PowerBuilder

SSH Parallel Remote Commands on a Single Server

Demonstrates running several commands in parallel on one SSH server and collecting each command's output as it finishes. QuickCmdSend starts each command and returns immediately; QuickCmdCheck reports them as they complete.

Background: Because SSH multiplexes channels, several commands can run at once over one authenticated connection — far faster than running them one after another when each involves waiting. Results arrive in completion order rather than the order the commands were started, so the loop keys off the returned channel number. Distinguish the two negative returns carefully: -1 means "still working, ask again," while -2 means nothing remains to collect or the connection failed.

Chilkat PowerBuilder Downloads

Download Chilkat for PowerBuilder

PowerBuilder

integer li_rc
integer li_Success
oleobject loo_Ssh
integer li_Port
string ls_Password
integer li_Channel1
integer li_Channel2
integer li_Channel3
integer li_PollTimeoutMs
integer li_NumFinished
integer li_Channel
string ls_CmdOutput

li_Success = 0

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

//  Demonstrates running several commands in parallel on a single SSH server and collecting each
//  command's output as it finishes.

loo_Ssh = create oleobject
li_rc = loo_Ssh.ConnectToNewObject("Chilkat.Ssh")
if li_rc < 0 then
    destroy loo_Ssh
    MessageBox("Error","Connecting to COM object failed")
    return
end if

li_Port = 22
li_Success = loo_Ssh.Connect("ssh.example.com",li_Port)
if li_Success = 0 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_Ssh
    return
end if

//  Normally you would not hard-code the password in source.  You should instead obtain it
//  from an interactive prompt, environment variable, or a secrets vault.
ls_Password = "mySshPassword"

li_Success = loo_Ssh.AuthenticatePw("mySshLogin",ls_Password)
if li_Success = 0 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_Ssh
    return
end if

//  QuickCmdSend starts a command and returns immediately, so all three run concurrently, each on
//  its own session channel.
li_Channel1 = loo_Ssh.QuickCmdSend("df")
if li_Channel1 < 0 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_Ssh
    return
end if

li_Channel2 = loo_Ssh.QuickCmdSend("date")
if li_Channel2 < 0 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_Ssh
    return
end if

li_Channel3 = loo_Ssh.QuickCmdSend("echo hello world")
if li_Channel3 < 0 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_Ssh
    return
end if

//  Collect the results.  QuickCmdCheck returns the channel number of a completed command,
//  -1 when commands are still pending but none finished within the timeout, or -2 when nothing
//  remains to be checked (or an error occurred).
li_PollTimeoutMs = 50
li_NumFinished = 0
do while li_NumFinished < 3
    li_Channel = loo_Ssh.QuickCmdCheck(li_PollTimeoutMs)
    if li_Channel = -2 then
        Write-Debug loo_Ssh.LastErrorText
        destroy loo_Ssh
        return
    end if

    if li_Channel >= 0 then
        Write-Debug "---- channel " + string(li_Channel) + " finished ----"
        ls_CmdOutput = loo_Ssh.GetReceivedText(li_Channel,"utf-8")
        if loo_Ssh.LastMethodSuccess = 0 then
            Write-Debug loo_Ssh.LastErrorText
            destroy loo_Ssh
            return
        end if

        Write-Debug ls_CmdOutput
        li_NumFinished = li_NumFinished + 1
    end if

loop

loo_Ssh.Disconnect()


destroy loo_Ssh