App-db-service.md

DB Service and Client App Guide

In this guide, we will show you how to write a hello world database service app. To do so, two apps are required, one for running a database service on a server, and a client app, which accesses to the database service. A server is usually a Tizen device, such as a Tizen TV, and a client is typically a Tizen app. The database service runs on top of a Web server, which in turn runs on lwnode in our framework.

1. Run DB service on a server

1.1. Build and install a DB service app

Build lwnode RPMs and install lwnode-sqlite3.armv7l.rpm on your device. The RPMs can also be downloaded from tizen.org.

$ rpm -Uvh lwnode-sqlite3.armv7l.rpm

1.2. Run the DB service app

Run the DB service app on your device.

$ lwnode /usr/apps/lwnode/apps/sqlite3/script

We use lwnode to run a Web server, which in turn, runs a DB server. When successful, a message below is printed.

[xx:xx:xx][INFO] listening port: 8140

2. Run a client app

2.1. Download libsqlite.js

Download libsqlite.js from http://<your device ip>:8140/api/download/libsqlite.js. A client app will use this library to communicate with the DB service.

$ wget http://<your device ip>:8140/api/download/libsqlite.js

2.2. Add libsqlite.js library to your client Web app

Add the library to your Tizen Web app. This library provides Database API required to commnunite with the DB service.

<!-- index.html -->
<script src="./libsqlite.js"></script>

2.3. Run DB operations on the client

To perform DB operations in your Web app, use the sqlite3 object that is defined in global.

The following example shows you how to create a table.

// main.js
const DB_HOSTNAME = '127.0.0.1';
const DB_PORT = 8140;
const DB_PATH = '/';
const url = `ws://${DB_HOSTNAME}:${DB_PORT}${DB_PATH}`;

window.onload = async function () {
  sqlite3.configure(url);

  // use the sqlite3 object to access to Database service
  let db = await new sqlite3.Database(':memory:', sqlite3.OPEN_READWRITE | sqlite3.OPEN_CREATE);

  const q = `CREATE TABLE user (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        name text,
        email text UNIQUE,
        password text,
        CONSTRAINT email_unique UNIQUE (email)
        );`;
  try {
    let result = await db.run(q);
    console.log('success', result);
  } catch (err) {
    console.log('fail');
    throw err;
  }
};