.NET Remoting Basic(9)-上下文(CallContext)

CallContext 是类似于方法调用的线程本地存储区的专用集合对象，并提供对每个逻辑执行线程都唯一的数据槽。
使用该功能，存储对象必须实现ILogicalThreadAffinative接口

1.定义接口

[Serializable]
public class LogSettings: ILogicalThreadAffinative
{
public bool EnableLog;
}

2.客户端设置一个对象

static void Main(string[] args)
{
String filename = AppDomain.CurrentDomain.SetupInformation.ConfigurationFile;
RemotingConfiguration.Configure(filename);

if (args.Length > 0 && args[0].ToLower() == "/enablelog")
{
LogSettings ls = new LogSettings();
ls.EnableLog = true;
CallContext.SetData("log_settings", ls);
}

IRemoteCustomerManager mgr =
(IRemoteCustomerManager) RemotingHelper.CreateProxy(typeof(IRemoteCustomerManager));
Customer cust = mgr.GetCustomer(42);

Console.WriteLine("Done");
Console.ReadLine();
}

3.服务器端接收对象

根据key获取对象，然后判断属性

class CustomerManager: MarshalByRefObject, IRemoteCustomerManager
{
public Customer GetCustomer(int id)
{
LogSettings ls = CallContext.GetData("log_settings") as LogSettings;

if (ls!= null && ls.EnableLog)
{
// simulate write to a logfile
Console.WriteLine("LOG: Loading Customer " + id);
}

Customer cust = new Customer();
return cust;
}
}

class ServerStartup
{
static void Main(string[] args)
{
String filename = AppDomain.CurrentDomain.SetupInformation.ConfigurationFile;
RemotingConfiguration.Configure(filename);
Console.WriteLine ("ServerStartup.Main(): Server started");
Console.ReadLine();
}
}

4.将客户端和服务器端上下文数据操作进行封装

因为上下文数据可以在客户端和服务器端同时交互，所以可以进行封装，而无需让客户端和服务器端知道细节

4.1 定义LogSettingContext类

public class LogSettingContext
{
public static bool EnableLog
{
get
{
LogSettings ls = CallContext.GetData("log_settings") as LogSettings;

if (ls!= null)
{
return ls.EnableLog;
}
else
{
return false;
}
}
set
{
LogSettings ls = new LogSettings();
ls.EnableLog = value;
CallContext.SetData("log_settings", ls);
}
}
}

4.2 前端调用

LogSettingContext.EnableLog=true;

4.3后端调用

if (LogSettingContext.EnableLog)
{
// simulate write to a logfile
Console.WriteLine("LOG: Loading Customer " + id);
}

如此便简化了操作