Cloud Services

Cloud Services are divided into 3 main abstractions:

• Infrastructure-as-a-Service (IaaS);
• Platform-as-a-Service (PaaS);
• Software-as-a-Service (SaaS).

IaaS

• Data centers around the world;
• Each with around 80000 server;
• Top players: Google, Amazon and Microsoft.

Goals

• Provides virtualized hardware resources such as computing, storage and networking;
• Resources allocated on demand and in a pay-per-use fashion;

OpenStack

• Open-Source software for creating private and public clouds;
• Controls large pools of compute, storage, and networking resources throughout a datacenter;
• Managed through a dashboard or via the OpenStack API.

Nova Service

Provides different types of compute instances:

• Baremetal Servers;
• VMs;
• Containers.

Requires integration with different other OpenStack services:

• Keystone: identity and authentication services;
• Glance: compute image repository;
• Neutron: provides virtual or physical networks for compute instances;
• Placement: tracks available hardware resources in a cloud and allocates them, for instance, when creating virtual machines.

Cinder, Manila, and Swift services

• Compute instances have ephemeral storage provided by the OpenStack Nova service;
• For persistent storage, several services exist:
  • Cinder: block storage services;
  • Manila: file system services;
  • Swift: object storage services.

Neutron and Telemetry services

• Neutron: delivers Networking-as-a-Service(NaaS) in virtual compute environments;
• Telemetry: monitoring for cloud infrastructures and virtual resources.

PaaS

• Base on container instances;
• Supports multiple languages;
• Versioning, testing, monitoring, and logging features.

SaaS

• Features full applications or generic software offered as a service:
  • some are software components that export their traditional APIs;
  • others are accessible as web services or through a web browser.
• Database management systems: there is no deployment item - the DB is exposed through a client and used as a traditional DB but with minimal configuration needed and with remote access;
• SalesForce.com and Google Apps like Gmail are well-known instances of web-based services.

Convenience

• From IaaS:
  • Avoid upfront costs on infrastructure management and hardware;
  • “Easily” deploy legacy applications.
• To PaaS:
  • Focus on the application development itself and its requirements;
  • Powerful development, deployment, debugging, and benchmarking tools already in place.
• To SaaS:
  • Leverage existing components (databases, web/application servers).

Speed

• From IaaS:
  • Infrastructure is already installed and configured.
• To PaaS:
  • A development framework is already installed and configured.
• To SaaS:
  • Quick integration of different cloud software solutions.

Elasticity

• From IaaS:
  • Illusion of virtually infinite resources (computation, storage, etc);
  • Users may increase/decrease computational power, storage space, …, according to demand.
• To PaaS:
  • The elasticity of computational, storage, and network resources is handled by the cloud provider;
  • Usually the unit of scale is the application.
• To SaaS:
  • Typically the cloud software or service being provided automatically handles elasticity.

Loss of Control

• From IaaS:
  • No control over hardware and virtualization software being used.
• To PaaS:
  • No control over specific hardware and the PaaS platform.
• To SaaS:
  • Third-party cloud software, which is optimized and mainly configured by the cloud provider.

Dependability and Security

• Dependability: If the provider fails, the application fails and recovery is out of the control of the application owner.
• Security: The application is at most as secure as the provider:
  • any vulnerability of the provider is a vulnerability of the application;
  • fixes to cloud services vulnerabilities must be done by the provider.
• Privacy: The cloud provider holds data from users:
  • risk of data being leaked either by external or internal attacks;
  • critical data sometimes is protected by legislation that prevents some institutions from using third-party services to store such information.