Using the YcFunction interface for a Java handler
To create a handler in Java, you can implement the YcFunction interface. To do this, add the SDK to the dependencies.
Example of a valid handler:
import yandex.cloud.sdk.functions.YcFunction;
import yandex.cloud.sdk.functions.Context;
public class Handler implements YcFunction<Integer, String> {
@Override
public String handle(Integer i, Context c) {
return String.valueOf(i);
}
}
Warning
Specify two values for YcFunction type parameters: the first one being the input argument type and the second one, the return value type. For the handle method, make sure to provide the invocation context as its second argument.
Examples of invalid handlers:
import yandex.cloud.sdk.functions.YcFunction;
import yandex.cloud.sdk.functions.Context;
// YcFunction has only one parameter type specified
// Handler should not have any parameter types (for details, see handler requirements)
public class Handler<T> implements YcFunction<T, Integer> {
@Override
public Integer handle(T i, Context c) {
return 2;
}
}
import yandex.cloud.sdk.functions.YcFunction;
import yandex.cloud.sdk.functions.Context;
// YcFunction has neither parameter types specified.
public class Handler implements YcFunction {
@Override
public Object apply(Object i, Context c) {
return i;
}
}
You can use any classes as input and return types.
Note
Fields of these classes can have any access modifiers. For non-public fields, defining the getter or setter method is optional.
Example of function information output
The following function receives a number as an input, outputs the function data obtained from the invocation context to the execution log, and returns data on whether the received number is even.
Warning
To invoke the function, use the Yandex Cloud CLI or an HTTP request with the ?integration=raw parameter.
Handler.java:
import yandex.cloud.sdk.functions.YcFunction;
import yandex.cloud.sdk.functions.Context;
public class Handler implements YcFunction<Integer, Boolean> {
private String format(String f, String s) {
return String.format(f, s);
}
@Override
public Boolean handle(Integer number, Context c) {
System.out.println(format("Function name: %s", c.getFunctionName()));
System.out.println(format("Function version: %s", c.getFunctionVersion()));
// If no service account is selected, the output will be an empty string.
System.out.println(format("Service account token: %s", c.getTokenJson()));
return number % 2 == 0;
}
}
Example of input data:
41
The log will contain the following:
Function name: <function_name>
Function version: <function_version_ID>
Service account token: <service_account_token>
Returned string:
false