Secure API calls with C# & SQL.

Historical code examples retained from the Starfleet-themed guide. They are reading material, not commands executed by this page or a production deployment recipe. Verify platform support, trust, authorization and outbound-network policy before using any example.

A Starfleet guide to the integration boundary.

The stored procedure supplies a document payload, the C# example sends an HTTP request, and the remote service supplies a response. The interactive console above models permission outcomes only: it never executes SQL, renders the payload or sends the request.

The C# example

using System;
using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;

public partial class DocumentFabricationProtocol
{
    // A single, static HttpClient is mission-critical for performance.
    private static readonly HttpClient client = new HttpClient();

    [SqlFunction(DataAccess = DataAccessKind.None, SystemDataAccess = SystemDataAccessKind.None)]
    public static SqlString CreateDocument(SqlString apiUrl, SqlString htmlPayload)
    {
        // Protocol 1.1: Verify fabrication station coordinates.
        if (apiUrl.IsNull || !Uri.TryCreate(apiUrl.Value, UriKind.Absolute, out Uri uri))
            return new SqlString("Error: Invalid API coordinates.");

        // Protocol 2.4: Secure channels only.
        if (uri.Scheme != Uri.UriSchemeHttps)
            return new SqlString("Error: Unsecure channel.");

        // Protocol 2.5: Verify destination is a trusted Starfleet fabricator.
        if (!uri.Host.EndsWith(".starfleet.local", StringComparison.OrdinalIgnoreCase))
            return new SqlString("Error: Untrusted destination.");

        try
        {
            // Prepare the schematic (HTML) for transport.
            var content = new StringContent(htmlPayload.Value, Encoding.UTF8, "application/json");

            // Transmit data via POST and await response.
            Task<HttpResponseMessage> responseTask = client.PostAsync(uri, content);
            HttpResponseMessage response = responseTask.GetAwaiter().GetResult();

            response.EnsureSuccessStatusCode();

            // Confirmation that API placed file in buffer. Archival is handled by SSU.
            return new SqlString("Success: Schematic received by fabricator.");
        }
        catch (Exception ex) {
            return new SqlString($"Fabrication Error: {ex.Message}");
        }
    }
}

The T-SQL command

CREATE PROCEDURE dbo.usp_GenerateArchivedDocument
    @HtmlContent NVARCHAR(MAX)
AS
BEGIN
    SET NOCOUNT ON;
    -- Set target fabrication station coordinates. Store this in a config table, not here!
    DECLARE @ApiEndpoint NVARCHAR(2048) = N'https://api.example.invalid/api/createpdf';
    DECLARE @Status NVARCHAR(MAX);

    -- Log the attempt.
    PRINT 'Authorizing transmission to ' + @ApiEndpoint;

    BEGIN TRY
        -- Execute the CLR function, passing the coordinates and the schematic.
        SELECT @Status = dbo.CreateDocument(@ApiEndpoint, @HtmlContent);

        -- Verify mission success.
        IF (@Status LIKE 'Success:%')
        BEGIN
            PRINT 'Confirmation received. Document fabrication initiated.';
        END
        ELSE
        BEGIN
            -- Report failure to the bridge.
            THROW 50001, @Status, 1;
        END
    END TRY
    BEGIN CATCH
        PRINT 'RED ALERT: Mission failed. An unknown anomaly occurred during transmission.';
        THROW;
    END CATCH
END

Assembly registration example

-- Load the compiled .dll file into SQL Server.
-- The DLL must be on a path accessible by the SQL Server service account.
CREATE ASSEMBLY DocumentFabricationAssembly
FROM 'C:\Example\CLR\DocumentFabricationProtocol.dll'
WITH PERMISSION_SET = EXTERNAL_ACCESS;
GO

-- Create the SQL function that maps to the C# method.
-- Note the parameter types match the C# SqlString types.
CREATE FUNCTION dbo.CreateDocument(
    @apiUrl NVARCHAR(2048),
    @htmlPayload NVARCHAR(MAX)
)
RETURNS NVARCHAR(MAX)
AS EXTERNAL NAME DocumentFabricationAssembly.[DocumentFabricationProtocol].CreateDocument;
GO

Read the permission-boundary notes or return to the local demonstration to compare SAFE, EXTERNAL_ACCESS and UNSAFE. There is no second transmission form hidden in this reference section.