The .2me archive model

The central transport artifact in epi4you is a .2me tarball.

This is the unit that lets a prepared analysis move between machines while preserving enough structure to be meaningful on the target side.

What the archive contains

At a high level, a .2me archive contains:

  • a manifest file named 4u_manifest.json,

  • one or more typed payloads,

  • file inventory information,

  • provenance, and

  • a signature over the manifest payload.

Manifest responsibilities

The manifest serves three different roles at once.

Inventory

It describes which payloads are present and which files belong to them.

Context

It records the metadata needed to interpret the archive as an EPI2ME-style asset rather than as an arbitrary tar file.

Integrity

It stores a digest-based signature for the serialized manifest so import can reject obviously inconsistent archives.

Payload types

The codebase models three payload classes:

Epi2mePayload

A Desktop-style analysis record with associated files.

Epi2meWf

A workflow installation tree.

Epi2meContainer

A set of exported container artefacts associated with a workflow.

Why manifests matter for liftover

For training-course and offline deployment use, a manifest is not busywork. It is what turns a file drop into a transport object with intent.

Without the manifest, the target side has to guess:

  • what this bundle represents,

  • whether it is complete,

  • where files belong,

  • how to label the imported analysis, and

  • whether the archive still matches what the source side produced.

With the manifest, those questions are answered explicitly.

Current integrity model

The current trust check is manifest-centric:

  • the manifest is serialized in a canonical form,

  • the signature field is blanked during signature generation, and

  • a SHA-256 digest is stored and checked during import.

This is intentionally lightweight. It is enough to detect obvious tampering or serialization mismatch at the manifest layer, even though it is not yet a full cryptographic attestation of every unpacked file.