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+# API Connectivity
+
+## Overview
+The tapio allows integration partners to connect ERP systems, Tool Managers, and measurement systems with tapio services.  
+Partners can securely access Tadamo and MaintenanceService (MS) APIs through **AuthorizationKeys** generated from add-ons.
+
+### Supported Add-ons
+- **ERP Add-on (SharpeningUI)**  
+- **Measurement Add-on (SharpeningUI)**  
+- **ToolManagerOffice Add-on (Twinio)**  
+
+Each add-on can generate its own **AuthorizationKey**, which serves as the credential for API access.
+
+## 🔑 Authentication
+
+### AuthorizationKey
+
+An **AuthorizationKey** is issued via the add-on settings in the tapio portal.  
+- The key is generated by the customer and shared with the integration partner (e.g., ERP, Measurement, or Tool Manager system).
+- The key is **valid until explicitly revoked**.
+
+### Scope
+
+Keys are scoped to the customer subscription and application.
+
+## ⚙️ Add-on Configuration
+
+- Go to the tapio portal.
+
+- Navigate to the relevant Add-on (ERP, Measurement, ToolManagerOffice).
+![Choose Add-on](./assets/choose-addon.png)
+
+- Create an AuthorizationKey (one-time copy).
+![Create key](./assets/create-key.png)
+
+- Paste the key into your integration system configuration.
+
+## 🔄 Data Flow
+
+- ERP / Measurement / ToolManager → calls TADAMO or MaintenanceService with AuthorizationKey.
+
+- Tadamo/MS validate AuthorizationKey with subscriptionId and applicationId.
+
+- SharpeningUI and Twinio act as the customer-facing add-ons where keys are managed.
+
+```plantuml
+@startuml azure-architecture
+
+' azure symbols
+!define AzurePuml https://raw.githubusercontent.com/plantuml-stdlib/Azure-PlantUML/master/dist
+!includeurl AzurePuml/AzureCommon.puml
+!includeurl AzurePuml/Databases/AzureSqlDatabase.puml
+!includeurl AzurePuml/Networking/AzureCDNProfile.puml
+!includeurl AzurePuml/Compute/AzureFunction.puml
+!includeurl AzurePuml/Web/AzureWebApp.puml
+!includeurl AzurePuml/Security/AzureKeyVault.puml
+!includeurl AzurePuml/Integration/AzureServiceBus.puml
+!includeurl AzurePuml/DevOps/AzureApplicationInsights.puml
+!includeurl AzurePuml/Storage/AzureStorage.puml
+!includeurl AzurePuml/Analytics/AzureEventHub.puml
+!includeurl AzurePuml/Analytics/AzureDataExplorer.puml
+!includeurl AzurePuml/Compute/AzureServiceFabric.puml
+!includeurl AzurePuml/Databases/AzureRedisCache.puml
+!includeurl AzurePuml/Storage/AzureBlobStorage.puml
+!includeurl AzurePuml/Storage/AzureQueueStorage.puml
+!includeurl AzurePuml/Compute/AzureFunction.puml
+!includeurl AzurePuml/Web/AzureSearch.puml
+!includeurl AzurePuml/Integration/AzureServiceBus.puml
+!includeurl AzurePuml/Web/AzureAPIManagement.puml
+
+
+left to right direction
+' skinparam linetype ortho
+skinparam linetype polyline
+
+skinparam actor {
+  BorderColor DeepSkyBlue
+  BackgroundColor #d6eaf8
+}
+skinparam component {
+  BorderColor DeepSkyBlue
+  BackgroundColor #d6eaf8
+}
+
+actor ERP
+actor Measurement
+actor ToolManagerOffice
+
+AzureAPIManagement(applicationGateway, "Application Gateway", applicationGateway)
+AzureWebApp(apiTadamo, "Tadamo", "astdm")
+AzureWebApp(apiMaintenanceService, "MaintenanceService", "asms")
+
+[ERP] -->"AuthorizationKey" [applicationGateway]
+[Measurement] -->"AuthorizationKey" [applicationGateway]
+[ToolManagerOffice] "AuthorizationKey"--> [applicationGateway]
+
+
+[applicationGateway] --> [apiTadamo]
+[applicationGateway] --> [apiMaintenanceService]
+@enduml
+```
+
+## 💻 Code Samples
+
+For practical implementation examples of how to configure authentication for the TadamoApiClient and MaintenanceServiceApiClient, see the code samples and documentation at:
+
+**[tapio Auth API Documentation](https://tapioone.github.io/tapio-auth-api/)**
+
+This resource provides detailed examples and best practices for implementing authentication configuration for both API clients.
\ No newline at end of file
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+# Data Exchange
+
+- [How to connect to API](./connect-api.md)