Release of Daml SDK 1.0

Daml SDK 1.0.0 has been released on the 15th of April 2020. You can install it using

daml install latest

If you're planning to upgrade your Daml SDK to take advantage of our newest features please note that some action may be required on your part. If you're not planning to upgrade then no change is necessary.


The summary of the release is available in video format on the Daml Youtube channel:



  • New JavaScript/TypeScript client-side tooling is now stable and the recommended way to build Daml applications. A new Getting Started Guide based on these tools has replaced the Quickstart guide.
  • The Time Model has been improved so that it works seamlessly without user input to the Ledger API. Action needed when you update to the latest version of API bindings or recompile gRPC clients.
  • More TLS configuration options for Daml Ledgers.
  • The next generation Sandbox is now the default, bringing an experience closer to a distributed ledger. Immediate action is needed if your project is relying on scenarios for ledger initialization.
  • Cleanup of names, deprecated features and language versions. Immediate action needed if you use any Java dependencies withcom.digitalasset packages or Maven coordinates.

Known Issues

  • The new Sandbox has a known issue where some false negative contract key lookups
    are only correctly validated on the read path, not on the write path. The net
    effect is that with carefully constructed Daml models, non-conformant transactions can
    be recorded in the underlying storage, which may lead to data continuity issues when this issue is fixed. Full details can be found on GitHub issue #5563.

What’s New

New Client Tooling


Distributed applications are much more than smart contracts running on a distributed ledger, and in 2019 we set out to make it significantly easier to build that part of applications which lives off-ledger: Automations, Integrations, and UIs. The new tooling is focused on giving application developers an easy-to-consume, real-time ledger state, which moves the development experience away from event sourcing and makes it similar to working with a database.

  • The HTTP JSON API: giving a queryable view of the ledger state and endpoints to submit transactions, all using an easy-to-consume JSON format.
  • A JavaScript/TypeScript code generator: turning a Daml package into a (typed) library to interact with the HTTP JSON API.
  • A set of JavaScript/TypeScript client libraries: working hand in hand with the code generator to interact with the HTTP JSON API, and bind ledger data to React components.
  • A new Getting Started Guide shows how all these pieces fit together to build a complete distributed end-to-end application with a custom UI.

The HTTP JSON API is designed to be consumable from any language ecosystem. The choice of JavaScript (and React) for the rest of the tooling was driven by the desire to aid application development all the way up to UIs, using the most widely adopted technologies.

Specific Changes

  • The documentation has a new Getting Started Guide. The previous Quickstart guide has moved under the Java Bindings section.
  • There is a new SDK template with a skeleton for an end-to-end application using the new tooling. It’s documented and used in the new Getting Started Guide. Use daml new my-proj create-daml-app to get started.
  • The /v1endpoints of the HTTP JSON API and the JavaScript Code Generator and Support Libraries are now stable.
    • The JSON API has gained an endpoint to allocate parties:/v1/parties/allocate.
  • Support for maps and lists has been removed from the query language.
  • Note that the WebSockets streaming endpoint of the HTTP JSON API is still under development.

Impact and Migration

The new client tooling is almost purely additive so for most, no action is needed. For new applications, we recommend this tooling as it makes a lot of things quicker and easier. However, direct use of the Ledger API and HTTP JSON API continues to be a good option for anyone needing lower-level control or wanting to use a different language for their applications.

The only non-backwards compatible change compared to previous versions is the removal of queries on lists and maps in the HTTP JSON API. There is no trivial migration for this. If you were relying on these capabilities please get in touch with us via or on Slack. We’d like to hear how you were making use of the feature so that we can replace it with something better, and we will make some suggestions to work around the removal.

Improved Time Model


SDK Release 0.13.55 introduced a new method for command deduplication and deprecated the command field maximum_record_time. SDK Release 1.0 further improves the Ledger Time model so that users no longer need to pass in any time related information to the Ledger API. The new time model is designed to work under almost all circumstances without user intervention, making developing applications against Daml Ledgers easier in practice.

Specific Changes:

  • The Sandbox no longer emits Checkpoints at regular intervals in wall clock mode.
  • The ledger_effective_time and maximum_record_timefields have been removed from the Ledger API, and corresponding fields have been removed from the  HTTP JSON API and Ledger API language bindings.
  • The --default-ttl command line argument of the HTTP JSON API is gone.
  • Ledger Time is no longer strictly monotonically increasing, but only follows causal monotonicity: Ledger Time of transactions is greater than or equal to the Ledger Time of any input contract.
  • The Command Service is no longer idempotent with respect to duplicate submissions. Duplicate submissions now instead return an ALREADY_EXISTS error, consistent with the new deduplication mechanism of the Command Submission Service.

Impact and Migration:

Old applications will continue running against new ledgers, but ledger effective time and maximum record time set on submissions will be ignored. As soon as the client-side language bindings or compiled gRPC services are updated, the fields will need to be removed as they are no longer part of the API specification.

Better TLS Support


Daml Ledgers have always supported exposing the Ledger API via TLS, but support on consuming applications was inconsistent and often required client certificates. From this release onward, more client components support consuming the Ledger API via TLS without client authentication.

Specific Changes

  • When Sandbox is run with TLS enabled, you can now configure the requirement for client authentication via  --client-auth. See the documentation for more information.
  • The daml deploy and daml ledger commands now support connecting to the Ledger API via TLS. See their documentation for more information.
  • Daml Script and Daml Triggers now support TLS by passing the --tls flag. You can set certificates for client authentication via --pem and --crt and a custom root CA for validating the server certificate via --cacrt.

  • Navigator, Daml Script, Daml REPL, Daml Triggers, and Extractor can now run against a TLS-enabled ledger without client authentication. You can enable TLS without any special certificates by passing --tls.
  • Daml Script and Daml Triggers have the option to configure certificates for client authentication via --pem and --crt and a custom root CA for validating the server certificate via --cacrt.

Impact and Migration
This is a new capability, so no action is needed. These new features are useful in production environments where client to ledger connections may need to be secured.

Next Generation Sandbox


The Daml Sandbox has had a major architectural overhaul to bring it and its user experience even closer in line with other Daml Ledgers. The new Sandbox is now the default, but the “classic” Sandbox is included as a deprecated version in this release. The classic Sandbox will be removed from the SDK in a future release and will not be actively developed further.

Specific Changes

  • daml sandbox and daml start start the new Sandbox. The classic sandbox can be invoked via daml sandbox-classic and daml start --sandbox-classic=yes.

  • Wall Clock Time mode (--wall-clock-time) is now the default.
  • Scenarios are no longer supported for ledger initialization.
  • Contract identifiers are hashes instead of longer sequence numbers.
    • A new static contract identifier seeding scheme has been added to enable reproducible contract identifiers in combination with --static-time. Set flag --contract-id-seeding=static to use it.

  • Ledger API Offsets are no longer guaranteed to be a parsable number. They are an opaque string that can be compared lexicographically.
  • The command line flags --auth-jwt-ec256-crt and --auth-jwt-ec512-crt were renamed to --auth-jwt-es256-crt and --auth-jwt-es512-crt, respectively, to align them with the cryptographic algorithms used.

Impact and Migration

The impact is primarily on demo applications running in static time mode and/or using scenarios for ledger initialization. Since both the classic  and new Sandbox are compliant Daml Ledgers, there is no difference in behavior apart from these fringes.

  • If you rely on static time mode, set it explicitly using --static-time.
    • If you rely on reproducible contract identifiers, also set --contract-id-seeding=static.
  • If you use a scenario for ledger initialization, migrate to Daml Script.
  • If you were parsing ledger offsets, you need to find a way to stop doing so. This is not guaranteed to be possible on Daml Ledgers other than the classic Sandbox. If you were relying on doing so, get in touch with us on We’d like to help with migration and want to understand how you were using this so we can better support your use case.
  • If you were using ES256 or ES512 signing for authentication, adjust your command line flags.
  • If you were running the now classic sandbox with persistence in a SQL database, you need to recreate contracts in the ledger run with the new sandbox. There is no automatic data migration available.

To ease transition, you can revert back to the classic Sandbox using daml sandbox-classic and daml start --sandbox-classic=yes. Note that the classic Sandbox is deprecated and will be removed in a future release.

Cleanup for Daml SDK 1.0


As we are moving into the 1.0 release line, we have done some cleanup work, aligning names of artifacts, removing deprecated language versions, streamlining the release process, and finishing a few language tweaks by turning select warnings into errors. 

Specific Changes

  • All Java and Scala packages starting with com.digitalasset.daml and com.digitalasset are now consolidated under com.daml
    • Impact: Changing the version of some artifacts to 1.0 will cause a resolution error.
    • Migration: Changing Maven coordinates and imports using a find and replace should be enough to migrate your code.
  • Ledger API services are now under the com.daml package. A compatibility layer has been added to also expose the services under the com.digitalasset package.
    • Impact: grpcurl does not work with the compatibility layer.
    • Migration: Scripts using grpcurl need to change the service name from com.digitalasset to com.daml.
  • < Daml SDK 1.0: com.digitalasset.ledger.api.v1.TransactionService
    >= Daml SDK 1.0: com.daml.ledger.api.v1.TransactionService)

  • The default Daml-LF target version is now 1.8.
    • Impact: Projects will not run against old Daml Ledgers that do not support Daml-LF 1.8.
    • Migration: You can target 1.7 by specifying --target=1.7 in the build-options field in your daml.yaml.
  • All Daml-LF versions <1.6 are deprecated and will not be supported on Daml Ledgers.
    • Impact: The new Sandbox will not run Daml code compiled to Daml-LF 1.5 or earlier.
    • Migration: Use classic Sandbox to run older Daml models.
  • We no longer release the SDK to Bintray.
    • Impact: If you were relying on artifacts on Bintray, you will not be able to update to version 1.0 without changing the repository.
    • Migration: The new locations are as follows:
      • SDK Releases and Protobuf files are released to GitHub Releases.
      • Java/Scala artifacts are on Maven Central.
      • JavaScript artifacts are on NPM.
  • File names must now match up with module names. This already produced a warning in previous releases
    • Impact: Projects in which there are mismatches will no longer build.
    • Migration: Change your .daml filenames to match module names.
  • It is now an error to define a record with a single constructor where the constructor does not match the type name. This restriction only applies to single-constructor records. Variants and enums are not affected. This already produced a warning in SDK 0.13.55.
    • Impact: Projects with now illegal type declarations will no longer build.
    • Migration: In declarations of the type data X = Y with .., you have to change the type name (X) to match data constructor name (Y) or vice versa.
  • The compiler name collision check has been extended to also count the case as a collision where you have a type B in module A and a module A.B.C (but no module A.B).
    • Impact: Projects with such module names will produce warnings and stop compiling in a future release. The JavaScript Code Generator is not usable on packages that don’t uphold this restriction.
    • Migration: You have to rename your modules to avoid such name clashes.

Impact and Migration

Impacts and migrations are covered item by item in Specific Changes above.

Progress on Features Under Development


Work is progressing on two features that are currently under active development.

  1. The Daml REPL, introduced with SDK 0.13.55 is becoming richer in its abilities, getting ever closer in capabilities to Daml Script.
  2. Work on a Websockets streaming version of the HTTP JSON API’s querying endpoints is progressing. The aim with this streaming service is to combine the ease of consumption of the HTTP JSON API with the liveness provided by a streaming API.

Specific Changes

  • Daml REPL
    • You can now use import declarations at the REPL prompt to bring additional modules into scope.
    • You can now use more complex patterns in statements, e.g., (x,y) <- pure (1,2).
    • You can now connect to a ledger with authentication by passing it to  daml repl using --access-token-file option.
  • Websockets on the HTTP JSON API
    • The error format has changed to match the synchronous API: {"status": <400 | 401 | 404 | 500>, "errors": <JSON array of strings> }.
    • The streaming version of the query and fetch-by-key endpoints now emit the last seen ledger offset. These offsets can be fed back to new requests to start the stream at said offset. Such offset messages are also used for heartbeating instead of the previous explicit heartbeat messages.

Impact and Migration

The only impacts are on consumers of the Websocket streaming APIs. Those consumers will have to make some minor adjustments to include the API changes around error handling and ledger offsets.

Minor Changes and Fixes

  •  Better support for snapshot releases in the Daml Assistant.
  • daml version can now list the available snapshot versions by passing the flag --snapshots=yes.
    • daml install latest can now include the latest snapshot version by passing the flag --snapshots=yes.
    • Daml Script can now be run over the HTTP JSON API, which means it now runs against project:DABL. Take a look at the documentation for instructions and limitations.
  • Party strings are now restricted to 255 characters.
    • Impact: If you used the Sandbox with very long Party strings they’ll be rejected by the new Sandbox and other Daml Ledgers.
    • Migration: Shorten your Party strings. Note that in ledgers other than Sandbox, you may not be able to choose them entirely freely anyway.
  • You can now disable starting Navigator as part of daml start in your daml.yaml file by adding start-navigator: false.
  • Calls to the GetParties API function with an empty list of parties no longer results in an error, but in an empty response.