mongoc_server_description_t * mongoc_client_get_handshake_description (mongoc_client_t *client, uint32_t server_id, bson_t *opts, bson_error_t *error) BSON_GNUC_WARN_UNUSED_RESULT;
Returns a description constructed from the initial handshake response to a server.
mongoc_client_get_handshake_description() is distinct from mongoc_client_get_server_description(). mongoc_client_get_server_description() returns a server description constructed from monitoring, which may differ from the server description constructed from the connection handshake.
mongoc_client_get_handshake_description() will attempt to establish a connection to the server if a connection was not already established. It will perform the MongoDB handshake and authentication if required.
Use this function only for building a language driver that wraps the C Driver. When writing applications in C, higher-level functions automatically select a suitable server.
Single-threaded client behavior
Single-threaded clients only have one active connection to each server. The one connection is used for both monitoring and application operations. However, the server description returned by mongoc_client_get_handshake_description() may still differ from the server description returned by mongoc_client_get_server_description(). Notably, if connected to a load balanced cluster, the server description returned by mongoc_client_get_server_description() will describe the load balancer server (mongoc_server_description_type() will return "LoadBalancer"). And the server description returned by mongoc_client_get_handshake_description() will describe the backing server.
- client: A mongoc_client_t.
- server_id: The ID of the server. This can be obtained from the server description of mongoc_client_select_server().
- opts: Unused. Pass NULL.
- error: An optional location for a bson_error_t or NULL.
A mongoc_server_description_t that must be freed with mongoc_server_description_destroy(). If a connection has not been successfully established to a server, returns NULL and error is filled out.
- mongoc_client_select_server() To select a server from read preferences.
- mongoc_client_get_server_description() To obtain the server description from monitoring for a server.
- mongoc_server_description_type() To obtain the type of server from a server description.
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