Cloud Computing Stack: Composability

Exploring Cloud Computing Stack

• Main components include composability, infrastructure, platforms, virtual appliances, and communication protocols
• Cloud architecture joins software running on virtualized hardware in multiple locations to provide on-demand service to end-users
• A unique combination of abstraction and metered service distinguishes cloud computing systems from general n-tiered Internet applications

Composability

• Involves building applications from a collection of components
• A composable system uses components to assemble services tailored for specific purposes
• Composable components must be modular and stateless

Modular

• A modular component is self-contained, independent, reusable, and replaceable
• Modularity makes system design easier
• IaaS vendors may not offer non-standard machine instances due to customer reliance on standard OS like Linux or Windows
• PaaS vendors might narrow standard parts to those working on their platforms
• SaaS vendors might eliminate composability for users since they deliver applications as a service, limiting custom applications

Stateless

• A transaction is executed without regard to other transactions or requests

Infrastructure

• Most IaaS providers use virtual machine technology
• Virtual machines can be described in terms of machine image or instance characteristics similar to real machines
• Virtual servers introduce a new way of thinking about and programming applications for developers

Platforms

• Platforms in the cloud act as software layers used to create higher levels of service
• Platforms offer hosted hardware and software for building and deploying Web applications or services
• Operating system vendors, like Microsoft, provide platforms that allow Windows developers to use ASP.NET application framework, support SQL Server, and program within Visual Studio through Azure Platform
• Platforms include tools and utilities for application design and deployment: team collaboration, testing, instrumentation, database, Web service integration, and storage

Virtual Appliances

• Applications like Web or database servers that run on a virtual machine image
• A virtual appliance is an platform instance and sits in the middle of the cloud computing stack "PaaS"
• Advantages: use virtual appliances to assemble complex services and removes the need for application configuration and maintenance
• The operating system is often cleared of unnecessary functionality
• Virtual appliances can be converted from one platform to another using Open Virtualization Format (OVF), which is a standard file format

Communication Protocols

• Cloud computing uses standard Internet protocol suite underpinned by HTTP and HTTPS transfer protocols
• Many client/server protocols (Remote Procedure Call "RPC") have been applied to distributed networking
• The first RPC technologies was XML-RPC, which uses platform independent XML data that encodes program calls and transports them through HTTP
• SOAP (Simple Object Access Protocol) is used for exchanging structured information in web services
• It allows applications running on different operating systems and programming languages to communicate via the Internet

SOAP Characteristics

• XML-Based: SOAP messages are formatted in XML, making them platform-independent and easy to read
• Protocol-Independent: SOAP works over various transport protocols like HTTP, SMTP, TCP, etc., with HTTP being the most common
• Language-Independent: Since SOAP uses XML, it can be implemented in any programming language that supports XML parsing
• Interoperability: Enables communication between applications on different platforms (e.g., Java, .NET, Python) and operating systems (e.g., Windows, Linux)
• Standardization: Provides a standardized way to structure messages, making it easier to integrate systems
• Security: Supports advanced security features like WS-Security, ensuring secure communication over networks

WSDL (Web Services Description Language)

• Closely related to SOAP and describes the web service itself
• WSDL is an XML-based language that describes the functionality of a web service and provides details about operations, message formats (SOAP), service location (endpoint URL), and communication protocols (HTTP)
• It acts as a "contract" between the client and the server, to indicates how to interact with the SOAP-based web service
• Once the client knows how to interact with the service (via WSDL), it uses SOAP to send and receive messages

Connecting to the Cloud

• Clients can connect via web browsers or proprietary applications running on servers, PCs, mobile devices, or cell phones
• These applications exchange data over an insecure and temporary mediums

Securely Connecting

• Use a secure protocol to transfer data such as SSL (HTTPS), FTPS, SSH, or IPsec
• Creating a virtual connection: data is protected by a tunneling mechanism using a virtual private network (VPN), or with a remote data transfer protocol such as Microsoft RDP
• Encrypt the data so that even if the data is intercepted or sniffed, the data will not be meaningful

Google Chrome OS

• A Linux open-source operating system designed to be a robust cloud client
• Shipped pre-installed on validated hardware from Google-approved OEMs, includes Trusted Platform Module "TPM" for a "trusted bootpath"
• Chrome OS exemplifies a cloud-first OS, integrating with Google Cloud services, suited for education, enterprise, and users prioritizing accessibility over local computing
• Relies on web applications and cloud services rather than traditional desktop software
• System updates, security patches, and feature enhancements are delivered seamlessly via the cloud without user intervention
• Stores preferences, bookmarks, and apps in the cloud, allowing users to log in from any Chrome OS device and retain their environment
• Data is encrypted in transit, reduces IT overhead with centralized cloud management and eliminates the need for expensive hardware, and key apps (e.g., Google Drive, Docs) offer offline functionality with syncing capabilities

Defining IaaS

• Virtualized resources are mapped to real systems
• When a client requests resources from the virtual systems, those requests are redirected to the real servers that do the actual work

Workload

• The fundamental unit of virtualized client in an IaaS deployment
• Simulates the ability of a physical server to do an amount of work
• Can be measured by: transactions per minute "TPM", disk Input/Output Per Second "IOPS", amount of RAM consumed under load in MB, network throughput in "Mbps", and Network latency in “milliseconds"
• Workloads support a certain number of users called "pods"
• Pods should get consideration when sizing limitations building a large cloudbased application
• Pods are aggregated into pools within an IaaS region called an availability zone "AZ"

Defining PaaS

• A software environment where developers can create customized solutions and applications
• Provides a fully integrated development environment
• Can be based on specific types of development languages or application frameworks
• The customer has no responsibility for maintaining the hardware or the software while vendor is responsible for operational aspects of the service, for maintenance, and for managing the product lifecycle
• The one example that's often quoted is Google's App Engine platform
• Locks the developers into a solution that is dependent upon the platform vendor

Defining SaaS

• is the most complete cloud computing service model and provides the computing hardware and software, as well as the solution itself
• Can be described as software that can be accessed globally over the Internet, using a browser
• Examples of SaaS software: Google Gmail, Google Docs
• Characteristics include: software is available over the Internet globally through a browser on demand, the license is subscription-based or usage-based, the service are monitored and maintained by the vendor, all users have the same version of the software, and supports multiple users and provides a shared data model through a multitenancy subscription

Defining IDaaS

• The Domain Name Service "DNS" provides identity authorization and lookup and the name servers that run domains are IDaaS servers
• An identity is a set of characteristics that make something recognizable or known.
• A digital identity is those attributes and metadata of an object that makes an object identifiable
• When working with IDaaS software, evaluate IDaaS applications on the following basis: User control for consent, Minimal Disclosure, Justifiable access, Decided human identification, and Consistency of Service