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Virtual Filesystem (VFS)

Hermes provides a virtual filesystem per application backed by HDF5. It exposes a hierarchical view with mount points corresponding to packaged content and writable areas controlled by permissions.

Structure (typical)

  • srv/www: Static web assets served by the HTTP gateway (read-only).
  • lib/<module>/: Module-specific data and WASM component binaries (read-only).
  • usr/ and usr/lib/: Application-provided shared assets (read-only).
  • etc/: Configuration (some files may be writable under controlled policy).
  • tmp/: Temporary storage (in-memory or ephemeral; writable).

Permissions

  • Read-only for packaged assets ensures reproducibility and integrity.
  • Selected write locations (e.g., tmp) allow modules to persist ephemeral data.

APIs

  • Read/write primitives are mediated by the VFS with permission checks.
  • Bootstrapping constructs the HDF5-backed structure and mounts packaged content.

References