Cancelling orders once placed

[TiggerTrader]

When a limit order is submitted in a strategy and not necessarily filled but needs to be cancelled, how does one do that?

For example, the strategy determines a condition where we want to place a buy stop limit to wait for the condition to play out but then the signal goes away. Enter order:
EnterLongStopLimit( 1, entryPrice, entryPrice, "tagLongOrderT1" );

How does that get cancelled if we know the signal is lost? I've looked at CancelOrder(IOrder order), but it sounds like I shouldn't use that. Does ExitLong(string fromEntrySignal) cancel the order if it is not filled?

[NinjaTrader_JoshP]

All you have to do to cancel a limit order is let it expire by not resubmitting it on the next OnBarUpdate().

[TiggerTrader]

You mean an order is only good for the life of the current bar? If that's true, how do I place an order and let it sit until it gets filled or I determine it needs to be cancelled?

[NinjaTrader_JoshP]

By default you need to keep resubmitting it on every single bar you want the order to be active. The moment you stop doing so, it will expire and be cancelled.

[TiggerTrader]

OK, so how, not by default, do I place the order to stay until I say so? In this strategy, I'm setting up a condition that will come true in a future bar.

[NinjaTrader_JoshP]

Use liveUntilCancelled = true overload method for the order and then use CancelOrder.