Welcome to Jess’ documentation!

Jess is based on Joern. Jess generates variability-aware code property graphs, a graph representation that exposes the code’s syntax, control-flow, data-flow, variability and type information in a joint data structure. Code property graphs are stored in an Titan DB graph database. This allows code to be mined using search queries formulated in the graph traversal language Gremlin. Jess uses program slicing to identify semantically related lines of code for a given entry point. The variability information and structure in those slices (implemented with preprocessor statements) stays intact. These slices can then be used to migrate/transplant a desired functionality from one software (donor) to another (target). Donor and target must originate from the same ancestor to utilize Jess’ full potential.

• Fuzzy Parsing. Jess employs a fuzzy parser. This allows code to be imported even if a working build environment cannot be supplied.
• Code Property Graphs. Jess creates code property graphs from the fuzzy parser output and makes and stores them in a Titan DB graph database. For background information on code property graphs, we strongly encourage you to read the paper of Joern’s authors on the topic.
• Extensible Query Language. Based on the graph traversal language Gremlin, Jess offers an extensible query language based on user-defined Gremlin steps that encode common traversals in the code property graph. These can be combined to create search queries easily.
• Variability-Awarness. Jess parses preprocessor statements and is therefore able to analyze variability in preprocessor-based product lines.
• Semantic Slicing. Jess uses queries to slice the imported source code in semantically related units. That means, you can select an entry point (a line of code) and Jess will give you all lines of code that have an behavioural impact on that entry point or are impacted by that entry point (forward and backward slicing). This process is highly customizable and allows control over the size and the composition of the slice.
• Software Transplantation. Jess implements a semi-automated software transplantation process, based on semantic slicing. This process is meant for software versions or variants that share the same ancestor (e.g. when you fork or clone the software). Jess analyzes the version history and transplants a semantic slice from one software to the other.

This is Jess’ official documentation. It covers its installation and configuration, discusses how code can be imported and retrieved from the database and gives an overview of the database contents.

Contents:

• Installation
  • System Requirements and Dependencies
  • Building Jess
  • Testing the server
  • Testing client scripts
• Parsing and Importing Code
  • Importing code
  • Parsing code without importing
• Semantic Unit Identification
  • INTRODUCTION
  • GENERAL IDEA
  • INPUT/OUTPUT RELATIONS
  • VARIABILITY HANDLING
  • CONFIGURATION OPTIONS
  • DEFAULT CONFIGURATION
  • HOW TO USE
• Semantic Unit Transplantation
  • Introduction
  • How to Use