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We've now got some publishers put together inside of our order service.

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And at this point time I'm really excited because we've got publishers available inside the order service

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and inside the ticket service.

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So here's what we're going to start to work on.

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We're going to start to put together some number of listeners in these two services.

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Remember that the goal of a listener is to process a number of incoming events inside of both these

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services.

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We have to create two different listeners.

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So you might recall seeing this diagram right here was a diagram of where all these different events

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are coming from and where they're going to go for the ticket created event.

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We need to make sure that the order service receives this event or it listens for ticket created.

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And I've got some notes on here about what that listener needs to do the order service also needs to

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listen for ticket updated.

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That's two listeners at least we have to build inside order service then inside the ticket service.

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We need to make sure that thing listens for the order created event and for the order canceled event.

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We're going to first begin working on our listeners or creating a ticket and updating a ticket.

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So these are both listeners we're going to put together inside of our orders service.

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And the reason I'm so excited about this is that this is where we're going to start to see some crazy

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concurrency issues start to come up and we're going to figure out how to solve these concurrency issues.

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You might recall discussing this diagram a little bit ago a couple hours ago inside the course where

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we discussed having some of these events of ticket created and ticket updated come into our application

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in some weird order and we saw that if they get processed in a weird order we could end up with some

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super invalid data.

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So we eventually came up with a solution of using this version field to somehow track in order these

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different events inside of our app.

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So this is where we're going to start to go back to all this concurrency stuff and implement this versioning

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thing.

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So again the first stuff we're gonna put together we're going to get a listener put together or ticket

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created and ticket updated inside of our order service.

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And as soon as we do that so we're going to start to see these version numbers start to become really

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important.

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All right.

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Now we got a little preview of what we're gonna be focusing on.

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Let's take a quick pause right here.

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We're going to get a quick reminder on how we create a listener in the next video.