erlyweb翻译 学习yaws的起点！

http://yaws.hyber.org/yaws.pdf 学习yaws从这里开始比较好！ 之前最好看看这个pdf， yaws网页里的链接比较零散，这个比较系统！

 

http://www.erlang-web .org/ 这个好像比erlyweb好

 

ErlyWeb: The Erlang Twist on Web Frameworks

Copyright � Yariv Sadan 2006-2007

Authors: Yariv Sadan.

Contents

Introduction
Directory Structure
Components
Models
Controllers
Views
Containers
The App Controller
Yaws Configuration

Introduction

ErlyWeb is a component-oriented web development framework that simplifies the creation of web applications in Erlang according to the tried-and-true MVC pattern. ErlyWeb's goal is to let web developers enjoy all the benefits of Erlang/OTP while creating web applications with simplicity, productivity and fun.

ErlyWeb is designed to work with Yaws, a high-performance Erlang web server. For more information on Yaws, visit http://yaws.hyber.org .

erlyweb是一个组件导向的web开发框架，简化在erlang上创建MVC web应用，erlyweb的目标是使web开发在创建web应用时简单高效有趣，使用到erlang/OTP的好处。erlyweb设计为使用yaws，一个高效的erlangweb server。

Installation

To install ErlyWeb, obtain the latest zip file from http://erlyweb.org and unzip it in your root Erlang code path. This path varies depending on your operating system (on OS X, it's '/usr/local/lib/erlang/lib'). If you don't know your path, you can discover it by starting the Erlang shell and calling "code:lib_dir()." (note that the last directory of the code path always erlang/lib).

安装：获取zip包解压到erlang code路径，一般是/usr/local/lib/erlang/lib   或C:\Program Files\erl5.7.5\lib  也可以命令获取Erlang shell and calling "code:lib_dir()."  最终目录一定是 erlang/lib.

Directory Structure

ErlyWeb applications have the following directory structure: 构建在erlyweb上的应用的目录结构如下：

[AppName]/
  src/                            contains non-component source files
    [AppName]_app_controller.erl  the app controller
    [AppName]_app_view.rt         the app view
  components/                     contains controller, view and
                                  model source files
  www/                            contains static assets
  ebin/                           contains compiled .beam files

where AppName is the name of the application. The 'src', 'components' and 'www' directories may contain additional subdirectories, whose contents are of the same type as those in the parent directory.

AppName是应用的名字，src,components www下面也许还有子目录。

Components

An ErlyWeb component is made of a controller and a view, both of which are Erlang modules. Controllers may use one or more models, but this isn't required.

(Technically, a component can be implemented without a view, but most components have views.)

一个erlyweb组件由一个controller和一个view，两个都是erlang的模块，controller可以使用一个或多个模块，但不是必须的，（组件可以不使用view，但是多数组件有views）

Controllers are implemented in Erlang source files . Views are typically implemented in ErlTL files , but views can be implemented in plain Erlang as well. The controller file is named '[ComponentName]_controller.erl ' and the view file is named '[ComponentName]_view.[Extension]' , where [ComponentName] is the name of the component, and [Extension] is 'erl' for Erlang files and 'et' for ErlTL files.

 

When ErlyWeb receives a request such as http://hostname.com/foo/bar/1/2/3 , ErlyWeb interprets it as follows: 'foo' is the component name, 'bar' is the function name, and ["1", "2", "3"] are the parameters (note that parameters from browser requests are always strings).

erlyweb收到一个请求比如：http://hostname.com/foo/bar/1/2/3 erlyweb解释如下： foo是组件名，bar是函数名， 123是参数


 

When only the component's name is present, ErlyWeb assumes the request is for the component's 'index' function and with no parameters (i.e. http://hostname.com/foo is equivalent to http://hostname.com/foo/index ).

只有组件名erlyweb认为请求的是组件的index函数而且无参数

If the module 'foo_controller' exists and it exports the function 'bar/4', ErlyWeb invokes the function foo_controller:bar/4 with the parameters [A, "1", "2", "3"] , where A is the Arg record that Yaws passes into the appmod's out/1 function. (For more information, visit http://yaws.hyber.org/ .)

 

http://yaws.hyber.org/yaws.pdf 学习yaws从这里开始比较好！

 

 

 

Since ErlyWeb 0.7, you can use the catch_all/2 hook to override the default behavior, i.e. treating the second token as a function name instead of as parameter. For more information, see catch_all/2 .

Models

ErlyWeb treats all Erlang modules whose names don't end with '_controller' or '_view' and whose files exist under 'src/components' as models. If such modules exist, erlyweb:compile() passes their names to erlydb:code_gen() in order to generate their ErlyDB database abstraction functions.

If your application uses ErlyDB for database abstraction, you have to call erlydb:start() before erlyweb:compile() (otherwise, the call to erlydb_codegen() will fail). If you aren't using ErlyDB, don't keep any models in 'src/components' and then you won't have to call erlydb:start().

Controllers

Controllers contain most of your application's logic. They are the glue between Yaws and your applications models and views.

Controller functions always accept the Yaws Arg for the request as the first parameter, and they may return any of the values that Yaws appmods may return (please read the section below on the {response, Elems} tuple to avoid running into trouble). In addition, controller functions may return a few special values, which are listed below with their meanings (note: 'ewr' stands for 'ErlyWeb redirect' and 'ewc' stands for 'ErlyWeb Component.').

ewr
Redirect the browser to the application's root url.

{ewr, ComponentName}
Redirect the browser to the component's default ('index') function

{ewr, ComponentName, FuncName}
Redirect the browser to the URL for the given component/function combination.

{ewr, ComponentName, FuncName, Params}
Redirect the browser to the URL with the given component/function/parameters combination.

{data, Data}
Call the view function, passing into it the Data variable as a parameter.

{ewc, A}
Analyze the Yaws Arg record 'A'. If the request matches a component, render the component and send the result to the browser. Otherwise, return {page, Path} , where Path is the Arg's appmoddata field.

{ewc, ComponentName, Params}
Render the component's 'index' function with the given parameters and send the result to the view function.

{ewc, ComponentName, FuncName, Params}
Render the component's function with the given parameters, and send the result to the view function.

{ewc, ControllerModule, ViewModule, FuncName, Params}
This tuple lets you specify exacly which controller and view modules ErlyWeb uses to render the sub-component. It is considered for advanced uses only.

{replace, Ewc}
This tuple, which was introduced in ErlyWeb 0.6, tells ErlyWeb to render a different component from the requested one (the new component, Ewc , can be described using any of the 'ewc' tuples listed above). This mechanism is conceptually similar to an internal redirect. It is useful, for example, when you want multiple components to share a common error screen. Instead of having multiple view functions check if the controller result indicates an error has occurred, you can use the replace tuple to simply redirect the rendering to an error component.

Controller functions may also return (nested) lists of 'ewc' and 'data' tuples, telling ErlyWeb to render the items in their order of appearance and then send the list of their results to the view function. This feature lets you build components that are composed of a mix of dynamic data and one or more sub-components.

If a component is only supposed to be used as a subcomponent, you should implement the function "private() -> true. " in its controller. This tells ErlyWeb to call exit({illegal_request, Controller}) when clients try to access the component by requesting its corresponding URL directly.

Returning Arbitrary Yaws Tuples

ErlyWeb provides the infrastructure for rendering components and redirecting to other components in the same application. This is sufficient for simple applications, but sometimes you may want to return to Yaws tuples that Yaws understands and that aren't directly supported by ErlyWeb (these are documented at http://yaws.hyber.org/yman.yaws?page=yaws_api ). A common requirement, for example, is to instruct Yaws to include arbitrary HTTP headers, such as cookies, in the response Yaws sends to the browser. ErlyWeb lets you do this by returning a tuple of the form {response, Elems} from controller functions.

The second element in the {response, Elems} is a list of values that ErlyWeb should return to Yaws verbatim, with the exception of the (optional) {body, Body} for HTML or {body, MimeType, Body} tuple and any of the ewr tuples listed above (ErlyWeb translates the latter into their redirect_local equivalents). If, in addition to returning standard Yaws tuples, you want ErlyWeb to render the response's body using the component's view, you can include the {body, Body} or {body, MimeType, Body} tuple in Elems . Body may be any single ewc or data tuple, or a list thereof. ErlyWeb renders the elements of Body , sends the result to the view function, and embeds the resulting iolist in an {html, Iolist} tuple prior to returning it to Yaws.

There is currently a restriction on the usage of {response, Elems} : only the top-level component for the request may return the {response, Elems} tuple. Sub-components may return only data and/or ewc tuples. This restriction makes sense because you normally only use sub-components for rendering segments of the response's body and not for setting HTTP headers or implementing arbitrary application logic.

Optional Controller Hooks

catch_all/2
before_call/2
before_return/3
after_render/3

catch_all/2

The catch_all/2 hook was introduced in ErlyWeb 0.7. By default, ErlyWeb treats the URL token following the component name as a function name. catch_all/2 lets you override this behavior on a per-controller basis by treating all URL tokens following the component name as parameters.

For example, if a user requests the url

http://my-cool-app.com/people/bob

ErlyWeb by default would try to invoke the function 'bob/1' in people_controller. You can tell ErlyWeb to override this behavior and instead pass "bob" as a parameter to people_controller:catch_all/2 as follows:

people_controller.erl: