Problem with get and set brower cookies.

Hi

I need put (save) some temporary data to client site. And then I need read this dada.

I decide use Cookies.

I set data using:

WDR_TASK=>REQUEST->SET_COOKIE(
        exporting
          NAME    =  'MYDATA'
           VALUE   =  'test value'
                       ).

I read data using this ways:

CALL METHOD LO_REQUEST->IF_HTTP_ENTITY~GET_COOKIE
     EXPORTING
       NAME    = 'MYDATA'
     IMPORTING
       VALUE   = zCookies
       .

   wdr_task=>REQUEST->GET_COOKIE(
     exporting
       NAME    = 'MYDATA'
     importing
       VALUE   = zCookies
   ).

   WDR_TASK=>REQUEST->GET_COOKIES(
     changing
       COOKIES = myCookies
   ).

When I use read and set in same method, I got data. But when I read data in different methods (or I use F5 - refresh browser) I don't get data from cookies.

How can I set/get data on client site?

Minor but important question:

Is possible read from client browser (computer) unique text/value (something with I can identify client)?

Thank you