How to connect to a WebServer mode H2 database in console?

Question

On H2 documentation, it says only the web server supports browser connections. Does this mean we can only access the H2 Database by console in WebServer mode, not TcpServer? But when I do below test, the result is totally not as expected.

public class TestMem {
    public static void main(String... args) throws Exception {

        Class.forName("org.h2.Driver");
        Connection conn = DriverManager.getConnection("jdbc:h2:mem:test");
        conn.createStatement().execute("create table test(id int)");

        Server server = Server.createTcpServer().start();//1.TcpServer
//      Server server = Server.createWebServer().start();//2.WebServer

        System.out.println("Server started and connection is open.");
        System.out.println("URL: jdbc:h2:" + server.getURL() + "/mem:test");

        Thread.sleep(5*60*1000);

        System.out.println("Stopping server and closing the connection");
        server.stop();
        conn.close();
    }
}

If I start a TcpServer, I can visit the DB by this url: jdbc:h2:tcp://localhost:9092/mem:test in console.

//Use TcpServer
  Server server = Server.createTcpServer().start();

But when I start a WebServer, I tried to connect use jdbc:h2:http ://localhost:8082/mem:test, below exception will throw: IO Exception: "java.io.IOException: The filename, directory name, or volume label syntax is incorrect"; "http ://localhost:8082/mem:test.h2.db" [90031-172] 90031/90031 (Help).

//Use WebServer
  Server server = Server.createWebServer().start();

Here are my questions

1. Can we access the WebServer mode h2 DataBase in console? How?
2. Did I misunderstand the H2 documentation about the Using the Server section?

Answer 1

The H2 Console tool (created using Server.createWebServer) is a web server and a small web application that allows you to connect to a database (any JDBC database) using a web browser (such as Firefox, Google Chrome, Internet Explorer, and so on).

The H2 TCP Server (created using Server.createTcpServer) is a server for H2 JDBC clients. It is not a web server and not a web application. You can not connect to this server from a web browser.

If you start both the Console tool (web server) and the TCP server, then you can connect using a browser to the Console tool, which can then connect to a H2 database in server mode.

About database URLs: see the documentation about database URLs.

Answer 2

Some additional comment on the answer of Thomas Mueller:

"The H2 Console tool ... a small web application"

You can see it as a "small alternative" to database applications like DBeaver or Navicat.

In addition to that, if you start the H2 console from within the same JVM as your H2 database (which has for example been started with org.h2.Tools.RunScript.execute(...)), you will be able to use the "embedded mode" of the H2 Console tool to connect to your H2 database without using a H2 TCP server.

(Other database tools like DBeaver will not run in the same JVM. If you use the embedded H2 mode with DBeaver, you will be connected to an extra temporary database inside the JVM of DBeaver.)

Example for embedded mode

If you started a H2 database "test_database" on port 8085 from within the same JVM, with the option DB_CLOSE_DELAY=-1 and without also starting a TCP server ... start a web browser and enter following address to show the H2 Console tool web application:

http://localhost:8085

Use for example following settings to connect in embedded mode:

Setting Name: Generic H2 (Embedded)
Driver Class: org.h2.Driver
JDBC URL: jdbc:h2:mem:test_database;MODE=MySQL
UserName: {user, e.g. root}
Password: {password, e.g mypassword}

Example for server mode

If you started a TCP server you can connect to the H2 database in server mode. You can do this with

• the H2 Console tool (from within the same JVM or from within another JVM)
• any other suitable database tool (e.g DBeaver).

Start a web browser and enter for example following address to show the H2 Console tool web application:

http://localhost:8085

Use for example following settings to connect in server mode:

Setting Name: Generic H2 (Server)
Driver Class: org.h2.Driver
JDBC URL: jdbc:h2:tcp://localhost:9095/mem:test_database;MODE=MySQL
UserName: {user, e.g. root}
Password: {password, e.g mypassword}

You can also use the url

jdbc:h2:tcp://localhost:9095/mem:test_database;MODE=MySQL 

to connect for example with DBeaver.