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In this lecture, I'll show you how to use a delanoe, it's a very useful note, it actually does two

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things.

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It allows you to delay a message input and output by an arbitrary amount of time, but also to limit

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the rate of messages that are passing through it, which is very useful if you want to connect your

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flow to some external resource on the cloud.

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For example, Google spreadsheet, those services typically introduce limits to how many messages they

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can receive, and if you exceed them, then you're locked out, or at least you are limited by the imposed

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rate limit.

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So you can then use the delay node to ensure that your flow does not bombard an external service with

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too many messages.

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So let's have a look at this in practice here.

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I've got a trigger that sent out the timestamp and I've got a debug note to show us the exact time stamp

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at the moment, what I trigger it, and then the time stamp trigger will also start the delay node.

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So I've got five seconds delay and after five seconds, the delayed message debug node will fire and

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show us the payload five seconds later.

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So let's try this out.

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Looking at the current flow, I'm going to trigger that inject node.

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And they go five seconds later, the same payload is let through by the DeLay node so he can see it

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here.

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Another thing that is interesting is this.

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Let's say that I generate multiple timestamps within a small amount of time just by clicking on the

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button here multiple times.

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It looks like this.

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So you can see that I've got a fairly high rate of messages being produced and all those are delayed

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by five seconds and eventually they do appear just five seconds delayed.

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Know, what I can do instead is I can say that I want to limit the rate of those messages and I want

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to drop any intermediate messages so that only one message per second is actually able to pass through.

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So let's see what the effect of this is.

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I'm going to do multiple clicks on this button to simulate a high rate of messages passing through the

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flow.

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And that is what happens in the output in the delete message debug node.

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OK, so I've got a bunch of royal messages here, you see the first delayed message did come through

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and then I've got a bunch of royal messages until another message came through.

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But these messages, you can see the time stamps should be of a second part.

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So thirty eight.

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Thirty eight seconds and then you've got thirty nine seconds.

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Instead of having multiple messages coming through to match the rate by which I was clicking on the

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button here to exaggerate a little bit more to make this a little bigger.

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Five seconds.

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So one message per five seconds and it drops the intermediate messages.

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So those are totally lost for good.

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Deploy that and clean up and I'm going to do a few consecutive clicks on the timestamp node.

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OK, so let's go back to the beginning, his first delete message at 39, nine, 34, four minutes or

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so, 39 minutes and 34 seconds.

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And the next one.

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So they put a number here for the next one.

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It's right here, 39, exactly five seconds later, we have a single message coming out of the delayed

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message, so we will be using the delay node in our project later on.