Structure of Android OS Android operating system consist of several layers, which are staring from bottom to top Linux Kernel : Takes care of threading, memory management, process management, hardware drivers, networking and security. Includes drivers for camera, audio, keypad, bluetooth, etc. Hardware Abstraction Layer HAL - Exposes hardware capabilities of hardware components such as Bluetooth, Camera etc to the Kotlin API through standard interfaces. When device is needed, the Kotlin API makes a call to the interface and a corresponding library is loaded for the hardware component. Android Runtime ART - Environment used to run the applications. Each application runs in its own process. Designed based on Java Virtual Machine to run apps in shared environment, where battery, CPU, memory are limited. Reads .dex files. Native C/C++ Libraries - Used to build core Android components such as ART and HAL.Their functionalities are exposed by Java Framework API Java API Framework - Set o...
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AWS Topics for certified Architect
AWS Config conformance packs AWS Config is a service that provides details on how your AWS resources are configured, how they relate to each other , how they were configured in the past Features Specify the resource types you want AWS Config to record. S3 bucket to receive a configuration snapshot SNS to send configuration stream notifications Rules that you want AWS Config to use to evaluate compliance information Conformance packs, or a collection of AWS Config rules and remediation actions Aggregator to get a centralized view of your resource inventory and compliance - collects AWS Config configuration and compliance data from multiple AWS accounts and AWS Regions into a single account and Region. Write advanced queries by referring to the configuration schema of the AWS resource. https://docs.aws.amazon.com/config/latest/developerguide/WhatIsConfig.html Ways to Use AWS Config notify you whenever resources are created, modified, or deleted ...
AWS Lambda little(?) known facts
Lambda can run on CloudFront edge locations closer to your servers (Lambda@Edge) in response to CloudFront events You can use a Lambda function to add HTTP security Headers when you cannot modify the application at the origin Lambda functions scale automatically, without you needed to configure, launch as many copies as needed To use a new version of specific programming language, you can change the runtime identifier of the Lambda function The event object passed to the Lambda function as input can be custom, user-defined object You are charged based on: number of requests that are served runtime duration of the function amount of allocated memory Maximum timeout is 15 minutes for Lambda. Minimum timeout is 1 second. You can use memory usage of your Lambda functions in Cloudwatch to ensure you have configured it correctly Duration of Lambda is calculated from when code begins executing till it ends rounded to nearest 1 ms You get better performance if you configure Lambda to run ...
Cloud and System Architecture Terminology - Answers
How do you define cloud architecture? - Applying cloud characteristics to a solution that uses cloud services and features What does serverless mean? Way to build and run applications and services without thinking about servers. It is the architecture of the cloud. You shift more operational responsibilities to AWS , and you focus on agility and innovation. You do not worry about provisioning, patching, OS maintenance and capacity provisioning of servers. How do you define "reliability"? Measure of system's ability to provide functionality when desired by the user How do you measure reliability? In what units? Hours How do you calculate and measure reliability? Using Mean time between failures (MTBF) over provided period of time, most commonly 1 year . MTBF = (Total time in service) / (Number of failures) How do you define availability? % of time your system is operating normally How do you measure availability? In what ...
Cloud and System Architecture Terminology - Questions
How do you define cloud architecture? What does serverless mean? How do you define "reliability"? How do you measure reliability? In what units? How do you calculate and measure reliability? How do you define availability? How do you measure availability? In what units? How do you calculate availability? What is a highly available system? How do you define "fault tolerance"? How do you define scalability? How do you define recoverability ? What is the relationship between availability, recoverability, fault tolerance and scalability? https://aws-architecture-svetlana.blogspot.com/2023/12/cloud-and-system-architecture.html - Answers
Caching and protecting against attacks
Types of attacks: Synchronize/ Acknowledge floods In a SYN flood attack, a malicious client sends a large number of SYN packets, but never sends the final ACK packets to complete the handshakes. The server is left waiting for a response to the half-open TCP connections and the idea is that the target eventually runs out of capacity to accept new TCP connections which prevents new users from connecting to the server, however the actual impact is more nuanced. UDP Floods https://docs.aws.amazon.com/whitepapers/latest/aws-best-practices-ddos-resiliency/udp-reflection-attacks.html Reflection attacks HTTP Flood attacks Distributed Denial of Service Attack Flooding your website with network traffic from multiple sources ( distributed groups of computers, IoT, etc) https://aws.amazon.com/blogs/security/how-to-protect-dynamic-web-applications-against-ddos-attacks-by-using-amazon-cloudfront-and-amazon-route-53/ Protection In AWS, DDoS mitigation capabilities are automatically provide...