how to post XML to URL?

Hi,

  I am trying to post a string (xml) to an url

 EXEC @nval = sp_OAMethod @bj, 'send', NULL, @myString

 where I have declared @mystring as 

 declare @mystring varchar(8000) 

 and I am trying to create @mystring using data from a table at runtime where the @mystring value will exceed more than 8000 character and the string is truncating after character limit.

Is there anyway where I can post the large file content either by storing the content in a variable or posting the file itself fetching from some location?

I am doing this in sql server 2000.

Thanks in advance.

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Pavan