How to avoid sp_OACreate limits? - sql-server

Question

Declare #Object as Int;
Declare #ResponseText as Varchar(8000);
Declare #Url as Varchar(MAX);
set #Url = 'http://mysite.ru/cgi-bin/my_xml.cgi'
Exec sp_OACreate 'MSXML2.XMLHTTP', #Object OUT;
Exec sp_OAMethod #Object, 'open', NULL, 'get', #Url, 'false'
Exec sp_OAMethod #Object, 'send'
Exec sp_OAMethod #Object, 'responseText', #ResponseText OUTPUT
Exec sp_OADestroy #Object
SELECT #ResponseText
XML length in url is 4210 and #ResponseText return NULL , when I change length to 3970 #ResponseText return me data. Does sp_OACreate have limit 400 ? If yes if it possible to avoid ?

Answer 1

despite the subject of your post i think that the issue is likely with sp_OAMethod and not sp_OACreate itself.
also IMHO accessing the web from sql code should be avoided at all costs but this is just my opinion because i don't like the idea having a RDBMS 'surfing the web'. ^^
to circumvent the limitation of sp_OAMethod you can try to elaborate an answer present on msdn.
your code should become something like this:
Declare #Object as Int;
Declare #ResponseText as Varchar(8000);
Declare #Url as Varchar(MAX);
set #Url = 'http://mysite.ru/cgi-bin/my_xml.cgi'
Exec sp_OACreate 'MSXML2.XMLHTTP', #Object OUT;
Exec sp_OAMethod #Object, 'open', NULL, 'get', #Url, 'false'
Exec sp_OAMethod #Object, 'send'
--Exec sp_OAMethod #Object, 'responseText', #ResponseText OUTPUT
INSERT #temptable ( appropriatefield )
EXEC #Result = sp_OAGetProperty #Obj, 'YourPropertyName'
Exec sp_OADestroy #Object
the solution requires a temp table with appropriate structure and datatype to store the value produced by the remote page and this should allow you to get more than 4k of data.

Answer 2

According to this thread on sqlservercentral.com, sp_OACreate is limited to 4000 characters.
A workaround is to split up the read into smaller "chunks" that are then concated together in SQL. Here is a code snippet from the above link, that might help you although it reads XML from file instead of through HTTP:
EXECUTE #hResult = sp_OACreate ''Scripting.FileSystemObject'' , #objFileSystem OUT
IF #hResult <> 0
BEGIN
EXEC sp_OAGetErrorInfo #objFileSystem, #ErrorSource OUT, #ErrorDesc OUT
SET #ErrorFailPoint = ''Creating FSO''
GOTO DestroyFSO
RETURN
END
SET #FileNameAndPath = #Path + ''\'' + #FileName
-- Read file
EXECUTE #hResult = sp_OAMethod #objFileSystem, ''OpenTextFile'', #objTextStream OUT, #FileNameAndPath, 1, false, 0--for reading, FormatASCII
IF #hResult <> 0
BEGIN
EXEC sp_OAGetErrorInfo #objFileSystem, #ErrorSource OUT, #ErrorDesc OUT
SET #ErrorFailPoint = ''Opening Reponse File''
GOTO Destroy
RETURN
END
SET #ResponseText = ''''
WHILE #hResult = 0
BEGIN
EXECUTE #hResult = sp_OAGetProperty #objTextStream, ''AtEndOfStream'', #YesOrNo OUTPUT
IF #hResult <> 0
BEGIN
EXEC sp_OAGetErrorInfo #objTextStream, #ErrorSource OUT, #ErrorDesc OUT
SET #ErrorFailPoint = ''Checking AtEndOfStream''
GOTO Destroy
RETURN
END
IF #YesOrNo <> 0
BREAK
EXECUTE #hResult = sp_OAMethod #objTextStream, ''Read'', #Chunk OUTPUT, 4000
IF #hResult <> 0
BEGIN
EXEC sp_OAGetErrorInfo #objTextStream, #ErrorSource OUT, #ErrorDesc OUT
SET #ErrorFailPoint = ''Reading Chunk''
GOTO Destroy
RETURN
END
SET #ResponseText = #ResponseText + ISNULL(#Chunk, '''')
END
EXECUTE #hResult = sp_OAMethod #objTextStream, ''Close''
IF #hResult <> 0
BEGIN
EXEC sp_OAGetErrorInfo #objTextStream, #ErrorSource OUT, #ErrorDesc OUT
SET #ErrorFailPoint = ''Closing Response File''
GOTO Destroy
RETURN
END
-- Record response info
SET #ResponseXml = CAST(#ResponseText AS XML)
Destroy:
EXEC sp_OADestroy #objTextStream
DestroyFSO:
EXEC sp_OADestroy #objFileSystem

Answer 3

This is what I use to overcome the limitation. I use it for a RESTful api communication. I can receive varchar(max) but am still limited on the amount of data I can send. This might get you where you need to be. The top 5 variables are the arguments I use for the sproc.
Declare #url as varchar(1024)
Declare #connection_type as varchar(6)='GET' --POST, PUT, GET DELETE
Declare #post_string as varchar(max)=null
Declare #response_text as Varchar(max)
Declare #content_type varchar(254)='application/json'
Declare #oa_object as Int;
Declare #err_code as Int
Declare #result_table Table (xml_result varchar(max))
Select #post_string=dbo.fn_regex_replace('([ ]{2,10})|\r|\n', #post_string,'') --remove carriage returns and multiple spaces
Exec #err_code=sp_OACreate 'MSXML2.ServerXMLHTTP.3.0', #oa_object OUT;
If #err_code<>0
Set #response_text=dbo.fn_oa_error_message(#oa_object)
Else
Begin
Exec #err_code=sp_OAMethod #oa_object, 'open', NULL, #connection_type, #url,'false','d0b1a0aaed2a529356471de4fe99cae2','8e7aa1a91fa68d06cd027914d3aa1140'
If #err_code<>0
Set #response_text='Open '+dbo.fn_oa_error_message(#oa_object)
Else
Begin
Exec #err_code=sp_OAMethod #oa_object, 'setRequestHeader', NULL, 'User-Agent', 'Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)'
If #err_code<>0
Set #response_text='setRequestHeader:User-Agent '+dbo.fn_oa_error_message(#oa_object)
Else
Begin
Exec #err_code=sp_OAMethod #oa_object, 'setRequestHeader', NULL, 'Content-Type', #content_type
If #err_code<>0
Set #response_text='setRequestHeader:Content-Type '+dbo.fn_oa_error_message(#oa_object)
Else
Begin
Exec #err_code=sp_OAMethod #oa_object, 'send', Null, #post_string
If #err_code<>0
Set #response_text='Send '+dbo.fn_oa_error_message(#oa_object)
Else
Begin
Set #response_text=null--make sure we don't return garbage
INSERT #result_table (xml_result)
Exec #err_code = sp_OAGetProperty #oa_object, 'responseText'
If #err_code<>0
Set #response_text='responseText '+dbo.fn_oa_error_message(#oa_object)
Else
SELECT #response_text=xml_result FROM #result_table
End
End
End
End
End
Exec sp_OADestroy #oa_object
Although you don't need it, the error handler is below. It helps with troubleshooting.
CREATE FUNCTION
dbo.n_oa_error_message(#oa_object int)
RETURNS varchar(max)
AS
BEGIN
Declare #source varchar(255)
Declare #description varchar(255)
exec sp_OAGetErrorInfo #oa_object, #source OUT, #description OUT
return 'Error: '+IsNull(#description,'no description')
END

Answer 4

I used the following query to solve this issue. The problem is probably not sp_OACreate or sp_OAMethod, but the way to return the #ResponseText. Inserting the data into a table variable instead of using "#ResponseText OUTPUT" is the key. Note that I changed the #Response to VARCHAR(MAX).
DECLARE #TABLEVAR TABLE (responseXml VARCHAR(MAX))
DECLARE #URL VARCHAR(200)
SELECT #URL = 'http://mysite/php-start/callxml.php'
DECLARE #Response NVARCHAR(MAX)
DECLARE #Xml XML
DECLARE #Obj INT
DECLARE #Result INT
EXEC #Result = sp_OACreate 'MSXML2.XMLHttp', #Obj OUT
EXEC #Result = sp_OAMethod #Obj, 'open', NULL, 'GET', #URL, false
EXEC #Result = sp_OAMethod #Obj, 'setRequestHeader', NULL, 'Content-Type', 'application/x-www-form-urlencoded'
EXEC #Result = sp_OAMethod #Obj, SEND, NULL, ''
INSERT INTO #TABLEVAR
EXEC #Result = sp_OAGetProperty #Obj, 'responseXML.xml'--, #Response OUT
EXEC sp_OADestroy #Obj
SELECT #Response = responseXml FROM #TABLEVAR
SELECT #Xml = CONVERT(XML, #Response, 2)
DECLARE #handle INT
EXEC sp_xml_preparedocument #handle OUTPUT, #Xml
SELECT *
FROM OPENXML(#handle, '/data/record', 2)
WITH [dbo].[tblDialogTechTemp]
EXEC sp_xml_removedocument #handle
My query suddenly returned null without changing anything. After changing 'MSXML2.XMLHttp' to 'MSXML2.ServerXMLHTTP', it started to work again. To know more about the difference between these two, see this article and Microsoft documentation.