ChainScript

ChainScript is an open standard for representing Proof of Process data.

Proof of Process is a protocol that allows partners to follow the execution of a shared process. Proof of Process provides immutability and auditability of every step in the process.

Learn more here.

Documentation

To learn what you can do with ChainScript, please go to the documentation.

How to use

ChainScript is defined with protobuf to provide a portable encoding.

It is recommended to import this repository as a git subtree:

git subtree add --prefix proto git@github.com:stratumn/chainscript.git master --squash

Your application can then compile the protobuf file to types in your language of choice and add any helpers you need.

Changes to ChainScript should be done in the current repository: clients should pull the latest changes with git subtree.

Reference Implementations

Stratumn provides opinionated reference implementations that should suit most projects:

Language	Repository	Status
Golang	https://github.com/stratumn/go-chainscript	1.x.x
Javascript	https://github.com/stratumn/js-chainscript	1.x.x

Testing

For implementations to be compatible, we use a common set of test cases that every implementation needs to pass.

Regression samples

In the samples folder we provide serialized segments. ChainScript implementations should unit test that they're able to correctly deserialize and validate these segments.

See the test samples for more details.

Nightly tests

The ./test.sh script is run nightly and verifies that known implementations remain compatible with each other.

Every implementation needs to provide a docker image that allows generating and validating test segments.

Design Choices

Stable Encoding

ChainScript needs a stable encoding as it contains signatures and hashes of parts of the data. If a link didn't have the same hash in different languages, cross-platform applications wouldn't work.

ChainScript only uses protobuf types that have a canonical encoding. That means that in particular, protobuf maps can't be used as their ordering is not specified by the protobuf specification and can vary depending on the implementation.

Dynamic data (such as a link's state) is represented as bytes. It is your application's responsibility to use a stable byte encoding for that data.

You have several options to define a stable encoding (not exhaustive):

• protobuf
• canonical JSON
• amino
• custom binary encoding

Versioning

ChainScript should follow protobuf's guidelines for backwards-compatible updates.

ChainScript provides multiple version fields. These fields should be used by applications to update the dynamic parts of their data (such as link.data and link.meta.data) in a backwards-compatible way.