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2.2 messaging model - Coggle Diagram
2.2 messaging model
Azure Event Grid
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- distributes events from different sources
- to different handlers
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- What happened.
- data messages passing through Event Grid that describe what has taken place
- can be up to 64 KB
- sending events to Event Grid
- related to one or more event types.
- categorize events into groups
- represented by a public endpoint
- you can decide how many topics to create
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- The endpoint or built-in mechanism to route events, sometimes to multiple handlers.
- Subscriptions are also used by handlers to filter incoming events intelligently.
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why
- simplicity
- filtering
- subscribe to an unlimited numbers of endoints
- reliability
- pay per event
Queues
uses Azure Storage to store large numbers of messages that can be securely accessed from anywhere in the world using a simple REST-based interface
- message broker system intended for enterprise applications
- multiple communication protocols, have different data contracts, higher security requirements, and can include both cloud and on-premises services
- like queues, but can have multiple subscribers
- processed by each subscription branch
Benefits
- Increased reliability
- Message delivery guarantees
- At-Least-Once Delivery: guaranteed to be delivered to at least one of the components that retrieve messages from the queue
- At-Most-Once Delivery: very small chance that it may not arrive; no chance that the message will be delivered twice
- First-In-First-Out (FIFO):
- Transactional support
choose
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service Bus queues if:
You need an At-Most-Once delivery guarantee.
You need a FIFO guarantee.
You need to group messages into transactions.
You want to receive messages without polling the queue.
You need to provide a role-based access model to the queues.
You need to handle messages larger than 64 KB but less than 256 KB.
Your queue size will not grow larger than 80 GB.
You would like to be able to publish and consume batches of messages.
Queue storage if:
You need an audit trail of all messages that pass through the queue.
You expect the queue to exceed 80 GB in size.
You want to track progress for processing a message inside of the queue.
Azure Event Hubs
- intermediary for the publish-subscribe communication
- massive number of events
Partitions
- Partitions are buffers into which the communications are saved
- By default, events stay in the buffer for 24 hours before they automatically expire
- default partitions: 4
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why
- You need to support authenticating a large number of publishers.
- You need to save a stream of events to Data Lake or Blob storage.
- You need aggregation or analytics on your event stream.
- You need reliable messaging or resiliency.
- the components sending the event are known as publishers
- receivers are known as subscribers.
subscription is managed by an intermediary,
like Azure Event Grid or Azure Event Hubs
- An event is a lightweight notification that indicates that something happened.
- The event may be sent to multiple receivers, or to none at all.
- Events are often intended to "fan out," or have a large number of subscribers for each publisher.
- The publisher of the event has no expectation about the action a receiving component takes.
- Some events are discrete units and unrelated to other events.
- Some events are part of a related and ordered series.
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- contains raw data, produced by one component, that will be consumed by another component
- contains the data itself, not just a reference to that data
- The sending component expects the message content to be processed in a certain way by the destination component.
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