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Overview

The OnlyOffice Control is a comprehensive ASP.NET Web Forms user control that integrates OnlyOffice Document Server into your web applications. This control provides a seamless way to view, edit, and collaborate on documents directly within your ASP.NET applications.

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What is OnlyOffice Control?

OnlyOffice Control (OnlyOfficeEditor) is a reusable ASP.NET user control that wraps the OnlyOffice Document Server API, providing:
  • Document Editing: Full-featured document, spreadsheet, and presentation editing
  • Real-time Collaboration: Multiple users can edit documents simultaneously
  • Format Support: Supports Word, Excel, PowerPoint, and various other document formats
  • PDF Conversion: Built-in document-to-PDF conversion capabilities
  • JWT Security: Secure communication with OnlyOffice Document Server using JSON Web Tokens
  • Callback Handling: Automatic document saving and version management

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Key Features

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Document Management

  • Load documents from bytes, files, or upload streams
  • Automatic document key generation and tracking
  • Support for multiple document types (word, cell, slide)
  • Document download and save functionality

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Editor Modes

  • Edit Mode: Full editing capabilities with save functionality
  • View Mode: Read-only document viewing

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Document Conversion

  • Convert documents to PDF format
  • Support for edited document conversion
  • Configurable retry logic for conversion operations

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Security

  • JWT token-based authentication
  • Configurable secret key management
  • Secure callback endpoints

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Requirements

Ensure all requirements are met before installing the OnlyOffice Control.

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Server Requirements

  • ASP.NET Web Forms: .NET Framework 4.8 or higher
  • IIS: Internet Information Services 7.0 or higher
  • OnlyOffice Document Server: A running instance of OnlyOffice Document Server (self-hosted or cloud)

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Project Requirements

  • ASP.NET Web Forms project targeting .NET Framework 4.8
  • Web.config configured for large file uploads (optional, but recommended)
  • Access to OnlyOffice Document Server API endpoint

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Browser Requirements

  • Modern web browsers with JavaScript enabled
  • Support for HTML5 and iframes

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Architecture Overview

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Component Structure

The OnlyOffice Control consists of several key components: 
Controls/OnlyOfficeEditor/
├── OnlyOfficeEditor.ascx          # User control markup
├── OnlyOfficeEditor.ascx.cs       # Main control logic
├── OnlyOfficeEditor.js            # Client-side JavaScript
├── OnlyOfficeEditor.css           # Styling
├── OnlyOfficeHandler.ashx         # HTTP handler for callbacks
├── OnlyOfficeHandler.ashx.cs      # Handler implementation
└── OnlyOfficeJwt.cs               # JWT token generation

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Data Flow

  1. Document Loading: Application loads document into control
  2. Editor Initialization: Control generates configuration with JWT token
  3. OnlyOffice API: JavaScript initializes OnlyOffice editor
  4. User Editing: User makes changes in the editor
  5. Callback: OnlyOffice server sends edited document to callback URL
  6. Document Capture: Control captures edited document as base64
  7. Save/Download: Application retrieves edited document bytes

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Key Properties

The control exposes several important properties:
PropertyTypeDescription
DocumentUrlstringURL where OnlyOffice can download the document
DocumentNamestringDisplay name of the document
DocumentKeystringUnique key for document versioning
CallbackUrlstringURL for OnlyOffice to send edited documents
OnlyOfficeApiUrlstringOnlyOffice Document Server API URL
JwtSecretstringSecret key for JWT token generation
PublicBaseUrlstringPublic-facing base URL for your application
ModestringEditor mode: “edit” or “view”
LangstringLanguage code (e.g., “es”, “en”)
EditorHeightstringHeight of the editor (e.g., “520px”)
UserIdstringCurrent user identifier
UserDisplayNamestringCurrent user display name

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Handler Actions

The OnlyOfficeHandler.ashx supports three actions:
  • download: Serves documents to OnlyOffice Document Server
  • callback: Receives edited documents from OnlyOffice Document Server
  • proxy: Proxies external URLs (for embedded resources)

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Document Types

The control automatically detects document types based on file extensions:
  • Word (default): .doc, .docx, .odt, .txt, .pdf, etc.
  • Cell (spreadsheet): .xls, .xlsx, .ods, .csv
  • Slide (presentation): .ppt, .pptx, .odp

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Use Cases

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Enterprise Document Management

Integrate document editing into your document management system with version control and audit trails.

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Collaborative Workflows

Enable multiple users to collaborate on contracts, reports, and proposals in real-time.

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Form Processing

Allow users to fill out and edit document templates with pre-populated data.

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Document Review

Provide view-only access to documents with optional conversion to PDF for archival.

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Next Steps

Installation

Learn how to install and configure the OnlyOffice Control in your project

Quick Start

Get started quickly with a basic implementation

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