DDevelopment & Design

Cross-platform mobile apps – possible or not?

What is Titanium and how it works. Titanium is an open-source solution for cross-platform, almost-native mobile app development. It has its own MVC, JavaScript and XML-based framework Alloy. Titanium is based on assumption, that each app can be divided into two parts: UI, which is platform-specific part and application core – business logic, common to all […]What is Titanium and how it works. Titanium is an open-source solution for cross-platform, almost-native mobile app development. It has its own MVC, JavaScript and XML-based framework Alloy. Titanium is based on assumption, that each app can be divided into two parts: UI, which is platform-specific part and application core – business logic, common to all […]

blog-product-titanium1

What is Titanium and how it works.

Titanium is an open-source solution for cross-platform, almost-native mobile app development. It has its own MVC, JavaScript and XML-based framework Alloy. Titanium is based on assumption, that each app can be divided into two parts: UI, which is platform-specific part and application core – business logic, common to all platforms. So, inside the app, we have native UI components and JavaScript interpreted logic, communicating with each other.

If you want to write your app in titanium, you only need to know JavaScript and learn to call Titanium API for UI components. Alloy, on the other hand, is more fun, because you have to write views in XML, model and controllers in JavaScript (+ Titanium API mentioned before) and styles in something called Titanium StyleSheets, which is CSS+JSON hybrid. I must admit, the language is not an obstacle for anybody who ever did web development, or any kind of script and markup languages. It’s easy to start working with this framework.

Beginnings.

To work with Titanium, you will need Titanium Studio – an Eclipse-based IDE adapted to write and deploy Titanium apps into various platforms and stores – AppStore, Google Play etc. It has a direct access to Appcelerator Titanium Marketplace, where you can download e.g. sample applications, widgets and plugins – paid for or free of charge.

After downloading Titanium Studio and necessary SDK’s I downloaded sample code called Kitchen Sink – an example, showing possibilities of Titanium Alloy framework. I chose a device and… it worked! After (very few ;-) years of programming I get used to difficult beginnings, long configurations before the first launch (whether regarding a web app, mobile app or any kind of desktop/command line app), but Appcelerator did a great job preparing IDE and integrating it with simulators, emulators etc. After the first success I played with Alloy for a few days and here comes my conclusions.

What is great about Titanium.

1. Simplicity. Apps can be build from small files and can be developed very fast. Everybody knows basics of XML and JavaScript, so you can start writing your apps straight away.

2. Architecture. Alloy framework is very well designed. It allows installing plugins, widgets, or even native modules in a convenient way. “Convention over configuration” makes this process faster – all you need to do is put the downloaded widget into the “widget” directory and add a dependency into config.json file.

3. GitTio is a search engine that indexes all Titanium modules and Alloy widgets. It is something similar to Cocoa Controls for iOS, but more comprehensive, because it automatically finds new modules in GitHub and indexes them. GitTio provides Command Line Interface, which facilitates installing and managing widgets.

What is not-so-great about Titanium.

1. There is not such thing as “one app to rule them all”. Mobile platforms have different controls, components and UI elements. The same things are implemented by different solutions. The more complex the app gets, the more platform dedicated code needs to be written. After all, I end up writing views and controllers for each platform separately.

2. Even if you can write one view for each platform, you probably shouldn’t do it. There is one thing I have not mentioned yet – User Experience. It is extremely different for each mobile OS. Android users are used to “back” and “menu” buttons, iOS users are using navigation bar, some OS’s are using swipe moves to navigate between window. Therefore, a universal app for all platforms is doubtful idea to start with.

3. Cross-platform idea stops working when you want to use external module. There are “iOS-only” modules or “iOS and Android” modules. Very rarely, they may also include mobileweb.

What is totally not-great about Titanium.

1. Titanium is still young. It develops really fast. A lot of things have bugs, while at the same time, a lot of features get deprecated. When you find a tutorial from 2011, you may never be sure whether it’s up to date. Differences between close versions (like 3.1.3 and 3.2) sometimes force re-writing the whole view or using another widget.

2. Titanium and Titanium Alloy are two different worlds. Having got used to the beautiful Alloy MVC code I tried downloading a widget written in “plain Titanium”. This was a lot of code with a completely different approach and not so easy to integrate with Alloy. Then I found out, that I don’t have “631 Titanium modules” (gitt.io), but “178 Alloy Widgets”, so I had to found widget with similar functionality, written in Alloy. Another “little” bump on the road.

So what?

With some experience with Titanium and some experience with PhoneGap, I don’t think it is possible to write a good cross-platform app. It is hard even when you try to do this for iOS and Android only, but we have also Bada, Tizen, Firefox OS and new OS’s are developed as we speak – Ubuntu Touch, Sailfish OS and some more. Also, it is always good to have mobile web version of the app. But, even if a cross-platform app would be possible to write…

You shouldn’t do this. When you write a native app, you can learn user habits and good practises for each platform. When you write one app for every platform, you probably break about a million good-UX rules. But, if you are desperate and want to do this anyway…

It won’t save you a lot of time. When you write cross-platform apps, you have to deal with OS-specific quirks, you sometimes get native-code errors (good luck with Objective-C errors without any iOS knowledge) and it is not too difficult to miss some crucial things (while testing on 9 devices at the time).

Of course, in some cases, cross-platform apps can be a good solution. Nevertheless, in my opinion, it is not the universal solution for mobile app development.

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DDevelopment & Design

Multi module Gradle project with IDE support

This article is a short how-to about multi-module project setup with usage of the Gradle automation build tool.

Here's how Rich Seller, a StackOverflow user, describes Gradle:
Gradle promises to hit the sweet spot between Ant and Maven. It uses Ivy's approach for dependency resolution. It allows for convention over configuration but also includes Ant tasks as first class citizens. It also wisely allows you to use existing Maven/Ivy repositories.
So why would one use yet another JVM build tool such as Gradle? The answer is simple: to avoid frustration involved by Ant or Maven.

Short story

I was fooling around with some fresh proof of concept and needed a build tool. I'm pretty familiar with Maven so created project from an artifact, and opened the build file, pom.xml for further tuning.
I had been using Grails with its own build system (similar to Gradle, btw) already for some time up then, so after quite a time without Maven, I looked on the pom.xml and found it to be really repulsive.

Once again I felt clearly: XML is not for humans.

After quick googling I found Gradle. It was still in beta (0.8 version) back then, but it's configured with Groovy DSL and that's what a human likes :)

Where are we

In the time Ant can be met but among IT guerrillas, Maven is still on top and couple of others like for example Ivy conquer for the best position, Gradle smoothly went into its mature age. It's now available in 1.3 version, released at 20th of November 2012. I'm glad to recommend it to anyone looking for relief from XML configured tools, or for anyone just looking for simple, elastic and powerful build tool.

Lets build

I have already written about basic project structure so I skip this one, reminding only the basic project structure:
<project root>

│

├── build.gradle

└── src

    ├── main

    │   ├── java

    │   └── groovy

    │

    └── test

        ├── java

        └── groovy
Have I just referred myself for the 1st time? Achievement unlocked! ;)

Gradle as most build tools is run from a command line with parameters. The main parameter for Gradle is a 'task name', for example we can run a command: gradle build.
There is no 'create project' task, so the directory structure has to be created by hand. This isn't a hassle though.
Java and groovy sub-folders aren't always mandatory. They depend on what compile plugin is used.

Parent project

Consider an example project 'the-app' of three modules, let say:
  1. database communication layer
  2. domain model and services layer
  3. web presentation layer
Our project directory tree will look like:
the-app

│

├── dao-layer

│   └── src

│

├── domain-model

│   └── src

│

├── web-frontend

│   └── src

│

├── build.gradle

└── settings.gradle
the-app itself has no src sub-folder as its purpose is only to contain sub-projects and build configuration. If needed it could've been provided with own src though.

To glue modules we need to fill settings.gradle file under the-app directory with a single line of content specifying module names:
include 'dao-layer', 'domain-model', 'web-frontend'
Now the gradle projects command can be executed to obtain such a result:
:projects


------------------------------------------------------------

Root project

------------------------------------------------------------


Root project 'the-app'

+--- Project ':dao-layer'

+--- Project ':domain-model'

\--- Project ':web-frontend'
...so we know that Gradle noticed the modules. However gradle build command won't run successful yet because build.gradle file is still empty.

Sub project

As in Maven we can create separate build config file per each module. Let say we starting from DAO layer.
Thus we create a new file the-app/dao-layer/build.gradle with a line of basic build info (notice the new build.gradle was created under sub-project directory):
apply plugin: 'java'
This single line of config for any of modules is enough to execute gradle build command under the-app directory with following result:
:dao-layer:compileJava

:dao-layer:processResources UP-TO-DATE

:dao-layer:classes

:dao-layer:jar

:dao-layer:assemble

:dao-layer:compileTestJava UP-TO-DATE

:dao-layer:processTestResources UP-TO-DATE

:dao-layer:testClasses UP-TO-DATE

:dao-layer:test

:dao-layer:check

:dao-layer:build


BUILD SUCCESSFUL


Total time: 3.256 secs
To use Groovy plugin slightly more configuration is needed:
apply plugin: 'groovy'


repositories {

    mavenLocal()

    mavenCentral()

}


dependencies {

    groovy 'org.codehaus.groovy:groovy-all:2.0.5'

}
At lines 3 to 6 Maven repositories are set. At line 9 dependency with groovy library version is specified. Of course plugin as 'java', 'groovy' and many more can be mixed each other.

If we have settings.gradle file and a build.gradle file for each module, there is no need for parent the-app/build.gradle file at all. Sure that's true but we can go another, better way.

One file to rule them all

Instead of creating many build.gradle config files, one per each module, we can use only the parent's one and make it a bit more juicy. So let us move the the-app/dao-layer/build.gradle a level up to the-app/build-gradle and fill it with new statements to achieve full project configuration:
def langLevel = 1.7


allprojects {


    apply plugin: 'idea'


    group = 'com.tamashumi'

    version = '0.1'

}


subprojects {


    apply plugin: 'groovy'


    sourceCompatibility = langLevel

    targetCompatibility = langLevel


    repositories {

        mavenLocal()

        mavenCentral()

    }


    dependencies {

        groovy 'org.codehaus.groovy:groovy-all:2.0.5'

        testCompile 'org.spockframework:spock-core:0.7-groovy-2.0'

    }

}


project(':dao-layer') {


    dependencies {

        compile 'org.hibernate:hibernate-core:4.1.7.Final'

    }

}


project(':domain-model') {


    dependencies {

        compile project(':dao-layer')

    }

}


project(':web-frontend') {


    apply plugin: 'war'


    dependencies {

        compile project(':domain-model')

        compile 'org.springframework:spring-webmvc:3.1.2.RELEASE'

    }

}


idea {

    project {

        jdkName = langLevel

        languageLevel = langLevel

    }

}
At the beginning simple variable langLevel is declared. It's worth knowing that we can use almost any Groovy code inside build.gradle file, statements like for example if conditions, for/while loops, closures, switch-case, etc... Quite an advantage over inflexible XML, isn't it?

Next the allProjects block. Any configuration placed in it will influence - what a surprise - all projects, so the parent itself and sub-projects (modules). Inside of the block we have the IDE (Intellij Idea) plugin applied which I wrote more about in previous article (look under "IDE Integration" heading). Enough to say that with this plugin applied here, command gradle idea will generate Idea's project files with modules structure and dependencies. This works really well and plugins for other IDEs are available too.
Remaining two lines at this block define group and version for the project, similar as this is done by Maven.

After that subProjects block appears. It's related to all modules but not the parent project. So here the Groovy language plugin is applied, as all modules are assumed to be written in Groovy.
Below source and target language level are set.
After that come references to standard Maven repositories.
At the end of the block dependencies to groovy version and test library - Spock framework.

Following blocks, project(':module-name'), are responsible for each module configuration. They may be omitted unless allProjects or subProjects configure what's necessary for a specific module. In the example per module configuration goes as follow:
  • Dao-layer module has dependency to an ORM library - Hibernate
  • Domain-model module relies on dao-layer as a dependency. Keyword project is used here again for a reference to other module.
  • Web-frontend applies 'war' plugin which build this module into java web archive. Besides it referes to domain-model module and also use Spring MVC framework dependency.

At the end in idea block is basic info for IDE plugin. Those are parameters corresponding to the Idea's project general settings visible on the following screen shot.


jdkName should match the IDE's SDK name otherwise it has to be set manually under IDE on each Idea's project files (re)generation with gradle idea command.

Is that it?

In the matter of simplicity - yes. That's enough to automate modular application build with custom configuration per module. Not a rocket science, huh? Think about Maven's XML. It would take more effort to setup the same and still achieve less expressible configuration quite far from user-friendly.

Check the online user guide for a lot of configuration possibilities or better download Gradle and see the sample projects.
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DDevelopment & Design

Use asInstanceOf[T] carefully!

BackgroundScala has nice static type checking engine but from time to time there are situations when we must downcast some general object. If this casting is not possible we expect that virtual machine will throw ClassCastExeption as fast as possible. ...