Sample code for 30+ languages & platforms
Perl

SharePoint OAuth2 Client Credentials Authentication

Demonstrates how to authenticate with OAuth 2.0 using the client credentials grant type. This is for SharePoint Online which is the cloud-based service provided by Microsoft as part of Office 365. (Users access SharePoint Online through a web browser, and the service is hosted on Microsoft's servers.)

Chilkat Perl Downloads

Perl
use chilkat();

$success = 0;

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

$http = chilkat::CkHttp->new();

# Provide the information needed for Chilkat to automatically fetch the OAuth2.0 
# access token as needed.
$jsonOAuthCC = chilkat::CkJsonObject->new();

# --------------------------------------------------------------------------------------------------------
# You'll need to have registered an app in Azure beforehand.
# See How to Create SharePoint App Registration for OAuth 2.0 Client Credentials
# --------------------------------------------------------------------------------------------------------

# Use the values from your App Registration in Azure.
$jsonOAuthCC->UpdateString("client_id","CLIENT_ID");
$jsonOAuthCC->UpdateString("client_secret","SECRET_VALUE");

# You'll always use this scope for client credentials, because the allowed actions
# are determined by the App Permissions defined when you registered the app in Azure.
$jsonOAuthCC->UpdateString("scope","https://graph.microsoft.com/.default");

# The token endpoint includes your tenant ID. 
$jsonOAuthCC->UpdateString("token_endpoint","https://login.microsoftonline.com/TENANT_ID/oauth2/v2.0/token");

# Provide the OAuth2 information. Chilkat will use this information to automatically fetch the OAuth2 access token as needed,
$http->put_AuthToken($jsonOAuthCC->emit());

# Get information about all SharePoint sites.
$sbJson = chilkat::CkStringBuilder->new();
$success = $http->QuickGetSb("https://graph.microsoft.com/v1.0/sites/getAllSites",$sbJson);
if ($success == 0) {
    print $http->lastErrorText() . "\r\n";
    exit;
}

$statusCode = $http->get_LastStatus();

print "Response status code = " . $statusCode . "\r\n";

if ($statusCode != 200) {
    print $sbJson->getAsString() . "\r\n";
    print "Failed." . "\r\n";
    exit;
}

$jsonResp = chilkat::CkJsonObject->new();
$jsonResp->LoadSb($sbJson);
$jsonResp->put_EmitCompact(0);

print $jsonResp->emit() . "\r\n";
print "Success." . "\r\n";

# Use this online tool to generate parsing code from sample JSON: 
# Generate Parsing Code from JSON