Amazon ELB load balancing, Amazon SQS and SNS note

 elastic load balance:

- route request to multiple instances

- evenly distribution load to multiple ec2 instance

- monitor ec2 instance ( combine with auto scalling ) to forward request whenever the server is up / down. stop forwarding to dead ec2 instance

- adding more  backend without interupting front end process  // decoupled architecturee

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- low demand period

- high demand period

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// messaging and queueing

buffer = placing message into a buffer

// tight coupled architecture

cashier - straigh talk to barista.   // single component fail it causes issues for other compontents or even the whole system.

app a error - app b ikt error

// loosely coupled architecture

single failure wont cause cascading failures

one single failure is isolated so wont cause cascading failures

app A -- Message Queue -- app B

if app B fail.. A not fail.

app A will still send to message Queue until app B up again

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// messaging and queueing

messaging  remain in the quue until they are consumed or deleted

// amazon simple queue service ( SQS - queue)

Using Amazon SQS, you can send, store, and receive messages between software components, without losing messages or requiring other services to be available. In Amazon SQS, an application sends messages into a queue. A user or service retrieves a message from the queue, processes it, and then deletes it from the queue.

- send store receive  msg between  software component at any vol.

- msg are placed in queue until they are processed

- scale automatically, easy configure and used

- can send notification

data contained within msg is called payload.  // protected until delivery 

- person name, coffee order, time order  => digabung jd payload. dimasukin ke SQS

// amazon simple notification service ( SNS )

bs berupa email,txt msg , push notif / http request. skali di push, sent ke semua subscriber

// buat ngasih notification ke user.   => bs berupa email,txt msg , push notif / http request

publish / subscribe model

sns topic : a channel for msg to be delivered

configure subscriber ke topic -> lalu publish msg to those subscriber

1 message to topic => disebar ke banyak subscriber skali jalan.

subscribernya bs end point jg kyk : 

- sqs queues

- aws lambda

- https / http web hook 

bs jg ngasih notification ke end user via:

- mobile push

- sms

- email 

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monolithic application.