(Xojo Plugin) Generate an AWS (S3) Pre-Signed URL using Signature V4

Demonstrates how to generate a pre-signed URL using AWS Signature Version 4. This example generates a pre-signed URL for the Amazon S3 service.

Note: this example requires Chilkat v9.5.0.66 or greater.

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

// Note: This example requires Chilkat v9.5.0.66 or greater.

Dim http As New Chilkat.Http

http.AwsAccessKey = "AWS_ACCESS_KEY"
http.AwsSecretKey = "AWS_SECRET_KEY"

// Make sure to set your AWS region correctly
http.AwsRegion = "us-east-1"

Dim bucketName As String
bucketName = "chilkat100"
Dim objectName As String
objectName = "starfish/starfish.jpg"
Dim localFilePath As String
localFilePath = "qa_output/starfish.jpg"
Dim awsService As String
awsService = "s3"

// The signed URL will be valid for this number of seconds:
Dim numSecondsValid As Int32
numSecondsValid = 86400

// Choose between a URL beginning with "http://" or "https://"...
Dim bUseHttps As Boolean
bUseHttps = False

// Generate the pre-signed URL
Dim preSignedUrl As String
preSignedUrl = http.S3_GenerateUrlV4(bUseHttps,bucketName,objectName,numSecondsValid,awsService)
If (http.LastMethodSuccess <> True) Then
    System.DebugLog(http.LastErrorText)
    Return
End If

// The following URL can be copy-and-pasted into a browser..
System.DebugLog("Pre-Signed AWS S3 URL: " + preSignedUrl)

// Here's an example of a pre-signed URL. 
// This URL will only work within 1 day (86400 seconds) after the time this example was published.
// 
//     http://chilkat100.s3.amazonaws.com/starfish/starfish.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=16QXXDGY83AJJR6RVQ02%2F20170111%2Fus-west-2%2Fs3%2Faws4_request&X-Amz-Date=20170111T161959Z&X-Amz-Expires=86400&X-Amz-SignedHeaders=host&X-Amz-Signature=72bf4fd9a15d7bbcdd313a3318d937a778905f62a3fbff9b789d8dc28acd9232

// Now try to do an HTTP Download using the signed URL.
Dim success As Boolean
success = http.Download(preSignedUrl,"qa_output/starfish.jpg")
If (success <> True) Then
    System.DebugLog(http.LastErrorText)
Else
    System.DebugLog("Success.")
End If