(Objective-C) S3 Upload the Parts for a Multipart Upload

This example uploads a large file in parts. The multipart upload needs to have been first initiated prior to uploading the parts.

See http://docs.aws.amazon.com/AmazonS3/latest/API/mpUploadUploadPart.html for more information about uploading parts.

Chilkat Objective-C Library Downloads MAC OS X (Cocoa) Libs iOS Libs

#import <CkoXml.h>
#import <NSString.h>
#import <CkoFileAccess.h>
#import <CkoRest.h>
#import <CkoAuthAws.h>
#import <CkoStringBuilder.h>
#import <CkoStream.h>

// In the 1st step for uploading a large file, the multipart upload was initiated
// as shown here: Initiate Multipart Upload

// Other S3 Multipart Upload Examples:
// Complete Multipart Upload
// Abort Multipart Upload
// List Parts

// When we initiated the multipart upload, we saved the XML response to a file.  This
// XML response contains the UploadId.  We'll begin by loading that XML and getting
// the Upload ID.

CkoXml *xmlInit = [[CkoXml alloc] init];
BOOL success = [xmlInit LoadXmlFile: @"s3_multipart_uploads/initiate.xml"];
if (success != YES) {
    NSLog(@"%@",@"Did not find the initiate.xml XML file.");
    return;
}

NSString *uploadId = [xmlInit GetChildContent: @"UploadId"];
NSLog(@"%@%@",@"UploadId = ",uploadId);

// When uploading parts, we need to keep an XML record of each part number
// and its corresponding ETag, which is received in the response for each part.
// There can be up to 10000 parts, numbered 1 to 10000.  
// After all parts have been uploaded, the final step will be to complete
// the multipart upload (see Complete Multipart Upload)

// In this example, the large file we want to upload is somethingBig.zip
NSString *fileToUploadPath = @"s3_multipart_uploads/somethingBig.zip";

// The minimum allowed part size is 5MB (5242880 bytes).  The last part can be smaller because
// it will contain the remainder of the file.  (This minimum is enforced by the AWS service.)
// We'll use the minimum allowed part size for this example.
int partSize = 5242880;

// Let's use Chilkat's FileAccess API to examine the file to be uploaded.  We'll get the size
// of the file and find out how many parts will be needed, including the final "partial" part.
CkoFileAccess *fac = [[CkoFileAccess alloc] init];
[fac OpenForRead: fileToUploadPath];

// How many parts will there be if each part is 5242880 bytes?
int numParts = [[fac GetNumBlocks: [NSNumber numberWithInt: partSize]] intValue];
NSLog(@"%@%d",@"numParts = ",numParts);
[fac FileClose];

// Imagine that we may be running this for the 1st time, or maybe we already
// attempted to upload parts, and something failed. Maybe there was a network problem
// the resulted in not all parts getting uploaded.  We'll write this code so that if run again,
// it will upload whatever parts haven't yet been uploaded.

// We'll keep a partsList.xml file to record the parts that have already been successfully
// uploaded.  If this file does not yet exist, we'll create it..
NSString *partsListFile = @"s3_multipart_uploads/partsList.xml";
CkoXml *partsListXml = [[CkoXml alloc] init];
if ([fac FileExists: partsListFile] == YES) {
    [partsListXml LoadXmlFile: partsListFile];
}

// Make sure the top-level tag is "CompleteMultipartUpload"
partsListXml.Tag = @"CompleteMultipartUpload";

// --------------------------------------
// Before entering the loop to upload parts,
// setup the REST object with AWS authentication,
// and make the initial connection.
CkoRest *rest = [[CkoRest alloc] init];

// Connect to the Amazon AWS REST server.
BOOL bTls = YES;
int port = 443;
BOOL bAutoReconnect = YES;
success = [rest Connect: @"s3.amazonaws.com" port: [NSNumber numberWithInt: port] tls: bTls autoReconnect: 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.
CkoAuthAws *authAws = [[CkoAuthAws alloc] init];
authAws.AccessKey = @"AWS_ACCESS_KEY";
authAws.SecretKey = @"AWS_SECRET_KEY";
authAws.ServiceName = @"s3";
success = [rest SetAuthAws: authAws];

// Set the bucket name via the HOST header.
// In this case, the bucket name is "chilkat100".
rest.Host = @"chilkat100.s3.amazonaws.com";
// --------------------------------------

int partNumber = 1;
CkoStringBuilder *sbPartNumber = [[CkoStringBuilder alloc] init];

while ((partNumber <= numParts)) {
    NSLog(@"%@%d%@",@"---- ",partNumber,@" ----");

    // This cumbersome way of converting an integer to a string is because
    // Chilkat examples are written in a script that is converted to many programming languages.
    // At this time, the translator does not have integer-to-string code generation capability..
    [sbPartNumber Clear];
    [sbPartNumber AppendInt: [NSNumber numberWithInt: partNumber]];

    BOOL bPartAlreadyUploaded = NO;

    // If there are no children, then the XML is empty and no parts have yet been uploaded.
    int numUploadedParts = [partsListXml.NumChildren intValue];
    if (numUploadedParts > 0) {
        // If some parts have been uploaded, check to see if this particular part was already upload.
        // If so, then it can be skipped.

        // Position ourselves at the 1st record.
        CkoXml *xRec0 = [partsListXml GetChild: [NSNumber numberWithInt: 0]];
        CkoXml *foundRec = [xRec0 FindNextRecord: @"PartNumber" contentPattern: [sbPartNumber GetAsString]];
        if (xRec0.LastMethodSuccess == YES) {
            bPartAlreadyUploaded = YES;
            NSLog(@"%@%d%@",@"Part ",partNumber,@" was previously uploaded.");
            NSLog(@"%@",[foundRec GetXml]);

        }

    }

    // If this part was not already uploaded, we need to upload.
    // Also update the partsListXml and save as each part is successfully uploaded.
    if (bPartAlreadyUploaded == NO) {
        NSLog(@"%@%d%@",@"Uploading part ",partNumber,@" ...");

        // Setup the stream source for the large file to be uploaded..
        CkoStream *fileStream = [[CkoStream alloc] init];
        fileStream.SourceFile = fileToUploadPath;
        // The Chilkat Stream API has features to make uploading a parts
        // of a file easy.  Indicate the part size by setting the SourceFilePartSize
        // property.
        fileStream.SourceFilePartSize = [NSNumber numberWithInt: partSize];

        // Our HTTP start line to upload a part will look like this:
        // PUT /ObjectName?partNumber=PartNumber&uploadId=UploadId HTTP/1.1

        // Set the query params.  We'll need partNumber and uploadId.
        // Make sure the query params from previous iterations are clear.
        [rest ClearAllQueryParams];
        [rest AddQueryParam: @"partNumber" value: [sbPartNumber GetAsString]];
        [rest AddQueryParam: @"uploadId" value: uploadId];

        // Upload this particular file part.
        // Tell the fileStream which part is being uploaded.
        // Our partNumber is 1-based (the 1st part is at index 1), but the fileStream's SourceFilePart
        // property is 0-based.  Therefore we use partNumber-1.
        fileStream.SourceFilePart = [NSNumber numberWithInt: (partNumber - 1)];

        // Because the SourceFilePart and SourceFilePartSize properties are set, the stream will 
        // will provide just that part of the file.  
        NSString *responseStr = [rest FullRequestStream: @"PUT" uriPath: @"/somethingBig.zip" stream: fileStream];
        if (rest.LastMethodSuccess != YES) {
            NSLog(@"%@",rest.LastErrorText);
            return;
        }

        if ([rest.ResponseStatusCode intValue] != 200) {
            // Examine the request/response to see what happened.
            NSLog(@"%@%d",@"response status code = ",[rest.ResponseStatusCode intValue]);
            NSLog(@"%@%@",@"response status text = ",rest.ResponseStatusText);
            NSLog(@"%@%@",@"response header: ",rest.ResponseHeader);
            NSLog(@"%@%@",@"response body: ",responseStr);
            NSLog(@"%@",@"---");
            NSLog(@"%@%@",@"LastRequestStartLine: ",rest.LastRequestStartLine);
            NSLog(@"%@%@",@"LastRequestHeader: ",rest.LastRequestHeader);
            return;
        }

        // OK, this part was uploaded..
        // The response will have a 0-length body.  The only information we need is the 
        // ETag response header field.
        NSString *etag = [rest ResponseHdrByName: @"ETag"];
        // It should be present, but just in case there was no ETag header...
        if (rest.LastMethodSuccess != YES) {
            NSLog(@"%@",@"No ETag response header found!");
            NSLog(@"%@%@",@"response header: ",rest.ResponseHeader);
            return;
        }

        // We need to add record to the partsListXml.
        // The record will look like this:
        // &lt;Part>
        //   &lt;PartNumber>PartNumber&lt;/PartNumber>
        //   &lt;ETag>ETag&lt;/ETag>
        // &lt;/Part>
        CkoXml *xPart = [partsListXml NewChild: @"Part" content: @""];
        [xPart NewChildInt2: @"PartNumber" value: [NSNumber numberWithInt: partNumber]];
        [xPart NewChild2: @"ETag" content: etag];

        success = [partsListXml SaveXml: partsListFile];
        if (success != YES) {
            NSLog(@"%@",partsListXml.LastErrorText);
            return;
        }

        NSLog(@"%@%d%@",@"-- Part ",partNumber,@" uploaded. ---------------------");
    }

    partNumber = partNumber + 1;
}

NSLog(@"%@",@"Finished.  All parts uploaded.");