Welcome to twa

What is twa

twa is a Python wrapper for TheWorldAvatar project. The code is heavily based on the py4j package, which enables Python programs running in a Python interpreter to dynamically access Java objects in a Java Virtual Machine. It has a precedent python package, py4jps, which is now deprecated.

Notes to developers

The aim of twa is to provide Python access to the Java classes and methods in TheWorldAvatar project. The Python-Java communication, handled by the py4j package, happens via the local network sockets. The main interaction point between a Python and Java is provided by the py4j.java_gateway.JavaGateway class. This class is wrapped within the twa.JPSGateway class for convenience. The JPSGateway class is the parent class for any installed java resources that one wishes to access. Although, it is not recommended to use it directly, the JPSGateway class can be useful in experimenting with different resources without installing them first, as it allows to change the resources at runtime.

However, it is important to understand that not all TheWorldAvatar classes/functions in Java are provided with a high-level abstraction in twa. Therefore, the java project documentation should also be consulted with to know which Java objects to call to perform a desired task. Additionally, not all TheWorldAvatar classes can be accessed. Namely, any servlet depending classes can not be instantiated in Python without running the Apache Tomcat server first. Since this has not been tested, it is not guaranteed that running the Apache Tomcat server would fix the problem. However, this should not be an issue for the twa users, given that the main purpose of the wrapper is to use the client-side TheWorldAvatar Java code to perform knowledge graph operations (e.g. queries and updates). Should the developers wish to develop agents (server-side code which normally developed in Java) in Python using twa, the native Python class DerivationAgent should be used.

Authors

Jiaru Bai

Daniel Nurkowski