LATCH JAVA SDK

#### PREREQUISITES ####

• Java 1.5 or above.

• Read API documentation (https://latch.telefonica.com/www/developers/doc_api).

• To get the "Application ID" and "Secret", (fundamental values for integrating Latch in any application), it’s necessary to register a developer account in Latch's website: https://latch.telefonica.com. On the upper right side, click on "Developer area".

CREATING THE JAR DEPENDENCY

Now using Maven (maven.apache.org) is easy to compile and pack all the code for using externally:

mvn install

And the compiled jar was located in the target directory.

You can also compile the jar with all Latch dependencies included:

mvn clean compile assembly:single =======

USING THE SDK IN JAVA

• Include all SDK files and dependencies in your project.

• Create a Latch object with the "Application ID" and "Secret" previously obtained.

     Latch latch = new Latch(APP_ID, SECRET);

• Call to Latch Server. Pairing will return an account id that you should store for future api calls

     LatchResponse pairResponse = latch.pair(TOKEN);
     LatchResponse statusResponse = latch.status(ACCOUNT_ID);
     LatchResponse opStatusResponse = latch.operationStatus(ACCOUNT_ID, OPERATION_ID);
     LatchResponse unpairResponse = latch.unpair(ACCOUNT_ID);

• After every API call, get Latch response data and errors and handle them.

     JsonObject jObject = latchResponse.getData();
     com.elevenpaths.latch.Error error = latchResponse.getError();

USING JAVA SDK FOR WEB3 SERVICES

For using the Java SDK within an Web3 service, you must complain with the following:

• In the Latch website, having an developer account, with the Web3 permissions activated. You must see a new button for creating a Web3 new app.

• Tutorial to follow for creating a new WEB3 app

• You need a wallet to operate on Polygon blockchain. You can easily create one through Metamask.

You need this additional parameters:

• WEB3WALLET: The Ethereum-based address wallet for the user that wants to pair the service.
• WEB3SIGNATURE: A proof-of-ownership signature of a constant, in order to verify that the user owns the private key of the wallet. You can use https://etherscan.io/verifiedSignatures# to sign the following message:
• MESSAGE TO SIGN : "Latch-Web3"

Example of using it java example

TROUBLESHOOTING

A javax.net.ssl.SSLHandshakeException with a nested sun.security.validator.ValidatorException is thrown when invoking an API call.

This exception is normally thrown when the JDK doesn't trust the CA that signs the digital certificate used in Latch's website (https://latch.telefonica.com). You may need to install the CA (http://www.startssl.com/certs/ca.pem) as a trusted certificate in your JDK's truststore (normally in jre/lib/security/cacerts) using the keytool utility.