使用SQL Server存储ASP.NET Session变量
创建和配置ASP.NET Session状态数据库
在基于NLB(网络负载平衡)环境下的ASP.NET Web应用程序开发,我们需要将Session存储在数据库中供多个Web应用程序调用,以下为配置方法及注意事项。
1.创建用于存储ASP.NET Session的数据库(远程、本地皆可,使用数据库用户身份认证)
在Windows\Microsoft.NET\Framework/V2.0.50727目录下使用如下命令:
命令: aspnet_regsql.exe -S QQ442518843 -U sa -P Admin123456 -ssadd -sstype c -d SessionDemo
参数说明:
服务器地址如:QQ442518843
用户名:sa
密码:Admin123456
数据库名:SessionDemo
命令执行后会创建两张表:ASPStateTempApplications ,ASPStateTempSessions 和相关的存储过程
命令执行后就会成功建立起用于存储ASP.NET Session变量的数据库了。
2.Web.Config文件配置项
我们需要在ASP.NET Web应用程序中的Web.Config文件修改sessionState配置项以使Session状态数据库生效。
配置节点如下:
<sessionState mode="SQLServer"
sqlConnectionString="server=<Server IP>;database=<Database Name>;uid=<User Name>;pwd=<Password>;"
allowCustomSqlDatabase="True"
cookieless="false"
timeout="20" />
3.注意在进行系统测试(主要是负载测试)的时候,因为数据库访问负载的增加,需要调整SQL Server相应超时的配置项以适应负载。(默认值为10,请适度进行调整。)
ASP.NET Session状态数据库数据模型
1.ASPStateTempSessions表定义
列名
类型
描述
SessionId
nvarchar(88)
Session ID + application ID
Created
datetime
Date and time session was created (UTC)
Expires
datetime
Date and time session expires (UTC)
LockDate
datetime
UTC date and time session was locked
LockDateLocal
datetime
Local date and time session was locked
LockCookie
int
Lock ID
Timeout
int
Session timeout in minutes
Locked
bit
1=Session locked, 0=Session not locked
SessionItemShort
varbinary(7000)
Serialized session state (if <= 7,000 bytes)
SessionItemLong
image
Serialized session state (if > 7,000 bytes)
Flags
int
Session state flags (1=Uninitialized session)
2.ASPStateTempApplications表定义
列名
类型
描述
AppId
int
Application ID
AppName
char(280)
Application name
3.使用的存储过程
Stored Procedure
Description
CreateTempTables
Creates the ASPStateTempSessions and ASPStateTempApplications tables; called during setup, but not called by SqlSessionStateStore.
DeleteExpiredSessions
Used by SQL Server Agent to remove expired sessions.
GetHashCode
Hashes an application name and returns the hash; called by TempGetAppID.
GetMajorVersion
Returns SQL Server's major version number.
TempGetAppID
Converts an application name into an application ID; queries the ASPStateTempApplications table and inserts a new record if necessary.
TempGetStateItem
Retrieves read-only session state from the database (ASP.NET 1.0; ASP.NET 1.1/SQL Server 7).
TempGetStateItem2
Retrieves read-only session state from the database (ASP.NET 1.1).
TempGetStateItem3
Retrieves read-only session state from the database (ASP.NET 2.0).
TempGetStateItemExclusive
Retrieves read/write session state from the database (ASP.NET 1.0; ASP.NET 1.1/SQL Server 7).
TempGetStateItemExclusive2
Retrieves read/write session state from the database (ASP.NET 1.1).
TempGetStateItemExclusive3
Retrieves read/write session state from the database (ASP.NET 2.0).
TempGetVersion
Marker whose presence indicates to ASP.NET 2.0 that the session state database is ASP.NET 2.0-compatible.
TempInsertStateItemLong
Adds a new session, whose size is > 7,000 bytes, to the database.
TempInsertStateItemShort
Adds a new session, whose size is <= 7,000 bytes, to the database.
TempInsertUninitializedItem
Adds a new uninitialized session to the database in support of cookieless sessions.
TempReleaseStateItemExclusive
Releases a lock on a session; called when ASP.NET determines that a request has timed out and calls the provider'sReleaseItemExclusive method.
TempRemoveStateItem
Removes a session from the database when the session is abandoned.
TempResetTimeout
Resets a session's timeout by writing the current date and time to the corresponding record's Expires field.
TempUpdateStateItemLong
Updates a session whose size is > 7,000 bytes.
TempUpdateStateItemLongNullShort
Updates a session whose old size is <= 7,000 bytes, but whose new size is > 7,000 bytes.
TempUpdateStateItemShort
Updates a session whose size is <= 7,000 bytes.
TempUpdateStateItemShortNullLong
Updates a session whose old size is > 7,000 bytes, but whose new size is <= 7,000 bytes.
ASP.NET 状态数据库FAQ
1.如果把SESSION值存放到数据库中去,用户关闭了程序那怎么样清空数据库里的SESSION值呢?
实际ASP.NET在创建状态数据库的时候会在SQL Server代理(SQL Server Agent)的作业中添加一个作业,名称为<状态数据库名>_Job_DeleteExpiredSessions。如果打开SQL Server代理服务数据库可以通过添加的状态记录的超时时间字段(Exprires)定期对超时的状态数据进行删除。
2.ASPStateTempSessions表中的SessionId字段如何使用?
数据库中此表的SessionID字段的值,由SessionID和AppID共同组成,最后8位为AppID所以,后8位之前一定是SessionID。例如,存储在数据库中的值为"ekr30c3mwvnc3145yrswew3a037e5e5a",后8位的"037e5e5a"为AppID,而前面的"ekr30c3mwvnc3145yrswew3a"为应用程序中你可以使用Session.SessionID获得的字符串。
3.如何判断Session何时被更新的?
Session记录被更新时会同时更新Expires和LockDateLocal,Expires字段为UTC时间,如果想通过本地之间进行比较判断还是需要使用LockDateLocal。
4.获得Web.config配置文件节点信息的程序?