继上一篇(初尝dinnernow)之后，通过配置并驱动起了web应用。从今天起本系列文章将以一个购物流程为主线，介绍一下DinnerNow是如何使用WCF,LINQ,ASP.NET Ajax Extensions等技术来架构应用的。
首先请用VS2008打开下面两个解决方案:
安装目录下\solution\DinnerNow - Web\DinnerNow - Web.sln
\solution\DinnerNow - ServicePortfolio2\DinnerNow - ServicePortfolio2.sln
这是关于DinnerNow - Web.sln中项目的说明：
DinnerNow.WebUX 项目包括表示层（UI）的应用逻辑，WCF客户端调用的CS文件（CODE文件夹下）
DinnerNow.Web 项目则提供了一些简单的变量声明和定义，相关的CS代码并不多．
Microsoft.DPE.Samples.CardSpace 是一些关于Card Space数据访问和操作的封装和实例代码.
因此目前网站上的主要代码和功能实现都集中在了DinnerNow.WebUX这个项目．
为了完整的演示一个购买流程，本人将会以执行页面为单位．逐个说明相关页面的程序执行逻辑和功能实现．
在介绍之前，请大家先看一下DinnerNow的系统架构图．相信这会对我们从整体上把握这个产品提供一个切入点．相关图示如下：
首先运行网站的首页http://localhost/dinnernow/default.aspx，如下图：
上图中红框标记部分的部分页面页容如下(SearchBar.ascx):
<
table border
=
"
0
"
cellspacing
=
"
2
"
cellpadding
=
"
2
"
>
<
tr
>
<
td align
=
"
right
"
nowrap
=
"
nowrap
"
class
=
"
boldWhite
"
>
Food Type
td
>
<
td align
=
"
left
"
>
<
asp:ObjectDataSource ID
=
"
RestaurantCategoryDataSource
"
runat
=
"
server
"
SelectMethod
=
"
SelectAll
"
TypeName
=
"
DinnerNow.RestaurantCategoryDataSource
"
/>
<
asp:DropDownList ID
=
"
restaurantCategoryList
"
runat
=
"
server
"
DataSourceID
=
"
RestaurantCategoryDataSource
"
DataTextField
=
"
Description
"
DataValueField
=
"
RestaurantId
"
/>
td
>
tr
>
table
>
<
table border
=
"
0
"
cellspacing
=
"
2
"
cellpadding
=
"
2
"
>
<
tr
>
<
td align
=
"
right
"
class
=
"
boldWhite
"
>
Meal
td
>
<
td align
=
"
left
"
>
<
asp:ObjectDataSource ID
=
"
MenuTypeDataSource
"
runat
=
"
server
"
SelectMethod
=
"
SelectAll
"
TypeName
=
"
DinnerNow.MenuTypeDataSource
"
/>
<
asp:DropDownList ID
=
"
menuTypeList
"
runat
=
"
server
"
DataSourceID
=
"
MenuTypeDataSource
"
DataTextField
=
"
MenuTypeName
"
DataValueField
=
"
MenuTypeName
"
/>
td
>
tr
>
table
>
可以看出菜单下拉框选项使用ObjectDataSource方式进行加载，而页面代码中的下列两条语句是所加载类型的说明:
TypeName="DinnerNow.RestaurantCategoryDataSource'
TypeName="DinnerNow.MenuTypeDataSource"
这两个类型我们可以在下列路径下找到:
DinnerNow.WebUX\Code\DataSources\RestaurantCategoryDataSource.cs
DinnerNow.WebUX\Code\DataSources\MenuTypeDataSource.cs
它们两个的功能就是调用相应的SelectAll方法如下(仅以MenuTypeDataSource.cs为例)：
MenuTypeDataSource.cs
public
IEnumerable
<
RestaurantCategory
>
SelectAll()
{
try
{ using (MenuSearchServiceClient client = new MenuSearchServiceClient("WSHttpBinding_IMenuSearchService")) { return client.GetRestaurantCategories();
} } catch (Exception) { //@TODO: Need to put some error handling in here } return null;
}
因为代码太简单没什么可说的，下面就根据其所请求的服务绑定项"WSHttpBinding_IMenuSearchService", 在web.config中查找到如下配置节:
<
endpoint address
=
"
http://localhost/DinnerNow/service/MenuSearch.svc
"
binding
=
"
wsHttpBinding
"
bindingConfiguration
=
"
WSHttpBinding_IMenuSearchService
"
contract
=
"
MenuSearchService.IMenuSearchService
"
name
=
"
WSHttpBinding_IMenuSearchService
"
>
<
identity
>
<
servicePrincipalName value
=
"
host
"
/>
identity
>
endpoint
>
而相关的MenuSearch.svc（执行）文件就是其所引用的服务地址．好的，看清了这一块之后，我们切换到刚才所说的第二个解决方案中（DinnerNow - ServicePortfolio2.sln），看一下这个SVC中是如何执行相应逻辑的:)
在DinnerNow - ServicePortfolio2.sln中的DinnerNow.ServiceHost项目是服务配置站点，我们可从该站点的web.config文件中找出如下内容:
......
<
service behaviorConfiguration
=
"
DinnerNow.Services.MenuSearchServiceBehavior
"
name
=
"
DinnerNow.Services.MenuSearchService
"
>
<
endpoint address
=
""
binding
=
"
wsHttpBinding
"
contract
=
"
DinnerNow.Services.IMenuSearchService
"
/>
<
endpoint address
=
"
mex
"
binding
=
"
mexHttpBinding
"
contract
=
"
IMetadataExchange
"
/>
<
endpoint address
=
"
ajax
"
behaviorConfiguration
=
"
DinnerNow.Services.MenuSearchServiceAjax
"
binding
=
"
webHttpBinding
"
bindingConfiguration
=
"
AjaxBinding
"
contract
=
"
DinnerNow.Services.IMenuSearchService
"
/>
service
>
......
这里定义了当前服务所使用的contract接口(MenuSearchService)以及所使用的服务MenuSearchService（业务逻辑）,
而有关这两部分内容定义如下:
[ServiceContract(Namespace
=
"
DinnerNow.Services
"
)]
public
interface
IMenuSearchService
{ [OperationContract] [WebGet] IEnumerable<MenuType> GetMenuTypes(); [OperationContract] [WebGet] IEnumerable<RestaurantCategory> GetRestaurantCategories(); [OperationContract] [WebGet] IEnumerable<RestaurantHeader> FindRestaurant(string postalCode, string menuType, string restaurantCategoryId, string deadline); [OperationContract] [WebGet] IEnumerable<RestaurantMenuItem> GetMenuItemsForMenu(string restaurantId, string menuType);}
该接口定义了搜索菜单的数据获取方法，相信大家通过字面就能看出个大概了，所以我就不多说什么了.
下面主要说一下MenuSearchService.cs文件(DinnerNow.Services项目下)：
[AspNetCompatibilityRequirements(RequirementsMode
=
AspNetCompatibilityRequirementsMode.Allowed)]
public
class
MenuSearchService : IMenuSearchService
{
IMenuSearchService Members}
因为我们在网站客户端调用的是如下方法:
using
(MenuSearchServiceClient client
=
new
MenuSearchServiceClient(
"
WSHttpBinding_IMenuSearchService
"
))
{ return client.GetMenuTypes();}
所以对这个方法的使用应该就是对菜单类型数据的加载，而相应的方法定义在DinnerNow.Business\Menu.cs文件中：
public
IEnumerable
<
DinnerNow.Business.Data.MenuType
>
GetMenuTypes()
{ var s = (from m in db.Menus select new DinnerNow.Business.Data.MenuType() { MenuTypeName = m.MenuType.Trim() }).Distinct(); return s.ToList();}
这里使用了linq to sql来执行数据的操作。可以这么说, DinnerNow的数据访问和操作基本上都是使用LINQ语法完成的．
它的作用相当于如下语句（即找出不重复的菜单类型）：
SELECT DISTINCT [t1].[value] AS [MenuTypeName] FROM (SELECT LTRIM(RTRIM([t0].[MenuType])) AS [value]
FROM [dbo].[Menu] AS [t0]) AS [t1]
这样，对首页的整个数据加载过程就完成了，当然页面上的数据查询操作又是如何进行的呢？
下面就来说明一下这方面的业务执行流程：
请再切换回DinnerNow - Web.sln解决方案，还是刚才的那个SearchBar.ascx页面，下面的代码即是完成了搜索提交以及查询操作(详情见注释)：
<
asp:ScriptManagerProxy ID
=
"
ScriptManagerProxy1
"
runat
=
"
server
"
>
<
services
>
<
asp:ServiceReference Path
=
"
~/service/MenuSearch.svc/ajax
"
/>
services
>
asp:ScriptManagerProxy
>
function searchButton_Click()
{
var DeadLine = $ get ( " <%= deadlineSelect.ClientID %> " ).value;
if (DeadLine == " -1 " || DeadLine == null )
{
DeadLine = " 90 " ;
}
var MenuType = $ get ( " <%= menuTypeList.ClientID %> " ).value.trim();
var PostalCode = $ get ( " <%= postalCodeTextBox.ClientID %> " ).value;
var RestaurantCategory = $ get ( " <%= restaurantCategoryList.ClientID %> " ).value;
var searchUrl = " search.aspx " ;
var path = document.location.pathname.toLowerCase();
var isInSearchAspx = path.length >= searchUrl.length && path.substr(path.length - searchUrl.length,searchUrl.length) == searchUrl;
if ( ! isInSearchAspx) // 当前页面是否为搜索页(search.aspx)
{
var href = " search.aspx?PostalCode= " + PostalCode + " &MenuType= " + MenuType + " &RestaurantCategory= " + RestaurantCategory + " &DeadLine= " + DeadLine;
document.location.href = href; // 当不在搜索页面则将查询参数绑定后跳转到搜索页面
}
else
{
var service = new DinnerNow.Services.IMenuSearchService();
// 如果在搜索页面，则调用下面的JS方法来查找相当的记录
service.FindRestaurant(PostalCode, MenuType, RestaurantCategory, DeadLine, restaurantSearch_onSuccess, restaurantSearch_onFailed, null );
}
return false ;
}
function restaurantSearch_onSuccess(result) // 查询成功
{
if ( typeof (onRestaurantSeachSuccess) != " #ff0000 " )
{
onRestaurantSeachSuccess(result);
}
}
function restaurantSearch_onFailed(result) // 查询失败
{
alert( " The search has failed " );
}
script >
因为使用了ASP.NET Ajax Extensions，所以上面的代码段里的service.FindRestaurant(PostalCode, MenuType, RestaurantCategory, DeadLine, restaurantSearch_onSuccess, restaurantSearch_onFailed, null);
写法很接近于我们习惯的C#。
而实际的JS方法如下:
///
///
///
///
///
///
///
return this ._invoke( this ._get_path(), ' FindRestaurant ' , true ,{postalCode:postalCode,menuType:menuType,restaurantCategoryId:restaurantCategoryId,deadline:deadline},succeededCallback,failedCallback,userContext); }
上面代码中的_invoke就是完成一个ajax请求的方法．而succeededCallback和succeededCallback方法分别是ajax成功或失败后的回调函数参数，也是本例中的方法restaurantSearch_onSuccess,restaurantSearch_onFailed.
而最终ajax请求会成为对如下方法的调用(DinnerNow.Business\Menu.cs文件中):
{
var results = from r in db.Restaurants
join m in db.Menus on r.RestaurantId equals m.RestaurantId
where m.MenuType == menuType
&& r.PostalCode == postalCode
&& r.RestaurantCategoryId == restaurantCategoryId
select new Business.Data.RestaurantHeader()
{
LogoImageLocation = r.LogoImageLocation,
Name = r.Name,
RestaurantId = r.RestaurantId
};
return results.ToList();
}
这个LINQ语句相当于如下SQL语句（Restaurant,RestaurantId联表查询）：
SELECT [t0].[RestaurantId], [t0].[Name], [t0].[LogoImageLocation] FROM [dbo].[Restaurant] AS [t0]
INNER JOIN [dbo].[Menu] AS [t1] ON [t0].[RestaurantId] = [t1].[RestaurantId]
WHERE ([t1].[MenuType] = @p0) AND ([t0].[PostalCode] = @p1) AND ([t0].[RestaurantCategoryId] = @p2)
在搜索这个地方使用了AJAX，主要是为了UE(用户体验)．当然在DinnerNow中还有一些地方如选餐, 支付等也使用了AJAX，相信也是出于这方面的考虑)
说到了这里，今天的内容就要告一段落了．纵观DinnerNow的架构，可以说访问数据库的操作基本上都以LINQ To Sql实现方式。而业务流程(服务)则采用WCF的方式进行封装和调用．而网站上只保留了显示逻辑及AJAX请求操作．这样可以说做到了将数据访问层与业务逻辑层的分离．同时也便于团队开发并进行相应分工。
因为本人认为可以将开发小组成员分为三组：
A组负责数据访问接口和相关数据操作(采用LINQ)
B组负责设计业务流程组织（采用WCF, 后面的购买流程中使用了WWF,将会在下文中详加说明）
C组负责前台程序逻辑设计包括ajax调用等等
当然这种分工的好处是让小组成员的长处都能得到发挥，必定有专攻数据操作访问，也有专攻SOA的．有专功LINQ，也有熟练WCF和WF的。当然这只是我的一面之词，目前也只是猜测，如果大家有什么意见，欢迎在回复中进行讨论:)