task " + e.Task.Command + " failed.")
myTelnet.Disconnect()
End Sub
End Class