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: aspnet_regsql.exe -S <SQL Server IP> -U <User Name> -P <Password> -E -ssadd -sstype c -d <Database Name> 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) |
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's ReleaseItemExclusive 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?
''获得状态配置节点实例Dim mSessionStateSection As System.Web.Configuration.SessionStateSection =CType(configuration.GetSection("system.web/sessionState"),System.Web.Configuration.SessionStateSection)
''获得状态模式Response.Write(mSessionStateSection.Mode) ''获得状态超时时间Response.Write(mSessionStateSection.Timeout)