Ticomix.Attachments.Storage.AzureBlob

Purpose Statement

A .NET library that provides Azure Blob Storage implementation for the Ticomix attachments system, enabling secure and scalable cloud storage for application file attachments.

Technical Context

• Implements the IAttachments<TKey> interface from the Ticomix.Attachments.Common library
• Built on Azure.Storage.Blobs SDK version 12.21.2
• Supports .NET 8.0 and .NET 10.0 frameworks.
• Uses generics to support multiple key types for attachment identification

Key Capabilities

• Blob Container Management: Automatically creates and manages Azure Blob Storage containers with customizable access policies
• Hierarchical File Organization: Supports directory-like organization through virtual folder paths within blob storage
• Streaming Content Delivery: Provides optimized streaming download capabilities for efficient file retrieval
• Attachment Lifecycle Management: Implements complete attachment operations including upload, download, copy, and deletion

Integration Points

• Seamlessly integrates with the Ticomix attachments ecosystem via the standard IAttachments<TKey> interface
• Compatible with Entity Framework Core for database storage of attachment metadata
• Works alongside other storage providers in the Ticomix.Attachments namespace

Use Case Scenarios

• Enterprise applications requiring secure cloud storage for user-uploaded files
• Systems needing scalable attachment storage with metadata tracking
• Applications migrating from on-premises storage to cloud-based solutions
• Multi-tenant applications requiring isolation of attachment data

Database Models Used

• Attachment: Represents attachment metadata including file name, directory path, and other attributes stored in a database context that implements IAttachmentsDbContext<TKey>

Classes and Functions

AzureBlobAttachments

Main implementation class that provides Azure Blob Storage functionality for the attachment system.

Key Functions:

• UploadAsync: Uploads a file stream to Azure Blob Storage
• DownloadStreamingAsync: Downloads file content as a stream
• DeleteAsync: Removes an attachment from blob storage
• CopyAsync: Creates a copy of an existing attachment
• GetContainerAsync: Retrieves or creates a blob container
• GetBlobClient: Gets a reference to a specific blob
• DownloadBlob: Retrieves blob content and metadata

AzureBlobLegacy provider (read-by-BlobId)

AzureBlobAttachments<TKey> resolves a blob by Directory+FileName. Applications that previously stored a GUID blob name in Attachment.BlobId (and never set AttachmentLocation) need AzureBlobLegacyAttachments<TKey> to read those blobs.

• AttachmentLocation = "AzureBlobLegacy".
• DownloadStreamingAsync/DeleteAsync resolve the blob via GetBlobName(attachment) (defaults to attachment.BlobId).
• CanHandle claims "AzureBlobLegacy" rows and null-location rows that have a BlobId.
• Read-only: UploadAsync/CopyAsync throw NotSupportedException — write new attachments through AzureBlobAttachments<TKey>.

Register it alongside the canonical provider (see the Common package README).

IAttachmentBlobStore (path-addressed blobs)

AzureBlobAttachments also implements IAttachmentBlobStore for low-level, row-less blob access (path download/upload/exists, bulk prefix delete) -- used by image thumbnail caches and container maintenance. The FileSystem provider deliberately does NOT implement it: the only consumers are Azure-blob-backed thumbnail caches; the FileSystem provider is the local-dev/ offline staging backend and maintains no such cache.