\t\t不同的services之间的调用

不同的services之间调用是有可能，如我们封装了DBSerives，而LoginServices也相对独立，但初次校验Session的用户账号和密码，有可能使用到DBSerives的方法。

我在新闻组看到RO的一个范例，代码如下：

Provided that

- you have 3 services (srvcLogin, srvcOne, srvcTwo)
- these three are connected to a SessionManager
- srvcOne and srvcTwo have RequiresSession = true
- session was initialized with a call to srvcLogin


you can call srvcTwo.CalledBySrvcOne via srvcOne.CallSrvcTwo:

procedure TsrvcOne.CallSrvcTwo;
var
instance: IInterface;
factory: IROClassFactory;
srvc2: IsrvcTwo;
begin
factory := GetClassFactory('srvcTwo');
try
    factory.CreateInstance(Session.SessionID, instance);
    if (Supports(instance, IsrvcTwo, srvc2)) then
      srvc2.CalledBySrvcOne;
finally
    factory.ReleaseInstance(Session.SessionID, instance);
end;
end;