otupy.apps.ctxd

The discovery application recursively queries context actuators to build a chain of interconnected services. It starts from one or more root services (which consumers are known a priori) and periodically and iteratively queries additional peers found in the responses.

The application is designed to publish context data to multiple sinks.

Setup

To run the discovery, either download the source code or install from PyPI (see setup).

Configuration

The discovery application works according to a yaml configuration file that contains the following parameters:

frequency: The time interval before starting a new round of queries (the real interval will be longer because the timer starts after receving the last answer). Run one-shot if sets to 0.
loop: Number of times to repeat the discovery. Loops forever if set to -1, does not run if set to 0.
publishers: a list of places where the context data are published after each round. The configuration changes according to the specific publisher:
- mongodb: A dictionary with configuration to write data to MongoDB
  host: IP address or hostname of the server hosting the database
  
  port: Port number where the mongodb service listens to
  
  db_name: Name of the internal database to store data (data are saved in the services and links collections
  
  user: username to connect to the database
  
  pass: password to connect to the database
services: A list of “root services” to query, indicated as their Consumer endpoints:
- host
- port
- profile
- encoding
- transfer
- endpoint
- actuator (x-ctxd py:class:~otupy.actuators.ctxd.actuator.Specifiers)

A template configuration file is available here.

Run

Run the discovery service:

python3 discovery.py [-c | --config <config.yaml>]

Code reference

discovery

Service discovery