Empress SDK for Android with Empress SQLite Interface

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Empress Technical News – May 2012

Empress SDK for Android
Now with Empress SQLite Interface

Introduction
The latest Empress SDK for Android offers Android application developers new ways to develop advanced database applications requiring robustness, reliability, security, high performance, large data sets, multi-tasking control and much more.

Since Android comes with SQLite support, most Android application developers use SQLite for their database data driven applications. In many cases, application developers find that SQLite based applications will outgrow SQLite capabilities and these developers will find themselves scratching their heads and looking for an alternate solution.

Empress SDK for Android with Empress SQLite Interface is a nice alternate solution.

Empress for Android supports the following APIs:

1. Empress JDBC API (JDBC)
2. Empress Android SQLite Compatibility API (sqlite API)
3. Empress Database Administration API (dbadmin API)
4. Empress Set-Up API (setup API)

Empress SDK for Android supports the database access standard API, JDBC. The JDBC API can help developers create new database applications or migrate existing database applications to Android. The JDBC API can access databases on the local Android device (Figure 1).

Figure 1: Empress Android JDBC API

In addition, Empress JDBC Android application developers can create applications where data is stored outside of the local device such as on a local LAN, an Internet location or even in a Cloud (Figure 2).

It is even possible to mix and match local, LAN, Internet and Cloud database storage from the same Android device.

Figure 2: Different Ways to Use Empress Android JDBC Applications

In addition to JDBC, SDK for Android supports the Empress Sqlite database interface (see Figure 3) as defined in the Android package android.database.sqlite. Android application developers can utilize the Empress Sqlite API to convert an existing Android sqlite application or create a new application.

This Empress Sqlite API helps developers migrate existing database applications to Android or create new ones quickly and with low conversion effort.

Figure 3: Empress Android SQLite Compatibility API (sqlite API)

Empress SDK for Android also supports the usage of callable administration functions (e.g. creating and removing databases, exporting and importing data, checking and repairing databases) and setting Empress System variables in the Android environment.

Empress SQLite versus SQLite on Android Devices
Empress SDK for Android offers many advantages compared to SQLite on Android devices. To mention a few:

Robustness and Reliability

Empress database engine has a long history of over 30 years of usage in embedded applications. Bringing the same database engine to Android devices allows developers to experience the same kind of reliability and robustness that many production systems have experienced for decades.

Additional Features

With Empress, database developers are offered a full-fledged database development environment comparable to enterprise environments. Many features, such as encryption, allow application developers to enhance their Android applications.

Large data set solution

Empress allows application developers to build applications that can go way beyond just contacts and address book data

Multi-access solution

Empress APIs for Android supports concurrent access that allows applications to run multiple tasks at the same time.

Database degradation over time

Since SQLite has a single file to contain all the data, there is a greater likelihood of the database file being fragmented compared to Empress where the database data is spread over multiple files.

Performance

Performance of Android devices (phones, tablets, special devices, …) depends on factors such as: the location of the data storage, memory, CPU, Android version, etc. Benchmarks have shown that Empress APIs beat SQLite on Android devices with larger data sets.

Develop Empress Applications Using sqlite API
Since Android defines classes and methods in its package android.database.sqlite.

The following classes are supported:

Classes
SQLiteClosable
SQLiteCursor
SQLiteDatabase
SQLiteOpenHelper
SQLiteProgram
SQLiteQuery
SQLiteQueryBuilder
SQLiteStatement

android.database.sqlite classes are referenced in:
http://developer.android.com/reference/android/database/sqlite/package-summary.html

Converting SQLite Applications to Empress
When converting SQLite Android application to work with Empress SQLite, here are the major areas that application developers need to be aware of:

Import Lines

import database.sqlite.*

Import lines related to SQLite should be changed in the following way:

import com.empress.database.sqlite.*

Set up Empress Temporary Directory on the Android Target
At runtime, the Empress Database engine needs a temporary directory to store temporary files when necessary. This task is optional if your default temporary directory is writeable. On Android devices, the typical default is: /sdcard which is usually writeable, so you don’t need to do anything.

Set License Key
In order to enable Empress applications to be used in Android environment, a valid license key must be set in the application before using Empress methods. An Empress license key will be provided to you by Empress Software Inc. The key could be an evaluation key that expires after a certain time or a runtime key that does not expire for production purpose.

For example:

lic_str = " 18a94c3c3a2d4a9f3c0b0a225bae78398561c30476be1ad3"
if (SetUp.getLicenceKey() == null)
SetUp.setLicenceKey (lic_str)

Example
The Empress sample project EmpressEmpSQLiteSample included in the Empress SDK for Android zip file has all the Empress components pre-configured so that users can try it and run it in their Android emulator or a real device. 4 shows the EmpressEmpSQLiteSample directory structure:

Figure 4: EmpressEmpSQLiteSample Directory Structure

To demonstrate the minimal need for modification when converting a SQLite application to Empress, an example is given in the following text (part of the source code included in the sample project EmpressEmpSQLiteSample).

package com.empress.EmpressSQLiteSample

import com.empress.database.sqlite.SQLiteDatabase
import com.empress.util.EmpressException

import com.empress.database.sqlite.SQLiteStatement
import com.empress.util.SetUp

import android.app.Activity
import android.database.Cursor
import android.graphics.Color
import android.os.Bundle
import android.view.View
import android.widget.ScrollView
import android.widget.TextView

public class EmpressSQLiteSample extends Activity
{

TextView tv = null
ScrollView sv = null
String output = " "

String dbLocation = " "

public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState)

sv = new ScrollView(this)
sv.setBackgroundColor(Color.WHITE)

tv = new TextView(this)
tv.setTextColor(Color.BLACK)

sv.addView(tv)
setContentView(sv)

//dbLocation = " /sdcard"
dbLocation = this.getApplicationInfo().dataDir

runSampleInThread()

}

private void runSampleInThread()
{
Thread runner = new Thread()
{
public void run()
{
DoEmpSQLite()
}

}

runner.start()
}

private void DoEmpSQLite()
{
Cursor rs
SQLiteDatabase db1
SQLiteStatement stmt
EmpressOpenHelp DbHelp
String sql
String first_name
String last_name
String ColumnNames[]
String DBString
long manager_id
long k

rs = null
DbHelp = null
db1 = null
stmt = null

String appdatadir = this.getApplicationInfo().dataDir
String tmpdir = System.getProperty(" java.io.tmpdir" )
//By default java.io.tmpdir is set to " /sdcard" .
//If your /sdcard is not writable, you need to reset it
//to a writable location. In this example, the application
//data directory is chosen.
if (!dbLocation.equals (tmpdir))
{
postText (" DoEmpSQLite:Resetting javio.io.tmpdir '"
+ tmpdir + " ' to '" + appdatadir + " '" )
System.setProperty(" java.io.tmpdir" , appdatadir)
}

// We need to set the license
try
{
String lic_str
//Note:
//This key has expired as of
//Wednesday April 11 17:03:23 EDT 2012
lic_str =
" 18a94c3c3a2e5a9f3c0b0a225bae78398561b20476be1ad3"
if (SetUp.getLicenceKey() == null)
SetUp.setLicenceKey (lic_str)
postText(" DoEmpSQLite:setLicenceKey success" )
postText(" Expiry Date:" +
SetUp.getLicenceExpiryDateString())
}
catch (EmpressException e)
{
postText(" DoEmpSQLite:setLicenceKey failure e:" +
e.toString())
return
}

DBString = dbLocation + " /emp_db"
postText (" DoEmpSQLite:Working with database:" + DBString)

try
{
DbHelp = new EmpressOpenHelp (this,
DBString, null, 1)
db1 = DbHelp.getWritableDatabase ()
// Insert 3 records into the table employee
sql = " INSERT INTO employee " +
" (employee_id, first_name, " +
" last_name, hire_date, manager_id) VALUES (" +
" NULL, ?, ?, now(), ?)"
stmt = db1.compileStatement (sql)
first_name = " Dan"
for (manager_id = 0 manager_id < 3 manager_id++)
{
last_name = " Smitters_0" + manager_id
stmt.bindString (1, first_name)
stmt.bindString (2, last_name)
stmt.bindLong (3, manager_id)
k = stmt.executeInsert ()
if (k != 1)
{
postText(" Unable to insert record " +
manager_id)
break
}
}
stmt.close ()
stmt = null

// Retrieve the records back
rs = db1.rawQuery (" SELECT * FROM employee" , null)
// Get the Column Names
ColumnNames= rs.getColumnNames ()
while (rs.moveToNext ())
{
postText (" ================" )
for (int i = 0 i < ColumnNames.length i++)
{
postText (ColumnNames[i] + " :" +
rs.getString (i))
}
postText (" ================\n" )
}
rs.close ()
rs = null

db1.close ()
db1 = null

DbHelp.close ()
DbHelp = null

postText(" \nExample is done" )
}
catch (Exception e)
{
if (stmt != null)
stmt.close ()
if (rs != null)
rs.close ()
if (db1 != null)
db1.close()
if (DbHelp != null)
DbHelp.close ()
postText (" Exception caught e:" + e)
postText (" " )
}

}

private void postText(String t)
{
final String txt = t
sv.post(new Runnable() {

public void run() {
tv.append(txt + " \n" )
sv.fullScroll(View.FOCUS_DOWN)

}
})
}

}

Instead of Summary
Empress SDK for Android with Empress SQLite Interface addresses the growing need for more secure, complex, reliable and efficient database data driven Android applications that fall short when using the Android SQLite solution. In addition to the standard JDBC API, Empress SDK for Android supports Empress Android SQLite Compatibility API which helps developers migrate existing database applications to Android quickly and with the least effort. Furthermore, Empress also provides robustness, reliability, additional features, large data set handling, multi-access solutions, increased performance and much more.

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