Work with Ruby package exceptions in Python app

This article provides an introduction to cross-technology handling of exceptions. Exceptions in programming are events that occur during the execution of programs that disrupt the normal flow of instructions.

Any exception thrown by called technology is handled and thrown as any other exception in Python code. Details of exception depend on called technology, but in most cases final exception has all the information passed by called side.

Javonet allows you to reference and use modules or packages written in (Java/Kotlin/Groovy/Clojure, C#/VB.NET, Ruby, Perl, Python, JavaScript/TypeScript) like they were created in your technology. If have not yet created your first project check Javonet overview and quick start guides for your technology.

Custom Ruby package with exception handling

With Javonet it is possible to reference any custom Ruby package and interact with its methods declared on types defined within that module almost the same as with any other Python library.

Snippet below represents the sample code from Ruby package which contains a chain of methods:

module TestClass
    class TestClass

        def self.divide_by(x, y)
          return self.divide_by_second(x, y)
        end
        
        def self.divide_by_second(x, y)
          return self.divide_by_third(x, y)
        end
        
        def self.divide_by_third(x, y)
          return x / y
        end
    end
end
def self.divide_by(x, y)
  return self.divide_by_second(x, y)
end

def self.divide_by_second(x, y)
  return self.divide_by_third(x, y)
end

def self.divide_by_third(x, y)
  return x / y
end

To invoke these methods in Python:

from javonet.sdk import Javonet

resources_directory = "."

# use activate only once in your app
try:
    Javonet.activate("your-license-key")

    # create called runtime context
    called_runtime = Javonet.in_memory().ruby()

    # set up variables
    library_path = resources_directory + '/TestClass.rb'
    class_name = "TestClass::TestClass"

    # load custom library
    called_runtime.load_library(library_path)

    # get type from the runtime
    called_runtime_type = called_runtime.get_type(class_name).execute()

    # invoke static method
    response = called_runtime_type.invoke_static_method("divide_by", 10, 0).execute()
except Exception as e:
    # write exception to console
    print(e)
module TestClass
    class TestClass

        def self.divide_by(x, y)
          return self.divide_by_second(x, y)
        end
        
        def self.divide_by_second(x, y)
          return self.divide_by_third(x, y)
        end
        
        def self.divide_by_third(x, y)
          return x / y
        end
    end
end
# use activate only once in your app
try:
    Javonet.activate("your-license-key")

    # create called runtime context
    called_runtime = Javonet.in_memory().ruby()

    # set up variables
    library_path = resources_directory + '/TestClass.rb'
    class_name = "TestClass::TestClass"

    # load custom library
    called_runtime.load_library(library_path)

    # get type from the runtime
    called_runtime_type = called_runtime.get_type(class_name).execute()

    # invoke static method
    response = called_runtime_type.invoke_static_method("divide_by", 10, 0).execute()
except Exception as e:
    # write exception to console
    print(e)

The last method throws exception which is handled and rethrown in Python. Then the exception in catched and printed.

The same operation can be performed remotely by just changing the new Runtime Context invocation from in memory to tcp that will create and interact with your Ruby package objects on any remote node, container or service that hosts Javonet Code Gateway. This way you can preserve the same logic in your application and instantly switch between monolithic and microservices architecture without the need to implement the integration layer based on web services or other remote invocation methods.

Read more about use cases and software architecture scenarios where Javonet runtime bridging technology can support your development process.