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CBFS Connect is a developer SDK component from Callback Technologies that lets you present any data source—cloud storage, databases, REST APIs, or custom content—as local files and folders, without writing kernel-mode driver code. It fits when your goal is to make non-file data behave like a normal filesystem for existing applications. It is not the right choice if you only need to mount a specific cloud provider (CBFS Cloud), intercept and control existing filesystem operations (CBFS Filter), or embed an encrypted store inside a single file (CBFS Vault).

What CBFS Connect actually does

The component creates a virtual filesystem: your application supplies the logic for what files and folders exist and what their contents are, and CBFS Connect handles the system-level plumbing so other programs see a normal drive. The site frames the value as "system-level filesystem technology, application-level simplicity"—you work through an API, drivers and samples are included, and you avoid low-level kernel driver development.

Typical data sources you can expose:

• Cloud storage
• Databases
• REST APIs
• Custom or proprietary content

A concrete example: a team stores project documents in a database with metadata and versioning. Rather than building an export tool, they use CBFS Connect to present those records as a folder tree, so users open and save files through familiar desktop applications while the database remains the source of truth.

How it compares to the other CBFS components

The product line overlaps, so pick by the job rather than by name. The table uses the same dimensions for each option.

If your data source is one of the supported cloud providers and you don't need custom filesystem semantics, CBFS Cloud is the narrower fit. If you need to watch or block access to files that already exist on disk, that is CBFS Filter, not Connect.

What the SDK includes and how to evaluate it

Per the site, the development libraries ship with APIs, drivers, documentation, and samples. A free trial is offered, and the product is positioned as subscription-based; the page does not publish prices, so confirm licensing terms directly with Callback Technologies before committing.

A practical evaluation path:

1. Download the free trial and confirm your target OS and language bindings are covered in the samples.
2. Build the smallest possible virtual drive—one folder, one read-only file—backed by your real data source.
3. Verify with ordinary tools: open the file in a text editor, list the directory from a command prompt, and check that writes (if supported) round-trip to your source.
4. Test the awkward cases early: large files, concurrent access, renaming, and deletion. These are where virtual filesystem designs usually need adjustment.
5. Only then expand to the full folder structure and permissions model.

Common sticking points to plan for: mapping your data model onto file and folder semantics (what is a directory in a REST API?), handling metadata such as timestamps and sizes, and deciding whether the mount is read-only or writable. The site's samples and documentation are the place to resolve these, since exact API behavior is version-specific.

When a different component is the better fit

Choose something else if:

• You only need cloud mounting. CBFS Cloud covers S3, Azure, OneDrive, SharePoint, Google Drive, SFTP, and more through one component API.
• You need monitoring or policy enforcement on real files. CBFS Filter intercepts filesystem, registry, and process operations in real time.
• You need encryption rather than exposure. CBFS Encrypt keeps data as ciphertext for untrusted processes; CBFS Vault gives you an encrypted container file.
• You need Explorer UI changes. CBFS Shell extends File Explorer safely.

CBFS Connect earns its place when the core requirement is "make my data look like a disk"—custom sources, non-file backends, or content that only your application knows how to interpret.

CBFS Filter is a developer SDK component from Callback Technologies that intercepts, monitors, and controls filesystem, registry, and process operations in real time. You use it when an application must enforce filesystem-level access control or security policies — for example, blocking writes to protected folders, logging who opens which files, or redirecting an operation before it completes. It is aimed at Windows-style production software where the alternative would be writing a kernel-mode driver yourself; the component supplies the driver layer and exposes an application-level API, so your code works at the API level rather than in kernel mode.

How the interception works

The mechanism is a filter placed in the operating system's I/O path. Every filesystem, registry, or process operation passes through this filter before it reaches its target, and the filter calls back into your application. Your handler then decides what happens next:

• Allow — the operation proceeds unchanged.
• Block — the operation is denied and the caller receives an error.
• Modify — the operation is altered before it completes (for example, changing a path or the data being written).

Because the decision happens in real time, before the operation finishes, the policy is enforced at the system level rather than after the fact. A concrete case: a compliance tool that must prevent any process except an approved backup agent from reading a set of files. The filter sees each open request, checks the requesting process identity, allows the backup agent, and returns access-denied to everything else — without the tool needing its own kernel driver.

What you build with it

The page positions CBFS Filter around "enforce filesystem-level access control and security policies by intercepting filesystem, registry, and process operations in real time." Typical applications:

• Access control and security policy enforcement — allow/deny rules tied to users, processes, or paths.
• Monitoring and auditing — capture a record of file, registry, and process activity.
• Real-time control — intervene in an operation while it is in flight, not just observe it afterward.

The SDK ships with APIs, drivers, documentation, and samples, per the product description, and the same API family is described as consistent across the vendor's components.

How it differs from neighboring components

CBFS Filter is one of several components, and choosing the right one depends on what you need to do:

The distinction matters: CBFS Connect and CBFS Filter are often confused because both touch the filesystem layer, but Connect supplies content while Filter governs operations on content that already exists. If your goal is encryption specifically, CBFS Encrypt is the narrower fit; Filter is the general-purpose interception layer.

What to check before committing

• Platform fit. The product is described in Windows-oriented terms (filesystem, registry, and process operations). Confirm the target OS support in the current documentation before designing around it.
• Driver installation. Even though you avoid writing kernel code, a driver is still installed as part of deployment; plan for installation and signing requirements in your release process.
• Evaluation. The site advertises a free trial and subscription licensing, so you can prototype against real workloads before purchase. Pricing details are not published on the page, so confirm terms with the vendor.
• Scope of interception. Decide up front whether you need filesystem operations only or also registry and process events, since that shapes your handler design and performance testing.

If your requirement is to watch and control what happens to files in real time, CBFS Filter is the direct fit; if you instead need to expose data as a drive or encrypt files transparently, start with CBFS Connect or CBFS Encrypt.

A virtual file system (VFS) is an abstraction layer that presents files and folders to applications while routing each file operation to a different underlying implementation—a local disk, a database, a REST API, cloud storage, or custom content. Applications see ordinary paths and standard file calls; the VFS translates those calls into whatever the real data source understands. This approach fits when you need existing software to work with data that isn't stored as native files, or when you want to centralize access control and monitoring without changing the applications themselves.

The core mechanism: one interface, many backends

A VFS works by intercepting the standard file operations an application already uses—open, read, write, close, enumerate a directory, query file attributes—and dispatching them to a handler for the specific data source. The application never learns where the bytes actually live.

The flow looks like this:

1. Application calls a normal file API (for example, opening X:\reports\q3.csv).
2. The VFS layer receives the request and resolves the path to a backend.
3. The backend performs the real work—fetching an object from cloud storage, running a database query, or calling a REST endpoint.
4. The VFS returns results in standard file form—a file handle, a byte stream, directory entries, or metadata.

Because the contract is the same regardless of backend, one interface can serve many sources. Callback Technologies describes this pattern in its developer components: CBFS Connect presents "any data source as local files and folders: cloud storage, databases, REST APIs, or custom content," and CBFS Cloud mounts cloud and remote storage (S3, Azure, OneDrive, SharePoint, Google Drive, SFTP) as local virtual drives programmatically. The company frames the value as "system-level filesystem technology" with "application-level simplicity"—you get filesystem behavior without writing kernel-mode driver code.

VFS vs. a physical file system vs. application-level virtualization

These three terms are often confused, so it helps to separate them by where the abstraction sits.

A physical file system owns storage. An OS-level VFS is the kernel's internal switchboard that lets one set of system calls work across many mounted file systems. An application-level virtual file system is what most developers mean when they ask "how do I make my data look like files?"—it's a component you add to your product so that other software can treat your data as ordinary files.

Where virtual file systems show up

• Operating system internals. Linux's VFS and the Windows I/O manager are the classic examples: they let open() and ReadFile() work identically on different mounted volumes.
• User-mode virtual drives. A product mounts a remote or generated data source as a drive letter or mount point, so existing tools (editors, backup software, scripts) work unchanged.
• Cloud storage integration. Rather than teaching every application a cloud API, a VFS exposes the bucket as a local folder. Callback's CBFS Cloud is built for exactly this: "Mount any cloud storage as a local drive in code."
• Filtering and monitoring layers. A related component intercepts file operations in real time to enforce access policies or log activity—Callback's CBFS Filter does this for filesystem, registry, and process operations.
• Embedded or encrypted stores. A complete file system can live inside a single file, as with CBFS Vault, which offers per-file and whole-vault encryption, compression, journaling, and random read/write access from one portable file.

Practical implications

Transparency is the main benefit. If an application can read a file, it can read your virtual file—no SDK integration, no custom protocol, no retraining users. That's why VFS designs are common in migration and integration projects.

Performance depends on the backend and the layer. A user-mode VFS adds a translation step per operation, and a cloud-backed drive inherits network latency. Caching, placeholder files, and on-demand hydration (as in CBFS Sync's bidirectional sync with placeholder files) are the usual mitigations. For latency-sensitive workloads, measure before committing.

Choose a VFS when the file interface is the requirement. If downstream software expects paths, directory listings, and standard file semantics, a VFS is the right fit. If you control both ends of the integration, a direct API may be simpler and faster.

Consider the driver question early. Kernel-mode drivers are powerful but carry stability and signing burdens. Components that handle the driver layer for you—the pitch behind Callback's "without writing kernel-mode driver code"—trade some low-level control for faster, safer delivery. Callback offers a free trial and subscription options for its components; confirm licensing terms for your deployment before shipping.

The short version: a virtual file system is a translation layer that makes non-file data behave like files. Understand which layer you're working at—OS kernel, driver component, or application code—and the rest of the design decisions follow.

File access monitoring is the practice of intercepting and recording filesystem operations—open, read, write, rename, delete—as they happen, so you can audit who touched what, enforce access policies, or trigger downstream actions. You can implement it two ways: rely on OS-level auditing (built-in logs, coarse-grained, no code), or embed a filesystem filter component in your application (real-time interception, policy enforcement, requires an SDK such as CBFS Filter). Choose the embedded approach when you need to block operations, not just observe them, or when you need the same logic across Windows, Linux, and macOS.

How file access monitoring actually works

Every file operation passes through the operating system's filesystem stack. Monitoring means placing a hook somewhere in that path:

• OS auditing layer — the OS logs operations to an event log or audit trail after the fact. You get visibility but no control, and log formats and coverage differ per platform.
• Filter driver layer — a kernel-mode component sits in the I/O path and sees each request before it completes. It can allow, deny, modify, or redirect the operation, and it can capture context (which process, which user) at the moment of the request.

The filter-driver approach is what makes real-time policy enforcement possible. The trade-off is that kernel drivers are hard to write, sign, and maintain—which is exactly the gap that SDK components like CBFS Filter are built to close.

A concrete example

Suppose you need to stop a backup agent from reading files in a folder marked confidential, while letting an approved scanner read them. With OS auditing you would see the backup agent's reads in a log after they happened—too late. With a filter component you intercept the open request, check the requesting process identity against your policy, and return access-denied for the backup agent while passing the scanner through. The same hook can log every attempt for your compliance report.

OS auditing vs. embedded filtering: same dimensions, different fit

Choose OS auditing if you only need a record and your platforms already produce acceptable logs. Choose embedded filtering if the requirement includes blocking, redacting, encrypting on the fly, or reacting within the same operation.

Implementing monitoring with a filter SDK

Callback Technologies positions CBFS Filter as the component for this job: it "intercept[s], monitor[s], and control[s] filesystem operations in real time" and enforces "filesystem-level access control and security policies by intercepting filesystem, registry, and process operations in real time." The vendor's stated value is that you get system-level behavior with application-level simplicity—"without writing kernel-mode driver code."

A typical implementation follows this shape:

1. Define the policy inputs. Decide which operations matter (open, write, rename, delete), which processes or users are trusted, and what the response is (allow, deny, log, encrypt).
2. Install the filter component in your application and register callbacks for the operations you care about. The SDK supplies the driver, APIs, documentation, and samples per the vendor's component description.
3. Evaluate each intercepted request against your policy using the context the filter provides (requesting process, target path, operation type).
4. Act and record. Return the decision to the filesystem and write your audit record. Because interception is in-path, the decision applies to that operation, not a later one.
5. Verify. Test with a known-allowed process and a known-denied process against the same file, and confirm your audit log captures both attempts with correct context.

Common sticking points

• Performance overhead. Every intercepted operation adds work in the I/O path. Keep policy checks cheap and cache decisions where the vendor's API permits.
• Process identity spoofing. Trust decisions based on process identity need care; validate how the component reports the requester rather than assuming a name is enough.
• Deployment complexity. Kernel components must be installed and, on Windows, signed. Confirm signing and installation requirements with the vendor before committing to a release plan.
• Cross-platform gaps. Verify that the operations and context you depend on are exposed on every OS you ship. The vendor lists Windows, Linux, and macOS support for related components such as CBFS Sync; confirm filter coverage per platform in the documentation.

Where file access monitoring pays off

• Compliance auditing — a per-operation record with user and process context that satisfies review requirements.
• Security policy enforcement — blocking unauthorized reads or writes at the moment of the request.
• Transparent encryption — the related CBFS Encrypt component lets "authorized processes decrypt on the fly; all others see ciphertext," which is a monitoring decision applied to data visibility.
• Data loss prevention — intercepting writes or copies to removable or network paths and denying or logging them.
• Sync and virtualization triggers — using access events to hydrate placeholder files or route reads to cloud storage, as in the vendor's virtual filesystem and cloud-mount components.

Deciding

If your requirement is "know what happened," start with OS auditing and only move to a filter SDK when logs prove insufficient. If your requirement is "prevent, transform, or react during the operation," plan for an embedded filter component from the start, budget for in-path performance testing, and confirm signing, platform coverage, and licensing terms—the vendor advertises a free trial and subscription options, but confirm current terms directly—before you build it into your release.

Filesystem virtualization presents data that does not live in a conventional on-disk directory tree as if it were ordinary local files and folders. Applications and users then read, write, list, and delete that data through standard file APIs, while a software layer translates each operation into whatever the real backend requires. It is the right approach when you want existing programs to work unmodified against cloud storage, databases, REST services, or generated content. Building it yourself means writing kernel-mode driver code; using a component library such as CBFS Connect lets you implement the same behavior at the application level.

How a virtual filesystem maps data to files and folders

A virtual filesystem sits between the operating system's file interface and your data source. The OS sends familiar requests — open, read, write, enumerate a directory, query attributes, delete — and your layer answers them.

The mapping is yours to define. A "folder" might be a database table, an S3 prefix, or a REST collection; a "file" might be a row, an object, or a generated document. Once the mapping exists, any program that uses normal file I/O can consume the data without knowing where it actually lives.

Two properties matter in practice:

• Transparency. The consumer sees paths, handles, and attributes, not backend protocols.
• Control. Because every operation passes through your layer, you can enforce access rules, log activity, cache content, or synthesize data on demand.

Kernel drivers vs. user-mode SDK components

The traditional route is a kernel-mode file system driver. It offers deep integration but carries real costs: driver development and signing, debugging in kernel context, crash risk that takes down the whole machine, and separate work for each OS.

The alternative is a component library that handles the driver plumbing and exposes an application-level API. Callback Technologies positions its components this way — "system-level filesystem technology, application-level simplicity" — with APIs, drivers, documentation, and samples included so you add virtual filesystems "without writing kernel-mode driver code."

Choose a custom driver only if you need behavior the library cannot express. For most product teams, the library route removes the riskiest part of the project.

Common use cases

• Cloud storage as a local drive. CBFS Cloud mounts S3, Azure, OneDrive, SharePoint, Google Drive, SFTP, and similar sources as local virtual drives through one component API.
• Databases and REST APIs as files. CBFS Connect presents "any data source as local files and folders: cloud storage, databases, REST APIs, or custom content."
• Access monitoring and policy enforcement. CBFS Filter intercepts filesystem, registry, and process operations in real time to enforce access control and security policies.
• Transparent encryption. CBFS Encrypt lets authorized processes decrypt on the fly while all others see ciphertext.
• Sync and on-demand hydration. CBFS Sync does bidirectional sync using native OS APIs on Windows, Linux, and macOS, with placeholder files and on-demand hydration.
• Embedded encrypted stores. CBFS Vault packs a complete encrypted filesystem — per-file and whole-vault encryption, compression, journaling, random read/write — into a single portable file.
• Explorer integration. CBFS Shell adds virtual folders, context menus, overlay icons, and detail columns to Windows File Explorer without risking its stability.

Implementation considerations

Performance. Every file operation crosses your layer, so latency and throughput depend on your backend calls and caching strategy. Batch metadata queries, cache directory listings, and avoid synchronous round-trips on the read path where possible.

Access control. Virtualization centralizes enforcement: you decide which process or user sees plaintext, which sees ciphertext, and which operations are blocked. Decide this before exposing the mount, not after.

Cross-platform support. Confirm the target OSes explicitly. CBFS Sync states Windows, Linux, and macOS; other components should be checked against your deployment matrix rather than assumed.

Consistency and failure handling. Network-backed sources fail differently from local disks. Define behavior for timeouts, partial writes, and stale caches so consumers see predictable errors.

Lifecycle. Plan how mounts are created, torn down, and recovered after a crash, and how updates roll out to machines already running the component.

Getting started

Callback offers a free trial download, and the components are described as production-grade and used by organizations worldwide. A practical first step is to prototype your specific mapping — one folder, one file type — against the trial, measure read/write latency with your real backend, and only then commit to the full data model. If the prototype meets your performance and platform requirements, the component approach will typically get you to production faster than a custom driver.