Custom JDBC driver without database introspection

Hello,

I am trying to write a simple JDBC driver that, instead of interacting with a database directly, sends queries to another system over HTTPS.

The end goal is to be able to set up a Driver + Data Source in IntelliJ IDEA Ultimate, have IntelliJ send the SQL queries over, and present the results in the IDE's table view (https://resources.jetbrains.com/help/img/idea/2022.3/db_ui_query_console_result_tab.png).

The interfaces to implement are quite large (especially `PreparedStatement` and `DatabaseMetadata`), and I was wondering if it is possible to implement a subset of these to get _just_ the ability to see results of SELECT queries? I know the IDE is able to perform DB introspection to figure out what schemas are available, etc. but I do not need that information.

I can see the JOOQ library allows turning a `ResultSet` into JSON, and then turn JSON back into a `ResultSet`. So I made the system with access to the DB serialize its ResultSet, send it over, and then my driver turns the JSON back into a `ResultSet`. Given result sets contain both the data and column type information, I was hoping it would be enough for IntelliJ, however I'm getting errors while executing simple `SELECT 1` queries and am not sure what is actually being called.

In the Data Source view, the "Test Connection" action succeeds and I get the metadata back from the driver. I can also see the `SELECT version()` query is sent to the server. But if I try to execute "SELECT 1" in the "Playground" view, I get back "Connection was established but closed as invalid".

2022-12-02 11:13:58,193 [44345239]   INFO - #c.i.d.d.DatabaseConnectionEstablisher - Connecting to: <URL>
2022-12-02 11:13:58,195 [44345241]   INFO - #c.i.d.d.DatabaseConnectionEstablisher - Auth provider: user-pass
2022-12-02 11:13:58,205 [44345251]   INFO - #c.i.d.d.DatabaseCredentialsAuthProvider - No user name provided (may be in url)
2022-12-02 11:13:58,263 [44345309]   INFO - #c.i.e.r.RemoteProcessSupport - setting driver log level to FINEST
2022-12-02 11:13:58,263 [44345309]   INFO - #c.i.e.r.RemoteProcessSupport - setting driver log path to /Users/martynas/Desktop/log.txt
2022-12-02 11:13:58,264 [44345310]   INFO - #c.i.e.r.RemoteProcessSupport - DriverManager.LogWriter.level=FINEST
2022-12-02 11:13:58,264 [44345310]   INFO - #c.i.e.r.RemoteProcessSupport - lt.martynas.driver.level=FINEST
2022-12-02 11:13:58,264 [44345310]   INFO - #c.i.e.r.RemoteProcessSupport - Setting `LogLevel` to `6`
2022-12-02 11:13:58,264 [44345310]   INFO - #c.i.e.r.RemoteProcessSupport - Setting `LogPath` to `/Users/martynas/Desktop/log.txt`
2022-12-02 11:13:58,991 [44346037]   INFO - #c.i.i.s.IdeScriptEngineManagerImpl - 129 ms to enumerate javax.scripting engines on EDT
2022-12-02 11:13:59,904 [44346950]   INFO - #c.i.e.r.RemoteProcessSupport - Driver: MyCustomDriver 1.1
2022-12-02 11:14:00,743 [44347789]   INFO - #c.i.e.r.RemoteProcessSupport - version: PostgreSQL 13.7 on aarch64-unknown-linux-gnu, compiled by aarch64-unknown-linux-gnu-gcc (GCC) 7.4.0, 64-bit
2022-12-02 11:14:00,743 [44347789]   INFO - #c.i.e.r.RemoteProcessSupport - Detected: POSTGRES null
2022-12-02 11:14:00,786 [44347832]   INFO - #c.i.d.c.JdbcEngineUtils - Connection is invalid

Is there a way to get more information about _why_ it is not valid? I tried updating the "VM Options" of the driver and attaching a debugger, but can't step into any of IntelliJ's internal classes.

Alternatively, maybe it's possible to feed IntelliJ the serialized `ResultSet` and have it open up a read-only table window, without involvinig JDBC at all?

Serialized output of `SELECT 1`:

{
  "fields": [
    {
      "name": "?column?",
      "type": "INTEGER"
    }
  ],
  "records": [
    [1]
  ]
}

Regards,
Martynas