th2 common library (Python)

Installation

pip install th2-common

This package can be found on PyPI.

Usage

First things first, you need to import CommonFactory class:

from th2_common.schema.factory.common_factory import CommonFactory

Then you create an instance of imported class, choosing one of the options:

1. Create factory with configs from default path (/var/th2/config/*):

   factory = CommonFactory()
   

2. Create factory with configs from specified directory path (path/*):

   factory = CommonFactory(config_path=...)
   

3. Create factory with configs from specified file paths:

   factory = CommonFactory(rabbit_mq_config_filepath=...,
                           mq_router_config_filepath=...,
                           grpc_router_config_filepath=...,
                           cradle_config_filepath=...,
                           custom_config_filepath=...)
   

4. Create factory with configs from command line arguments (sys.argv):

   factory = CommonFactory.create_from_arguments()
   

5. Create factory with configs from specified arguments:

   factory = CommonFactory.create_from_arguments(args)
   

6. Create factory with a namespace in Kubernetes and the name of the target th2 box from Kubernetes:

   factory = CommonFactory.create_from_kubernetes(namespace, box_name)
   

Requirements for creatring factory with Kubernetes

1. It is necessary to have Kubernetes configuration written in ~/.kube/config. See more on kubectl configuration here.

2. It is necessary to have environment variables CASSANDRA_PASS and RABBITMQ_PASS to use configs from cradle.json and rabbitMQ.json as the passwords are not stored there explicitly.

3. Also note that generated_configs directory will be created to store .json files with configs from Kubernetes. Those files are overridden when CommonFactory.create_from_kubernetes(namespace, box_name) is invoked again.

After that you can get various Routers through factory properties:

message_parsed_batch_router = factory.message_parsed_batch_router
message_raw_batch_router = factory.message_raw_batch_router
event_batch_router = factory.event_batch_router

message_parsed_batch_router is working with MessageBatch
message_raw_batch_router is working with RawMessageBatch
event_batch_router is working with EventBatch

See th2-grpc-common for details.

With router created, you can subscribe to pins (specifying callback function) or send data that router works with:

router.subscribe(callback)  # subscribe to only one pin 
router.subscribe_all(callback)  # subscribe to one or several pins
router.send(message)  # send to only one pin
router.send_all(message)  # send to one or several pins

You can do these actions with extra pin attributes in addition to default ones.

router.subscribe(callback, attrs...)  # subscribe to only one pin
router.subscribe_all(callback, attrs...)  # subscribe to one or several pins
router.send(message, attrs...)  # send to only one pin
router.send_all(message, attrs...)  # send to one or several pins

Default attributes are:

• message_parsed_batch_router
  • Subscribe: subscribe, parsed
  • Send: publish, parsed
• message_raw_batch_router
  • Subscribe: subscribe, raw
  • Send: publish, raw
• event_batch_router
  • Subscribe: subscribe, event
  • Send: publish, event