├── PingPong ├── multi-package.yaml ├── script │ ├── daml.yaml │ └── daml │ │ └── PingPongTest.daml ├── main │ ├── daml.yaml │ └── daml │ │ └── PingPong.daml ├── src │ └── main │ │ ├── resources │ │ └── logback.xml │ │ └── java │ │ └── examples │ │ └── pingpong │ │ ├── codegen │ │ ├── PingPongCodegenMain.java │ │ └── PingPongProcessor.java │ │ └── grpc │ │ ├── PingPongGrpcMain.java │ │ └── PingPongProcessor.java ├── pom.xml ├── start.sh └── README.rst ├── StockExchange ├── daml.yaml ├── src │ └── main │ │ ├── resources │ │ └── logback.xml │ │ └── java │ │ └── examples │ │ └── stockexchange │ │ ├── ParticipantSession.java │ │ ├── parties │ │ ├── Bank.java │ │ ├── Buyer.java │ │ ├── Seller.java │ │ └── StockExchange.java │ │ └── Common.java ├── canton_ledger.conf ├── pom.xml ├── setup.sh ├── daml │ └── StockExchange.daml ├── stock_exchange_bootstrap_script.canton └── README.rst ├── .gitignore ├── README.rst ├── .github └── workflows │ └── cla.yml └── LICENSE /PingPong/multi-package.yaml: -------------------------------------------------------------------------------- 1 | packages: 2 | - ./main 3 | - ./script -------------------------------------------------------------------------------- /PingPong/script/daml.yaml: -------------------------------------------------------------------------------- 1 | # Copyright (c) 2025 Digital Asset (Switzerland) GmbH and/or its affiliates. All rights reserved. 2 | # SPDX-License-Identifier: Apache-2.0 3 | 4 | sdk-version: 3.4.9 5 | name: ex-java-bindings-script 6 | source: daml/PingPongTest.daml 7 | init-script: PingPongTest:setup 8 | version: 0.0.2 9 | dependencies: 10 | - daml-prim 11 | - daml-stdlib 12 | - daml-script 13 | -------------------------------------------------------------------------------- /StockExchange/daml.yaml: -------------------------------------------------------------------------------- 1 | # Copyright (c) 2025 Digital Asset (Switzerland) GmbH and/or its affiliates. All rights reserved. 2 | # SPDX-License-Identifier: Apache-2.0 3 | 4 | sdk-version: 3.4.9 5 | name: ex-java-bindings-stock-exchange 6 | source: daml/StockExchange.daml 7 | version: 0.0.1 8 | dependencies: 9 | - daml-prim 10 | - daml-stdlib 11 | codegen: 12 | java: 13 | package-prefix: examples.codegen 14 | output-directory: src/main/java/ 15 | -------------------------------------------------------------------------------- /PingPong/main/daml.yaml: -------------------------------------------------------------------------------- 1 | # Copyright (c) 2025 Digital Asset (Switzerland) GmbH and/or its affiliates. All rights reserved. 2 | # SPDX-License-Identifier: Apache-2.0 3 | 4 | sdk-version: 3.4.9 5 | name: ex-java-bindings 6 | source: daml/PingPong.daml 7 | init-script: PingPong:setup 8 | version: 0.0.2 9 | dependencies: 10 | - daml-prim 11 | - daml-stdlib 12 | codegen: 13 | java: 14 | package-prefix: examples.pingpong.codegen 15 | output-directory: ../src/main/java/ -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | # Copyright (c) 2020, Digital Asset (Switzerland) GmbH and/or its affiliates. All rights reserved. 2 | # SPDX-License-Identifier: Apache-2.0 3 | 4 | lib/ 5 | logs/ 6 | log/ 7 | target/ 8 | **/navigator.log 9 | **/sandbox.log 10 | dependency-reduced-pom.xml 11 | .navigator.conf 12 | navigator.history 13 | *.iml 14 | .idea/ 15 | example-ping-pong-java.iml 16 | .vscode/settings.json 17 | **/.daml 18 | StockExchange/temp_stock_exchange_example 19 | StockExchange/src/main/java/examples/codegen 20 | -------------------------------------------------------------------------------- /PingPong/script/daml/PingPongTest.daml: -------------------------------------------------------------------------------- 1 | -- Copyright (c) 2025 Digital Asset (Switzerland) GmbH and/or its affiliates. All rights reserved. 2 | -- SPDX-License-Identifier: Apache-2.0 3 | 4 | module PingPongTest where 5 | 6 | import Daml.Script 7 | 8 | setup : Script() 9 | setup = script do 10 | -- Set up parties 11 | alice <- allocatePartyByHint (PartyIdHint "Alice") 12 | bob <- allocatePartyByHint (PartyIdHint "Bob") 13 | 14 | -- Needed in 2.0, see https://docs.daml.com/tools/navigator/index.html 15 | aliceId <- validateUserId "alice" 16 | bobId <- validateUserId "bob" 17 | createUser (User aliceId (Some alice)) [CanActAs alice] 18 | createUser (User bobId (Some bob)) [CanActAs bob] 19 | -------------------------------------------------------------------------------- /PingPong/src/main/resources/logback.xml: -------------------------------------------------------------------------------- 1 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 14 | 15 | %d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n 16 | 17 | 18 | 19 | 20 | 21 | 22 | -------------------------------------------------------------------------------- /StockExchange/src/main/resources/logback.xml: -------------------------------------------------------------------------------- 1 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 14 | 15 | %d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | -------------------------------------------------------------------------------- /README.rst: -------------------------------------------------------------------------------- 1 | Java Bindings Examples 2 | ---------------------- 3 | 4 | :: 5 | 6 | Copyright (c) 2025 Digital Asset (Switzerland) GmbH and/or its affiliates. All rights reserved. 7 | SPDX-License-Identifier: Apache-2.0.0 8 | 9 | This repository contains two subprojects that demonstrate building of Daml client applications with the usage of Java Bindings: 10 | 11 | - `Ping-Pong `_ is a collection of three examples that shows how a Java application would use the `Java Binding library `_ to connect to and exercise a Daml model running on a ledger 12 | - `Stock Exchange `_ shows an advanced use-case of the Java bindings for building a Daml client application that leverages off-ledger data distribution by using `Explicit Contract Disclosure `_ 13 | -------------------------------------------------------------------------------- /PingPong/main/daml/PingPong.daml: -------------------------------------------------------------------------------- 1 | -- Copyright (c) 2025 Digital Asset (Switzerland) GmbH and/or its affiliates. All rights reserved. 2 | -- SPDX-License-Identifier: Apache-2.0 3 | 4 | module PingPong where 5 | 6 | template Ping 7 | with 8 | sender: Party 9 | receiver: Party 10 | count: Int 11 | where 12 | signatory sender 13 | observer receiver 14 | 15 | choice RespondPong : () 16 | controller receiver 17 | do 18 | if count > 10 then return () 19 | else do 20 | create Pong with sender = receiver; receiver = sender; count = count + 1 21 | return () 22 | 23 | template Pong 24 | with 25 | sender: Party 26 | receiver: Party 27 | count: Int 28 | where 29 | signatory sender 30 | observer receiver 31 | 32 | choice RespondPing : () 33 | controller receiver 34 | do 35 | if count > 10 then return () 36 | else do 37 | create Ping with sender = receiver; receiver = sender; count = count + 1 38 | return () 39 | -------------------------------------------------------------------------------- /StockExchange/canton_ledger.conf: -------------------------------------------------------------------------------- 1 | canton { 2 | participants { 3 | stockExchangeParticipant { 4 | http-ledger-api.port = 5013 5 | admin-api.port = 5012 6 | ledger-api.port = 5011 7 | } 8 | bankParticipant { 9 | http-ledger-api.port = 5023 10 | admin-api.port = 5022 11 | ledger-api.port = 5021 12 | } 13 | buyerParticipant { 14 | http-ledger-api.port = 5033 15 | admin-api.port = 5032 16 | ledger-api.port = 5031 17 | } 18 | sellerParticipant { 19 | http-ledger-api.port = 5043 20 | admin-api.port = 5042 21 | ledger-api.port = 5041 22 | } 23 | } 24 | sequencers.local { 25 | public-api { 26 | address = localhost 27 | port = 5018 28 | } 29 | admin-api { 30 | address = localhost 31 | port = 5019 32 | } 33 | } 34 | mediators.localMediator { 35 | admin-api { 36 | address = localhost 37 | port = 5017 38 | } 39 | } 40 | // enable ledger_api commands for setup simplicity of the Ledger API 41 | features.enable-testing-commands = yes 42 | } 43 | -------------------------------------------------------------------------------- /PingPong/pom.xml: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4.0.0 4 | 5 | com.daml.ledger.examples 6 | example-ping-pong-java 7 | jar 8 | 0.0.1-SNAPSHOT 9 | 10 | 11 | UTF-8 12 | 11 13 | 11 14 | 3.4.9 15 | 16 | 17 | 18 | 19 | com.daml 20 | bindings-java 21 | ${sdk-version} 22 | 23 | 24 | ch.qos.logback 25 | logback-classic 26 | 1.4.12 27 | 28 | 29 | 30 | 31 | -------------------------------------------------------------------------------- /StockExchange/pom.xml: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4.0.0 4 | 5 | com.daml.ledger.examples 6 | example-stock-exchange-java 7 | jar 8 | 0.0.1-SNAPSHOT 9 | 10 | 11 | UTF-8 12 | 11 13 | 11 14 | 3.4.9 15 | 16 | 17 | 18 | 19 | com.daml 20 | bindings-java 21 | ${sdk-version} 22 | 23 | 24 | ch.qos.logback 25 | logback-classic 26 | 1.4.12 27 | 28 | 29 | 30 | 31 | -------------------------------------------------------------------------------- /PingPong/start.sh: -------------------------------------------------------------------------------- 1 | #!/usr/bin/env bash 2 | set -euo pipefail 3 | 4 | function getSandboxPid(){ 5 | ss -lptn 'sport = :7575' | grep -P -o '(?<=pid=)([0-9]+)' 6 | } 7 | function cleanup(){ 8 | echo "Cleaning up" 9 | sandboxPID=$(ss -lptn 'sport = :7575' | grep -P -o '(?<=pid=)([0-9]+)') 10 | if [[ $sandboxPID ]]; then 11 | # kill the sandbox which is running in the background 12 | kill $sandboxPID 13 | rm ports.json 14 | echo "Done" 15 | fi 16 | } 17 | 18 | trap cleanup ERR EXIT 19 | 20 | echo "Compiling daml" 21 | dpm build --all 22 | 23 | pushd main 24 | packageId=$(dpm damlc inspect-dar --json .daml/dist/ex-java-bindings-0.0.2.dar | jq '.main_package_id' -r) 25 | 26 | echo "Generating java code" 27 | dpm codegen-java 28 | popd 29 | 30 | echo "Compiling code" 31 | mvn compile 32 | 33 | # Could also run this manually in another terminal without the redirects 34 | echo "Starting sandbox" 35 | dpm sandbox \ 36 | --ledger-api-port 7600 \ 37 | --json-api-port 7575 \ 38 | --canton-port-file ports.json \ 39 | --dar main/.daml/dist/ex-java-bindings-0.0.2.dar \ 40 | > sandbox.log 2>&1 & PID=$! 41 | 42 | echo "Waiting for sandbox to write the port file" 43 | until [ -e ports.json ]; do sleep 1; done 44 | 45 | echo "Running the script" 46 | dpm script \ 47 | --dar script/.daml/dist/ex-java-bindings-script-0.0.2.dar \ 48 | --ledger-host localhost \ 49 | --ledger-port 7600 \ 50 | --script-name PingPongTest:setup 51 | 52 | 53 | while [[ "$(getSandboxPid)" -eq '' ]] 54 | do 55 | sleep 1 56 | done 57 | 58 | echo "Running the java program" 59 | mvn exec:java -Dexec.mainClass=$1 -Dpackage.id=$packageId -Dexec.args="localhost 7600" 60 | -------------------------------------------------------------------------------- /StockExchange/setup.sh: -------------------------------------------------------------------------------- 1 | #!/usr/bin/env bash 2 | set -o pipefail 3 | 4 | function build_example() { 5 | echo "Compiling daml" 6 | dpm build 7 | 8 | echo "Generating java code" 9 | dpm codegen-java 10 | 11 | echo "Compiling code" 12 | mvn compile 13 | } 14 | 15 | function start_canton() { 16 | CANTON_PATH=$1 17 | if [[ -z "$CANTON_PATH" ]]; then 18 | echo "Pass the path to the Canton install dir" 19 | else 20 | echo "Starting Canton" 21 | "$CANTON_PATH"/bin/canton daemon -c canton_ledger.conf --bootstrap stock_exchange_bootstrap_script.canton 22 | fi 23 | } 24 | 25 | function run_stock_exchange() { 26 | echo "Running StockExchange" 27 | stockExchangePartiesFile="temp_stock_exchange_example/stock_exchange_parties.txt" 28 | if [ -e "$stockExchangePartiesFile" ]; then 29 | buyerPartyId=$(sed -n "3p" $stockExchangePartiesFile) 30 | sellerPartyId=$(sed -n "4p" $stockExchangePartiesFile) 31 | stockExchangePartyId=$(sed -n "1p" $stockExchangePartiesFile) 32 | mvn exec:java -Dexec.mainClass=examples.stockexchange.parties.Bank -Dexec.args="5021 Bank ""$buyerPartyId"" 10" 33 | mvn exec:java -Dexec.mainClass=examples.stockexchange.parties.StockExchange -Dexec.args="5011 StockExchange ""$sellerPartyId"" Daml 3" 34 | mvn exec:java -Dexec.mainClass=examples.stockexchange.parties.Seller -Dexec.args="5041 Seller ""$stockExchangePartyId""" 35 | mvn exec:java -Dexec.mainClass=examples.stockexchange.parties.Buyer -Dexec.args="5031 Buyer" 36 | echo "Finished StockExchange example" 37 | else 38 | echo "'$stockExchangePartiesFile' does not exist. Check that the current user has write rights in the current dir and run start_canton before running this function" 39 | fi 40 | } 41 | -------------------------------------------------------------------------------- /StockExchange/src/main/java/examples/stockexchange/ParticipantSession.java: -------------------------------------------------------------------------------- 1 | package examples.stockexchange; 2 | 3 | import com.daml.ledger.api.v2.CommandServiceGrpc; 4 | import com.daml.ledger.api.v2.StateServiceGrpc; 5 | import com.daml.ledger.api.v2.admin.UserManagementServiceGrpc; 6 | import com.daml.ledger.api.v2.admin.UserManagementServiceGrpc.UserManagementServiceBlockingStub; 7 | import com.daml.ledger.javaapi.data.GetUserRequest; 8 | import com.daml.ledger.api.v2.StateServiceGrpc.StateServiceBlockingStub; 9 | import io.grpc.ManagedChannel; 10 | import io.grpc.ManagedChannelBuilder; 11 | 12 | public class ParticipantSession implements AutoCloseable { 13 | private final String partyId; 14 | private final ManagedChannel channel; 15 | private final StateServiceBlockingStub stateService; 16 | private final UserManagementServiceBlockingStub userManagementService; 17 | private final CommandServiceGrpc.CommandServiceBlockingStub commandService; 18 | 19 | public ParticipantSession(int ledgerApiPort, String userId) { 20 | channel = ManagedChannelBuilder.forAddress("127.0.0.1", ledgerApiPort).usePlaintext().build(); 21 | stateService = StateServiceGrpc.newBlockingStub(channel); 22 | userManagementService = UserManagementServiceGrpc.newBlockingStub(channel); 23 | commandService = CommandServiceGrpc.newBlockingStub(channel); 24 | this.partyId = 25 | userManagementService 26 | .getUser(new GetUserRequest(userId).toProto()) 27 | .getUser() 28 | .getPrimaryParty(); 29 | } 30 | 31 | public String getPartyId() { 32 | return partyId; 33 | } 34 | 35 | public StateServiceBlockingStub getStateService() { return stateService; } 36 | public CommandServiceGrpc.CommandServiceBlockingStub getCommandService() { return commandService; } 37 | 38 | @Override 39 | public void close() throws Exception { 40 | channel.shutdown(); 41 | } 42 | } 43 | -------------------------------------------------------------------------------- /StockExchange/src/main/java/examples/stockexchange/parties/Bank.java: -------------------------------------------------------------------------------- 1 | package examples.stockexchange.parties; 2 | 3 | import com.daml.ledger.javaapi.data.Command; 4 | import com.daml.ledger.javaapi.data.CommandsSubmission; 5 | import com.daml.ledger.javaapi.data.SubmitAndWaitRequest; 6 | import examples.codegen.stockexchange.IOU; 7 | import examples.stockexchange.Common; 8 | import examples.stockexchange.ParticipantSession; 9 | import java.util.List; 10 | import java.util.Optional; 11 | import java.util.UUID; 12 | import org.slf4j.Logger; 13 | import org.slf4j.LoggerFactory; 14 | 15 | public class Bank { 16 | private static final Logger logger = LoggerFactory.getLogger(Bank.class); 17 | 18 | public static void main(String[] args) throws Exception { 19 | if (args.length < 4) 20 | throw new IllegalArgumentException( 21 | "Arguments: "); 22 | int ledgerApiPort = Integer.parseInt(args[0]); 23 | String userId = args[1]; 24 | String buyerPartyId = args[2]; 25 | long issuedIouValue = Long.parseLong(args[3]); 26 | 27 | logger.info("BANK: Initializing"); 28 | 29 | try (ParticipantSession participantSession = new ParticipantSession(ledgerApiPort, userId)) { 30 | issueIou(participantSession, buyerPartyId, issuedIouValue); 31 | } 32 | } 33 | 34 | private static void issueIou( 35 | ParticipantSession participantSession, String buyerPartyId, long issuedIouValue) { 36 | List newIouCommand = 37 | new IOU(participantSession.getPartyId(), buyerPartyId, issuedIouValue).create().commands(); 38 | CommandsSubmission commandsSubmission = 39 | CommandsSubmission.create(Common.APP_ID, UUID.randomUUID().toString(), Optional.empty(), newIouCommand) 40 | .withWorkflowId("Bank-issue-IOU") 41 | .withActAs(participantSession.getPartyId()); 42 | 43 | logger.info("BANK: Issuing IOU with value {} to {}", issuedIouValue, buyerPartyId); 44 | participantSession 45 | .getCommandService() 46 | .submitAndWait(SubmitAndWaitRequest.toProto(commandsSubmission)); 47 | 48 | logger.info("BANK: Done"); 49 | } 50 | } 51 | -------------------------------------------------------------------------------- /StockExchange/daml/StockExchange.daml: -------------------------------------------------------------------------------- 1 | module StockExchange where 2 | 3 | import DA.Assert 4 | import DA.Action 5 | 6 | template IOU 7 | with 8 | issuer: Party 9 | owner: Party 10 | value: Int 11 | where 12 | signatory issuer 13 | observer owner 14 | 15 | choice IOU_Transfer: () 16 | with 17 | target: Party 18 | amount: Int 19 | controller owner 20 | do 21 | -- Check that the transferred amount is not higher than the current IOU value 22 | assert (value >= amount) 23 | create this with issuer = issuer, owner = target, value = amount 24 | -- No need to create a new IOU for owner if the full value is transferred 25 | if value == amount then pure () 26 | else void $ create this with issuer = issuer, owner = owner, value = value - amount 27 | pure () 28 | 29 | template Stock 30 | with 31 | issuer: Party 32 | owner: Party 33 | stockName: Text 34 | where 35 | signatory issuer 36 | observer owner 37 | 38 | choice Stock_Transfer: () 39 | with 40 | newOwner: Party 41 | controller owner 42 | do 43 | create this with owner = newOwner 44 | pure () 45 | 46 | template PriceQuotation 47 | with 48 | issuer: Party 49 | stockName: Text 50 | value: Int 51 | where 52 | signatory issuer 53 | 54 | nonconsuming choice PriceQuotation_Fetch: PriceQuotation 55 | with fetcher: Party 56 | controller fetcher 57 | do pure this 58 | 59 | template Offer 60 | with 61 | seller: Party 62 | quotationProducer: Party 63 | offeredAssetCid: ContractId Stock 64 | where 65 | signatory seller 66 | 67 | choice Offer_Accept: () 68 | with 69 | priceQuotationCid: ContractId PriceQuotation 70 | buyer: Party 71 | buyerIou: ContractId IOU 72 | controller buyer 73 | do 74 | priceQuotation <- exercise 75 | priceQuotationCid PriceQuotation_Fetch with 76 | fetcher = buyer 77 | asset <- fetch offeredAssetCid 78 | 79 | -- Assert the quotation issuer and asset name 80 | priceQuotation.issuer === quotationProducer 81 | priceQuotation.stockName === asset.stockName 82 | 83 | _ <- exercise 84 | offeredAssetCid Stock_Transfer with 85 | newOwner = buyer 86 | 87 | _ <- exercise 88 | buyerIou IOU_Transfer with target = seller, amount = priceQuotation.value 89 | pure () 90 | -------------------------------------------------------------------------------- /StockExchange/stock_exchange_bootstrap_script.canton: -------------------------------------------------------------------------------- 1 | import java.nio.file.{Paths, Files, StandardOpenOption} 2 | import java.nio.charset.StandardCharsets 3 | import com.digitalasset.canton.config.RequireTypes.PositiveInt 4 | import com.digitalasset.canton.version.ProtocolVersion 5 | 6 | nodes.local.start() 7 | 8 | val staticSynchronizerParameters = StaticSynchronizerParameters.defaults(local.config.crypto, ProtocolVersion.forSynchronizer) 9 | val synchronizerOwners = Seq(local, localMediator) 10 | bootstrap.synchronizer("mysynchronizer", Seq(local), Seq(localMediator), synchronizerOwners, PositiveInt.one, staticSynchronizerParameters) 11 | 12 | stockExchangeParticipant.synchronizers.connect_local(local, "mysynchronizer") 13 | bankParticipant.synchronizers.connect_local(local, "mysynchronizer") 14 | buyerParticipant.synchronizers.connect_local(local, "mysynchronizer") 15 | sellerParticipant.synchronizers.connect_local(local, "mysynchronizer") 16 | 17 | println("All nodes are ready.") 18 | 19 | val javaBindingsDarPath = ".daml/dist/ex-java-bindings-stock-exchange-0.0.1.dar" 20 | 21 | stockExchangeParticipant.dars.upload(javaBindingsDarPath) 22 | bankParticipant.dars.upload(javaBindingsDarPath) 23 | buyerParticipant.dars.upload(javaBindingsDarPath) 24 | sellerParticipant.dars.upload(javaBindingsDarPath) 25 | 26 | val stockExchange = stockExchangeParticipant.parties.enable("stockExchange") 27 | val bank = bankParticipant.parties.enable("bank") 28 | val buyer = buyerParticipant.parties.enable("buyer") 29 | val seller = sellerParticipant.parties.enable("seller") 30 | 31 | // Write party ids to a file for allowing easy discovery 32 | val partiesFileContent = s"${stockExchange.toProtoPrimitive}\n${bank.toProtoPrimitive}\n${buyer.toProtoPrimitive}\n${seller.toProtoPrimitive}" 33 | Files.createDirectories(Paths.get("temp_stock_exchange_example")); 34 | Files.write(Paths.get("temp_stock_exchange_example/stock_exchange_parties.txt"), partiesFileContent.getBytes(StandardCharsets.UTF_8)) 35 | 36 | println("Waiting for the parties to appear on their hosting participants' Ledger API...") 37 | utils.retry_until_true(buyerParticipant.ledger_api.parties.list().exists(_.party.toProtoPrimitive.toString.startsWith("buyer::"))) 38 | utils.retry_until_true(sellerParticipant.ledger_api.parties.list().exists(_.party.toProtoPrimitive.toString.startsWith("seller::"))) 39 | utils.retry_until_true(bankParticipant.ledger_api.parties.list().exists(_.party.toProtoPrimitive.toString.startsWith("bank::"))) 40 | utils.retry_until_true(stockExchangeParticipant.ledger_api.parties.list().exists(_.party.toProtoPrimitive.toString.startsWith("stockExchange::"))) 41 | 42 | stockExchangeParticipant.ledger_api.users.create("StockExchange", actAs = Set(stockExchange), primaryParty = Some(stockExchange)) 43 | bankParticipant.ledger_api.users.create("Bank", actAs = Set(bank), primaryParty = Some(bank)) 44 | buyerParticipant.ledger_api.users.create("Buyer", actAs = Set(buyer), primaryParty = Some(buyer)) 45 | sellerParticipant.ledger_api.users.create("Seller", actAs = Set(seller), primaryParty = Some(seller)) 46 | 47 | println("Canton server initialization DONE") 48 | -------------------------------------------------------------------------------- /StockExchange/src/main/java/examples/stockexchange/Common.java: -------------------------------------------------------------------------------- 1 | package examples.stockexchange; 2 | 3 | import com.daml.ledger.api.v2.StateServiceGrpc.StateServiceBlockingStub; 4 | import com.daml.ledger.api.v2.StateServiceOuterClass.GetLedgerEndRequest; 5 | import com.daml.ledger.javaapi.data.*; 6 | import com.google.protobuf.ByteString; 7 | import java.io.*; 8 | import java.util.Base64; 9 | import java.util.Collections; 10 | import java.util.Optional; 11 | import java.util.Set; 12 | 13 | public class Common { 14 | public static final String APP_ID = "StockExchangeApp"; 15 | public static final String PRICE_QUOTATION_DISCLOSED_CONTRACT_FILE = 16 | "temp_stock_exchange_example/price_quotation_disclosed_contract.txt"; 17 | public static final String STOCK_DISCLOSED_CONTRACT_FILE = 18 | "temp_stock_exchange_example/stock_disclosed_contract.txt"; 19 | public static final String OFFER_DISCLOSED_CONTRACT_FILE = 20 | "temp_stock_exchange_example/offer_disclosed_contract.txt"; 21 | 22 | public static DisclosedContract fetchContractForDisclosure( 23 | StateServiceBlockingStub client, String reader, ContractFilter contractFilter) { 24 | Long ledgerEnd = client.getLedgerEnd(GetLedgerEndRequest.newBuilder().build()).getOffset(); 25 | EventFormat eventFormat = contractFilter.withIncludeCreatedEventBlob(true).eventFormat(Optional.of(Set.of(reader))); 26 | CreatedEvent event = CreatedEvent.fromProto( 27 | client 28 | .getActiveContracts(new GetActiveContractsRequest(eventFormat, ledgerEnd).toProto()) 29 | .next() 30 | .getActiveContract() 31 | .getCreatedEvent()); 32 | return new DisclosedContract( 33 | event.getTemplateId(), event.getContractId(), event.getCreatedEventBlob()); 34 | } 35 | 36 | public static void shareDisclosedContract(DisclosedContract disclosedContract, String fileName) 37 | throws IOException { 38 | try (BufferedWriter writer = new BufferedWriter(new FileWriter(fileName, false))) { 39 | writer.append( 40 | String.format( 41 | "%s,%s,%s,%s,%s", 42 | disclosedContract.contractId.orElse(""), 43 | disclosedContract.templateId.map(Identifier::getPackageId).orElse(""), 44 | disclosedContract.templateId.map(Identifier::getModuleName).orElse(""), 45 | disclosedContract.templateId.map(Identifier::getEntityName).orElse(""), 46 | Base64.getEncoder() 47 | .encodeToString(disclosedContract.createdEventBlob.toByteArray()))); 48 | } 49 | } 50 | 51 | public static DisclosedContract readDisclosedContract(String fileName) throws IOException { 52 | try (FileReader fr = new FileReader(fileName); 53 | BufferedReader bufferedReader = new BufferedReader(fr)) { 54 | return Optional.ofNullable(bufferedReader.readLine()) 55 | .map( 56 | line -> { 57 | String[] splitted = line.split(","); 58 | return new DisclosedContract( 59 | new Identifier(splitted[1], splitted[2], splitted[3]), 60 | splitted[0], 61 | ByteString.copyFrom(Base64.getDecoder().decode(splitted[4]))); 62 | }) 63 | .orElseThrow( 64 | () -> new IllegalArgumentException(String.format("File %s was empty", fileName))); 65 | } 66 | } 67 | } 68 | -------------------------------------------------------------------------------- /.github/workflows/cla.yml: -------------------------------------------------------------------------------- 1 | name: "CLA Assistant" 2 | on: 3 | issue_comment: 4 | types: [created] 5 | pull_request_target: 6 | types: [opened,closed,synchronize] 7 | 8 | # explicitly configure permissions, in case your GITHUB_TOKEN workflow permissions are set to read-only in repository settings 9 | permissions: 10 | actions: write 11 | contents: write # this can be 'read' if the signatures are in remote repository 12 | pull-requests: write 13 | statuses: write 14 | 15 | jobs: 16 | CLAAssistant: 17 | runs-on: ubuntu-latest 18 | steps: 19 | - name: "CLA Assistant" 20 | if: (github.event.comment.body == 'recheck' || github.event.comment.body == 'I have hereby read the Digital Asset CLA and agree to its terms') || github.event_name == 'pull_request_target' 21 | uses: digital-asset/cla-action@v0.0.2 22 | env: 23 | GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }} 24 | # the below token should have repo scope and must be manually added by you in the repository's secret 25 | # This token is required only if you have configured to store the signatures in a remote repository/organization 26 | PERSONAL_ACCESS_TOKEN: ${{ secrets.PAT_FG_CCI_VALIDATOR_CLA }} 27 | with: 28 | path-to-document: 'https://github.com/digital-asset/daml/blob/main/CODE_OF_CONDUCT.md' # e.g. a CLA or a DCO document 29 | # branch should not be protected 30 | branch: 'main' 31 | allowlist: bot* 32 | custom-notsigned-prcomment: '🎉 Thank you for your contribution! It appears you have not yet signed the Agreement [DA Contributor License Agreement (CLA)](https://gist.github.com/digitalasset-cla), which is required for your changes to be incorporated into an Open Source Software (OSS) project. Please kindly read the and reply on a new comment with the following text to agree:' 33 | custom-pr-sign-comment: 'I have hereby read the Digital Asset CLA and agree to its terms' 34 | custom-allsigned-prcomment: '✅ All required contributors have signed the CLA for this PR. Thank you!' 35 | # Remote repository storing CLA signatures. 36 | remote-organization-name: DACH-NY 37 | remote-repository-name: cla-action-data 38 | # Branch where CLA signatures are stored. 39 | path-to-signatures: signatures/signatures.json 40 | 41 | # the followings are the optional inputs - If the optional inputs are not given, then default values will be taken 42 | #remote-organization-name: enter the remote organization name where the signatures should be stored (Default is storing the signatures in the same repository) 43 | #remote-repository-name: enter the remote repository name where the signatures should be stored (Default is storing the signatures in the same repository) 44 | #create-file-commit-message: 'For example: Creating file for storing CLA Signatures' 45 | #signed-commit-message: 'For example: $contributorName has signed the CLA in $owner/$repo#$pullRequestNo' 46 | #custom-notsigned-prcomment: 'pull request comment with Introductory message to ask new contributors to sign' 47 | #custom-pr-sign-comment: 'The signature to be committed in order to sign the CLA' 48 | #custom-allsigned-prcomment: 'pull request comment when all contributors has signed, defaults to **CLA Assistant Lite bot** All Contributors have signed the CLA.' 49 | #lock-pullrequest-aftermerge: false - if you don't want this bot to automatically lock the pull request after merging (default - true) 50 | #use-dco-flag: true - If you are using DCO instead of CLA 51 | -------------------------------------------------------------------------------- /StockExchange/README.rst: -------------------------------------------------------------------------------- 1 | Example of Explicit Disclosure with Java Bindings 2 | ---------------------------------------------- 3 | 4 | :: 5 | 6 | Copyright (c) 2025 Digital Asset (Switzerland) GmbH and/or its affiliates. All rights reserved. 7 | SPDX-License-Identifier: Apache-2.0.0 8 | 9 | This project demonstrates the usage of `Explicit Contract Disclosure `_ 10 | in Daml client applications built with the `Java Binding library `_. 11 | 12 | In this example, four parties, each hosted on their own participant (see the topology configuration in `canton_ledger.conf `_), are involved in a simplified trade. 13 | Each party interacts with the Canton ledger via a standalone Java application. The example interaction flow is modelled as follows: 14 | 15 | - Party **Bank** (see `Bank `_) issues ``IOU`` as units of cash to the **Buyer** 16 | - Party **StockExchange** (see `StockExchange `_) issues ``Stock`` as on-ledger asset to the **Seller** party. 17 | Additionally, it issues price ticks for the stock as ``PriceQuotation``. Since **StockExchange** is the sole stakeholder of the ``PriceQuotation``, 18 | it discloses the contract for usage as reference data in commands requiring it as an input. 19 | - Then, party **Seller** (see `Seller `_) owns a unit of ``Stock`` issued by the **StockExchange**. 20 | **Seller** creates an ``Offer`` contract on-ledger that can be accepted by any interested party (see ``Offer_Accept`` in the Daml model). 21 | Similarly to the **StockExchange**, the **Seller** discloses its ``Stock`` and ``Offer`` contracts off-ledger 22 | for interested parties. 23 | - **Buyer** (see `Buyer `_) owns an amount of ``IOU`` issued by **Bank**. 24 | **Buyer** wants to exchange with the **Seller** and accepts its ``Offer`` on-ledger at the correct ``IOU`` market value in exchange of **Seller** s ``Stock``. 25 | In the command submission that exercises ``Offer_Accept``, the **Buyer** uses contracts previously disclosed by the **Seller** and **StockExchange**. 26 | 27 | **Note**: For illustration, the disclosed contracts in this project are shared via files. 28 | (see `Common.shareDisclosedContract `_). 29 | 30 | The Daml model for the templates involved is located in `daml/StockExchange.daml `_`. 31 | 32 | For a better understanding of the explicit disclosure concept and off-ledger data sharing, refer to the 33 | `Explicit Contract Disclosure `_ documentation 34 | where this example's flow is also presented in more detail. 35 | 36 | Running the example 37 | =================== 38 | 39 | #. If you do not have it already, install the DAML SDK by running:: 40 | 41 | curl -sSL https://get.digitalasset.com/install/install.sh | sh -s 3.4.9 42 | 43 | #. Use the setup script for exposing the bash example utility functions in two shell terminal windows 44 | 45 | source setup.sh 46 | 47 | #. In one terminal, build the project 48 | 49 | build_example 50 | 51 | #. In the other terminal, start the Canton ledger and wait for initialization until the process prints *Canton server initialization DONE* 52 | 53 | start_canton 54 | 55 | #. In the first terminal, run the example 56 | 57 | run_stock_exchange 58 | -------------------------------------------------------------------------------- /StockExchange/src/main/java/examples/stockexchange/parties/Buyer.java: -------------------------------------------------------------------------------- 1 | package examples.stockexchange.parties; 2 | 3 | import com.daml.ledger.api.v2.*; 4 | import com.daml.ledger.javaapi.data.*; 5 | import examples.codegen.stockexchange.IOU; 6 | import examples.codegen.stockexchange.Offer; 7 | import examples.codegen.stockexchange.PriceQuotation; 8 | import examples.stockexchange.Common; 9 | import examples.stockexchange.ParticipantSession; 10 | import java.io.IOException; 11 | import java.util.*; 12 | 13 | import org.slf4j.Logger; 14 | import org.slf4j.LoggerFactory; 15 | 16 | public class Buyer { 17 | private static final Logger logger = LoggerFactory.getLogger(Buyer.class); 18 | 19 | public static void main(String[] args) throws Exception { 20 | if (args.length < 2) 21 | throw new IllegalArgumentException("Arguments: "); 22 | int ledgerApiPort = Integer.parseInt(args[0]); 23 | String userId = args[1]; 24 | 25 | logger.info("BUYER: Initializing"); 26 | 27 | try (ParticipantSession participantSession = new ParticipantSession(ledgerApiPort, userId)) { 28 | acceptOffer(participantSession); 29 | } 30 | } 31 | 32 | private static void acceptOffer(ParticipantSession participantSession) throws IOException { 33 | logger.info("BUYER: Fetching contract-id of owned IOU"); 34 | StateServiceGrpc.StateServiceBlockingStub stateClient = participantSession.getStateService(); 35 | 36 | Long ledgerEnd = stateClient.getLedgerEnd(StateServiceOuterClass.GetLedgerEndRequest.newBuilder().build()).getOffset(); 37 | 38 | EventFormat eventFormat = IOU.contractFilter().eventFormat(Optional.of(Set.of(participantSession.getPartyId()))); 39 | 40 | IOU.ContractId iouCid = 41 | new IOU.ContractId( 42 | stateClient 43 | .getActiveContracts(new GetActiveContractsRequest(eventFormat, ledgerEnd).toProto()) 44 | .next() 45 | .getActiveContract() 46 | .getCreatedEvent() 47 | .getContractId()); 48 | 49 | logger.info("BUYER: Reading shared disclosed contracts"); 50 | DisclosedContract offer = Common.readDisclosedContract(Common.OFFER_DISCLOSED_CONTRACT_FILE); 51 | DisclosedContract priceQuotation = 52 | Common.readDisclosedContract(Common.PRICE_QUOTATION_DISCLOSED_CONTRACT_FILE); 53 | DisclosedContract stock = Common.readDisclosedContract(Common.STOCK_DISCLOSED_CONTRACT_FILE); 54 | 55 | List disclosedContracts = new java.util.ArrayList<>(); 56 | disclosedContracts.add(priceQuotation); 57 | disclosedContracts.add(offer); 58 | disclosedContracts.add(stock); 59 | 60 | List exerciseAcceptOfferCommand = 61 | new Offer.ContractId(validateContractId(offer.contractId, "offer")) 62 | .exerciseOffer_Accept( 63 | new PriceQuotation.ContractId(validateContractId(priceQuotation.contractId, "priceQuotation")), 64 | participantSession.getPartyId(), 65 | iouCid) 66 | .commands(); 67 | 68 | CommandsSubmission commandsSubmission = 69 | CommandsSubmission.create( 70 | Common.APP_ID, UUID.randomUUID().toString(), Optional.empty(), exerciseAcceptOfferCommand) 71 | .withWorkflowId("Buyer-buy-stock") 72 | .withDisclosedContracts(disclosedContracts) 73 | .withActAs(participantSession.getPartyId()); 74 | 75 | logger.info("BUYER: Submitting command for offer acceptance"); 76 | participantSession 77 | .getCommandService() 78 | .submitAndWait(SubmitAndWaitRequest.toProto(commandsSubmission)); 79 | 80 | logger.info("BUYER: Success"); 81 | } 82 | 83 | private static String validateContractId(Optional contractId, String where) { 84 | return contractId 85 | .orElseThrow( 86 | () -> new RuntimeException(String.format("contractId not set for %s", where))); 87 | } 88 | } 89 | -------------------------------------------------------------------------------- /StockExchange/src/main/java/examples/stockexchange/parties/Seller.java: -------------------------------------------------------------------------------- 1 | package examples.stockexchange.parties; 2 | 3 | import com.daml.ledger.api.v2.StateServiceGrpc; 4 | import com.daml.ledger.api.v2.StateServiceOuterClass; 5 | import com.daml.ledger.javaapi.data.*; 6 | import examples.codegen.stockexchange.IOU; 7 | import examples.codegen.stockexchange.Offer; 8 | import examples.codegen.stockexchange.Stock; 9 | import examples.stockexchange.Common; 10 | import examples.stockexchange.ParticipantSession; 11 | import java.io.IOException; 12 | import java.util.*; 13 | 14 | import org.slf4j.Logger; 15 | import org.slf4j.LoggerFactory; 16 | 17 | public class Seller { 18 | private static final Logger logger = LoggerFactory.getLogger(Seller.class); 19 | 20 | public static void main(String[] args) throws Exception { 21 | logger.info("SELLER: Initializing"); 22 | 23 | if (args.length < 3) 24 | throw new IllegalArgumentException( 25 | "Arguments: "); 26 | 27 | int ledgerApiPort = Integer.parseInt(args[0]); 28 | String userId = args[1]; 29 | String stockExchangePartyId = args[2]; 30 | 31 | try (ParticipantSession participantSession = new ParticipantSession(ledgerApiPort, userId)) { 32 | announceStockSaleOffer(stockExchangePartyId, participantSession); 33 | } 34 | } 35 | 36 | private static void announceStockSaleOffer( 37 | String stockExchangePartyId, ParticipantSession participantSession) throws IOException { 38 | logger.info("SELLER: Fetching contract-id of owned Stock"); 39 | 40 | StateServiceGrpc.StateServiceBlockingStub stateClient = participantSession.getStateService(); 41 | 42 | Long ledgerEnd = stateClient.getLedgerEnd(StateServiceOuterClass.GetLedgerEndRequest.newBuilder().build()).getOffset(); 43 | 44 | EventFormat eventFormat = Stock.contractFilter().eventFormat(Optional.of(Set.of(participantSession.getPartyId()))); 45 | 46 | Stock.ContractId stockCid = 47 | new Stock.ContractId( 48 | stateClient 49 | .getActiveContracts(new GetActiveContractsRequest(eventFormat, ledgerEnd).toProto()) 50 | .next() 51 | .getActiveContract() 52 | .getCreatedEvent() 53 | .getContractId()); 54 | 55 | List createOfferCommand = 56 | new Offer(participantSession.getPartyId(), stockExchangePartyId, stockCid) 57 | .create() 58 | .commands(); 59 | 60 | CommandsSubmission commandsSubmission = 61 | CommandsSubmission.create(Common.APP_ID, UUID.randomUUID().toString(), Optional.empty(), createOfferCommand) 62 | .withWorkflowId("Seller-Offer") 63 | .withActAs(participantSession.getPartyId()); 64 | 65 | logger.info("SELLER: Creating on-ledger Offer for selling owned Stock"); 66 | participantSession 67 | .getCommandService() 68 | .submitAndWait(SubmitAndWaitRequest.toProto(commandsSubmission)); 69 | 70 | logger.info("SELLER: Fetching Stock disclosed contract for sharing"); 71 | DisclosedContract stockDisclosedContract = 72 | Common.fetchContractForDisclosure( 73 | participantSession.getStateService(), 74 | participantSession.getPartyId(), 75 | Stock.contractFilter()); 76 | 77 | logger.info("SELLER: Fetching Offer disclosed contract for sharing"); 78 | DisclosedContract offerDisclosedContract = 79 | Common.fetchContractForDisclosure( 80 | participantSession.getStateService(), 81 | participantSession.getPartyId(), 82 | Offer.contractFilter()); 83 | 84 | logger.info("SELLER: Sharing Stock disclosed contract"); 85 | Common.shareDisclosedContract(stockDisclosedContract, Common.STOCK_DISCLOSED_CONTRACT_FILE); 86 | 87 | logger.info("SELLER: Sharing Offer disclosed contract"); 88 | Common.shareDisclosedContract(offerDisclosedContract, Common.OFFER_DISCLOSED_CONTRACT_FILE); 89 | 90 | logger.info("SELLER: Done"); 91 | } 92 | } 93 | -------------------------------------------------------------------------------- /StockExchange/src/main/java/examples/stockexchange/parties/StockExchange.java: -------------------------------------------------------------------------------- 1 | package examples.stockexchange.parties; 2 | 3 | import static examples.stockexchange.Common.APP_ID; 4 | import static examples.stockexchange.Common.fetchContractForDisclosure; 5 | 6 | import com.daml.ledger.javaapi.data.*; 7 | import examples.codegen.stockexchange.PriceQuotation; 8 | import examples.codegen.stockexchange.Stock; 9 | import examples.stockexchange.Common; 10 | import examples.stockexchange.ParticipantSession; 11 | import java.io.IOException; 12 | import java.util.List; 13 | import java.util.Optional; 14 | import java.util.Set; 15 | import java.util.UUID; 16 | import org.slf4j.Logger; 17 | import org.slf4j.LoggerFactory; 18 | 19 | public class StockExchange { 20 | private static final Logger logger = LoggerFactory.getLogger(StockExchange.class); 21 | 22 | public static void main(String[] args) throws Exception { 23 | logger.info("STOCK_EXCHANGE: Initializing"); 24 | 25 | if (args.length < 5) 26 | throw new IllegalArgumentException( 27 | "Arguments: "); 28 | int ledgerApiPort = Integer.parseInt(args[0]); 29 | String userId = args[1]; 30 | String sellerPartyId = args[2]; 31 | String issuedStockName = args[3]; 32 | long issuedStockPriceQuotation = Long.parseLong(args[4]); 33 | 34 | try (ParticipantSession participantSession = new ParticipantSession(ledgerApiPort, userId)) { 35 | issueStockAndPriceQuotation( 36 | sellerPartyId, issuedStockName, issuedStockPriceQuotation, participantSession); 37 | } 38 | } 39 | 40 | private static void issueStockAndPriceQuotation( 41 | String sellerPartyId, 42 | String issuedStockName, 43 | long issuedStockPriceQuotation, 44 | ParticipantSession participantSession) 45 | throws IOException { 46 | List createStockCommand = 47 | new Stock(participantSession.getPartyId(), sellerPartyId, issuedStockName) 48 | .create() 49 | .commands(); 50 | 51 | CommandsSubmission issueStockSubmission = 52 | CommandsSubmission.create(APP_ID, UUID.randomUUID().toString(), Optional.empty(), createStockCommand) 53 | .withWorkflowId("Stock-issue") 54 | .withActAs(participantSession.getPartyId()); 55 | 56 | logger.info("STOCK_EXCHANGE: Issuing stock with name {} to {}", issuedStockName, sellerPartyId); 57 | participantSession 58 | .getCommandService() 59 | .submitAndWait(SubmitAndWaitRequest.toProto(issueStockSubmission)); 60 | 61 | List createPriceQuotationCommand = 62 | new PriceQuotation( 63 | participantSession.getPartyId(), issuedStockName, issuedStockPriceQuotation) 64 | .create() 65 | .commands(); 66 | 67 | CommandsSubmission emitPriceQuotationSubmission = 68 | CommandsSubmission.create(APP_ID, UUID.randomUUID().toString(), Optional.empty(), createPriceQuotationCommand) 69 | .withWorkflowId("PriceQuotation-issue") 70 | .withActAs(participantSession.getPartyId()); 71 | 72 | TransactionFormat transactionFormat = PriceQuotation.contractFilter().transactionFormat(Optional.of(Set.of(participantSession.getPartyId()))); 73 | 74 | logger.info( 75 | "STOCK_EXCHANGE: Emitting price quotation for {} at value {}", 76 | issuedStockName, 77 | issuedStockPriceQuotation); 78 | participantSession 79 | .getCommandService() 80 | .submitAndWaitForTransaction(new SubmitAndWaitForTransactionRequest(emitPriceQuotationSubmission, transactionFormat).toProto()) 81 | .getTransaction() 82 | .getEvents(0) 83 | .getCreated() 84 | .getContractId(); 85 | 86 | logger.info( 87 | "STOCK_EXCHANGE: Fetching PriceQuotation for stock with name {} for disclosure", 88 | issuedStockName); 89 | DisclosedContract priceQuotationDisclosedContract = 90 | fetchContractForDisclosure( 91 | participantSession.getStateService(), 92 | participantSession.getPartyId(), 93 | PriceQuotation.contractFilter()); 94 | 95 | logger.info("STOCK_EXCHANGE: Sharing PriceQuotation disclosed contract"); 96 | Common.shareDisclosedContract( 97 | priceQuotationDisclosedContract, Common.PRICE_QUOTATION_DISCLOSED_CONTRACT_FILE); 98 | } 99 | } 100 | -------------------------------------------------------------------------------- /PingPong/src/main/java/examples/pingpong/codegen/PingPongCodegenMain.java: -------------------------------------------------------------------------------- 1 | // Copyright (c) 2025 Digital Asset (Switzerland) GmbH and/or its affiliates. All rights reserved. 2 | // SPDX-License-Identifier: Apache-2.0 3 | 4 | package examples.pingpong.codegen; 5 | 6 | import com.daml.ledger.api.v2.CommandSubmissionServiceGrpc; 7 | import com.daml.ledger.api.v2.CommandSubmissionServiceGrpc.CommandSubmissionServiceFutureStub; 8 | import com.daml.ledger.api.v2.admin.UserManagementServiceGrpc; 9 | import com.daml.ledger.api.v2.admin.UserManagementServiceGrpc.UserManagementServiceBlockingStub; 10 | import com.daml.ledger.api.v2.admin.UserManagementServiceOuterClass.GetUserRequest; 11 | import com.daml.ledger.api.v2.admin.UserManagementServiceOuterClass.GetUserResponse; 12 | import com.daml.ledger.javaapi.data.Command; 13 | import com.daml.ledger.javaapi.data.CommandsSubmission; 14 | import com.daml.ledger.javaapi.data.SubmitRequest; 15 | import examples.pingpong.codegen.pingpong.Ping; 16 | import io.grpc.ManagedChannel; 17 | import io.grpc.ManagedChannelBuilder; 18 | 19 | import java.util.List; 20 | import java.util.Optional; 21 | import java.util.UUID; 22 | 23 | public class PingPongCodegenMain { 24 | 25 | // application id used for sending commands 26 | public static final String APP_ID = "PingPongCodegenApp"; 27 | 28 | // constants for referring to the users with access to the parties 29 | public static final String ALICE_USER = "alice"; 30 | public static final String BOB_USER = "bob"; 31 | 32 | public static void main(String[] args) { 33 | // Extract host and port from arguments 34 | if (args.length < 2) { 35 | System.err.println("Usage: HOST PORT [NUM_INITIAL_CONTRACTS]"); 36 | System.exit(-1); 37 | } 38 | String host = args[0]; 39 | int port = Integer.parseInt(args[1]); 40 | 41 | // each party will create this number of initial Ping contracts 42 | int numInitialContracts = args.length == 3 ? Integer.parseInt(args[2]) : 10; 43 | 44 | // Initialize a plaintext gRPC channel 45 | ManagedChannel channel = ManagedChannelBuilder.forAddress(host, port).usePlaintext().build(); 46 | 47 | // fetch the party IDs that got created in the Daml init script 48 | String aliceParty = fetchPartyId(channel, ALICE_USER); 49 | String bobParty = fetchPartyId(channel, BOB_USER); 50 | 51 | // initialize the ping pong processors for Alice and Bob 52 | PingPongProcessor aliceProcessor = new PingPongProcessor(aliceParty, channel); 53 | PingPongProcessor bobProcessor = new PingPongProcessor(bobParty, channel); 54 | 55 | // start the processors asynchronously 56 | aliceProcessor.runIndefinitely(); 57 | bobProcessor.runIndefinitely(); 58 | 59 | // send the initial commands for both parties 60 | createInitialContracts(channel, aliceParty, bobParty, numInitialContracts); 61 | createInitialContracts(channel, bobParty, aliceParty, numInitialContracts); 62 | 63 | 64 | try { 65 | // wait a couple of seconds for the processing to finish 66 | Thread.sleep(15000); 67 | System.exit(0); 68 | } catch (InterruptedException e) { 69 | e.printStackTrace(); 70 | } 71 | } 72 | 73 | /** 74 | * Creates numContracts number of Ping contracts. The sender is used as the submitting party. 75 | * 76 | * @param channel the gRPC channel to use for services 77 | * @param sender the party that sends the initial Ping contract 78 | * @param receiver the party that receives the initial Ping contract 79 | * @param numContracts the number of initial contracts to create 80 | */ 81 | private static void createInitialContracts(ManagedChannel channel, String sender, String receiver, int numContracts) { 82 | CommandSubmissionServiceFutureStub submissionService = CommandSubmissionServiceGrpc.newFutureStub(channel); 83 | 84 | for (int i = 0; i < numContracts; i++) { 85 | // command that creates the initial Ping contract with the required parameters according to the model 86 | List createCommands = Ping.create(sender, receiver, 0L).commands(); 87 | 88 | // wrap the create command in a command submission 89 | CommandsSubmission commandsSubmission = CommandsSubmission.create( 90 | APP_ID, 91 | UUID.randomUUID().toString(), 92 | Optional.empty(), 93 | createCommands) 94 | .withActAs(List.of(sender)) 95 | .withReadAs(List.of(sender)) 96 | .withWorkflowId(String.format("Ping-%s-%d", sender, i)); 97 | 98 | // convert the command submission to a proto data structure 99 | final var request = SubmitRequest.toProto(commandsSubmission); 100 | // asynchronously send the request 101 | submissionService.submit(request); 102 | } 103 | } 104 | 105 | private static String fetchPartyId(ManagedChannel channel, String userId) { 106 | UserManagementServiceBlockingStub userManagementService = UserManagementServiceGrpc.newBlockingStub(channel); 107 | GetUserResponse getUserResponse = userManagementService.getUser(GetUserRequest.newBuilder().setUserId(userId).build()); 108 | return getUserResponse.getUser().getPrimaryParty(); 109 | } 110 | } 111 | -------------------------------------------------------------------------------- /PingPong/src/main/java/examples/pingpong/grpc/PingPongGrpcMain.java: -------------------------------------------------------------------------------- 1 | // Copyright (c) 2025 Digital Asset (Switzerland) GmbH and/or its affiliates. All rights reserved. 2 | // SPDX-License-Identifier: Apache-2.0 3 | 4 | package examples.pingpong.grpc; 5 | 6 | import java.util.Optional; 7 | import java.util.UUID; 8 | 9 | import com.daml.ledger.api.v2.CommandSubmissionServiceGrpc; 10 | import com.daml.ledger.api.v2.CommandSubmissionServiceGrpc.CommandSubmissionServiceFutureStub; 11 | import com.daml.ledger.api.v2.CommandSubmissionServiceOuterClass.SubmitRequest; 12 | import com.daml.ledger.api.v2.CommandsOuterClass.Command; 13 | import com.daml.ledger.api.v2.CommandsOuterClass.Commands; 14 | import com.daml.ledger.api.v2.CommandsOuterClass.CreateCommand; 15 | import com.daml.ledger.api.v2.ValueOuterClass.Identifier; 16 | import com.daml.ledger.api.v2.ValueOuterClass.Record; 17 | import com.daml.ledger.api.v2.ValueOuterClass.RecordField; 18 | import com.daml.ledger.api.v2.ValueOuterClass.Value; 19 | import com.daml.ledger.api.v2.admin.UserManagementServiceGrpc; 20 | import com.daml.ledger.api.v2.admin.UserManagementServiceGrpc.UserManagementServiceBlockingStub; 21 | import com.daml.ledger.api.v2.admin.UserManagementServiceOuterClass.GetUserRequest; 22 | import com.daml.ledger.api.v2.admin.UserManagementServiceOuterClass.GetUserResponse; 23 | 24 | import io.grpc.ManagedChannel; 25 | import io.grpc.ManagedChannelBuilder; 26 | 27 | public class PingPongGrpcMain { 28 | 29 | // application id used for sending commands 30 | public static final String APP_ID = "PingPongGrpcApp"; 31 | 32 | // constants for referring to the users with access to the parties 33 | public static final String ALICE_USER = "alice"; 34 | public static final String BOB_USER = "bob"; 35 | 36 | public static void main(String[] args) { 37 | // Extract host and port from arguments 38 | if (args.length < 2) { 39 | System.err.println("Usage: HOST PORT [NUM_INITIAL_CONTRACTS]"); 40 | System.exit(-1); 41 | } 42 | String host = args[0]; 43 | int port = Integer.parseInt(args[1]); 44 | 45 | // each party will create this number of initial Ping contracts 46 | int numInitialContracts = args.length == 3 ? Integer.parseInt(args[2]) : 10; 47 | 48 | // Initialize a plaintext gRPC channel 49 | ManagedChannel channel = ManagedChannelBuilder.forAddress(host, port).usePlaintext().build(); 50 | 51 | // fetch the party IDs that got created in the Daml init script 52 | String aliceParty = fetchPartyId(channel, ALICE_USER); 53 | String bobParty = fetchPartyId(channel, BOB_USER); 54 | 55 | String packageId = Optional.ofNullable(System.getProperty("package.id")) 56 | .orElseThrow(() -> new RuntimeException("package.id must be specified via sys properties")); 57 | 58 | Identifier pingIdentifier = Identifier.newBuilder() 59 | .setPackageId(packageId) 60 | .setModuleName("PingPong") 61 | .setEntityName("Ping") 62 | .build(); 63 | Identifier pongIdentifier = Identifier.newBuilder() 64 | .setPackageId(packageId) 65 | .setModuleName("PingPong") 66 | .setEntityName("Pong") 67 | .build(); 68 | 69 | // initialize the ping pong processors for Alice and Bob 70 | PingPongProcessor aliceProcessor = new PingPongProcessor(aliceParty, channel, pingIdentifier, pongIdentifier); 71 | PingPongProcessor bobProcessor = new PingPongProcessor(bobParty, channel, pingIdentifier, pongIdentifier); 72 | 73 | // start the processors asynchronously 74 | aliceProcessor.runIndefinitely(); 75 | bobProcessor.runIndefinitely(); 76 | 77 | // send the initial commands for both parties 78 | createInitialContracts(channel, aliceParty, bobParty, pingIdentifier, numInitialContracts); 79 | createInitialContracts(channel, bobParty, aliceParty, pingIdentifier, numInitialContracts); 80 | 81 | 82 | try { 83 | // wait a couple of seconds for the processing to finish 84 | Thread.sleep(15000); 85 | System.exit(0); 86 | } catch (InterruptedException e) { 87 | e.printStackTrace(); 88 | } 89 | } 90 | 91 | /** 92 | * Creates numContracts number of Ping contracts. The sender is used as the submitting party. 93 | * 94 | * @param channel the gRPC channel to use for services 95 | * @param sender the party that sends the initial Ping contract 96 | * @param receiver the party that receives the initial Ping contract 97 | * @param pingIdentifier the PingPong.Ping template identifier 98 | * @param numContracts the number of initial contracts to create 99 | */ 100 | private static void createInitialContracts(ManagedChannel channel, String sender, String receiver, Identifier pingIdentifier, int numContracts) { 101 | CommandSubmissionServiceFutureStub submissionService = CommandSubmissionServiceGrpc.newFutureStub(channel); 102 | 103 | for (int i = 0; i < numContracts; i++) { 104 | // command that creates the initial Ping contract with the required parameters according to the model 105 | Command createCommand = Command.newBuilder().setCreate( 106 | CreateCommand.newBuilder() 107 | .setTemplateId(pingIdentifier) 108 | .setCreateArguments( 109 | Record.newBuilder() 110 | // the identifier for a template's record is the same as the identifier for the template 111 | .setRecordId(pingIdentifier) 112 | .addFields(RecordField.newBuilder().setLabel("sender").setValue(Value.newBuilder().setParty(sender))) 113 | .addFields(RecordField.newBuilder().setLabel("receiver").setValue(Value.newBuilder().setParty(receiver))) 114 | .addFields(RecordField.newBuilder().setLabel("count").setValue(Value.newBuilder().setInt64(0))) 115 | ) 116 | ).build(); 117 | 118 | 119 | SubmitRequest submitRequest = SubmitRequest.newBuilder().setCommands(Commands.newBuilder() 120 | .setCommandId(UUID.randomUUID().toString()) 121 | .setWorkflowId(String.format("Ping-%s-%d", sender, i)) 122 | .addActAs(sender) 123 | .setUserId(APP_ID) 124 | .addCommands(createCommand) 125 | ).build(); 126 | 127 | // asynchronously send the commands 128 | submissionService.submit(submitRequest); 129 | } 130 | } 131 | 132 | private static String fetchPartyId(ManagedChannel channel, String userId) { 133 | UserManagementServiceBlockingStub userManagementService = UserManagementServiceGrpc.newBlockingStub(channel); 134 | GetUserResponse getUserResponse = userManagementService.getUser(GetUserRequest.newBuilder().setUserId(userId).build()); 135 | return getUserResponse.getUser().getPrimaryParty(); 136 | } 137 | } 138 | -------------------------------------------------------------------------------- /PingPong/src/main/java/examples/pingpong/codegen/PingPongProcessor.java: -------------------------------------------------------------------------------- 1 | // Copyright (c) 2025 Digital Asset (Switzerland) GmbH and/or its affiliates. All rights reserved. 2 | // SPDX-License-Identifier: Apache-2.0 3 | 4 | package examples.pingpong.codegen; 5 | 6 | import com.daml.ledger.api.v2.*; 7 | import com.daml.ledger.api.v2.CommandSubmissionServiceGrpc.CommandSubmissionServiceBlockingStub; 8 | import com.daml.ledger.api.v2.EventOuterClass.Event; 9 | import com.daml.ledger.api.v2.TransactionOuterClass.Transaction; 10 | import com.daml.ledger.api.v2.UpdateServiceGrpc.UpdateServiceStub; 11 | import com.daml.ledger.api.v2.UpdateServiceOuterClass.GetUpdatesResponse; 12 | import com.daml.ledger.javaapi.data.*; 13 | import com.daml.ledger.javaapi.data.codegen.Contract; 14 | import com.daml.ledger.javaapi.data.codegen.ContractCompanion; 15 | import com.daml.ledger.javaapi.data.codegen.Exercised; 16 | import com.daml.ledger.javaapi.data.codegen.Update; 17 | import examples.pingpong.codegen.pingpong.Ping; 18 | import examples.pingpong.codegen.pingpong.Pong; 19 | import io.grpc.ManagedChannel; 20 | import io.grpc.stub.StreamObserver; 21 | 22 | import java.util.*; 23 | import java.util.function.Function; 24 | import java.util.stream.Collectors; 25 | import java.util.stream.Stream; 26 | 27 | /** 28 | * This class subscribes to the stream of transactions for a given party and reacts to Ping or Pong contracts. 29 | */ 30 | public class PingPongProcessor { 31 | 32 | private final String party; 33 | 34 | private final UpdateServiceStub transactionService; 35 | private final CommandSubmissionServiceBlockingStub submissionService; 36 | 37 | private final Identifier pingIdentifier; 38 | private final Identifier pongIdentifier; 39 | 40 | public PingPongProcessor(String party, ManagedChannel channel) { 41 | this.party = party; 42 | this.transactionService = UpdateServiceGrpc.newStub(channel); 43 | this.submissionService = CommandSubmissionServiceGrpc.newBlockingStub(channel); 44 | this.pingIdentifier = Ping.TEMPLATE_ID; 45 | this.pongIdentifier = Pong.TEMPLATE_ID; 46 | } 47 | 48 | public void runIndefinitely() { 49 | // restrict the subscription to ping and pong template types through an inclusive filter 50 | final var inclusiveFilter = new CumulativeFilter( 51 | Collections.emptyMap(), 52 | Map.of(pingIdentifier, Filter.Template.HIDE_CREATED_EVENT_BLOB, pongIdentifier, Filter.Template.HIDE_CREATED_EVENT_BLOB), 53 | Optional.empty()); 54 | // specify inclusive filter for the party attached to this processor 55 | final var eventFormat = new EventFormat( 56 | Map.of(party, inclusiveFilter), 57 | Optional.empty(), 58 | true 59 | ); 60 | final var includeTransactions = new TransactionFormat( 61 | eventFormat, 62 | TransactionShape.ACS_DELTA 63 | ); 64 | final var updateFormat = new UpdateFormat( 65 | Optional.of(includeTransactions), 66 | Optional.empty(), 67 | Optional.empty() 68 | ); 69 | // assemble the request for the transaction stream 70 | final var GetUpdatesRequest = new GetUpdatesRequest( 71 | 0L, 72 | Optional.empty(), 73 | updateFormat 74 | ); 75 | 76 | // this StreamObserver reacts to transactions and prints a message if an error occurs or the stream gets closed 77 | StreamObserver transactionObserver = new StreamObserver<>() { 78 | @Override 79 | public void onNext(GetUpdatesResponse value) { 80 | if(value.hasTransaction()) 81 | processTransaction(value.getTransaction()); 82 | } 83 | 84 | @Override 85 | public void onError(Throwable t) { 86 | System.err.printf("%s encountered an error while processing transactions!\n", party); 87 | t.printStackTrace(); 88 | } 89 | 90 | @Override 91 | public void onCompleted() { 92 | System.out.printf("%s's transactions stream completed.\n", party); 93 | } 94 | }; 95 | System.out.printf("%s starts reading transactions.\n", party); 96 | transactionService.getUpdates(GetUpdatesRequest.toProto(), transactionObserver); 97 | } 98 | 99 | /** 100 | * Processes a transaction and sends the resulting commands to the Command Submission Service 101 | * 102 | * @param tx the Transaction to process 103 | */ 104 | private void processTransaction(Transaction tx) { 105 | List commands = tx.getEventsList().stream() 106 | .filter(Event::hasCreated).map(Event::getCreated) 107 | .flatMap(e -> processEvent(tx.getWorkflowId(), e)) 108 | .collect(Collectors.toList()); 109 | 110 | if (!commands.isEmpty()) { 111 | CommandsSubmission commandsSubmission = CommandsSubmission.create( 112 | PingPongCodegenMain.APP_ID, 113 | UUID.randomUUID().toString(), 114 | Optional.empty(), 115 | commands) 116 | .withActAs(List.of(party)) 117 | .withReadAs(List.of(party)) 118 | .withWorkflowId(tx.getWorkflowId()); 119 | submissionService.submit(SubmitRequest.toProto(commandsSubmission)); 120 | } 121 | } 122 | 123 | /** 124 | * For each {@link CreatedEvent} where the receiver is 125 | * the current party, exercise the Pong choice of Ping contracts, or the Ping 126 | * choice of Pong contracts. 127 | * 128 | * @param workflowId the workflow the event is part of 129 | * @param protoEvent the {@link CreatedEvent} to process 130 | * @return an empty Stream if this event doesn't trigger any action for this {@link PingPongProcessor}'s 131 | * party 132 | */ 133 | private Stream processEvent(String workflowId, EventOuterClass.CreatedEvent protoEvent) { 134 | String templateName = protoEvent.getTemplateId().getEntityName(); 135 | Map fields = protoEvent 136 | .getCreateArguments() 137 | .getFieldsList() 138 | .stream() 139 | .collect(Collectors.toMap(ValueOuterClass.RecordField::getLabel, ValueOuterClass.RecordField::getValue)); 140 | 141 | // check that this party is set as the receiver of the contract 142 | boolean thisPartyIsReceiver = fields.get("receiver").getParty().equals(party); 143 | 144 | if (!thisPartyIsReceiver) return Stream.empty(); 145 | 146 | String contractId = protoEvent.getContractId(); 147 | boolean isPing = templateName.equals(pingIdentifier.getEntityName()); 148 | String choice = isPing ? "RespondPong" : "RespondPing"; 149 | 150 | Long count = fields.get("count").getInt64(); 151 | System.out.printf("%s is exercising %s on %s in workflow %s at count %d\n", party, choice, contractId, workflowId, count); 152 | 153 | final var event = CreatedEvent.fromProto(protoEvent); 154 | 155 | return Stream.concat( 156 | processPingPong( 157 | Ping.COMPANION, 158 | Ping.Exercises::exerciseRespondPong, 159 | event), 160 | processPingPong( 161 | Pong.COMPANION, 162 | Pong.Exercises::exerciseRespondPing, 163 | event) 164 | ); 165 | } 166 | 167 | private , Id, Data> 168 | Stream processPingPong( 169 | ContractCompanion companion, 170 | Function>> createUpdate, 171 | CreatedEvent event) { 172 | if (!event.getTemplateId().getEntityName().equals(companion.TEMPLATE_ID.getEntityName())) 173 | return Stream.empty(); 174 | Ct ct = companion.fromCreatedEvent(event); 175 | Update> update = createUpdate.apply(ct.id); 176 | return update.commands().stream(); 177 | } 178 | } 179 | -------------------------------------------------------------------------------- /PingPong/src/main/java/examples/pingpong/grpc/PingPongProcessor.java: -------------------------------------------------------------------------------- 1 | // Copyright (c) 2025 Digital Asset (Switzerland) GmbH and/or its affiliates. All rights reserved. 2 | // SPDX-License-Identifier: Apache-2.0 3 | 4 | package examples.pingpong.grpc; 5 | 6 | import com.daml.ledger.api.v2.CommandSubmissionServiceGrpc; 7 | import com.daml.ledger.api.v2.CommandSubmissionServiceGrpc.CommandSubmissionServiceBlockingStub; 8 | import com.daml.ledger.api.v2.CommandSubmissionServiceOuterClass.SubmitRequest; 9 | import com.daml.ledger.api.v2.CommandsOuterClass.Command; 10 | import com.daml.ledger.api.v2.CommandsOuterClass.Commands; 11 | import com.daml.ledger.api.v2.CommandsOuterClass.ExerciseCommand; 12 | import com.daml.ledger.api.v2.EventOuterClass.CreatedEvent; 13 | import com.daml.ledger.api.v2.EventOuterClass.Event; 14 | import com.daml.ledger.api.v2.TransactionFilterOuterClass.CumulativeFilter; 15 | import com.daml.ledger.api.v2.TransactionFilterOuterClass.EventFormat; 16 | import com.daml.ledger.api.v2.TransactionFilterOuterClass.Filters; 17 | import com.daml.ledger.api.v2.TransactionFilterOuterClass.TemplateFilter; 18 | import com.daml.ledger.api.v2.TransactionFilterOuterClass.TransactionFormat; 19 | import com.daml.ledger.api.v2.TransactionFilterOuterClass.TransactionShape; 20 | import com.daml.ledger.api.v2.TransactionFilterOuterClass.UpdateFormat; 21 | import com.daml.ledger.api.v2.TransactionOuterClass.Transaction; 22 | import com.daml.ledger.api.v2.UpdateServiceGrpc; 23 | import com.daml.ledger.api.v2.UpdateServiceGrpc.UpdateServiceStub; 24 | import com.daml.ledger.api.v2.UpdateServiceOuterClass.GetUpdatesRequest; 25 | import com.daml.ledger.api.v2.UpdateServiceOuterClass.GetUpdatesResponse; 26 | import com.daml.ledger.api.v2.ValueOuterClass.Identifier; 27 | import com.daml.ledger.api.v2.ValueOuterClass.Record; 28 | import com.daml.ledger.api.v2.ValueOuterClass.RecordField; 29 | import com.daml.ledger.api.v2.ValueOuterClass.Value; 30 | import io.grpc.ManagedChannel; 31 | import io.grpc.stub.StreamObserver; 32 | 33 | import java.util.List; 34 | import java.util.Map; 35 | import java.util.UUID; 36 | import java.util.stream.Collectors; 37 | import java.util.stream.Stream; 38 | 39 | /** 40 | * This class subscribes to the stream of transactions for a given party and reacts to Ping or Pong contracts. 41 | */ 42 | public class PingPongProcessor { 43 | 44 | private final String party; 45 | 46 | private final UpdateServiceStub transactionService; 47 | private final CommandSubmissionServiceBlockingStub submissionService; 48 | 49 | private final Identifier pingIdentifier; 50 | private final Identifier pongIdentifier; 51 | 52 | public PingPongProcessor(String party, ManagedChannel channel, Identifier pingIdentifier, Identifier pongIdentifier) { 53 | this.party = party; 54 | this.transactionService = UpdateServiceGrpc.newStub(channel); 55 | this.submissionService = CommandSubmissionServiceGrpc.newBlockingStub(channel); 56 | this.pingIdentifier = pingIdentifier; 57 | this.pongIdentifier = pongIdentifier; 58 | } 59 | 60 | private CumulativeFilter newTemplate(Identifier identifier){ 61 | return CumulativeFilter 62 | .newBuilder() 63 | .setTemplateFilter( 64 | TemplateFilter 65 | .newBuilder() 66 | .setTemplateId(identifier) 67 | .build() 68 | ) 69 | .build(); 70 | } 71 | 72 | public void runIndefinitely() { 73 | // restrict the subscription to ping and pong template types through an inclusive filter 74 | final var eventFormat = EventFormat.newBuilder() 75 | .setVerbose(true) 76 | .putFiltersByParty( 77 | party, 78 | Filters 79 | .newBuilder() 80 | .addCumulative(newTemplate(pingIdentifier)) 81 | .addCumulative(newTemplate(pongIdentifier)) 82 | .build( 83 | )).build(); 84 | final var transactionFormat = TransactionFormat.newBuilder() 85 | .setEventFormat(eventFormat) 86 | .setTransactionShape(TransactionShape.TRANSACTION_SHAPE_ACS_DELTA) 87 | .build(); 88 | final var updateFormat = UpdateFormat.newBuilder() 89 | .setIncludeTransactions(transactionFormat) 90 | .build(); 91 | // assemble the request for the transaction stream 92 | GetUpdatesRequest transactionsRequest = GetUpdatesRequest.newBuilder() 93 | .setBeginExclusive(0L) 94 | .setUpdateFormat(updateFormat) 95 | .build(); 96 | 97 | // this StreamObserver reacts to transactions and prints a message if an error occurs or the stream gets closed 98 | StreamObserver transactionObserver = new StreamObserver() { 99 | @Override 100 | public void onNext(GetUpdatesResponse value) { 101 | if(value.hasTransaction()) processTransaction(value.getTransaction()); 102 | } 103 | 104 | @Override 105 | public void onError(Throwable t) { 106 | System.err.printf("%s encountered an error while processing transactions!\n", party); 107 | t.printStackTrace(); 108 | } 109 | 110 | @Override 111 | public void onCompleted() { 112 | System.out.printf("%s's transactions stream completed.\n", party); 113 | } 114 | }; 115 | System.out.printf("%s starts reading transactions.\n", party); 116 | transactionService.getUpdates(transactionsRequest, transactionObserver); 117 | } 118 | 119 | /** 120 | * Processes a transaction and sends the resulting commands to the Command Submission Service 121 | * 122 | * @param tx the Transaction to process 123 | */ 124 | private void processTransaction(Transaction tx) { 125 | List commands = tx.getEventsList().stream() 126 | .filter(Event::hasCreated).map(Event::getCreated) 127 | .flatMap(e -> processEvent(tx.getWorkflowId(), e)) 128 | .collect(Collectors.toList()); 129 | 130 | if (!commands.isEmpty()) { 131 | SubmitRequest request = SubmitRequest.newBuilder() 132 | .setCommands(Commands.newBuilder() 133 | .setCommandId(UUID.randomUUID().toString()) 134 | .setWorkflowId(tx.getWorkflowId()) 135 | .addActAs(party) 136 | .setUserId(PingPongGrpcMain.APP_ID) 137 | .addAllCommands(commands) 138 | .build()) 139 | .build(); 140 | submissionService.submit(request); 141 | } 142 | } 143 | 144 | /** 145 | * For each {@link CreatedEvent} where the receiver is 146 | * the current party, exercise the Pong choice of Ping contracts, or the Ping 147 | * choice of Pong contracts. 148 | * 149 | * @param workflowId the workflow the event is part of 150 | * @param event the {@link CreatedEvent} to process 151 | * @return an empty Stream if this event doesn't trigger any action for this {@link PingPongProcessor}'s 152 | * party 153 | */ 154 | private Stream processEvent(String workflowId, CreatedEvent event) { 155 | Identifier template = event.getTemplateId(); 156 | 157 | boolean isPingPongModule = template.getModuleName().equals(pingIdentifier.getModuleName()); 158 | 159 | boolean isPing = template.getEntityName().equals(pingIdentifier.getEntityName()); 160 | boolean isPong = template.getEntityName().equals(pongIdentifier.getEntityName()); 161 | 162 | if (!isPingPongModule || !isPing && !isPong) return Stream.empty(); 163 | 164 | Map fields = event 165 | .getCreateArguments() 166 | .getFieldsList() 167 | .stream() 168 | .collect(Collectors.toMap(RecordField::getLabel, RecordField::getValue)); 169 | 170 | // check that this party is set as the receiver of the contract 171 | boolean thisPartyIsReceiver = fields.get("receiver").getParty().equals(party); 172 | 173 | if (!thisPartyIsReceiver) return Stream.empty(); 174 | 175 | String contractId = event.getContractId(); 176 | String choice = isPing ? "RespondPong" : "RespondPing"; 177 | 178 | Long count = fields.get("count").getInt64(); 179 | System.out.printf("%s is exercising %s on %s in workflow %s at count %d\n", party, choice, contractId, workflowId, count); 180 | 181 | // assemble the exercise command 182 | Command cmd = Command 183 | .newBuilder() 184 | .setExercise(ExerciseCommand 185 | .newBuilder() 186 | .setTemplateId(template) 187 | .setContractId(contractId) 188 | .setChoice(choice) 189 | .setChoiceArgument(Value.newBuilder().setRecord(Record.getDefaultInstance()))) 190 | .build(); 191 | 192 | return Stream.of(cmd); 193 | } 194 | } 195 | -------------------------------------------------------------------------------- /PingPong/README.rst: -------------------------------------------------------------------------------- 1 | Java Bindings Ping-Pong Example 2 | ------------------------------- 3 | 4 | :: 5 | 6 | Copyright (c) 2025 Digital Asset (Switzerland) GmbH and/or its affiliates. All rights reserved. 7 | SPDX-License-Identifier: Apache-2.0.0 8 | 9 | 10 | This is an example of how a Java application would use the `Java Binding library `_ to connect to and exercise a DAML model running on a ledger. Since there are three levels of interface available, this example builds a similar application with all three levels. 11 | 12 | The application is a simple ``PingPong`` application, which consists of: 13 | 14 | - a DAML model with two contract templates, ``Ping`` and ``Pong`` 15 | - two parties, ``Alice`` and ``Bob`` 16 | 17 | The logic of the application is the following: 18 | 19 | #. The application injects a contract of type ``Ping`` for ``Alice``. 20 | #. ``Alice`` sees this contract and exercises the consuming choice ``RespondPong`` to create a contract 21 | of type ``Pong`` for ``Bob``. 22 | #. ``Bob`` sees this contract and exercises the consuming choice ``RespondPing`` to create a contract 23 | of type ``Ping`` for ``Alice``. 24 | #. Points 1 and 2 are repeated until the maximum number of contracts defined in the DAML is 25 | reached. 26 | 27 | Setting Up the Example Projects 28 | ------------------------------- 29 | 30 | To set a project up: 31 | 32 | #. If you do not have it already, install the DAML SDK by running:: 33 | 34 | curl -sSL https://get.digitalasset.com/install/install.sh | sh -s 3.4.9 35 | 36 | #. Use the start script for starting a ledger & the java application: 37 | 38 | ./start.sh 39 | 40 | * examples.pingpong.grpc.PingPongGrpcMain 41 | * examples.pingpong.codegen.PingPongCodegenMain 42 | 43 | depending on which example you wish to run. The script will take care of stopping an already running sandbox & start a fresh one on every call. 44 | 45 | Example Project -- Ping Pong with gRPC Bindings 46 | ----------------------------------------------- 47 | 48 | The code for this example is in the package `examples.pingpong.grpc `_. 49 | 50 | PingPongGrpcMain.java 51 | ===================== 52 | 53 | The entry point for the Java code is the main class `PingPongGrpcMain `_. Look at this class to see: 54 | 55 | - how to connect to and interact with the DAML Ledger via the Java Binding library 56 | - how to use the gRPC layer to build an automation for both parties. 57 | 58 | The main function: 59 | 60 | - creates an instance of a ``ManagedChannel`` connecting to an existing ledger 61 | - fetches the ledgerID and packageId from the ledger 62 | - creates ``Identifiers`` for the Ping and Pong templates 63 | - creates and starts instances of `PingPongProcessor `_ that contain the logic of the automation 64 | - injects the initial contracts to start the process 65 | 66 | PingPongProcessor.java 67 | ====================== 68 | 69 | The core of the application is the method `PingPongProcessor.runIndefinitely() `_. 70 | 71 | This method retrieves a gRPC streaming endpoint using the ``GetUpdatesRequest`` request, and then creates a ``StreamObserver``, providing implementations of the ``onNext``, ``onError`` and ``onComplete`` observer methods. ``gRPC`` layer arranges that these methods receive stream events asynchronously. 72 | 73 | The method `onNext `_ is the main driver, extracting the transaction list from each ``GetUpdatesResponse``, and passing in to ``processTransaction()`` for processing. This method, and the method ``processTransaction()`` implements the application logic. 74 | 75 | `processTransaction() `_ extracts all creation events from the the transaction and passes them to ``processEvent()``. This produces a list of commands to be sent to the ledger to further the workflow, and these are packages up in a ``Commands`` request and sent to the ledger. 76 | 77 | `processEvent() `_ takes a transaction event and turns it into a stream of commands to be sent back to the ledger. To do this, it examines the event for the correct package and template (it's a create of a ``Ping`` or ``Pong`` template) and then looks at the receiving part to decide if this processor should respond. If so, an exercise command for the correct choice is created and returned in a ``Stream``. 78 | 79 | In all other cases, an empty ``Stream`` is returned, indication no action is required. 80 | 81 | Output 82 | ====== 83 | 84 | The application prints statements similar to these: 85 | 86 | .. code-block:: text 87 | 88 | Bob is exercising RespondPong on #1:0 in workflow Ping-Alice-1 at count 0 89 | Alice is exercising RespondPing on #344:1 in workflow Ping-Alice-7 at count 9 90 | 91 | The first line shows that: 92 | 93 | - ``Bob`` is exercising the ``RespondPong`` choice on the contract with ID ``#1:0`` for the workflow ``Ping-Alice-1``. 94 | - Count ``0`` means that this is the first choice after the initial ``Ping`` contract. 95 | - The workflow ID ``Ping-Alice-1`` conveys that this is the workflow triggered by the second initial ``Ping`` 96 | contract that was created by ``Alice``. 97 | 98 | The second line is analogous to the first one. 99 | 100 | Example Project -- Ping Pong with Generated Java Data Layer 101 | ----------------------------------------------------------- 102 | 103 | The code for this example is in the package `examples.pingpong.codegen `_. 104 | 105 | PingPongCodegenMain.java 106 | ======================== 107 | 108 | The entry point for the Java code is the main class `PingPongCodegenMain `_. Look at this class to see: 109 | 110 | - how to connect to and interact with the DAML Ledger via the Java Binding library 111 | - how to use the gRPC layer to build an automation for both parties. 112 | - how to streamline interactions with the ledger types by using auto generated data layer. 113 | 114 | The main function: 115 | 116 | - creates an instance of a ``ManagedChannel`` connecting to an existing ledger 117 | - fetches the ledgerID and packageId from the ledger 118 | - creates ``Identifiers`` for the Ping and Pong templates 119 | - creates and starts instances of `PingPongProcessor `_ that contain the logic of the automation 120 | - injects the initial contracts to start the process 121 | 122 | PingPongProcessor.java 123 | ====================== 124 | 125 | The core of the application is the method `PingPongProcessor.runIndefinitely() `_. 126 | 127 | This method retrieves a gRPC streaming endpoint using the ``GetUpdatesRequest`` request, and then creates a ``StreamObserver``, providing implementations of the ``onNext``, ``onError`` and ``onComplete`` observer methods. ``gRPC`` layer arranges that these methods receive stream events asynchronously. 128 | 129 | The method `onNext `_ is the main driver, extracting the transaction list from each ``GetUpdatesResponse``, and passing in to ``processTransaction()`` for processing. This method, and the method ``processTransaction()`` implements the application logic. 130 | 131 | `processTransaction() `_ extracts all creation events from the the transaction and passes them to ``processEvent()``. This produces a list of commands to be sent to the ledger to further the workflow, and these are packages up in a ``Commands`` request and sent to the ledger. 132 | 133 | `processEvent() `_ takes a transaction event and turns it into a stream of commands to be sent back to the ledger. To do this, it examines the event for the correct package and template (it's a create of a ``Ping`` or ``Pong`` template) and then looks at the receiving part to decide if this processor should respond. If so, an exercise command for the correct choice is created and returned in a ``Stream``. 134 | 135 | In all other cases, an empty ``Stream`` is returned, indication no action is required. 136 | 137 | Output 138 | ====== 139 | 140 | The application prints statements similar to these: 141 | 142 | .. code-block:: text 143 | 144 | Bob is exercising RespondPong on #1:0 in workflow Ping-Alice-1 at count 0 145 | Alice is exercising RespondPing on #344:1 in workflow Ping-Alice-7 at count 9 146 | 147 | The first line shows that: 148 | 149 | - ``Bob`` is exercising the ``RespondPong`` choice on the contract with ID ``#1:0`` for the workflow ``Ping-Alice-1``. 150 | - Count ``0`` means that this is the first choice after the initial ``Ping`` contract. 151 | - The workflow ID ``Ping-Alice-1`` conveys that this is the workflow triggered by the second initial ``Ping`` 152 | contract that was created by ``Alice``. 153 | 154 | The second line is analogous to the first one. 155 | 156 | The Generated Data Layer 157 | ======================== 158 | 159 | The ``codegen`` variant of the client application is similar to its ``grpc`` counterpart. Both are written in 160 | a traditional imperative style. What sets them apart is the usage of the generated data layer in the former. 161 | This layer simplifies construction of the ledger api calls and the analysis of the return values. 162 | 163 | - ``PingPongCodegenMain.createInitialContracts`` creates a strongly typed instance of a Ping contract and then embeds it in an equally strongly typed ``CommandsSubmission``. Then, it uses the built in ``toProto`` methods to convert the request into a wire-ready ``protobuf`` structure. 164 | - ``PingPongProcessor.runIndefinitely`` creates a per party inclusive filter by invoking a series of class constructors. Contrast this with the intricate process of defining a filter in the analogous method in the ``grpc`` variant of the application. 165 | - ``PingPongProcessor.processEvent`` starts off by extracting common data fields from the ``grpc`` version of the received events, to be later used for logging purposes. Events are then converted to the corresponding data layer format and passed to the individual template handlers. 166 | - ``PingPongProcessor.processPingPong`` creates a strongly typed representation of the daml contracts by means of the daml contract companions. A strongly typed instance can be used to create a command representing a desired choice exercise. 167 | - ``PingPongProcessor.processTransaction`` is responsible for creating a ledger request enveloping the choice exercises and submitting it to the ledger. 168 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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