Learn · Service models
IaaS vs PaaS vs SaaS on VirtEngine
Cloud service models describe how much of the stack the provider operates. VirtEngine does not add a fourth layer above them; it runs underneath all three as the market, identity and settlement rail. Here is what changes and what stays the same.
Figures
| Layer | IaaS | PaaS | SaaS |
|---|---|---|---|
| Application | You | You | Provider |
| Runtime | You | Provider | Provider |
| Platform | You | Provider | Provider |
| Operating system | You | Provider | Provider |
| Infrastructure | Provider | Provider | Provider |
VirtEngine market · identity · settlement rail — the same underneath all three
IaaS — you manage the software layer
An IaaS listing hands the tenant a resource and the responsibility that comes with it. The provider runs the physical infrastructure and the virtualisation or cloud control plane; the tenant manages the operating system, runtime and application.
- Provider manages: physical infrastructure, virtualisation and the cloud control plane.
- Tenant manages: OS, runtime, application, scaling decisions.
- Typical meter: CPU, RAM, GPU and storage components.
PaaS — the provider manages the platform
A PaaS listing moves the runtime into the provider's hands. The tenant orders a managed platform — Kubernetes, a database, an inference endpoint — and deploys onto it. The provider handles upgrades, orchestration and the platform lifecycle.
- Provider manages: platform, runtime, orchestration, upgrades, availability of the service itself.
- Tenant manages: deployments, data, application configuration.
- Typical meter: platform components such as vCPU-hours, RAM GB-hours and storage.
SaaS — the provider manages the whole service
A SaaS listing is access to software someone else operates end to end. The tenant consumes an account, seat or plan; the provider owns the application, its hosting and its support. No virtual machine has to be deployed for the listing to be real.
- Provider manages: the complete software service.
- Tenant consumes: account, seat, plan and function.
- Typical meter: seat, plan, subscription or a provider-defined component.
VirtEngine runs horizontally, not above
The common mistake is to read VirtEngine as another level stacked on top of SaaS. It is not. The same identity checks, catalogue, order and match, lease, escrow, signed usage and settlement sit beneath all three delivery models.
That is what makes a mixed catalogue coherent: a GPU node, a managed database and an analytics subscription are different products on the same market rail.
Why the distinction matters when ordering
The model tells you where responsibility starts and stops. It also tells you what you are metering and who you contact when something changes — the provider's control plane for the service itself, the protocol for the agreement and the money.
Asked about iaas vs paas vs saas
Is VirtEngine a SaaS platform?
No. It is a marketplace protocol. Software plans can be sold through it, but VirtEngine does not operate the software.
Does a SaaS listing need a virtual machine?
No. A listing can represent access to a service the provider already operates; fulfilment can be an entitlement rather than a deployment.
Which model is right for a workload I run myself?
IaaS, or PaaS if you would rather not operate the runtime. If the provider runs the whole application, that is SaaS.