---
source_files:
  - Common/DTS.Common/Events/DASFactory/DASConfigurationEvent.cs
generated_at: "2026-04-16T03:25:13.824064+00:00"
model: "Qwen/Qwen3-Coder-Next-FP8"
schema_version: 1
sha256: "e69018b59746b653"
---

# DASFactory

### 1. **Purpose**  
This module defines the `DASConfigurationEvent`, a Prism-based pub/sub event used to notify subscribers about DAS (Device Abstraction Service) configuration state changes—specifically, to signal when configuration data is blank or missing. It supports emergency download scenarios (per issue #17872) where DAS must fall back to XML configuration files on disk when filestore entries are blank, ensuring robustness during recovery operations.

### 2. **Public Interface**  
- **`DASConfigurationEvent`**  
  - *Type*: `class` (inherits from `PubSubEvent<IDASConfigurationArg>`)  
  - *Behavior*: A Prism `PubSubEvent` payload for publishing and subscribing to configuration-related notifications. The event carries an argument of type `IDASConfigurationArg`, which encapsulates the configuration state (e.g., blank/missing indicators). Subscribers receive this event when DAS configuration issues occur.

### 3. **Invariants**  
- The event **only publishes** when configuration data is blank or missing; it is not used for normal (valid) configuration updates.  
- The payload type is strictly `IDASConfigurationArg`; no other argument types are supported.  
- The event inherits Prism’s `PubSubEvent<TPayload>` semantics:  
  - Subscriptions are weak-referenced by default (to prevent memory leaks).  
  - Events are published asynchronously unless explicitly configured otherwise via Prism’s `ThreadOption`.

### 4. **Dependencies**  
- **Depends on**:  
  - `Prism.Events` (for `PubSubEvent<T>` base class).  
  - `DTS.Common.Interface.DASFactory.IDASConfigurationArg` (the payload interface defining the contract for configuration arguments).  
- **Used by**:  
  - Components in the DAS factory or configuration subsystem that detect blank/missing configurations (e.g., during emergency download workflows).  
  - Subscribers (e.g., UI or service layers) that need to react to configuration failures (e.g., by prompting user action or switching to fallback XML files).  

### 5. **Gotchas**  
- The event is **not intended for general configuration changes**—only for *blank/missing* states. Publishing it for valid configurations would violate its semantic contract.  
- The actual structure and contents of `IDASConfigurationArg` are defined externally (in `DTS.Common.Interface.DASFactory`); this file does not specify them, so behavior details (e.g., which properties indicate "blank/missing") are not inferable here.  
- No explicit error codes or metadata are included in the event itself; subscribers must rely on `IDASConfigurationArg`’s implementation for diagnostic details.  
- None identified from source alone.