We are seeking an experienced CFAPI Specialist with deep, hands-on expertise in Microsoft's Windows Cloud Files API (CFAPI) and the development of cloud-based file synchronization solutions. This position requires a specialist who has designed, developed, debugged, and maintained Windows file sync clients—not merely a general C# or Windows application developer.
The ideal candidate will have strong proficiency in C#, Windows APIs, P/Invoke, native interop, asynchronous programming, multithreading, and Windows file-system concepts. The candidate should have practical experience implementing cloud-backed files, placeholder management, on-demand file hydration and dehydration, synchronization state management, and reliable communication between Windows clients and cloud storage services.
You will be responsible for building robust, scalable, and high-performance file synchronization capabilities, troubleshooting complex file-system issues, and ensuring reliable synchronization across local Windows environments and remote storage platforms.
Key Responsibilities:-
1. Windows Cloud Files API (CFAPI) Development
- Design, develop, and maintain Windows-based file synchronization clients using Microsoft's Cloud Files API.
- Implement and manage Sync Root registration, connection lifecycle, synchronization callbacks, and cloud-backed file operations.
- Work extensively with CFAPI functions, including:
- CfRegisterSyncRoot
- CfConnectSyncRoot
- CfCreatePlaceholders
- CfExecute
- CfHydratePlaceholder
- CfDehydratePlaceholder
- CfSetPinState
- CfSetInSyncState
- Implement placeholder creation, metadata management, hydration and dehydration workflows, and synchronization state transitions.
- Develop and maintain callback handlers for operations such as FETCH_DATA and FETCH_PLACEHOLDERS.
- Implement pinning and unpinning functionality to manage local file availability and cloud-backed storage behavior.
- Ensure correct handling of callback execution, request completion, cancellation, and error conditions.
2. Cloud Storage and File Synchronization
- Build reliable synchronization mechanisms between Windows clients and cloud-based storage or backend services.
- Implement on-demand file access, remote content retrieval, local file availability, and synchronization status updates.
- Handle file uploads, downloads, metadata synchronization, and synchronization conflict scenarios as required.
- Ensure consistency between local file-system states and remote storage metadata.
- Design mechanisms for retry handling, recovery from interrupted operations, and synchronization resumption following network or application failures.
- Integrate file synchronization components with REST APIs and cloud storage services.
3. C#, Windows APIs, and Native Interoperability
- Develop production-grade applications and services using C# and the .NET ecosystem.
- Integrate managed code with native Windows APIs using P/Invoke and interoperability techniques.
- Work with native data structures, delegates, callbacks, handles, memory management, and API error codes.
- Diagnose issues arising from managed/native boundaries, resource management, and API lifecycle handling.
- Apply sound software design principles to develop maintainable, testable, and reliable Windows client components.
- Collaborate with engineering teams on API contracts, architecture decisions, and implementation strategies.
4. Windows File-System Internals
- Apply a strong understanding of Windows and NTFS file-system behavior to file synchronization development.
- Troubleshoot file locking, sharing violations, access permissions, open handles, reparse points, and file operation failures.
- Understand placeholder behavior, file attributes, directory enumeration, file metadata, and file-system state transitions.
- Investigate issues involving concurrent file access, hydration failures, interrupted operations, and local-versus-cloud state inconsistencies.
- Ensure synchronization operations behave reliably under real-world Windows usage conditions.
5. Asynchronous Programming and Concurrency
- Design asynchronous workflows for file hydration, content retrieval, synchronization callbacks, and background operations.
- Implement multithreaded processing with appropriate synchronization primitives and thread-safety controls.
- Handle cancellation tokens, timeouts, retries, race conditions, deadlocks, and resource contention.
- Ensure callbacks and asynchronous operations complete within the required lifecycle and API constraints.
- Optimize concurrent file operations without compromising data integrity or application stability.
6. Troubleshooting, Debugging, and Performance Optimization
- Investigate complex synchronization failures, placeholder errors, file access issues, and connectivity-related defects.
- Perform root-cause analysis using application logs, diagnostic tools, debugger traces, and Windows system information.
- Use Visual Studio debugging and, where appropriate, WinDbg to diagnose application crashes, hangs, and native interop issues.
- Analyze performance bottlenecks in file enumeration, hydration, metadata processing, and synchronization workflows.
- Improve throughput, responsiveness, memory usage, resource utilization, and recovery behavior.
- Develop preventive fixes and regression tests to reduce recurring production incidents.
7. Testing, Code Quality, and Production Support
- Develop unit, integration, and end-to-end tests for CFAPI components and synchronization workflows.
- Validate placeholder lifecycle operations, file state transitions, network interruption recovery, and concurrency scenarios.
- Participate in architecture reviews, code reviews, technical documentation, and engineering design discussions.
- Maintain existing production applications through defect resolution, performance tuning, and reliability improvements.
- Support releases, investigate production incidents, and collaborate with QA, backend, and infrastructure teams.
- Document technical designs, known limitations, troubleshooting procedures, and operational guidelines.
Mandatory Skills and Qualifications
Candidates must have demonstrable, hands-on experience in the following areas:
- Professional Experience: 7–8+ years of software development experience, preferably focused on Windows desktop applications, system-level development, or file synchronization products.
- CFAPI Expertise: Practical experience developing applications using Microsoft's Windows Cloud Files API.
- CFAPI Functions: Working knowledge of Sync Root registration and connection, placeholder creation, callback handling, hydration/dehydration, pin-state management, and synchronization state updates.
- File Synchronization Solutions: Proven experience building or maintaining cloud drive clients, file sync engines, or cloud-backed Windows file systems.
- C# and .NET: Strong programming skills in C# and experience developing reliable, production-grade Windows applications.
- Windows APIs: Hands-on experience with Windows APIs, native interop, and Windows-specific application behavior.
- P/Invoke and Interoperability: Practical experience integrating managed C# code with native Windows functions and data structures.
- Windows File-System Concepts: Strong understanding of NTFS, file handles, file locking, reparse points, file attributes, and access permissions.
- Asynchronous Programming: Experience with asynchronous workflows, task-based programming, cancellation, exception handling, and reliable background operations.
- Multithreading and Concurrency: Ability to diagnose and resolve race conditions, deadlocks, thread-safety issues, and concurrent file access problems.
- Debugging and Troubleshooting: Strong diagnostic skills using Visual Studio and Windows debugging tools to resolve complex production issues.
- Cloud Storage Integration: Experience integrating Windows clients with cloud storage platforms, backend services, or REST APIs.
- Software Engineering Practices: Proficiency in version control, code reviews, automated testing, documentation, and production support.
Important: This is a specialized CFAPI engineering position. Candidates with only general C#, .NET, Windows desktop development, or API development experience—but no practical CFAPI or cloud file synchronization experience—may not be suitable.
Good-to-Have Skills
- Experience developing OneDrive-like cloud drive applications or enterprise file synchronization clients.
- Familiarity with Windows Shell integration and File Explorer experiences.
- Experience with C++, Win32 programming, and native Windows debugging.
- Knowledge of Windows Services and background processing architectures.
- Experience with WinDbg, dump analysis, and advanced crash diagnostics.
- Understanding of file-system notifications and change tracking.
- Experience designing synchronization conflict resolution and recovery mechanisms.
- Exposure to distributed systems, large-scale Windows client applications, and enterprise cloud storage platforms.
- Experience with performance profiling, memory diagnostics, and reliability engineering.
Pay: ₹1,600,000.00 - ₹2,000,000.00 per year
Application Question(s):
- Do you have hands-on experience with P/Invoke, Windows/NTFS file-system concepts, asynchronous programming, multithreading, and debugging tools such as Visual Studio or WinDbg?
- Have you developed or maintained a cloud drive or file synchronization solution using CFAPI?
- How many years of hands-on experience do you have with Microsoft's Windows Cloud Files API (CFAPI), C#, and Windows APIs?
- What is your current CTC and expected CTC per annum (in LPA)?
- What is your current notice period, and how soon can you join?
Education:
Experience:
- CFAPI Specialist – Windows Cloud Files API: 7 years (Required)
Work Location: In person
