On the other hand, when the goal of using cloud computing is to reduce the infrastructure maintenance overhead, then PaaS can be considered as an option. The platform layer takes the complexity out of the equation, since the provider of the cloud service will be in charge of the operating system and the platform that provides the service. For instance, a development team is considering whether to install, maintain, and operate its own database platform or use a Database as a Service option such as the Relational Database Service (RDS) provided by Amazon Web Services.
In the case of building a database server, they can consume an IaaS virtual machine instance, install the database server, configure it with a database instance, and pass the connection details into the application. When using PaaS, they simply request the database instance to be created (this can be done via an API call) and the provider passes the connection details of the database instance back to the user as a reply to the initial request. As you can see, using PaaS can be a very effective way of using cloud computing services, as there is very little (if any) management overhead when provisioning, using, and releasing PaaS resources from the cloud. PaaS resources come in many forms including services such as the following:
- Highly available relational and NoSQL databases, database caching services
- Big data ingestion, processing, and warehousing solutions
- Scalable and durable web-accessible storage
- Services for message queuing, distribution, and delivery
- Serverless processing
- Analytics, transcoding, and searching
- Services for mobile and IoT
- Server management and automation tools
PaaS is also very effective when designing applications with a cloud-native approach, where applications are designed for the cloud and the most mundane tasks like updating, upgrading, and even some security tasks, are simply handed off to the cloud provider.
The SaaS layer represents the user domain where users come in and consume services straight from the cloud. No IT knowledge is usually required to use these applications and none or very little access to the underlying environment running the application is provided to the user.