This is the function I use to get data from a webservice, in SQL Anywhere v.12.0.1.3436:

CREATE FUNCTION test(in wsurl varchar(2048), in wsns varchar(2048), in cert varchar(2048),
    in username varchar(128), in password varchar(128), in idnum varchar(128), in productNumber varchar(128), in lang varchar(128))
RETURNS xml
url '!wsurl' type 'SOAP:DOC' namespace '!wsns' certificate 'cert=!cert' set 'SOAP(op=GetSaisWithPdf)';

Calling it I get error:

There was an error reading the results of the SQL statement. The displayed results may be incorrect or incomplete. HTTP request failed. Status code '0' SQLCODE=-983, ODBC 3 State="HY000"

And this is what I get in the log file (sensitive data is replaced with ***, sorry for that):

[connid = 15, 03/31 11:38:27.581]
[connid = 15, 03/31 11:38:27.581, REQUEST]
POST ***/SAIS/WebServices/getsais.asmx HTTP/1.0
ASA-Id: f373ec5c77a34acf9e25b85b54eb1150
User-Agent: SQLAnywhere/12.0.1.3436
Accept-Charset: windows-1257, UTF-8, *
Date: Mon, 31 Mar 2014 08:38:21 GMT
Host: ***
Connection: close
Content-Type: text/xml; charset=windows-1257
Content-Length: 528
SOAPAction: "http://tempuri.org/GetSaisWithPdf"

<?xml version="1.0"?>
<SOAP-ENV:Envelope
  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:m="http://tempuri.org/">
  <SOAP-ENV:Body>
    <m:GetSaisWithPdf>
      <m:username>***</m:username>
      <m:password>***</m:password>
      <m:idnum>***</m:idnum>
      <m:productNumber>***</m:productNumber>
      <m:lang>***</m:lang>
    </m:GetSaisWithPdf>
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>
[connid = 15, 03/31 11:38:44.788, RESPONSE]
H
[connid = 15, 03/31 11:38:44.792, RESPONSE]
TTP/1.1 200 OK
Cache-Control: private, max-age=0
Content-Type: text/xml; charset=utf-8
Server: Microsoft-IIS/8.0
X-AspNet-Version: 4.0.30319
X-Powered-By: ASP.NET
S: 2
Date: Mon, 31 Mar 2014 08:38:37 GMT
Connection: close
Content-Length: 1203439

<?xml version="1.0" encoding="utf-8"?><soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"><soap:Body><GetSaisWithPdfResponse xmlns="http://tempuri.org/"><GetSaisWithPdfResult><XmlDocument><root xmlns=""> <InfoBlock name="tblInfoBlock" title="Santrauka" sectionId="santrauka"> </InfoBlock><Summary name="tblSummary" UnknownValue="Nenustatyta"> <vat Name="Vėlavimo atsiskaityti reitingas" Probability="83,00%" ProbabilityText="tikimybė," ClassValue="10" ClassText="klasė," ClassName="Aukščiausia rizika" IsSet="true" /><bt Name="Bankroto reitingas" Probability="5,032%" ProbabilityText="tikimybė," ClassValue="8" ClassText="klasė," ClassName="A
[connid = 15, Protocol Error]
[connid = 15, socket closed]

As you can see, the response result is truncated some why to 1024 characters, I contacted the webservice maintainers and they confirmed that they send out the full response, I tried the same request (evelope generated by SA) in SoapUI and in C# and got correct results, no truncation, so I am prety sure the problem is somewhere within SQL Anywhere, any ideas where?

Update: Updated to v.12.0.1.4085, now I get the following error:

There was an error reading the results of the SQL statement. The displayed results may be incorrect or incomplete. HTTP request failed. Status code '<none>' SQLCODE=-983, ODBC 3 State="HY000"

And log now looks even worse:

[connid = 24, 03/31 17:09:19.113, REQUEST]
POST /***/SAIS/WebServices/getsais.asmx HTTP/1.0
Connection: close
User-Agent: SQLAnywhere/12.0.1.4085
Accept-Charset: windows-1257, UTF-8, *
Date: Mon, 31 Mar 2014 14:09:19 GMT
ASA-Id: 0ab81a2edc6f4a54b6ff2dad69d858be
Host: ***
Content-Length: 528
SOAPAction: "http://tempuri.org/GetSaisWithPdf"
Content-Type: text/xml; charset=windows-1257

[connid = 24, Error: socket closed]
[connid = 24, socket closed]
[connid = 24, Error: socket closed by peer]

After testing I rolled back to version 12.0.1.3895 and now I am back to error described at the top of this long post.