problem with executing method using DBUS, why parameters passing is changed.

[Nallammai S]

 Hi,
 
>Hi 
>I have written one server which have one method sum which is exposed to client through DBUS. my client calls this method with 2 input parameters >and one output parameter (collect the sum of 2 input nos), but i am not able to receive  any change in my output parameter though the method is >executed.

>  Following is my XML file
>   <?xml version="1.0" encoding="UTF-  8" ?>

>  <node name="/com/example/MyServer">
  
>  <interface name="com.example.MyServer">
>  <annotation name="org.freedesktop.DBus.GLib.CSymbol" value="my_server"/>
>    <method name="NoArgs">
>     <annotation name="org.freedesktop.DBus.GLib.CSymbol" value="my_server_no_args"/>
>    </method>
>
>   <method name="Sum">
>     <annotation name="org.freedesktop.DBus.GLib.CSymbol" value="my_server_sum"/>
>      <arg type="i" name="num1" direction="in" />
>     <arg type="i" name="num2" direction="in" />
>      <arg type="i" name="sum" direction="out" />
>   </method>

>   </interface>
>   </node>

> Following is the implementation of function in server

> gboolean my_server_sum(int num1,int num2,int *sum)
> {
>   printf("\n num1 = %d num2  = %d sum = %d \n",num1,num2,sum);    
>     *sum = num1 + num2;
>   return TRUE;
> }

The implementation of the function in server should be like this:

gboolean my_server_sum(SomeObject *obj, int num1,int num2,int *sum,GError *error)
{
    *sum = num1 + num2;
    printf("\n num1 = %d num2  = %d sum = %d \n",num1,num2,*sum);

   return TRUE;
}

The SomeObject is the object through which the methods are exposed. The functions implemented should conform to some rules as:

#1 The function must return a value of type gboolean; TRUE on success, and FALSE otherwise.
#2 The first parameter is a pointer to an instance of the object.
#3 Following the object instance pointer are the method input values.
#4 Following the input values are pointers to return values.
#5 The final parameter must be a GError **. If the function returns FALSE for an error, the error parameter must be initalized with g_set_error

> Following is the call in client
> com_example_MyServer_sum (proxy,num1,num2,ptr,&error);
> where int num1 = 4, num2 = 3 
> ptr is integer pointer holding add of integer variable.

> printf on server side prints 

> num1 = 134546064 num2 = 4 sum = 3

> why is this happening?

 From your printf statement, I found that you are trying to print the value of "sum". Since sum is a pointer variable, it will give the address value. You should first compute the sum and then use "*sum" inorder to print the sum value.

 For your reference, you can also look at the examples present in the d-bus source package as well as the D-Bus tutorial present in the D-bus homepage.



Nallammai.S