Question Re: retrieving header values of web client function in Technology Q&A

retrieving header values of web client function

Baron — Tue, 05 May 2020 04:30:07 GMT

I am consuming external webservices from my SQL-Anywhere 17 and I am interested in the HTTPSTATUS of the response more than the body itself, so I want just to check if the call to the webservice has succeeded (i.e. whether I got 200 OK as HTTP Status)!

I tried to write something like this, but I get always an empty string in my @ResponseStatus variable!

create or replace function UpdateAPI(EndPoint varchar(200), UserName varchar(200), PWD varchar(200), PayLoad long varchar)

returns long varchar

url 'http://!UserName:!PWD@!EndPoint'

type 'http:put:application/json';

begin

declare @ResponseBody long varchar;

declare @ResponseStatus long varchar;

set @ResponseBody = WC_UpdateAPI(@Endpoint, @username, @pwd, @PayLoad);
set @ResponseStatus = HTTP_RESPONSE_HEADER('@HttpStatus');

select @ResponseBody, @ResponseStatus;
end;

On the other side, I can see this HTTP Response in the WebClientLogFile (as HTTP/1.0 200 OK).

Could please somebody tell me Where I am doing mistake?

Re: retrieving header values of web client function

VolkerBarth — Tue, 05 May 2020 04:46:59 GMT

You need to use a web client procedure (instead of a web client function) to have access to the full response, web client functions just return the response's body.

See here and here for details.

Re: retrieving header values of web client function

Baron — Tue, 05 May 2020 07:42:38 GMT

Thank you very much. It has worked even with the parameter substitution

Re: retrieving header values of web client function

Baron — Tue, 05 May 2020 07:56:11 GMT

One more question, how can I then get both "body" and "Status" using one single call?

In the mentioned example how can I merge those both calls in one call:

SELECT "value" FROM SAPWebPage() WITH (Attribute LONG VARCHAR, Value LONG VARCHAR, Instance INT) WHERE Attribute = 'Status';

SELECT "value" FROM SAPWebPage() WITH (Attribute LONG VARCHAR, Value LONG VARCHAR, Instance INT) WHERE Attribute = 'body';

Re: retrieving header values of web client function

VolkerBarth — Tue, 05 May 2020 08:07:54 GMT

You mean, get those values

as two columns within one row or
within two rows?

For the 1. you can use a PIVOT clause:

SELECT "'Status'" AS STATUS, "'Body'" AS Body
FROM
   (SELECT "attribute", "value"
    FROM SAPWebPage() 
       WITH (Attribute LONG VARCHAR, Value LONG VARCHAR, Instance INT)) ST
   PIVOT (min("value") FOR "attribute" in ('Status', 'Body')) PT

For the second, you would obviously just do something like:

SELECT "attribute", "value"
FROM SAPWebPage() 
   WITH (Attribute LONG VARCHAR, Value LONG VARCHAR, Instance INT)
WHERE "attribute" in ('Status', 'Body')

Re: retrieving header values of web client function

Baron — Tue, 05 May 2020 08:36:42 GMT

Thanks, I was meaning the first one (with this MAGIC Clause PIVOT)

¯_(ツ)_/¯