Java Helper

Java Helper is a CLI tool that automatically analyzes your application's libraries and generates optimal weaving settings. To track frameworks and open source libraries used in Java applications, the WhaTap agent requires weaving configuration. Java Helper is included in the agent package as whatap.javahelper.jar and requires JDK 8 or later.

To manually specify weaving options, see Manual Configuration.

Supported Formats

Supports JAR, Spring Boot Fat JAR, Maven Shade JAR, and WAR formats. For EAR, it analyzes up to the root-level JAR modules.

Java Helper Commands

java -jar whatap.javahelper.jar conf generate <input> [options]

Input

Input	Description	Example
<JAR path>	Analyze by specifying a JAR file directly	/app/myapp.jar
--pid <PID>	Analyze a running Java process by PID	--pid 12345

You must specify either a JAR path or --pid.

Options

Option	Description	Default
-o <file>	Save matching results to a whatap.conf file	Screen output only if not specified
-v	Output detailed analysis logs (verbose)	off

Usage Scenarios

New Agent Installation

Specify a JAR file path to generate whatap.conf directly.

java -jar whatap.javahelper.jar conf generate /app/myapp.jar -o whatap.conf

Generated whatap.conf example:

whatap.conf

weaving=spring-boot-3.2,tomcat10,mongodb-4.8

# Recommended modules (uncomment if needed)
#weaving+=,reactor-kafka-1.3
#weaving+=,resilience4j

Add your license key and server information to the generated file to complete the installation.

Configuration Check During Operation

Analyze a running process by PID to check matching results.

java -jar whatap.javahelper.jar conf generate --pid 12345

Output example:

==========================================
  WhaTap Weaving Module Matching Results
==========================================

  Detected libraries: 25
  Matched modules:    8
  Version mismatch:   1
  Auto-included:      3

  LIBRARY                   VERSION   WEAVING MODULE        STATUS
  spring-boot               3.2.5     spring-boot-3.2       MATCHED
  mongodb-driver-sync       4.11.1    mongodb-4.8           MATCHED
  lettuce-core              6.3.2     lettuce-6.1           AUTO
  ...

Compare with the current whatap.conf to check for missing modules. Add the -o option to save as a configuration file.

After Library Upgrade

When libraries change, such as a Spring Boot version upgrade, re-analyze the upgraded JAR to get new weaving settings.

java -jar whatap.javahelper.jar conf generate /app/myapp-upgraded.jar

Matching Status

Status	Description	Action
MATCHED	artifactId, groupId, and version all match; weaving module applicable	Auto-applied
AUTO	Auto-included module (applied by default without weaving setting)	Auto-applied
VERSION_MISMATCH	Library detected but version is outside weaving module support range	Check for agent update
NO_MATCH	No corresponding module in weaving registry	N/A

Reference

Dependency Analysis Method

The process of identifying library versions from JAR files operates with a 3-level priority. Information extracted at a higher level is not overwritten by lower levels.

1. Maven pom.properties: Extracts groupId, artifactId, and version from META-INF/maven/{groupId}/{artifactId}/pom.properties inside the JAR. The most accurate method.

2. MANIFEST.MF: If pom.properties is unavailable, reads standard attributes such as Implementation-Title and Implementation-Version from META-INF/MANIFEST.MF.

3. Filename parsing: If both methods above fail, infers from the JAR filename. (e.g., jackson-databind-2.14.0.jar → version="2.14.0")