Cloud Computing

Often referred to as a "lift-and-shift" migration. This option doesn't require code changes and lets you migrate your existing apps to Azure quickly. Each app is migrated as-is to reap the benefits of the cloud without the risk and cost associated with code changes.

Often referred to as "repackaging“, refactoring requires minimal changes to apps so that they can connect to Azure PaaS and use cloud offerings. For example, you could migrate existing apps to Azure App Service or Azure Kubernetes Service (AKS). Or, you could refactor relational and non-relational databases into options such as Azure SQL Database Managed Instance, Azure Database for MySQL, Azure Database for PostgreSQL, and Azure Cosmos DB.

Rearchitecting for migration focuses on modifying and extending app functionality and the codebase to optimize the app architecture for cloud scalability. For example, you could break down a monolithic application into a group of microservices that work together and scale easily. Or, you could rearchitect relational and non-relational databases to fully managed DBaaS solutions, such as Azure SQL Database Managed Instance, Azure Database for MySQL, Azure Database for PostgreSQL, and Azure Cosmos DB.

Rebuild takes things a step further by rebuilding an app from scratch using Azure cloud technologies. For example, you could build greenfield apps with cloud-native technologies like Azure Functions, Azure Al, Azure SQL Database Managed Instance, and Azure Cosmos DB.

The following attributes can characterize the cloud

• On-demand self-service
• Broad Network access and accessible with different devices
• Resource pooling and multi-tenant
• Rapid elasticity
• Measured services report on resource usage

The Cloud Provider provides these shared resources.

• IaaS: Infrastructure as a Service
• PaaS: Platform as a Service
• SaaS: Software as a Services

See also Cloud Service Models - snippset

• Public Cloud: Cloud service provided by a third-party provider, hardware can be shared amongst multiple clients
• Private Cloud: Hardware is only used by a single company, which often owns the hardware and datacenter
• Hybrid Cloud: Combination of public and private cloud with automation and orchestration between the two
• Community Cloud: Infrastructure is shared between several organizations from a specific community with common concerns (security, compliance, jurisdiction, etc.)

Companies use different cloud environments for legacy reasons or leverage the right cloud service based on specific needs or requirements like data sovereignty or other regulation.

Reasons for a hybrid and multi-cloud strategy

• Regulatory and data sovereignty (patient record or financial records needs to stay in a country or region)
• Low latency and edge workloads (up to the cloud, process, and back down)
• Application and datacenter modernization
• Business continuity and resilience (backup of data and app into another cloud, no lock-in)
• Freedom to use more than one public cloud
• Acquisition
• Different offerings from different cloud providers

• What is Cloud Computing? Everything You Need to Know (techtarget.com)

The National Institute of Standards and Technology (NIST) recognizes three standard cloud computing models of as-a-service: Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS), and Software-as-a-Service (SaaS). 

In effect, each of these models offers a progressive level of abstraction – or management – by the cloud provider.

Definition: IaaS is the utilization of APIs to manage the lowest levels of network infrastructure, including networking, storage, servers, and virtualization. 

Examples: Digital Ocean, Google Compute Engine, Microsoft Azure, Rackspace, and Amazon Web Services (AWS)

Common Use Cases: IaaS is the most flexible service model for cloud computing, so it is especially effective for startups and organizations looking for agile scaling. It is also preferred by businesses that seek greater control over their resources.

Definition: PaaS offers an even greater abstraction of cloud service, offering users the capability to build or deploy applications using tools (i.e. programming languages, libraries, services) without maintaining the underlying infrastructure. Users instead have control over the applications themselves. 

Examples: Microsoft Azure, Salesforce, AWS Elastic Beanstalk, Heroku, Google App Engine (GAE), and OpenShift

Common Use Cases: PaaS is highly available and highly scalable, and it gives organizations the ability to build and create new services and solutions without the need for highly skilled developers focused on software maintenance. PaaS is preferred by IT in hybrid cloud environments. 

Definition: SaaS enables users to use and access the cloud provider’s applications that are running on the provider’s infrastructure from thin client or program interfaces. 

Examples: Microsoft O365, Google G-Suite, Dropbox, Cisco Webex, Concur, , Genesys, PayPal

Common Use Cases: SaaS is a comfortable service model for applications that are highly interoperable – used by multiple users internally and externally – and for short-term projects. SaaS models are preferred by small and medium-sized businesses that do not wish to invest heavily in IT maintenance. 

Each as-a-service model offers a unique set of benefits befitting your specific use case. Traditionally, organizations use a mix of these different models for different aspects of the business; for example, an organization may use the Salesforce platform (PaaS) and Google Docs (SaaS). 

There are many options for developers to build and deploy cloud-native and containerized applications on Microsoft Azure.

This post outlines why cloud-native is essential for organizations and describes the possibilities like AZURE Container Apps and Azure Kubernetes Services.

Modern containerized apps development using AZURE CLOUD Native – TechBubbles

The as-a-service label refers to the different service models cloud providers offer. There are three main as-a-service categories:

• IaaS: Infrastructure as a Service
• PaaS: Platform as a Service
• SaaS: Software as a Services