C

REST Read Response with Stream API

See more REST Examples

Demonstrates how to make a REST call that returns a binary body, and to receive the body through a stream API. C

#include <C_CkRest.h>
#include <C_CkAuthAws.h>
#include <C_CkStream.h>
#include <C_CkTask.h>
#include <C_CkByteData.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkRest rest;
    BOOL bTls;
    int port;
    BOOL bAutoReconnect;
    HCkAuthAws authAws;
    int responseStatusCode;
    const char *errResponse;
    HCkStream bodyStream;
    HCkTask readResponseBodyTask;
    HCkByteData nextChunk;

    success = FALSE;

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

    rest = CkRest_Create();

    //  Connect to the Amazon AWS REST server.
    bTls = TRUE;
    port = 443;
    bAutoReconnect = TRUE;
    success = CkRest_Connect(rest,"s3.amazonaws.com",port,bTls,bAutoReconnect);

    //  ----------------------------------------------------------------------------
    //  Important: For buckets created in regions outside us-east-1,
    //  there are three important changes that need to be made.
    //  See Working with S3 Buckets in Non-us-east-1 Regions for the details.
    //  ----------------------------------------------------------------------------

    //  Provide AWS credentials for the REST call.
    authAws = CkAuthAws_Create();
    CkAuthAws_putAccessKey(authAws,"AWS_ACCESS_KEY");
    CkAuthAws_putSecretKey(authAws,"AWS_SECRET_KEY");
    CkAuthAws_putServiceName(authAws,"s3");
    success = CkRest_SetAuthAws(rest,authAws);

    //  Set the bucket name via the HOST header.
    //  In this case, the bucket name is "chilkat100".
    CkRest_putHost(rest,"chilkat100.s3.amazonaws.com");

    //  Send the request to download the JPG.
    success = CkRest_SendReqNoBody(rest,"GET","/starfish.jpg");
    if (success != TRUE) {
        printf("%s\n",CkRest_lastErrorText(rest));
        CkRest_Dispose(rest);
        CkAuthAws_Dispose(authAws);
        return;
    }

    //  Read the response header.
    responseStatusCode = CkRest_ReadResponseHeader(rest);
    if (responseStatusCode < 0) {
        printf("%s\n",CkRest_lastErrorText(rest));
        CkRest_Dispose(rest);
        CkAuthAws_Dispose(authAws);
        return;
    }

    printf("Response status code = %d\n",responseStatusCode);

    //  We expect a 200 response status if the JPG data is coming.
    //  Otherwise, we'll get a string response body with an error message(or no response body).
    if (responseStatusCode != 200) {
        errResponse = CkRest_readRespBodyString(rest);
        if (CkRest_getLastMethodSuccess(rest) != TRUE) {
            printf("%s\n",CkRest_lastErrorText(rest));
        }
        else {
            printf("%s\n",errResponse);
        }

        CkRest_Dispose(rest);
        CkAuthAws_Dispose(authAws);
        return;
    }

    bodyStream = CkStream_Create();
    //  Set a 10 second read timeout for the stream. 
    //  (Give up if no data arrives within 10 seconds after calling a read method.)
    CkStream_putReadTimeoutMs(bodyStream,10000);

    //  Create a background thread task to read the response body (which feeds
    //  it to the bodyStream object.)
    readResponseBodyTask = CkRest_ReadRespBodyStreamAsync(rest,bodyStream,TRUE);

    //  Start the task. 
    success = CkTask_Run(readResponseBodyTask);

    //  The application can now read the bodyStream...
    nextChunk = CkByteData_Create();
    while ((CkStream_getEndOfStream(bodyStream) != TRUE)) {

        //  Read the next chunk of bytes (whatever is immediately available,
        //  or wait for more data (up to 10 seconds because we set the stream's ReadTimeoutMs property)
        success = CkStream_ReadBytes(bodyStream,nextChunk);
        if (success != TRUE) {
            printf("Failed to receive more response data.\n");
            //  Make sure the background task is aborted/cancelled.
            success = CkTask_Cancel(readResponseBodyTask);
            CkTask_Dispose(readResponseBodyTask);
            CkRest_Dispose(rest);
            CkAuthAws_Dispose(authAws);
            CkStream_Dispose(bodyStream);
            CkByteData_Dispose(nextChunk);
            return;
        }

        //  OK.. the app has the next chunk of the body, and may do whatever it wishes with it...
        //  See the CkByteData online reference documentation for 
        //  information about accessing and manipulating the byte data.

    }

    CkTask_Dispose(readResponseBodyTask);

    printf("Successfully received the entire response body.\n");


    CkRest_Dispose(rest);
    CkAuthAws_Dispose(authAws);
    CkStream_Dispose(bodyStream);
    CkByteData_Dispose(nextChunk);

    }