IT Architecture

What are the security issues with virtualization?

- All VMs share a common virtualization layer - if a process is able to get out of the VM and into the hypervisor, it can access ALL of the VMs - Virtualization systems make it easy to share information between various systems - Burden of additional security controls that are needed - Security boundaries need to be fluid so you can move VMs across systems - Entire VM can be written out to a single file which could potentially contain sensitive data; passwords

What is the value of a layered design for application architectures?

- Distribute responsibilities to each individual layer - Independently deploy, maintain, and update each layer without disrupting the entire application - Enable developers to work on each layer in parallel with each other - Supports reusability of components b/c each layer is grouped by functionality

What the advantages of a multi-core CPU architecture?

- Increased Performance - Saves energy - Suitable for intensive applications Dual-core is more efficient that 2 coupled singe-core processors

How is the layered application architecture deployed on physical machines?

- Layers describe logical grouping of functionality - Tiers describe the physical distribution of functionality - It is common for more than 1 layer to be stored on the same physical machine

What are the benefits of Virtualization?

- Operational efficiency= Organizations can use existing hardware more efficiency by putting more load on each computer - Desktop virtualization = ability to provide service regardless of users OS - Better control of OSs to ensure security requirements are met, constant updates - Scalability - Portable = VMs can be easily migrated from one physical system to another - Recoverability = Can be restored quickly on another system

What are the biggest concerns when designing a data center?

- Security - Energy - Location

What is the role of the Services Layer?

- To provide service to other applications and systems - Enables access directly to business layer so that application can be delivered through other channels

Describe 4 maturity levels of SaaS architectures.

1) Customized Each customer owns their own customized version of the hosted application 2) Configurable Each customer owns a tenant but all tenants have the same code 3) Multi-tenant-efficient configurable 4) Scalable, multi-tenant-efficient configurable Number of services can increase or decrease to match demand, update thousands of tenants instantly

Describe the four cloud deployment models with examples.

1) Public Cloud Available to the general public for free or charged. Has provision access control eg. Gmail 2) Private Cloud Services are delivered/managed within an organization. e,g. AWS 3) Community Cloud Controlled and used by a group of entities that have a shared interest or common mission e.g., NYSE Capital Market Community Platform 4) Hybrid Cloud Combination of public and private cloud. Activities that are non-critical are done on public, while rest are done on private e.g., OpenStack Cloud

Describe some of the parameters you would consider when deciding whether an Application should be deployed to the cloud? How will you pick the cloud deployment model?

1) Strategic alignment 2) BIA- readiness 3) Vendor Selection 4) Risk and Mitigation 5) Security & Price

Describe the 5 essential characteristics of cloud computing.

1. On-demand self-service 2. Broad network access 3. Resource pooling 4. Rapid elasticity 5. Measured Service

What are the components/functionalities of each layer of Application architecture?

1. Presentation Layer - Provides user interface for client to use application - Manages user interaction with the system - Contains components that connect UI with underlying business logic COMPONENTS - UI components - Presentation Layer Components 2. Business Layer - Implements core functionality of the application - Contains relevant business logic - Contains components that connect to other services and applications COMPONENTS - Application Façade - Business Workflows - Business Components - Business Entities 3. Data Layer - Provides access to data stored within the system as well as data from other networked systems - Generates data in a format that business layer can consume COMPONENTS - Data Access Components - Service Agents - Data Helpers/Utilities

What are the two components of the services layer?

1. Service Interfaces - Façade that exposes business logic to potential consumers 2. Message types - When data is exchanged across the services layer, the data structure is wrapped in a message structure that is supports various applications

Explain the process of designing a layered application architecture

1. Start with highest level of abstraction and group functionality into layers 2. Define public interface for each layer 3. Determine how the application will be deployed 4. Choose communication protocols for the various layers to interact

What is a virtual machine? How is it created?

A VM is an OS or application that simulates all of the hardware of the computer in multiple virtual machines Created by installing the entire OS and application environment onto a virtual disk, easily duplicate to create new VMs which can run in isolation all on the same physical server

What is middleware?

A piece of software that translates between software from different vendors

What is a virtual desktop?

A specific user's interface is displayed in a virtualized environment that is stored on a remote server. Different from desktop virtualization software which separates the physical machine from the software and presents an isolated OS for users

Explain the concept of a virtual infrastructure.

Abstracts compute resources with associated storage and network connectivity. Enables rapid scaling of resources.

What is multi-tenancy in the context of cloud computing?

An architecture where a single instance of software is used by multiple customers (tenants)

What is the Kernel in an operating system?

Central module of an operating system that loads first and stays in the main memory Connects system hardware to application software

What is presentation virtualization? Give example of its use.

Centralized systems that host multiple user sessions, all of the processing is done on the host system. Only presentation information updates are sent between client and host. eg. Citrix XenDesktop

What are some of the accepted industry definitions of cloud computing? How would you define it?

Cloud computing is a model that enables convenient, on demand network access to shared pool of configurable resources that can be rapidly provisioned.

What is a cloud infrastructure?

Cloud infrastructure can be divided into a physical layer and an abstraction layer. Physical layer = hardware resources Abstraction layer = software deployed across physical layer

What is n-tier deployment?

Components of the application are spread across many servers

How do you deploy an application in such way that you get high reliability?

Failover clusters Set of serves that are configured in such a way that if one server becomes unavailable, another server automatically takes over and continues processing

Explain Moore's Law. What impact does Moore's law have on computer purchase decisions?

Gordon Moore predicted that the number of transistors on a chip will double every two years - resulting in exponential growth in computing power *second part?

What are the two types of hypervisor architecture?

Monolithic hypervisor hosts hypervisor/VMM in a single layer that includes all required components; kernel, device drivers, I/O stack Microkernelized hypervisor Uses thin, specialized hypervisor that only perform core tasks or ensuring isolation

What does the word "cloud" denote in the context of cloud computing?

Network or physical machine that exists outside of your physical infrastructure or control

Explain the concept of privilege levels in an OS? How are these implemented in Windows and iOS?

Privilege level indicates a user's control of the underlying hardware Typically the application requests access from the next innermost layer

What is a process? How is it related to threads?

Process = basic unit of work in the OS Thread = subpart of a process that can be executed independently of other parts of the process - Advantage: Shared resources reduce overhead on OS

Describe the three cloud service models w/ examples

SaaS Enables consumer to use the provider's applications which are running entirely on the provider's cloud infrastructure. (GoogleDocs) IaaS Enables consumer to provision processing, storage, and network capability so that they can deploy and run their own software (Amazon Web Services) PaaS Enables consumer to deploy applications that are created using resources that are supported by the provider (Microsoft Azure)

What are the differences between the three cloud service models from the standpoint of application development?

SaaS The applications are accessible through a thin-client, like a web-browser. Consumer does not manage or control underlying cloud infrastructure IaaS Consumer does not manage or control underlying cloud infrastructure - but has control over OS, applications, storage, and networking components PaaS No control over underlying cloud infrastructure - but has control over deployed applications

Differentiate between scaling up and scaling out

Scale-up - Add hardware such as processers, RAM and network cards to support increased capacity Scale-out - Add more servers and load-balancing/cluster solutions - Depends more on application architecture than on underlying infrastructure

What is a thin client? What are the advantages of using a thin client? Where are thin clients typically used?

Thin client is an application that relies heavily on another server to execute processes Example: Web-browser; connects to Fat-client like google.com

Differentiate between type 1 and type 2 VMMs

Type-2 Creates an environment where processes can be executed without relying on the host system Type-1 (Hypervisor) VMM sits directly on top of the vendor's hardware - known as hypervisor layer - better for resource intensive workloads

Explain how security can be implemented when you deploy applications

Use of IAM protocols, users are provisioned access based to an application based on their role

How can optimum performance be obtained when large scale performance is required from an application?

Use of load balanced clusters Each client connects to load balancing logic which distributes traffic evenly across various application servers

What is a warehouse scale computer?

Very massive scale computer, enables a data center to pool of its resources together to create a giant computer

What is the role of a VMM in virtualization?

Virtual Machine Monitor Provides the ability to create multiple isolated instances that share the same underlying hardware resources

What is the relationship between virtualized infrastructure and cloud computing?

Virtualization pools together infrastructure resources and supports the use/delivery systems. Cloud computing determines how virtualized resources are allocated and delivered.

Differentiate between 2-tier, 3-tier and n-tier application deployment

n = number physical locations where an application layer is stored