docs/en/setup/service-agent/java-agent/Application-toolkit-trace-correlation-context.md - skywalking-java - Git at Google

 # Trace Correlation Context
 Trace correlation context APIs provide a way to put custom data in tracing context. All the data in
 the context will be propagated with the in-wire process automatically.

 * Use `TraceContext.putCorrelation()` API to put custom data in tracing context.
 ```java
 Optional<String> previous = TraceContext.putCorrelation("customKey", "customValue");
 ```
 CorrelationContext will remove the item when the value is `null` or empty.

 * Use `TraceContext.getCorrelation()` API to get custom data.
 ```java
 Optional<String> value = TraceContext.getCorrelation("customKey");
 ```
 CorrelationContext configuration descriptions could be found in [the agent configuration](README.md#table-of-agent-configuration-properties) documentation, with `correlation.` as the prefix.
 _Sample codes only_
	# Trace Correlation Context
	Trace correlation context APIs provide a way to put custom data in tracing context. All the data in
	the context will be propagated with the in-wire process automatically.

	* Use `TraceContext.putCorrelation()` API to put custom data in tracing context.
	```java
	Optional<String> previous = TraceContext.putCorrelation("customKey", "customValue");
	```
	CorrelationContext will remove the item when the value is `null` or empty.

	* Use `TraceContext.getCorrelation()` API to get custom data.
	```java
	Optional<String> value = TraceContext.getCorrelation("customKey");
	```
	CorrelationContext configuration descriptions could be found in [the agent configuration](README.md#table-of-agent-configuration-properties) documentation, with `correlation.` as the prefix.
	_Sample codes only_