About Debian
About Debian
is an association of
individuals who have made common cause to create a
operating system. This operating system that we have created is called
An operating system is the set of basic programs and utilities that make
your computer run.
At the core of an operating system is the kernel.
The kernel is the most fundamental program on the computer and does all the basic
housekeeping and lets you start other programs.
Debian systems currently use the
kernel or the
kernel. Linux is a piece of software started by
and supported by thousands of programmers worldwide.
FreeBSD is an operating system including a kernel and other software.
However, work is in progress to provide Debian for other kernels,
primarily for
The Hurd is a collection of servers that run on top of a microkernel (such as
Mach) to implement different features. The Hurd is free software produced by the
A large part of the basic tools that fill out the operating system come
hence the names:
GNU/Linux, GNU/kFreeBSD, and GNU/Hurd.
These tools are also free.
Of course, the thing that people want is application software: programs
to help them get what they want to do done, from editing documents to
running a business to playing games to writing more software. Debian comes
with over 37500
(precompiled
software that is bundled up in a nice format for easy installation on your
machine), a package manager (APT), and other utilities that make it possible
to manage thousands of packages on thousands of computers as easily as
installing a single application. All of it .
It's a bit like a tower. At the base is the kernel.
On top of that are all the basic tools.
Next is all the software that you run on the computer.
At the top of the tower is Debian & carefully organizing and fitting
everything so it all works together.
You may be wondering: why would people spend hours of their own time to write
software, carefully package it, and then give it all away?
The answers are as varied as the people who contribute.
Some people like to help others.
Many write programs to learn more about computers.
More and more people are looking for ways to avoid the inflated price of
A growing crowd contribute as a thank you for all the great free software they've
received from others.
Many in academia create free software to help get the results of
their research into wider use.
Businesses help maintain free software so they can have a say in how it develops --
there's no quicker way to get a new feature than to implement it yourself!
Of course, a lot of us just find it great fun.
Debian is so committed to free software that we thought it would be useful if that
commitment was formalized in a written document. Thus, our
Although Debian believes in free software, there are cases where people want or need to
put non-free software on their machine. Whenever possible Debian will support this.
There are even a growing number of packages whose sole job is to install non-free software
into a Debian system.
You might be asking: If the software is free, then why do I have to pay
a vendor for a CD, or pay an ISP for downloading?
When buying a CD, you are paying for someone's time, capital outlay
to make the disks, and risk (in case they don't sell them all). In other
words, you are paying for a physical medium used to deliver the software,
not for the software itself.
When we use the word "free", we are referring to software
freedom, not that it's without cost. You can read more on
on that subject.
A better question is how do software companies get away with charging so much?
Software is not like making a car. Once you've made one copy of your software, the
production costs to make a million more are tiny (there's a reason Microsoft has
so many billions in the bank).
Look at it another way: if you had an endless supply of sand in your backyard,
you might be willing to give sand away. It would be foolish, though, to pay for a truck
to take it to others. You would make them come and get it themselves (equivalent to
downloading off the net) or they can pay someone else to deliver it to their door (equivalent
to buying a CD).
This is exactly how Debian operates and why most of the CDs/DVDs are so cheap
(only about 12 USD for 4 DVDs).
Debian does not make any money from the sale of CDs.
At the same time, money is needed to pay for expenses such as domain
registration and hardware. Thus, we ask that you buy from one of the
a portion of your purchase to Debian.
Debian will run on almost all personal computers, including most older
models. Each new release of Debian generally supports a larger number of
computer architectures. For a complete list of currently supported ones,
Almost all common hardware is supported.
If you would like to be sure that all the devices connected to your machine
are supported, check out
There are a few companies that make support difficult by not releasing specifications
for their hardware. This means you might not be able to use their hardware
with GNU/Linux. Some companies provide non-free drivers, but that is a
problem because the company could later go out of business or stop support
for the hardware you have. We recommend that you only
purchase hardware from manufacturers that provide
drivers for their
You may want to check out our .
Don't take our word for it - try Debian yourself. Since hard disk
space has become less expensive, you can probably spare about 2GB.
If you don't want or need a graphical desktop, 600MB are sufficient.
Debian can be easily installed on this extra space
and can coexist with your existing OS. If you eventually need more space,
you can simply delete one of your OSes (and after you see the power of a
Debian system, we are confident you won't delete Debian).
As trying a new operating system will take some of your valuable time,
it is understandable that you may have reservations. For this reason we
compiled a list of . This
should help you decide whether you think it's worth it. We hope you'll
appreciate our honesty and frankness.
It's most popular to install Debian from a CD which you can buy for the
price of the media at one of our many CD vendors. If you have good Internet
access, you can download and install Debian over the Internet.
Please see
more information.
If you haven't yet, you may want to first look at the
Don't forget to take a look through the
we offer (hopefully you won't be intimidated by the sheer number).
You can get help by reading the documentation which is available
both on the web site and in packages you can install on your system.
You can also contact us via the mailing lists or using IRC.
One can even hire a consultant to do the work.
Please see our
pages for more information.
Debian is produced by almost a thousand active
who volunteer
in their spare time.
Few of the developers have actually met in person.
Communication is done primarily through e-mail (mailing lists at
lists.debian.org) and IRC (#debian channel at irc.debian.org).
The Debian Project has a carefully . For more information on how Debian looks from the inside,
please feel free to browse the .
Although no precise statistics are available (since Debian does not
require users to register), evidence is quite strong that Debian is
used by a wide range of organizations, large and small, as well as
many thousands of individuals. See our
page for a list of high-profile organizations which
have submitted short descriptions of how and why they use Debian.
Debian was begun in August 1993 by Ian Murdock, as a new distribution
which would be made openly, in the spirit of Linux and GNU. Debian was meant
to be carefully and conscientiously put together, and to be maintained and
supported with similar care. It started as a small, tightly-knit group of
Free Software hackers, and gradually grew to become a large, well-organized
community of developers and users. See
Since many people have asked, Debian is pronounced /ˈde.bi.ən/. It
comes from the names of the creator of Debian, Ian Murdock, and his wife,
How to set
To report a problem with the web site, e-mail . For other contact information, see the Debian . Web site source code is .
Last Modified: Thu, Aug 14 19:26:13 UTC 2014
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Apache Avalon 是一个用于开发服务器端应用的开发框架，其中体现了很多软件业最先进的思想。它的开发处于较低的层次，你可以把它看作是一个用来建造 AppServer 的开发框架（框架的框架）。如果你想要建造自己的开发框架或者 AppServer，Avalon 是一个非常好的起点。
Avalon 的中文文档：
基于 Component 或者 Service 的设计思想（COP、SOP）比基于 Object 的设计思想（OOP、OOAD）更加接近于业务领域（问题域），而且可以获得简化的体系结构和更好的性能。
如果觉得看不明白可以直接看英文文档：
看英文文档比看中文文档快，还可以避免产生歧义。
Avalon 文档中对 COP 的定义：
面向组件的编程（Component Oriented Programming ，COP）是把系统分割成一些组件或设施的一种思想。每种设施都有一个工作接口和围绕该接口的契约。这种方式允许容易地更换组件的实例，同时不影响系统其它部分的代码。面向对象编程（Object Oriented Programming ，OOP）和 COP 的主要区别在于集成的层次。COP 系统的复杂性更容易管理，这得益于类之间更少的相互依赖。这提高了代码重用的程度。
COP 的主要好处之一是修改项目代码的一些部分不会破坏整个系统。另一个好处是可以有某组件的多种实现，并可以在运行时刻进行选择。
Avalon 文档中对 SOP 的定义：
面向服务的编程（Service Oriented Programming ，SOP）的思想是把系统划分为由系统提供的一些服务。
1. 为其它人执行的工作或职责。
2. 提供修理或维护的一种设施。
3. 向公众提供工具的一种设施。
Avalon 的设计中最重要的两个模式是反向控制（IOC）和分离考虑（SOC）模式。以下是 Avalon 文档中的描述：
Avalon 整个是基于一些特定设计原理来构建的。最重要的两个模式是反向控制（Inversion of Control）和分离考虑（Separation of Concerns）。Component Oriented Programming、Aspect Oriented Programming和 Service Oriented Programming 也对 Avalon 产生了影响。每种程序设计原理都可以写出数卷的书，但它们都是一些设计思维习惯。
反向控制（Inversion of Control，IOC）的概念是指组件总是由外部进行管理的。这个短语是由Brian Foote在他的一篇论文中最先使用的。组件所需的一切通过 Contexts、Configurations 和 Loggers 的方式赋予组件。实际上，组件生命周期中的每个阶段都是由创建组件的代码所控制的。当您使用这种模式时，就实现了一种组件与您的系统安全交互的方法。
IOC 与安全性并不等价！IOC 提供了一种机制，允许你实现一个可扩展的安全模型。为了让一个系统真正做到安全，每个组件都必需安全，没有组件可以修改传递给它们的对象的内容，而且所有的交互都必须使用已知的实体。安全性是一个主要问题，IOC 是程序员工具库中的一种工具，用于实现安全性的目标。
您应该从不同的思考方向来看待您的系统，这一思想导致了分离考虑（Separation of Concerns，SOC）模式。 一个例子是从同一个问题空间的不同视角来看一个 Web 服务器。Web 服务器必需安全、稳定、可管理、可配置并满足 HTTP 规范。每种属性都是一个单独的考虑范围。这其中的某些考虑与其它考虑相关，如安全性和稳定性（如果一个服务器不稳定，它就不可能安全）。
分离考虑模式又导致了 Aspect Oriented Programming (AOP) 。研究者发现许多考虑不能在类或方法的粒度上进行处理。这些考虑被称为Aspect。Aspect 的例子包括管理对象的生命周期、记日志、处理异常和清理释放资源等。由于没有一种稳定的 AOP 实现，Avalon 开发团队选择通过提供一些小的接口，然后由组件来实现，从而实现 Aspect 或考虑。
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Avalon 以前看过，许多思想都是很好的，但一直没有机会在项目中应用，感觉他比较底层，如果有一个比较好的实现就好了
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newroc 写道Avalon 以前看过，许多思想都是很好的，但一直没有机会在项目中应用，感觉他比较底层，如果有一个比较好的实现就好了
Avalon 确实比较低层，它是用来帮助建造开发框架或者 AppServer 的，不是直接帮助开发应用程序的。Avalon 中体现了 SOP、AOP 的很多思想。WebService 就是一种 SOP 的体系结构。
Avalon 提供的组件是很丰富的，我们目前也只用到 Avalon 一部分功能，其它功能还有待我们进一步探索。
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Erazor 写道现在做Tapestry的Howard L。Ship也自己推出了一套系统HiveMind。
也是这种结构，不过据他说是集百家之长，而且更优更强。Tapestry马上可能要用HiveMind做底层结构重写。（Ps：Tapestry可是号东东啊，大家可别被Struts和JSF等等蒙蔽了双眼啊：））
最后，最新的技术中，这种微内核的结构都要融入IoC的技术。比较有代表性的有
PicoContainer
呵呵，你也再用Tapestry，能不能类似于上面的样子，简单介绍介绍
你对PicoContainer也在研究吗？我现在的一个项目，正考虑把它用于管理dao，而不再使用factory。
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avalon简直太老了,而且非常麻烦,其他好用的多的是:
type1 IoC:carbon,keel..
type2 IoC:spring,webwork2..
type3 IoC:pico..
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另外，一定要把tapestry放在spring框架内吗？
我是新手，正决定使用哪个框架比交好，望赐教。
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keel是基于avalon的，这个比较容易上手
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Haiqing 写道另外，一定要把tapestry放在spring框架内吗？
我是新手，正决定使用哪个框架比交好，望赐教。
no
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keel是基于avalon的，他的核心负责人也是原来expresso的负责人。
expresso是96年就开始了，虽然是基于struts的，但扩展的很好，很实用啊，我们就在用他，感觉很爽。
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别用 Avalon 了，已经被 Apache 废弃了。我们也不准备再用了。其实我们原来也仅仅用到了 Avalon 的 Configuration 和 Log 这两块的功能。我们以前也并不认为 Avalon 是一个非常理想的容器。
大家都改用 Spring 好了。
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