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AWS X-Ray
Developer Guide

Add Annotations and Metadata to Segments with the X-Ray SDK for Java

You can record additional information about requests or your application to the segments that the X-Ray SDK creates, or to custom subsegments that you create.

Annotations are key-value pairs with string, number, or Boolean values. Annotations are indexed for use with filter expressions. Use annotations to record data that you want to use to group traces in the console, or when calling the GetTraceSummaries API.

Metadata are key-value pairs that can have values of any type, including objects and lists, but are not indexed for use with filter expressions. Use metadata to record additional data that you want stored in the trace but don't need to use with search.

In addition to annotations and metadata, you can also record user ID strings on segments. User IDs are recorded in a separate field on segments and are indexed for use with search.

Recording Annotations with the X-Ray SDK for Java

Use annotations to record information on segments or subsegments that you want indexed for search.

Annotation Requirements

  • Keys – Up to 500 alphanumeric characters. No spaces or symbols except underscores.

  • Values – Up to 1,000 Unicode characters.

  • Entries – Up to 50 annotations per trace.

To record annotations

  1. Get a reference to the current segment or subsegment from AWSXRay.

    import com.amazonaws.xray.AWSXRay;
    import com.amazonaws.xray.entities.Segment;
    ...
    Segment document = AWSXRay.getCurrentSegment();

    or

    import com.amazonaws.xray.AWSXRay;
    import com.amazonaws.xray.entities.Subsegment;
    ...
    Subsegment document = AWSXRay.getCurrentSubsegment();
  2. Call putAnnotation with a String key, and a Boolean, Number, or String value.

    document.putAnnotation("mykey", "my value");

The SDK records annotations as key-value pairs in an annotations object in the segment document. Calling putAnnotation twice with the same key overwrites previously recorded values on the same segment or subsegment.

To find traces that have annotations with specific values, use the annotations.key keyword in a filter expression.

Example src/main/java/scorekeep/GameModel.java – Annotations and Metadata

import com.amazonaws.xray.AWSXRay;
import com.amazonaws.xray.entities.Segment;
import com.amazonaws.xray.entities.Subsegment;
...
  public void saveGame(Game game) throws SessionNotFoundException {
    // wrap in subsegment
    Subsegment subsegment = AWSXRay.beginSubsegment("## GameModel.saveGame");
    try {
      // check session
      String sessionId = game.getSession();
      if (sessionModel.loadSession(sessionId) == null ) {
        throw new SessionNotFoundException(sessionId);
      }
      Segment segment = AWSXRay.getCurrentSegment();
      subsegment.putMetadata("resources", "game", game);
      segment.putAnnotation("gameid", game.getId());
      mapper.save(game);
    } catch (Exception e) {
      subsegment.addException(e);
      throw e;
    } finally {
      AWSXRay.endSubsegment();
    }
  }

Recording Metadata with the X-Ray SDK for Java

Use metadata to record information on segments or subsegments that you don't need indexed for search. Metadata values can be strings, numbers, Booleans, or any object that can be serialized into a JSON object or array.

To record metadata

  1. Get a reference to the current segment or subsegment from AWSXRay.

    import com.amazonaws.xray.AWSXRay;
    import com.amazonaws.xray.entities.Segment;
    ...
    Segment document = AWSXRay.getCurrentSegment();

    or

    import com.amazonaws.xray.AWSXRay;
    import com.amazonaws.xray.entities.Subsegment;
    ...
    Subsegment document = AWSXRay.getCurrentSubsegment();
  2. Call putMetadata with a String namespace, String key, and a Boolean, Number, String, or Object value.

    document.putMetadata("my namespace", "my key", "my value");

    or

    Call putMetadata with just a key and value.

    document.putMetadata("my key", "my value");

If you don't specify a namespace, the SDK uses default. Calling putMetadata twice with the same key overwrites previously recorded values on the same segment or subsegment.

Example src/main/java/scorekeep/GameModel.java – Annotations and Metadata

import com.amazonaws.xray.AWSXRay;
import com.amazonaws.xray.entities.Segment;
import com.amazonaws.xray.entities.Subsegment;
...
  public void saveGame(Game game) throws SessionNotFoundException {
    // wrap in subsegment
    Subsegment subsegment = AWSXRay.beginSubsegment("## GameModel.saveGame");
    try {
      // check session
      String sessionId = game.getSession();
      if (sessionModel.loadSession(sessionId) == null ) {
        throw new SessionNotFoundException(sessionId);
      }
      Segment segment = AWSXRay.getCurrentSegment();
      subsegment.putMetadata("resources", "game", game);
      segment.putAnnotation("gameid", game.getId());
      mapper.save(game);
    } catch (Exception e) {
      subsegment.addException(e);
      throw e;
    } finally {
      AWSXRay.endSubsegment();
    }
  }

Recording User IDs with the X-Ray SDK for Java

Record user IDs on request segments to identify the user who sent the request.

To record user IDs

  1. Get a reference to the current segment from AWSXRay.

    import com.amazonaws.xray.AWSXRay;
    import com.amazonaws.xray.entities.Segment;
    ...
    Segment document = AWSXRay.getCurrentSegment();
  2. Call setUser with a String ID of the user who sent the request.

    document.setUser("U12345");

You can call setUser in your controllers to record the user ID as soon as your application starts processing a request. If you will only use the segment to set the user ID, you can chain the calls in a single line.

Example src/main/java/scorekeep/MoveController.java – User ID

import com.amazonaws.xray.AWSXRay;
...
  @RequestMapping(value="/{userId}", method=RequestMethod.POST)
  public Move newMove(@PathVariable String sessionId, @PathVariable String gameId, @PathVariable String userId, @RequestBody String move) throws SessionNotFoundException, GameNotFoundException, StateNotFoundException, RulesException {
    AWSXRay.getCurrentSegment().setUser(userId);
    return moveFactory.newMove(sessionId, gameId, userId, move);
  }

To find traces for a user ID, use the user keyword in a filter expression.