Chronicle Examples¶

This project contains contributed examples for Chronicle. The markdown documents in this repository are published on their own site. Documentation for Chronicle in general may be found here.

Prerequisites¶

To get started, there are some basic prerequisites which must be installed:

In addition, a working knowledge of GraphQL is assumed. If you are new to this, a good starting point is Introduction to GraphQL.

Clone the Repository¶

git clone https://github.com/chronicleworks/chronicle-examples

This contains several example domain yaml files, and Docker uses blockchaintp/chronicle-builder:BTP2.1.0-0.7.4 as the builder image by default

Build a Domain¶

Choose from one of the following examples:

For the purposes of these instructions we will use the manufacturing domain, but any domain will work. Simply substitute the name of the domain's directory for manufacturing in the following instructions. For the other listed domains, instead substitute artworld, corporate-actions, science-project, or time-recording, as desired.

Run a Standalone Node¶

In-Memory Ledger¶

You can run up a version of Chronicle which is a single node with a local database, recording transactions on an in-memory ledger rather than a blockchain.

gmake run-manufacturing

Now you are ready to connect to Chronicle and interact with this example, using a GraphQL client as detailed below.

To stop this node, simply use control-C or otherwise terminate the process.

Backed by Sawtooth¶

You can also run up a standalone node that, while still a single node with a local database, also includes a local Sawtooth node whose validator is used by Chronicle's transaction processor for recording transactions on a blockchain:

gmake run-stl-manufacturing

Now you are ready to connect to Chronicle and interact with this example, using a GraphQL client as detailed below.

To stop this node, a further command shuts it down:

gmake stop-stl-manufacturing

Deploy to a Chronicle-on-Sawtooth Environment¶

Rather than running a live Chronicle node locally, you may build a typed Chronicle image that is ready for deployment into an environment with Sawtooth nodes using the Chronicle Rancher by SUSE Cookbook. Options to decide on include:

Which domain example to build for Chronicle's typing.
debug for a debug build or release for a release build. The release build includes less debug information and takes longer to build but is more performant.

For example, for a debug build of the manufacturing domain,

gmake manufacturing-stl-debug

or a release build for the same domain,

gmake manufacturing-stl-release

As above, the name of any of the other listed domains may be substituted for manufacturing.

After the build, running docker image ls should show the built image that can then be pushed to the appropriate registry for installation.

By default, the images are given tags like, say, chronicle-manufacturing-stl-release:local. A value other than local can be set in the ISOLATION_ID environment variable prior to build.

Set Environment Variables¶

Additional environment variables can be set that are recogized by the running Chronicle process. You may list these in the docker/chronicle-environment file which is initially empty. To instead read them from a different file, set its location in the DOCKER_COMPOSE_ENV environment variable.

For example, to have Chronicle require all API requests to be authenticated, you could write your authentication provider's OIDC endpoints into docker/chronicle-environment thus,

REQUIRE_AUTH=1
JWKS_URI=https://id.example.com:80/.well-known/jwks.json
USERINFO_URI=https://id.example.com:80/userinfo

taking the variable names from chronicle serve-api --help. Then, after you use gmake run-my-domain or similar, the running Chronicle will use the specified authentication provider to verify incoming requests.

Generate the GraphQL Schema¶

Integration with Chronicle is primarily done through GraphQL. The GraphQL schema is specific to the domain and is generated from the domain.yaml file. To generate the GraphQL schema for your domain, simply run gmake <domain>-sdl. For example, for the manufacturing domain:

gmake manufacturing-sdl

Understanding the Makefile targets and Docker images¶

As described above, Chronicle can be built either with an in-memory ledger or backed by Sawtooth. These have inmem or stl in their image name, respectively. Also, it can be built either as a debug or a release build. The former suffixes image names with -debug, the latter with -release.

The gmake build target builds the in-memory release images for every example domain. For Sawtooth-backed release builds, use gmake stl-release instead.

The run-* targets build debug versions, other targets typically build release builds. Debug builds the code much faster for incremental changes but this advantage is irrelevant when each build is done in a fresh Docker container. Therefore, the better-optimized release builds are typically recommended.

To build any specific Docker image, use the form gmake A-B-C where,

A: the name of the domain, e.g., manufacturing
B: either inmem or stl
C: either release or debug

which builds and tags an image named chronicle-A-B-C. The previous chronicle-A-B tag names are deprecated.

Using the GraphQL Client¶

Chronicle Examples use Chronicle's serve-graphql function to provide the Chronicle GraphQL API. By using a GraphQL client, you can interact with Chronicle by running GraphQL queries, mutations, and subscriptions.

We recommend using the Altair GraphQL Client, which is available as a free desktop GraphQL IDE or web browser extension.

If you have previously used Chronicle Examples, you can still access the GraphQL Playground through your web browser at http://127.0.0.1:9982, unless you are using port forwarding or an ingress. However we will be deprecating support for the playground in future releases.

Both of the playground and the Altair GraphQL Client are persistent via cookies, therefore running the same browser on the same machine will preserves all your queries and tab positions, simplifying resubmittng them if you are iterating on an idea for example.

To add a new mutation or query tab, there is a + on the right-hand side of the tab bar. Don't forget to use Shift-R to refresh your client before rerunning an example.

In the case of the GraphQL Playground, the SCHEMA and DOCS tabs make it easy to explore the relationship between your domain.yaml configuration and the resulting strongly-typed Chronicle GraphQL API.

Subscribing to Events (1)¶

In order to see what is happening as you run GraphQL mutations and queries, you can subscribe to async events in one of the tabs. The GraphQL Playround handles this automatically upgrading your HTTP connection to a websocket end point. However, other GraphQL clients may ask you to explicitly provide this. Again, the default is .

subscription {
  commitNotifications {
    stage
    txId
    error
    delta
  }
}

Subscribing to Events (2)¶

If you are using JWT authorization you will need to install a GraphQL client that supports subscriptions correctly by passing the Authorization header.

Neither the Altair GraphQL Client nor the GraphQL Playground support this. However, we have verified that the CLI gql-cli included in GQL 3 handles this gracefully. To install this use pip:

pip install "gql[all]"

Once gql-cli is installed you can use it to run the same subscription. To faciliate this we have provided a script subscription.sh.

We recommend that you run this script first, then experiment with mutations and queries using your preferred GraphQL client.

NOTE If you haven't locked down your environment using JWT, the bearer token will be ignored.

Adding a Domain¶

Chronicle Definition¶

Adding a domain to the examples is as simple as adding a new domain.yaml file to a new folder under domains. The folder name will be used as the name of the docker image. For example, if you add a domains/mydomain/domain.yaml file, the debug and inmem docker image will be chronicle-mydomain-inmem:local.

User's Guide¶

The domain.yaml definition is typically the smaller part of what there is to say about the domain's usage. Users will appreciate an accompanying guide.md markdown document structured like those for the other example domains. Take a look through those domains' guides because they illustrate how to write the principal sections:

Modeling
Recording
Querying

Briefly explain what your domain is. Then, for the first section, take each of the domain's most important activities, describe the participating agents and entities, provide a diagram of how they relate to the activity, then show how each is modeled in the domain.yaml. In this way, you can step through various aspects of your domain, allowing the reader to accumulate a full picture gradually. Conclude these by bringing those descriptions together as the full domain.yaml. Note that yaml can be specified for the highlighting in domain definitions.

For producing those diagrams, use PlantUML's class diagrams with extension --|> arrows showing which are agents, entities, and activities, and directed association --> arrows for how those relate to each other. Include typed attributes as fields in the class boxes where appropriate. Notice that the docs/diagrams/ folder has two subdirectories; review their contents and follow the same pattern. Each of your domain agents, entities, and activities gets a corresponding include/*.iuml file and, from your diagrams in src/*.puml, you can !include the provided default.iuml, agent.iuml, entity.iuml, activity.iuml, and your extra *.iuml for consistency across your diagrams and those of the other example domains.

Follow the above tour of your domain with the other two sections: provide example mutations and queries expressed in GraphQL, and show how the responses should look, to give users some simple stories to try out in the Apollo Sandbox in their browser. These examples should lead them through the most important and common uses of your domain, giving them enough starting points to easily try it out in their own applications. Note that graphql for requests and json for responses can be specified for highlighting those interactions.

For rendering your new guide locally, docs/ also includes a list of the Python dependencies required for running mkdocs serve. In using it to review your guide, check that you have explained every aspect of your domain clearly so the community can draw the greatest benefit from your work.