Skip to content

Get a SQL Server connection string

This operation returns a fully formatted SQL Server connection string for a given server, instance, and user, serving it from the in-memory cache when available and retrieving it from the DBConnectionAPI otherwise.

Field Value
Operation ID OP-DBC-03
Trigger Caller invokes GetSqlServerConnection(server, instance, userName)
Inputs server, instance, userName
Outputs Full SQL Server connection string
Primary components ConnectionClient.GetSqlServerConnection
Entry point src/SAIF.NetCore.DbConnectionClient/SAIF.NetCore.DBConnectionClient/SAIF.NetCore.DBConnectionClient/ConnectionClient.cs

Steps

  1. Build the engine-prefixed cache key SQL_{server}_{instance}_{userName} (BR-DBC-04).
  2. Build the URL path /{SqlEndpoint}/{server}/{instance}/{userName}.
  3. Acquire the instance-wide connection-string lock and check the cache for this key. On a cache hit, release the lock and return the cached value immediately — no HTTP call is made.
  4. On a cache miss (still under the lock): validate the backoff configuration, then call HttpClient.GetAsync(urlPath) in a loop of up to MaxRetrieveAttempts (4, by default). A successful non-empty response is decoded, cached, and returned. HTTP 401/403/404 fail fast with no retry (BR-DBC-09). A 503 or network-level error is transient and retries with fixed backoff (2s, 3s, 5s) until attempts are exhausted (BR-DBC-10). Any other non-success or an empty body fails immediately (BR-DBC-11). A failed attempt is never cached; the lock is released once the outcome (value or exception) is determined.

  5. Origin: Steps 3.1–3.5 of Cached lookup, which embed the retry and classification logic from Retrieve with retry, are executed on behalf of this operation.

Process flow

flowchart TD
    Start([GetSqlServerConnection called]) --> Key[Build key SQL_server_instance_userName]
    Key --> Path[Build URL path /SqlEndpoint/server/instance/userName]
    Path --> Lock["Acquire lock, check cache"]
    Lock --> Hit{Cache hit?}
    Hit -->|Yes| Return([Return cached value])
    Hit -->|No| Get["GetAsync, up to 4 attempts"]
    Get --> Outcome{Outcome}
    Outcome -->|Success| Return
    Outcome -->|"401/403/404"| FailFast(["Throw DBClientException, no retry"])
    Outcome -->|"503/network error"| Retry["Backoff 2s/3s/5s, retry or throw"]
    Outcome -->|Other failure| ImmediateFail(["Throw DBClientException"])

Failure and edge-case behavior

  • Any exception from the underlying cached lookup (including DBClientException on permanent or exhausted-retry failures) propagates to the caller unchanged.

Sources

  • src/SAIF.NetCore.DbConnectionClient/SAIF.NetCore.DBConnectionClient/SAIF.NetCore.DBConnectionClient/ConnectionClient.cs