[AWS Certificate] Developer - SNS, SWF and Elastic Beanstalk

SNS (Simple Notification Service)

Amazon Simple Notification Service (Amazon SNS) is a web service that makes it easy to set up, operate, and send notifications from the cloud.

It provides developers with a highly scalable, flexible, and cost-effective capability to publish messages from an application and immediately deliver them to subscribers or other applications.

Amazon SNS follows the "publish-subscribe" (pub-sub) messaging paradigm, with notifications being delivered to clients using a "push" mechanism that eliminates the need to periodically check or "poll" for new information and updates.

With simple APIs requiring minimal up-front development effort, no maintenance or management overhead and pay-as-you-go pricing, Amazon SNS gives developers an easy mechanism to incorporate a powerful notification system with their applications.

Push notifications to Apple, Google, Fire OS, and Windows devices, as well as Android devices in China with Baidu Cloud Push.

Besides pushing cloud notifications directly to mobile devices, Amazon SNS can also deliver notifications by SMS text message or email, to Amazon Simple Queue Service (SQS) queues, or to any HTTP endpoint.

To prevent messages from being lost, all messages published to Amazon SNS are stored redundantly across multiple availability zones.

SNS - Topics

SNS allows you to group multiple recipients using topics. A topic is an "access point" for allowing recipients to dynamically subscribe for identical copies of the same notification.

One topic can support deliveries to multiple endpoint types -- for example, you can group together iOS, Android and SMS recipients. When you publish once to a topic, SNS delivers appropriately formatted copies of your message to each subscriber.

SNS Benefits

- Instantaneous, push-based delivery (no polling)

- Simple APIs and easy integration with applications

- Flexible message delivery over multiple transport protocols

- Inexpensive, pay-as-you-go model with no up-front costs

- Web-based AWS Management Console offers the simplicity of a point-and-click interface

SNS vs. SQS

- Both Messaging Services in AWS

- SNS - Push

- SQS - Polls (Pulls)

SNS Pricing

- Users pay $0.50 per 1 million Amazon SNS Requests

- $0.06 per 100,000 Notification deliveries over HTTP

- $0.75 per 100 Notification deliveries over SMS

- $2.00 per 100,000 Notification deliveries over Email

SNS FAQ

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Creating SNS Topic

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SNS Summary

- Instantaneous, push-based delivery (no polling)

- Protocols include

  : HTTP

  : HTTPS

  : Email

  : Email-JSON

  : Amazon SQS

  : Application

- Messages can be customized for each protocol

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SNS Quiz

- SNS is pull based rather than push based? : False

- Which of these is a protocol NOT supported by SNS

  HTTP, HTTPS, Email, Email-JSON, FTP, SQS, Application

  ==> The answer is FTP

- Messages cannot be customized for each protocol used in SNS? : False

- You have a list of subscribers email addresses that you need to push emails out to on a periodic bases. What do you subscribe them to? : A Topic

- You can use SNS in conjunction with SQS to fan a single message out to multiple SQS queues. : True

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AWS SWF (Simple Workflow Service)

Amazon Simple Workflow Service (Amazon SWF) is a web service that makes it easy to coordinate work across distributed application components. Amazon SWF enables applications for a range of use cases, including media processing, web application back-ends, business process workflows, and analytics pipelines, to be designed as a coordination of tasks.

Tasks represent invocations of various processing steps in an application which can be performed by executable code, web service calls, human actions, and scripts.

SWF Workers

Workers are programs that interact with Amazon SWF to get tasks, process received tasks, and return the results.

SWF Decider

The decider is a program that controls the coordination of tasks, i.e. their ordering, concurrency, and scheduling according to the application logic.

SWF Workers & Deciders

The workers and the decider can run on cloud infrastructure, such as Amazon EC2, or on machines behind firewalls. Amazon SWF brokers the interactions between workers and the decider. It allows the decider to get consistent views into the progress of tasks and to initiate new tasks in an ongoing manner.

At the same time, Amazon SWF stores tasks, assigns them to workers when they are ready, and monitors their progress. It ensures that a task is assigned only once and is never duplicated. Since Amazon SWF maintains the application's state durably, workers and deciders don't have to keep track of execution state. They can run independently, and scale quickly.

SWF Domains

Your workflow and activity types and the workflow execution itself are all scoped to a domain. Domains isolate a set of types, executions, and task lists from others within the same account.

You can register a domain by using the AWS Management Console or by using the RegisterDomain action in the Amazon SWF API.

The parameters are specified in JavaScript Object Notation (JSON) format.

How Long For workflow?

Maximum Workflow can be 1 year and the value is always measured in seconds.

SWF FAQ

SWF vs SQS

- Amazon SWF presents a task-oriented API, whereas 

  Amazon SQS offers a message-oriented API.

- Amazon SWF ensure that a task is assigned only once and is never duplicated. With Amazon SQS, you need to handle duplicated messages and may also need to ensure that a message is processed only once.

- Amazon SWF keeps track of all the tasks and events in an application. With Amazon SQS, you need to implement your own application-level tracking, especially if your application uses multiple queue.

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SWF Quiz

- SWF consists of a domain, workers an deciders? : True

- Maintaining your application's execution state (e.g. which steps have completed, which ones are running, etc.) is a perfect use case for SWF. : True

- Amazon SWF is useful for automating workflows that include long-running human task (e.g. approvals, reviews, investigations, etc.) Amazon SWF reliably tracks the status of processing steps that run up to several days or months. : True

- In Amazon SWF what is a worker? 

  : Workers are programs that interact with Amazon SWF to get tasks, process received tasks, and return the results

- In Amazon SWF what is a decider

  : The decider is a program that controls the coordination of tasks, i.e. their ordering, concurrency, and scheduling according to the application logic.

  

  

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Elastic Beanstalk (*** 4~5 questions in the Exam)

- With Elastic Beanstalk, you can deploy, monitor, and scale an application quickly

- It provides developers or end users with the ability to provision application infrastructure is an almost transparent way.

- It has a highly abstract focus towards infrastructure, focusing on components and performance - not configuration and specifications

- It attempts to remove, or significantly simplify infrastructure management, allowing applications to deployed into infrastructure environments easily.

Beanstalk key architecture components

- Applications are the high level structure in beanstalk

- Either your entire application, is one EB application, or

- Each logical component of your application, can be a EB application or a EB environment within an application

- Applications can have multiple environments (Prod, Staging, Dev, V1, V2, V1.1 or functional type (front-end, back-end)

- Environments are either single instance or scalable

- Environments are either web server environments or worker environments

- Application Versions are unique packages which represent versions of apps.

- An application is uploaded to Elastic beanstalk as a application bundle - .zip

- Each application can have many versions 1:M relationship

- Application versions can be deployed to environments within an Application

Elastic Beanstalk Exam Tips

- You can have multiple versions of your applications

- Your applications can be split in to tiers (Web Tier/Application Tier/Database Tier)

- You can update your application

- You can update your configuration

- Updates can be 1 instance at a time, a % of instances or an immutable update

- You pay for the resources that you use, but Elastic Beanstalk is free

- If elastic beanstalk creates your RDS database then it will delete it when you delete your application. If not then the RDS instance stays 

- Know what languages are supported

- Apache Tomcat for Java application

- Apache HTTP Server for PHP applications

- Apache HTTP Server for Python applications

- Nginx or Apache HTTP Server for Node.js applications

- Passenger or Puma for Ruby applications 

- Microsoft IIS 7.5, 8.0, and 8.5 for .NET applications

- JAVA SE

- Docker

- Go

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Elastic Beanstalk Quiz

- Elastic Beanstalk is object based storage. : False

- What languages and development stacks is NOT supported by AWS Elastic Beanstalk?

  : Jetty for jbos application 

- Unlike Cloud Formation, Elastic Beanstalk itself is not free AND you must also pay for the resources it provisions. : False

Elastic Beanstalk FAQ

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