The Elasticsearch transport layer is responsible for handling low-level communication between Elasticsearch nodes and clients. Here’s a brief overview of how the transport layer works:
1. Connection establishment: When a client sends a request to Elasticsearch, the request is sent to a node on the cluster, which then establishes a connection with the client. The connection is established using the Elasticsearch Transport Protocol, which is a binary protocol based on Google’s Protocol Buffers serialization format.
2. Request processing: When the connection is established, the client sends the request to the node. The node then processes the request, either by handling it locally or by forwarding it to the appropriate node or nodes in the cluster.
3. Response handling: When the request has been processed, the node sends a response back to the client through the same connection. The response is also serialized using the Elasticsearch Transport Protocol and the Protocol Buffers format.
4. Connection pooling: To optimize network performance, the transport layer uses connection pooling to reuse existing connections between nodes and clients. This helps to reduce the overhead of establishing new connections for each request, and it can improve the overall throughput and latency of the system.
5. Automatic node discovery: To ensure that requests are routed to the appropriate nodes in the cluster, the transport layer uses automatic node discovery. When a node joins or leaves the cluster, the other nodes automatically update their routing tables and connection pools to reflect the new cluster topology.
6. Security features: The transport layer provides several security features to protect data in transit. These include encryption using SSL/TLS, authentication using client certificates or username/password credentials, and the ability to restrict access to specific IP addresses or networks.
The Elasticsearch transport layer is designed to be fast, efficient, and reliable, with features like connection pooling and automatic node discovery to optimize performance and resilience. By using the Elasticsearch Transport Protocol and the Protocol Buffers format, the transport layer provides a lightweight and flexible binary interface for communicating with Elasticsearch nodes and clients.