changes.md

## 9.4.0

#### Project

* Bump up Zipkin and Zipkin lens UI dependency to 2.24.0.

#### OAP Server

* Add `ServerStatusService` in the core module to provide a new way to expose booting status to other modules.
* Adds Micrometer as a new component.(ID=141)
* Refactor session cache in MetricsPersistentWorker.
* Cache enhancement - don't read new metrics from database in minute dimensionality.

```
    // When
    // (1) the time bucket of the server's latest stability status is provided
    //     1.1 the OAP has booted successfully
    //     1.2 the current dimensionality is in minute.
    //     1.3 the OAP cluster is rebalanced due to scaling
    // (2) the metrics are from the time after the timeOfLatestStabilitySts
    // (3) the metrics don't exist in the cache
    // the kernel should NOT try to load it from the database.
    //
    // Notice, about condition (2),
    // for the specific minute of booted successfully, the metrics are expected to load from database when
    // it doesn't exist in the cache.
```

* Remove the offset of metric session timeout according to worker creation sequence.
* Correct `MetricsExtension` annotations declarations in manual entities.
* Support component IDs' priority in process relation metrics.
* Remove abandon logic in MergableBufferedData, which caused unexpected no-update.
* Fix miss set `LastUpdateTimestamp` that caused the metrics session to expire.
* Rename MAL rule `spring-sleuth.yaml` to `spring-micrometer.yaml`.
* Fix memory leak in Zipkin API.
* Remove the dependency of `refresh_interval` of ElasticSearch indices from `elasticsearch/flushInterval` config. Now,
  it uses `core/persistentPeriod` + 5s as `refresh_interval` for all indices instead.
* Change `elasticsearch/flushInterval` to 5s(was 15s).
* Optimize `flushInterval` of ElasticSearch BulkProcessor to avoid extra periodical flush in the continuous bulk streams.
* An unexpected dot is added when exp is a pure metric name and expPrefix != null.
* Support monitoring MariaDB.
* Remove measure/stream specific interval settings in BanyanDB.
* Add global-specific settings used to override global configurations (e.g `segmentIntervalDays`, `blockIntervalHours`) in BanyanDB.
* Use TTL-driven interval settings for the `measure-default` group in BanyanDB.
* Fix wrong group of non time-relative metadata in BanyanDB.
* Refactor `StorageData#id` to the new StorageID object from a String type.
* Support multiple component IDs in the service topology level.
* Add `ElasticSearch.Keyword` annotation to declare the target field type as `keyword`.
* [Breaking Change] Column `component_id` of `service_relation_client_side` and `service_relation_server_side` have been replaced by `component_ids`.
* Support `priority` definition in the `component-libraries.yml`.
* Enhance service topology query. When there are multiple components detected from the server side,
  the component type of the node would be determined by the priority, which was random in the previous release.
* Remove `component_id` from `service_instance_relation_client_side` and `service_instance_relation_server_side`.
* Make the satellite E2E test more stable.
* Add Istio 1.16 to test matrix.
* Register ValueColumn as Tag for Record in BanyanDB storage plugin.
* Bump up Netty to 4.1.86.
* Remove unnecessary additional columns when storage is in logical sharding mode.
* The cluster coordinator support watch mechanism for notifying `RemoteClientManager` and `ServerStatusService`.
* Fix ServiceMeshServiceDispatcher overwrite ServiceDispatcher debug file when open SW_OAL_ENGINE_DEBUG.
* Use `groupBy` and `in` operators to optimize topology query for BanyanDB storage plugin.
* Support server status watcher for `MetricsPersistentWorker` to check the metrics whether required initialization.
* Fix the meter value are not correct when using `sumPerMinLabeld` or `sumHistogramPercentile` MAL function.
* Fix cannot display attached events when using Zipkin Lens UI query traces.
* Remove `time_bucket` for both Stream and Measure kinds in BanyanDB plugin.
* Merge `TIME_BUCKET` of `Metrics` and `Record` into `StorageData`.
* Support no `layer` in the `listServices` query.
* Fix `time_bucket` of `ServiceTraffic` not set correctly in `slowSql` of MAL.
* Correct the TopN record query DAO of BanyanDB.
* Tweak interval settings of BanyanDB.

#### UI

* Add Zipkin Lens UI to webapp, and proxy it to context path `/zipkin`.
* Migrate the build tool from vue cli to Vite4.
* Fix Instance Relation and Endpoint Relation dashboards show up.

#### Documentation

* Remove Spring Sleuth docs, and add `Spring MicroMeter Observations Analysis` with the latest Java agent side
  enhancement.
* Update `monitoring MySQL document` to add the `MariaDB` part.
* Reorganize the protocols docs to a more clear API docs.

All issues and pull requests are [here](https://github.com/apache/skywalking/milestone/160?closed=1)