Pjack: Ubuntu Orchestra 筆記

Highlighted Components

Experience of provisioning

Rack a server
Turn on a server
Server netboots and 'registers' itself with the Orchestra provisioning server (cobbler)
Server shuts down
(WAIT)
When server is required, it is Wake'd on Lan via powerwake and installs a base Ubuntu server with cloud-init installed.
Juju customizes the install to be as required.

is a protocol specification for exchanging structured information in the implementation of Web Services
Relies onExtensible Markup Language (XML) for its message format
Relies on other Application Layer protocols, most notably Hypertext Transfer Protocol (HTTP) and Simple Mail Transfer Protocol (SMTP).

是一種 Protocol, 用在使用 Web Service 之間的溝通, 格式是 XML, 架構在 HTTP or SMTP 之上

What is WSDL?

A WSDL description of a web service (also referred to as a WSDL file) provides a machine-readable description of how the service can be called, what parameters it expects and what data structures it returns.
It thus serves a roughly similar purpose as aMethod signature in a programming language

意思就是傳統 programming language 的 header file，用來描述這個 web service 怎麼使用

What is UDDI?

Universal Description, Discovery and Integration (UDDI, pronounced Yu-di?) is a platform-independent, Extensible Markup Language (XML)-based registry for businesses worldwide to list themselves on the Internet
A mechanism to register and locate web service applications
UDDI is an open industry initiative

意思就是當你在網路上想要找到特定的 web service 來使用，那你怎麼知道要去那裡找? UDDI 就是一個提供查找的 "機制" 或是一個 "組織"，你可以透過它去拿到 WSDL 然後知道怎麼使用這個 web service

What is REST?

http://en.wikipedia.org/wiki/Representational_state_transfer

Representational state transfer (REST) is a style of software architecture for distributedhypermedia systems such as the World Wide Web.

老實說，看完後還是無法抓到到底怎麼樣的架構才能符合 REST，但至少明白他是在定義了一種 client-server 的軟體架構。

What is RESTful web service?

A RESTful web service (also called a RESTful web API) is a simple web service implemented using HTTP and the principles of REST

the base URI for the web service
The Internet media type of the data supported by the web service. This is often JSON, YAML
the set of operations supported by the web service using HTTP methods (e.g., GET, PUT, POST, or DELETE).
The API must be hypertext driven

目前很多 web service 都宣稱他們是 RESTful，基本上只代表能簡易透過一個 URL 再加上 GET/PUT/POST/DELETE 來操作網路上的物件或是使用他提供的 service，而格式目前我常看到的是 JSON

a XML-based business process modeling language that describes collaboration protocols of cooperating Web Service participants
Dancers dance following a global scenario without a single point of control
Each participant in a service choreography executes its part of it (i.e. its role) according to the behavior of the other participants

感覺就是各跳各的呀~

What is Service Orchestration?

http://en.wikipedia.org/wiki/Orchestration_%28computing%29

Automated arrangement, coordination, and management of complex computer systems, middleware, and services
This usage of orchestration is often discussed in the context of service oriented architecture, virtualization, provisioning, converged infrastructureand dynamic datacenter topics
A somewhat different usage relates to the process of coordinating an exchange of information through web service interactions.

有一個總帥.. 但仍各司其職

Different between Choreography and Orchestration

實在太難懂了.. 到底在寫什麼 @@

	Choreography	Orchestration
Point of View	the logic of the message-based interactions among the participants are specified from a global perspective	the logic is specified from the local point of view of one single participant, called the orchestrator.
Message exchange	a protocol for peer-to-peer interactions	specifies an executable process that involves message exchanges with other systems, such that the message exchange sequences are controlled by the orchestration designer
Control	a distributed system which operates according to rules but without centralized control	central control of the behavior of a distributed system

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