WEBVTT

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So guys, now finally we will going to implement the notification and subscription.

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So so far we have created a publisher thread and we have created a couple of subscriber threads and

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we have implemented a data source which is nothing but a routing table, and it is the publisher thread

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which performs Crud operations on this data source.

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Right.

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So far we have not yet implemented any mechanism using which subscriber can express their interest in

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the particular entry of a data source.

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And also we have not implemented any mechanism using which whenever a publisher updates the data source,

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a notification is sent to the subscriber about the update.

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Right?

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So this is what we will going to implement next.

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So we will going to implement the subscription.

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Subscription means that allow subscribers to subscribe or unsubscribe for a particular entry of interest

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for notifications.

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So it is the subscriber responsibility to express interest in a particular entry in a data source.

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And the other part is the notification.

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That is, whenever the publisher updates any entry in the data source, we need to notify all the subscribers

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which are interested in that particular entry whenever that entry is updated by the publisher.

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Right.

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So notification is a communication from the data source to the subscriber where a subscription is a

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communication from the subscriber towards the data source.

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Now note that in this diagram we have precisely captured the architecture of a publisher subscriber

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model.

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In this architecture you can see that publisher is absolutely unaware of the presence of subscribers.

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Publisher don't even know there is any subscriber or not.

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All publisher does is to update the data source.

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Right?

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It is the data source which is aware of the subscribers, right.

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So let us see how we will going to implement the mechanism of subscription and notification.