File not well formed: Process instruction name (may not be 'xml') expected

Question

I am a WBI developer whose end result is to produce one XML file. This file will receive a number of events that will constantly append to XML file. Each appendage will contain same structure but diff data than one before. Also I have created a WBI business object to mirror the XML structure.
However, below is my XML in a Not well formed state. My error happens at first appendage ( see second tag of ><?xml version='1.0' encoding='utf-8'?>)
My question: Can I actually produce a correct XML file? if so how do I do this, is it a change needed in my Busines Object? And if I cannot then what are my other options.
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE BATCH_AUTO>
<BATCH_AUTO><POLICY><POL_TRANCODE>CHKS</POL_TRANCODE><POL_EXTRACTDTE>20050602</POL_EXTRACTDTE><POL_POLICYNO>PAA-123456789</POL_POLICYNO><POL_EFFDATE>20050101</POL_EFFDATE><POL_DUEDATE>20051201</POL_DUEDATE><POL_TOTALPREMIUM>1</POL_TOTALPREMIUM><POL_ACCTBALANCE>2.00</POL_ACCTBALANCE><POL_MAILNAME1>John Doe</POL_MAILNAME1><POL_MAILNAME2>Jane Doe2</POL_MAILNAME2><POL_MAILNAME3>Mark Doe3</POL_MAILNAME3><POL_MAILADDR1>1234567891 W1 MAIN St. A ST A WA APTAPTAPTAPT 12345678 APTAPTAPTAPT 12345678</POL_MAILADDR1><POL_CANCELDATE>20050901</POL_CANCELDATE><POL_CANCELREASON>REASON</POL_CANCELREASON><POL_SUBTOTAL>7.00</POL_SUBTOTAL><POL_TOTALFEE>1</POL_TOTALFEE><POL_TOTALADJS>4.00</POL_TOTALADJS><POL_CHECKDATE>020050525</POL_CHECKDATE><POL_CHECKNO>000001</POL_CHECKNO><POL_CHKEXPLANATION>Cancelled</POL_CHKEXPLANATION><POL_CHECKAMOUNT>5</POL_CHECKAMOUNT><POL_BANKACCTNO>8765015692</POL_BANKACCTNO><POL_BANKROUTNO>719232845</POL_BANKROUTNO><POL_TOTAMTPAID>1</POL_TOTAMTPAID></POLICY></BATCH_AUTO><?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE BATCH_AUTO>
<BATCH_AUTO><POLICY><POL_TRANCODE>CHKS</POL_TRANCODE><POL_EXTRACTDTE>20050602</POL_EXTRACTDTE><POL_POLICYNO>PAA-123456789</POL_POLICYNO><POL_EFFDATE>20050101</POL_EFFDATE><POL_DUEDATE>20051201</POL_DUEDATE><POL_TOTALPREMIUM>1</POL_TOTALPREMIUM><POL_ACCTBALANCE>2.00</POL_ACCTBALANCE><POL_MAILNAME1>John Doe</POL_MAILNAME1><POL_MAILNAME2>Jane Doe2</POL_MAILNAME2><POL_MAILNAME3>Mark Doe3</POL_MAILNAME3><POL_MAILADDR1>1234567891 W1 MAIN St. A ST A WA APTAPTAPTAPT 12345678 APTAPTAPTAPT 12345678</POL_MAILADDR1><POL_CANCELDATE>20050901</POL_CANCELDATE><POL_CANCELREASON>REASON</POL_CANCELREASON><POL_SUBTOTAL>7.00</POL_SUBTOTAL><POL_TOTALFEE>1</POL_TOTALFEE><POL_TOTALADJS>4.00</POL_TOTALADJS><POL_CHECKDATE>020050525</POL_CHECKDATE><POL_CHECKNO>000001</POL_CHECKNO><POL_CHKEXPLANATION>Cancelled</POL_CHKEXPLANATION><POL_CHECKAMOUNT>5</POL_CHECKAMOUNT><POL_BANKACCTNO>8765015692</POL_BANKACCTNO><POL_BANKROUTNO>719232845</POL_BANKROUTNO><POL_TOTAMTPAID>1</POL_TOTAMTPAID></POLICY></BATCH_AUTO>

Answer 1

Hi,
The <?xml version='1.0' encoding='utf-8'?>) xml declaration can occur only once and that too at the very top of the xml file before everything else. I think your best bet would be to strip the xml declaration and the doctype declaration before appending. You might want to check the API documentation of the API you are using to serialize the xml to see if it supports suppressing xml and doctype declarations.
With apache xerces, you can do
OutputFormat.setOmitXMLDeclaration(true);
where OutputFormat dictates what underlying serialized is used to serialize the document based on the specified method.
Hope this helps.
Cheers,
vidyut