SQL Server

REST Receive Response in Chunks

See more REST Examples

Demonstrates how to receive a REST HTTP response in chunks.

Note: This example requires Chilkat 10.1.0 or greater.

SQL Server

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @iTmp0 int
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

    -- This example requires the Chilkat API to have been previously unlocked.
    -- See Global Unlock Sample for sample code.

    DECLARE @rest int
    EXEC @hr = sp_OACreate 'Chilkat.Rest', @rest OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    -- Connect to the web server
    DECLARE @bTls int
    SELECT @bTls = 1
    DECLARE @port int
    SELECT @port = 443
    DECLARE @bAutoReconnect int
    SELECT @bAutoReconnect = 1
    EXEC sp_OAMethod @rest, 'Connect', @success OUT, 'chilkatsoft.com', @port, @bTls, @bAutoReconnect
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @rest, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @rest
        RETURN
      END

    -- Send the request.
    -- This can be *any* kind of request: POST, GET, PUT, etc. using *any* of the Chilkat REST methods that send requests.
    -- For this example, we'll just GET a simple XML document that is about 274K in size.

    EXEC sp_OAMethod @rest, 'SendReqNoBody', @success OUT, 'GET', '/hamlet.xml'
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @rest, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @rest
        RETURN
      END

    -- Get the response header.
    DECLARE @statusCode int
    EXEC sp_OAMethod @rest, 'ReadResponseHeader', @statusCode OUT
    IF @statusCode < 0
      BEGIN
        EXEC sp_OAGetProperty @rest, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @rest
        RETURN
      END


    PRINT 'response status code = ' + @statusCode

    DECLARE @outputFile nvarchar(4000)
    SELECT @outputFile = 'c:/temp/qa_output/hamlet.xml'

    DECLARE @fac int
    EXEC @hr = sp_OACreate 'Chilkat.FileAccess', @fac OUT

    EXEC sp_OAMethod @fac, 'OpenForWrite', @success OUT, @outputFile
    IF @statusCode < 0
      BEGIN
        EXEC sp_OAGetProperty @fac, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @rest
        EXEC @hr = sp_OADestroy @fac
        RETURN
      END

    -- Get the response in chunks.
    -- (Note: There are more efficient ways to simply download a file from a web server, such as by calling Chilkat's Http.Download method.
    -- The purpose of this method is to show how to receive a response chunk-by-chunk.)
    DECLARE @bd int
    EXEC @hr = sp_OACreate 'Chilkat.BinData', @bd OUT

    DECLARE @status int
    SELECT @status = 1
    WHILE @status = 1
      BEGIN
        -- Read a minimum of 16000 bytes.
        -- Note: Because of TLS message lengths, or the possibility of the response being either compressed (gzip/deflate) or in the HTTP chunked encoding,
        -- the amount of data received in each call can be greater than the specified min size.
        -- Chilkat will return from the call as soon as it has received an amount equal to or more than the specified size,
        -- except for the very last chunk, which can be less that the min size or even 0 bytes.

        -- The status will be one of three values:
        -- -1 = error
        -- 0 = received the last chunk of the response.
        -- 1 = received a chunk, and more chunks are coming..

        -- The received data is *appended* to the contents of the BinData object.
        EXEC sp_OAMethod @rest, 'ReadRespChunkBd', @status OUT, 16000, @bd
        IF @status >= 0
          BEGIN

            EXEC sp_OAGetProperty @bd, 'NumBytes', @iTmp0 OUT

            PRINT 'Received chunk: ' + @iTmp0 + ' bytes'
            EXEC sp_OAMethod @fac, 'FileWriteBd', @success OUT, @bd, 0, 0
            EXEC sp_OAMethod @bd, 'Clear', @success OUT
          END
      END

    EXEC sp_OAMethod @fac, 'FileClose', NULL


    PRINT 'Success.'

    EXEC @hr = sp_OADestroy @rest
    EXEC @hr = sp_OADestroy @fac
    EXEC @hr = sp_OADestroy @bd


END
GO