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ADVANTAGES AND DISADVANTAGES OF PUB/SUB

ADVANTAGES Loose Coupling Publishers do not know about the existence of the subscribers so that both systems can operate independently of each other. By this method, the service dependencies which are present in traditional coupling are completely abolished. A Publisher doesn’t need to know about -                They will be able to work independently and this will allow them to develop both separately without worrying about any number of ripple effects, states, or implementation.  Scalability Pub/sub messaging will scale to volumes beyond the limited capabilities of a single traditional data-gathering center. This level of unprecedented scalability is primarily due to parallel operations, message caching, tree-based routing, and multiple other features built into the pub/sub model. But for all its advantages, Scalability has a limit. If the number of nodes and messages are increased, then the chances of experiencing a load surge or slowdown increase
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COMMON PUB/SUB USE-CASES

COMMON PUB/SUB USE-CASES 1. Implementing Asynchronous Workflows - You will be able to produce an application that's used to place and process orders. This application can use a Pub/Sub topic, wherever the order would be placed and might be picked up by multiple staff for its processing. 2. Distributing Event Notifications - You can produce an application that incorporates a module that handles new user registrations. This module can fetch the info from user-signups and send notifications whenever a new registration happens. the other module of the application can subscribe to receive the notifications sent by the primary module. 3. Refreshing a Distributed Cache - You can produce an application that will be accountable for publishing invalidation events to update the first keys of objects that are altered. 4. Reliability Improvement - You can produce a service in one region/zone and operate it from multiple regions by subscribing to a subject common to all or any re
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HOW DATA PROCESSES IN PUB/SUB

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  HOW DATA PROCESSES IN PUB/SUB   Create a topic:   1.     In the google cloud console, navigate to the Pub/Sub topic page. 2.     Click create  topic and enter a unique name.   Subscribe to the Topic :   1 .     Once the Pub/Sub topic is made, add a subscriber to this. For this navigate to Create subscriptions. 2.     Name the created subscription and select one of the options as push or pull and click the create button. Publish a message to the topic:   To publish a message to the topic. For the topic that we just created, click on the Publish a message button and subsequently enter any message in the message field and then finally, publish it with the help of the add an attribute button. Pull the data published:   Finally, execute the gcloud pubsub subscriptions pull –auto-ack [SUBSCRIPTION_NAME] command to pull the data from the subscription. The output should then display the message published as follows .
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DATA FLOW IN PUB/SUB

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PUB/SUB MESSAGE FLOW The diagram given below is a look of the components in the Pub/Sub system and how messages flow between them: 1.   A publisher application creates a topic in the Pub/Sub service and then sends some messages to the topic. The message consists of a payload and optional attributes that describe the related payload content. 2.   The service must ensure that published messages are retained on behalf of respective subscriptions. A published message is retained for a subscription until it is formally acknowledged by any subscriber which is consuming messages from that subscription. 3.   Pub/Sub then forwards messages from a topic to all its respective subscriptions individually. 4.    A subscriber receives messages either by Pub/Sub pushing them to that subscriber's chosen endpoint, or by the subscriber pulling them from the service. 5.   The subscriber then sends an acknowledgement to the Pub/Sub service for each of received message. 6.     The service finally remove
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INTRODUCTION TO CLOUD PUB/SUB

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Publish/subscribe messaging, or pub/sub messaging, is a type of asynchronous service-to-service communication employed in serverless and microservices architectures. in a pub/sub model, any message published to a subject is instantly received by all of the subscribers to a topic. Pub/sub messaging is often used to modify event-driven architectures, or to decouple applications so as to extend performance, reliability, and quantifiability. You can use Pub/Sub as messaging-oriented middleware or event activity and delivery for streaming analytics pipelines . Pub/Sub Messaging Basics In modern cloud design, applications are decoupled into smaller, freelance building blocks that are easier to develop, deploy, and maintain. Publish-Subscribe i.e. Pub/Sub messaging provides instant event notifications for all of these distributed applications.  The Publish-Subscribe model permits messages to be broadcast to completely different components of a system asynchronously. A sibling to a mes
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