Designing For Operational Excellence

CloudFront

• Content Delivery Network (CDN)
  • Distribute content to localized regions.
  • Reduces latency, provides high data transfer speeds.

3 Types of Items Usually Leveraged:

1. S3 - Cached locally near the user.
2. MediaPackage Channel - AWS service for different media types.
3. HTTP(s) Server.

Content Access: Public or Restricted.

Content Restraint: HTTPS required, Geo-Restrictions (ie Netflix).

CloudFront uses regional edge caches and edge locations to provide localized content.

Web Application Firewall (WAF)

• Controls access to HTTP and HTTPS servers.
  • Based on requests.
  • Based on source IPs.
• Works with CloudFront or Private Elastic Load Balancer.

WAF Behaviours:

• Allow all requests.
  • EXCEPT for the ones you specify. Monitoring:
• Requests that match specified parameters.

WAF Operations:

• Error Handling: HTTP Error, like HTTP 403 Forbidden.
• Configurable Default Behaviour: Allow or Deny.

AWS Shield

• Standard: Monitoring and DDoS support (Free)
• Advanced: $3k USD/month.

Simple Queue Service (SQS)

• Used to decouple applications.
  • Break applications into separate processing tasks.
  • Allow many small processes to form a complete solution.

SQS Messages:

• Outputs from other processes, inputs to other processes.
• Queued and processed asynchronously.
• Up to 25 KiB data.

SQS Participants:

• Message producers.
• Message consumers.
• Messaging service (SQS)

Good to Know:

• It’s redundant across multiple AZs.
• Queued until processed.
• Retention up to 14 days.
• Auto-scales.

Queue Types:

1. Standard (Default)
   • Doesn’t guarantee sequential delivery of messages.
2. First-In-First-Out:
   • Guarantees sequential delivery of messages.
   • Supports fewer transactions per second.

Simple Notification System (SNS)

• Getting alerts in the cloud.
• Uses the pub-sub messaging model based on “topics”.
• Stored across multiple AZs.
• Several Delivery Options:
  • HTTPS/HTTPS
  • Email
  • SMS
  • Lambda
• Max 256 Kib of Data
• SMS Max: 140 bytes.

Simple Workflow (SWF)

• Defines the sequence of events required to achieve a workflow.
• Used to decouple application.

Workflows: Activities that result in a desired objective, logic that controls the activities.

• Decider function determines the best workflow.
• Operates in a Domain:
  • Logical boundary to constrain scope of activities.

SWF Activity Workers: Applications that receives and processes activity tasks.

Step Functions

• Replacement for SWF, recommended by AWS. Can flow through different steps in parallel concurrently.