Academmia

Platform as a Service (PaaS)

az-900•beginner•

Cloud concepts

Platform as a Service (PaaS)

Short Summary

Platform as a Service (PaaS) is a cloud model where the provider runs the platform for you, and you focus on your application. You deploy code to a managed environment without managing servers or patching the Operating System (OS). This lesson explains what PaaS means, what you still own, and how to tell PaaS apart from Infrastructure as a Service (IaaS) and Software as a Service (SaaS).

Learning Objectives

By the end of this lesson, you will be able to:

  • Define Platform as a Service (PaaS) in simple terms.
  • Explain how responsibilities are split between the cloud provider and you in a PaaS model.
  • Distinguish PaaS from IaaS and SaaS using “who manages what” clues.
  • Identify common situations where PaaS helps teams move faster with less platform maintenance.

Core Concepts

Platform as a Service (PaaS) is often described as the “middle ground” between IaaS and SaaS:

  • With IaaS, you rent infrastructure and manage much more of the stack yourself.
  • With SaaS, you consume a finished application.
  • With PaaS, you deploy and run your application on a provider-managed platform.

In PaaS, the cloud provider manages the physical infrastructure (datacenters, hardware, physical security, and connectivity). They also manage major platform components that are typically time-consuming for teams to maintain, such as the OS and other platform services used to run applications.

A key PaaS benefit is reduced platform maintenance. For many PaaS scenarios, you don’t handle the licensing and patching work for the OS (and often platform-managed data services), which helps teams spend more time building and improving the application.

You still have responsibilities in PaaS. You typically manage:

  • Application code (what you build and deploy)
  • Application configuration (how it behaves and connects to dependencies)
  • Data (what you store, how you protect it, and who can access it)

A simple rule of thumb:

  • If you manage the OS, you’re usually in IaaS.
  • If you deploy code but don’t manage the OS, you’re usually in PaaS.
  • If you use a finished app and don’t deploy your own code, you’re usually in SaaS.

Practical Understanding

Practical Situation 1: When you want to deploy code without managing servers

A team wants to ship a web app quickly and doesn’t want to configure servers, install web server components, or patch an OS. They want a managed environment where they can deploy code and run it.

How to think about it: This points to PaaS. The provider runs the platform layer, so the team can focus on writing, deploying, and updating the application. The team still owns the app configuration and how the app handles and protects data.

Common misunderstanding: “Because it’s PaaS, the provider is responsible for my app security.” The provider manages the platform, but you still make key security choices for your application and data.

Practical Situation 2: When you’re still patching the OS, it’s probably not PaaS

A workload runs on a Virtual Machine (VM). The team chooses the OS version, installs updates, configures the host, and maintains the software stack.

How to think about it: This aligns with IaaS, because managing the OS is a strong signal you’re responsible for that part of the stack. PaaS is designed to remove most OS-level maintenance by providing a managed platform layer.

Common misunderstanding: “My app runs in the cloud, so it must be PaaS.” “Cloud-hosted” doesn’t define the service model; the service model depends on what you manage.

Practical Situation 3: When you’re just consuming software, that’s SaaS, not PaaS

A company subscribes to a productivity tool and uses it through a browser or installed client. They manage users and settings but do not deploy their own application code to it.

How to think about it: That’s SaaS. PaaS is for running your code on a provider-managed platform. SaaS is a complete application you consume.

Common misunderstanding: “Any cloud service where I don’t patch servers is PaaS.” Not patching servers could describe PaaS or SaaS; the key difference is whether you deploy and run your own code.

Practical Situation 4: When PaaS is about a “managed platform,” not one specific product type

You need a managed place to host an application, run code, or use a managed data service, and you want the provider to handle the platform layer.

How to think about it: PaaS is a model for managed platforms in general. The common pattern is consistent: the provider handles the platform maintenance work, and you focus on application logic, configuration, and data.

Common misunderstanding: “PaaS only means web hosting.” PaaS can apply to different kinds of managed platforms, as long as the provider manages the platform layer and you focus on your workload.

Common Pitfalls

  • Mistake: Treating “my app runs on a VM” as PaaS. Correction: If you manage the VM and the OS, that is typically IaaS, not PaaS.

  • Mistake: Assuming PaaS means “no responsibility at all.” Correction: In PaaS, the provider manages the platform, but you still manage your application code, configuration, and data.

  • Mistake: Misclassifying fully managed applications as PaaS. Correction: If you consume a finished application and don’t deploy your own code, that is usually SaaS.

  • Mistake: Forgetting that responsibilities can vary by service and configuration. Correction: Use the “who manages what” approach, and confirm what the provider manages for the specific PaaS service you’re using.

  • Mistake: Treating PaaS as a default choice without considering needs. Correction: Choose PaaS when reducing platform maintenance helps and when OS-level control isn’t required; choose IaaS when OS control is needed; choose SaaS when a finished app meets the need.

Check Your Understanding

  1. Explain PaaS in one sentence using the words “platform,” “provider,” and “application.”
  2. List three responsibilities the provider commonly handles in PaaS and three responsibilities you still handle.
  3. Pick a workload you know (a web app, API, or background job). Decide whether it feels more like IaaS, PaaS, or SaaS and justify the choice using the OS rule of thumb.
  4. Describe a situation where PaaS would reduce operational work compared to running the same app on a VM.
  5. Write down two security or compliance decisions you still need to make in PaaS, even though the platform is managed.

Further Reading