PowerBuilder

Wait for a Message on Any SSH Channel

Demonstrates the Chilkat Ssh.WaitForChannelMessage method, which waits for the next SSH channel message on any channel. The only argument is the poll timeout: 0 for a nonblocking check, a positive value to wait that long, or a negative value to wait with no method-level timeout. It returns the channel number the message belongs to, -1 if nothing arrived before the timeout, or -2 on another error such as a lost connection.

Background: When several channels are active at once, waiting on one specific channel would block while others sit ready. This method is the multiplexed alternative — it returns as soon as any channel has activity and tells you which one, so a single loop can service them all. The explicit timeout argument governs the wait; shorter ReadTimeoutMs values do not cut it short.

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integer li_rc
integer li_Success
oleobject loo_Ssh
integer li_SshPort
string ls_Password
integer li_ChannelNum
integer li_PollTimeoutMs
integer li_Result

li_Success = 0

//  Demonstrates the Ssh.WaitForChannelMessage method, which waits for the next SSH channel
//  message on ANY channel.  The only argument is the poll timeout in milliseconds: 0 for a
//  nonblocking check, a positive value to wait that long, or a negative value to wait with no
//  method-level timeout.

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_SshPort = 22
li_Success = loo_Ssh.Connect("ssh.example.com",li_SshPort)
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

li_ChannelNum = loo_Ssh.OpenSessionChannel()
if li_ChannelNum < 0 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_Ssh
    return
end if

li_Success = loo_Ssh.SendReqExec(li_ChannelNum,"ls -l /tmp")
if li_Success = 0 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_Ssh
    return
end if

//  Wait up to 5 seconds for the next channel message.  The return value is the channel number
//  the message belongs to, -1 if nothing arrived before the timeout, or -2 on another error.
li_PollTimeoutMs = 5000
li_Result = loo_Ssh.WaitForChannelMessage(li_PollTimeoutMs)

if li_Result = -2 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_Ssh
    return
end if

if li_Result = -1 then
    Write-Debug "No channel message arrived before the timeout."
end if

if li_Result >= 0 then
    Write-Debug "Processed a message for channel " + string(li_Result)
end if

loo_Ssh.Disconnect()


destroy loo_Ssh