Tcl

REST Asynchronous Streaming Upload

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Demonstrates how to create and write to a stream that feeds an asynchronous upload to cloud storage. This particular example demonstrates an upload to the Azure Cloud Storage service. The same concepts apply to S3, Google Cloud, and Google Drive. Tcl

load ./chilkat.dll

set success 0

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

set rest [new_CkRest]

# Connect to the Azure Storage Blob Service
set bTls 1
set port 443
set bAutoReconnect 1
# In this example, the storage account name is "chilkat".
set success [CkRest_Connect $rest "chilkat.blob.core.windows.net" $port $bTls $bAutoReconnect]
if {$success != 1} then {
    puts [CkRest_lastErrorText $rest]
    delete_CkRest $rest
    exit
}

# Provide Azure Cloud credentials for the REST call.
set azAuth [new_CkAuthAzureStorage]

CkAuthAzureStorage_put_AccessKey $azAuth "AZURE_ACCESS_KEY"
# The account name used here should match the 1st part of the domain passed in the call to Connect (above).
CkAuthAzureStorage_put_Account $azAuth "chilkat"
CkAuthAzureStorage_put_Scheme $azAuth "SharedKey"
CkAuthAzureStorage_put_Service $azAuth "Blob"
# This causes the "x-ms-version: 2021-08-06" header to be automatically added.
CkAuthAzureStorage_put_XMsVersion $azAuth "2021-08-06"
set success [CkRest_SetAuthAzureStorage $rest $azAuth]

# Set some request headers.
set success [CkRest_AddHeader $rest "x-ms-blob-content-disposition" "attachment; filename=\"thisIsATest.txt\""]
set success [CkRest_AddHeader $rest "x-ms-blob-type" "BlockBlob"]
set success [CkRest_AddHeader $rest "x-ms-meta-m1" "v1"]
set success [CkRest_AddHeader $rest "x-ms-meta-m2" "v2"]

# Note: The application does not need to explicitly set the following
# headers: x-ms-date, Authorization, and Content-Length.  These headers
# are automatically set by Chilkat.

set sendStream [new_CkStream]

# Create a background thread task to upload from the stream
# The name of the Azure storage container is "test".
# After the background task is started and running in a background thread,
# the foreground thread will write 100 text lines of "this is a test\r\n" to the
# stream.
# uploadTask is a CkTask
set uploadTask [CkRest_SendReqStreamBodyAsync $rest "PUT" "/test/thisIsATest.txt" $sendStream]

# Start the task. 
set success [CkTask_Run $uploadTask]

# The application can write to the stream, and close the stream
# when finished.  Whatever is written to the stream uploaded to the remote file.

for {set i 1} {$i <= 100} {incr i} {
    set success [CkStream_WriteString $sendStream "This is a test\r\n"]
    if {$success != 1} then {
        set success [CkTask_Cancel $uploadTask]
        delete_CkTask $uploadTask

        puts "Failed to write to sendStream."
        delete_CkRest $rest
        delete_CkAuthAzureStorage $azAuth
        delete_CkStream $sendStream
        exit
    }

}

# Close the stream to indicate no more data will be sent.
set success [CkStream_WriteClose $sendStream]

# Make sure the uploadTask has finished.
# It is likely that task is already finished..
# Wait a max of 5 seconds..
set success [CkTask_Wait $uploadTask 5000]

# OK.. we've sent the file, now we need to get the response..

# Read the response header.
set responseStatusCode [CkRest_ReadResponseHeader $rest]
if {$responseStatusCode < 0} then {
    # We were unable to receive the response header.
    puts [CkRest_lastErrorText $rest]
    delete_CkRest $rest
    delete_CkAuthAzureStorage $azAuth
    delete_CkStream $sendStream
    exit
}

# When successful, the Azure Storage service will respond with a 201 response code,
# with an empty body.  Therefore, in the success condition, the responseStr is empty.
if {$responseStatusCode == 201} then {
    puts "File uploaded."
} else {
    # It failed, so try reading the response body.  If no response body is coming,
    # then Chilkat will know and just return an empty string.
    set responseBodyStr [CkRest_readRespBodyString $rest]
    if {[CkRest_get_LastMethodSuccess $rest] == 1} then {
        puts "response body (if any): $responseBodyStr"
    }

    # Examine the request/response to see what happened.
    puts "response status code = [CkRest_get_ResponseStatusCode $rest]"
    puts "response status text = [CkRest_responseStatusText $rest]"
    puts "response header: [CkRest_responseHeader $rest]"
    puts "---"
    puts "LastRequestStartLine: [CkRest_lastRequestStartLine $rest]"
    puts "LastRequestHeader: [CkRest_lastRequestHeader $rest]"
}


delete_CkRest $rest
delete_CkAuthAzureStorage $azAuth
delete_CkStream $sendStream