Apache Cassandra Implementation for Chat Service

[parhamrahmani]

Apache Cassandra Implementation for Chat Service

Closes #293

This pull request implements a polyglot persistence within REMSFAL and replaces the MySQL database solution for the chat service with Apache Cassandra.

Changes

• Keyspace and Replication:

  • The REMSFAL keyspace uses the NetworkTopologyStrategy with replication set to 2 nodes in datacenter1, ensuring high availability and fault tolerance. You can add new containers to datacenter1 in docker compose file to also redistribute data and horizontally scale.
  • Warning: In order to reduce container to only 1, the NetworkTopologyStrategy with replication of 2 won't work anymore and should be set to SimpleStrategy without replication (which wouldn't align with the thesis issue._

• Data Models:

  • chat_messages Table: Stores chat messages, partitioned by chat_session_id and clustered by message_id for efficient retrieval. The table will be partitioned and grouped by each chat session and distributed across nodes to avoid chat_messages table getting too big on a node/server.
  • chat_sessions Table: Manages session metadata, partitioned by project_id and clustered by task_id and session_id to support queries of sessions on a project/task on a single partition.

• CassandraExecutor:

  • Automates the initialization of the Cassandra database, ensuring the keyspace and schema are correctly configured.
  • Processes changelogs sequentially from cassandra-changelogs.xml for schema updates.
  • To use this, Place CQL changelog files in src/main/resources/cassandra/changelogs/cql-scripts/. Then define changelog entries in cassandra-changelogs.xml, specifying the file names of the CQL scripts to execute.

• Controller and Repository Updates:

  • Refactored to align with Cassandra's schema and query patterns, including the permanent deletion of messages in "CLOSED" sessions. The status "ARCHIVED" is not used anymore for the sake of simplicity.

• Docker Integration:

  • Added two Cassandra containers for local testing, simulating a multi-node setup for data replication and distribution.

[parhamrahmani]

@astanik Can you please review this pull request? This will be hopefully the final implementation regarding the chat service database solution. T

I am getting connection refused on port 9042 which is needed for Cassandra. Is this a misconfiguration on my part? since i didn't have this on my personal environment.