David,
Thanks! It is about the same I was was thinking. I think I get too hung up
on what the patterns should be.
I will look into then "Object pool pattern".
Thanks again!
rich
Hello David Browne" davidbaxterbrowne no potted,
> "Richard" <(E-Mail Removed)> wrote in message
> news:0434447F-86A1-4AD9-B9ED-(E-Mail Removed)...
>
>> Hi,
>>
>> I need to wrap a DLL written in Cobol into a .net Dll. I am hoping of
>> some design guidance.
>>
>> To call the Cobol DLL basically there 3 data areas that get passed
>> into
>> the
>> call.
>> Comm area (which contains the data returned from the call to the
>> Cobol DLL)
>>
>> Transaction area (which contains the data instructing the Cobol DLL
>> of
>> what
>> function to execute, login information, return code for
>> success/failure).
>> Request area (which contains the parameter data Cobol DLL function
>> needs).
>>
>> All the areas are positional (and dynamic based on the function call)
>> so
>> without a lot of work on the programers side it is difficult to make
>> sure
>> you
>> have everything set correctly so you get the required result. That is
>> why
>> I
>> am wrapping it. So other users can make a simple
>> GetUserInfo(username) and
>> get a object back that contains the named members.
>> I have this working for some of the function. But am not sure I am
>> designing
>> it correctly. I am looking at the patterns books and kind of think
>> Facade
>> or
>> Adapter. But not quite sure either of them are correct.
>> I expect I should have one place in the .net DLL that actually makes
>> the
>> call to the DLL and in the separate functions (GetUserInfo(username))
>> set
>> the
>> Transaction and request areas and pass them into the single call. My
>> concern
>> is the comm area is pretty big (about 3000 bytes). And passing that
>> around
>> may not be the best solution.
> I assume that the commarea is a byte array. Don't worry about
> "passing it around" it's a reference type, and you are only passing a
> reference to it.
>
> here's the right pattern:
>
> public class UserInfo
> {
> string FirstName;
> string LastName;
> string Department;
> }
> public class CobolAdapter
> {
> public static string GetUserInfo(string UserName)
> {
> byte[] commArea = new byte[3000];
> byte[] transactionArea = new byte[300];
> byte[] requestArea = new byte[300];
> //set appropriate data into buffers
> CallCobolRoutine(commArea,transactionArea,requestArea);
> bool success = false;
> string errorMessage;
> //marshal the return code into success
> if (!success)
> {
> throw new RuntimeExeption("Cobol Routine Failed " +
> errorMessage);
> }
> UserInfo rv = new UserInfo();
> //pull info from requestArea and marshal it into rv
> return rv;
> }
>
> private static void CallCobolRoutine(byte[] CommArea, byte[]
> TransactionArea, byte[] RequestArea)
> {
> //PInvoke COBOL .dll here
> }
> }
> A possible optimization is to use a "Object Pool Pattern" to recycle
> the buffers.
>
> David
>
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