参考自：http://wiki.openstack.org/
Cloud compute (Nova)
Nova is a cloud computing fabric controller, the main part of an IaaS system. Individuals and organizations can use Nova to host and manage their own cloud computing systems. Nova originated as a project out of NASA Ames Research Laboratory.
Nova is written with the following design guidelines in mind:
Component based architecture: Quickly add new behaviors
Highly available: Scale to very serious workloads
Fault-Tolerant: Isolated processes avoid cascading failures
Recoverable: Failures should be easy to diagnose, debug, and rectify
Open Standards: Be a reference implementation for a community-driven api
API Compatibility: Nova strives to provide API-compatible with popular systems like Amazon EC2
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Cloud storage (Swift)
Swift is a highly available, distributed, eventually consistent object/blob store. organizations can use Swift to store lots of data efficiently, safely, and cheaply.
The Glance project provides services for discovering, registering, and retrieving virtual machine images. Glance has a RESTful API that allows querying of VM image metadata as well as retrieval of the actual image.
VM images made available through Glance can be stored in a variety of locations from simple filesystems to object-storage systems like the OpenStack Swift project.
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Image delivery and registration (Glance)
Glance, as with all OpenStack projects, is written with the following design guidelines in mind:
Component based architecture: Quickly add new behaviors
Highly available: Scale to very serious workloads
Fault tolerant: Isolated processes avoid cascading failures
Recoverable: Failures should be easy to diagnose, debug, and rectify
Open standards: Be a reference implementation for a community-driven api
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Identity (Keystone)
Keystone is an OpenStack project that provides Identity, Token, Catalog and Policy services for use specifically by projects in the OpenStack family. It implements OpenStack’s Identity API.
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Dashboard (Horizon)
Horizon is the canonical implementation of Openstack’s Dashboard, which provides a web based user interface to OpenStack services including Nova, Swift, Keystone, etc.
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Network Connectivity (Quantum)
Quantum is a "virtual network service" that aims to provide a powerful API to define the network connectivity between devices from other OpenStack services. The Quantum service has an API that presents a logical abstraction for describing network connectivity. The service relies on a Quantum plugin to manage virtual and/or physical switches within the cloud data center to make sure those devices forward packets according to the behavior defined in the logical API model. This notion of a plugin is similar to how Nova can use different types of hypervisors to implement the same virtual server API.