(Tcl) Lower-Level REST API Methods (Google Cloud Storage)

The FullRequest* methods, such as FullRequestBinary, FullRequestMultipart, FullRequestNoBody, FullRequestStream, FullRequestString, etc. are high-level REST API methods that both send the request and receive the response. It is often the case that an application needs make a REST call, but with a finer level of control. The Chilkat REST API provides this feature. An application can break a REST call into the following parts:

1. Send the HTTP request. (via the SendReq* methods)
2. Receive the HTTP response header. (ReadResponseHeader)
3. Receive the HTTP response body. (via the ReadRespBody* methods)

This example demonstrates a REST call using SendReqStringBody, ReadResonseHeader, and ReadRespBodyString.

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load ./chilkat.dll

# This example demonstrates a REST call using SendReqStringBody, ReadResonseHeader, and ReadRespBodyString.
# It will create a bucket in Google Cloud Storage.

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

set gAuth [new_CkAuthGoogle]

# Obtain an access token as shown in one of the following examples:
# See Get Access Token using a Service Account JSON Key
# See Get Access Token using a P12 File

set rest [new_CkRest]

# Connect using TLS.
set bAutoReconnect 1
set success [CkRest_Connect $rest "www.googleapis.com" 443 1 $bAutoReconnect]

# Provide the authentication credentials (i.e. the access key)
set success [CkRest_SetAuthGoogle $rest $gAuth]

# Build the JSON request body for creating a bucket.
# The only required property is the "name", but we'll add more
# to make a better example..
set jsonReqBody [new_CkJsonObject]

set success [CkJsonObject_AddStringAt $jsonReqBody -1 "name" "chilkat-bucket-c"]
set success [CkJsonObject_AddStringAt $jsonReqBody -1 "kind" "storage#bucket"]
set success [CkJsonObject_AddStringAt $jsonReqBody -1 "location" "US"]
set success [CkJsonObject_AddObjectAt $jsonReqBody -1 "versioning"]

# pObjVersioning is a CkJsonObject
set pObjVersioning [CkJsonObject_ObjectOf $jsonReqBody "versioning"]
set success [CkJsonObject_AddBoolAt $pObjVersioning -1 "enabled" 1]
delete_CkJsonObject $pObjVersioning

# Show the HTTP request body we'll be sending.
puts [CkJsonObject_emit $jsonReqBody]

# Add the required query parameter.
# See https://cloud.google.com/storage/docs/json_api/v1/buckets/insert
set success [CkRest_AddQueryParam $rest "project" "chilkattest-1050"]

# Add the Content-Type HTTP request header.
set success [CkRest_AddHeader $rest "Content-Type" "application/json; charset=UTF-8"]

# Send the REST HTTP request.
set success [CkRest_SendReqStringBody $rest "POST" "/storage/v1/b" [CkJsonObject_emit $jsonReqBody]]
if {$success != 1} then {
    puts [CkRest_lastErrorText $rest]
    delete_CkAuthGoogle $gAuth
    delete_CkRest $rest
    delete_CkJsonObject $jsonReqBody
    exit
}

# 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_CkAuthGoogle $gAuth
    delete_CkRest $rest
    delete_CkJsonObject $jsonReqBody
    exit
}

if {$responseStatusCode != 200} then {
    # The response was not successful.  We'll still need to receive 
    # the response body, which may contain an error message from the server.
    # If the response has no body, then the method for reading the
    # response body can still be called.  It will simply return with an empty
    # response body.

    # We can examine the response header and status text:
    puts "Response status text: [CkRest_responseStatusText $rest]"
    puts "Response header: [CkRest_responseHeader $rest]"
}

# Read the response body.  In this case we're expecting it to be JSON..
set responseBodyStr [CkRest_readRespBodyString $rest]
if {[CkRest_get_LastMethodSuccess $rest] != 1} then {
    # We were unable to receive the response body.
    # Note: If the response did not include a body (such as for cases where
    # the Content-Length header is 0, or if the response status code implicitly
    # indicates no body, then ReadRespBodyString returns cktrue, and the
    # responseBodyString will be an empty string.
    puts [CkRest_lastErrorText $rest]
    delete_CkAuthGoogle $gAuth
    delete_CkRest $rest
    delete_CkJsonObject $jsonReqBody
    exit
}

# Show the JSON response.
puts "Json Response: $responseBodyStr"

delete_CkAuthGoogle $gAuth
delete_CkRest $rest
delete_CkJsonObject $jsonReqBody