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Developing for Mobile Devices

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Introduction

Having just posted a couple of articles on the Argos Mobile SDK here and here; and with the news that Windows 8 has just been released to manufacturing; I thought it might be a good time to reflect a bit on mobile devices and how to develop for them.

By mobile devices we tend to mean smart phones and tablets and not laptop or desktop computers. Certainly there is a lot of blurring around the edges of these categories. Phones becoming as big as tablets, laptops with detachable keyboards and touch screens, etc. There are all sorts of charts showing the growth of mobile devices such as this one from Business Insider:

Today you see iPads, iPhones, and Android devices everywhere. There is a huge market already and from these growth trends you can only see the market demand accelerating in the future. We are already at the point where many workers perform all their computing tasks through a tablet or a phone and may not have access to a desktop or laptop computer at all.

How to develop for mobile devices is a very hot topic around the web. There is a lot of debate around whether to develop using the native SDK’s from the device manufacturers, using a third party toolset that targets multiple devices or writing a web application that runs on anything. What are the pros and cons of all these approaches? What are the tradeoffs you are making when deciding between these?

Device Experience

Apple has done a great job creating the iPhone and iPad and giving them a great user experience. Anyone writing apps that run on these devices want to make their apps as great as any app from Apple when run on one of these. The same goes for creating Android apps or for creating Windows 8 Metro apps. So what are some of the things that you want in your application to fit in naturally into these environments?

  • Follow the look and feel guidelines for the platform. Look and behave like any of the applications that the manufacturer provides. Honor all the touch gestures on the device, have great professional graphics and layout at the right resolution.
  • Integrate with all the build-in hardware on the device. For instance able to access contacts, dial the phone, use the GPS, read the accelerometer, take photos, record sound, receive input via voice, film movies or any other neat hardware feature where ever they make sense.
  • Integrate with the native operating system and utilize all its features. For instance on Windows 8 Metro, support the charms, command bar and integrated application search.
  • Have great performance. Feel just as snappy as any other app on the platform. Don’t hog bandwidth; remember bandwidth can cost money.

Device Differentiators

What distinguishes all these devices? What makes them different? What do you need to support for the best experience?

  • Screen size, we have all sorts of screen sizes from small but high resolution (iPhones with retina displays) to large with low resolution (cheap large screen desktop monitors). Being adaptable is quite a challenge.
  • Input methods. Devices support touch, voice, keyboard, mouse, pen, QR codes, NFC, etc. Supporting all these can be quite a challenge.
  • Different hardware devices. How multi-touch is the device, does it have GPS, does it have a thermometer, is there a sim card, etc.
  • Operating system version. How up to date are most people? Which version do you want to support?
  • Different processor power, battery life and memory.

Using a Web App as a Device App

With all these consideration, is it possible to have a web application pose as a native app? That is what we have been doing with the Argos SDK. The nice thing about Web applications is that they run pretty much anywhere; all the mobile devices have really good browser support. Web applications are also good at adapting to different screen sizes; HTML has always been doing this. The device manufacturers have been good about adding input events to the JavaScript programming model, so you do get notified of touch gestures in your JavaScript application.

However device support is limited. It slowly makes its way into JavaScript, but generally web apps tend to trail native applications in hardware and operating system support. Another key problem is that you can’t post a URL to the app stores like iTunes, these only take native applications.

Enter systems like PhoneGap. These take a web app and wrap it in a native application. In addition to creating a native wrapped app that you can post to the app store, it also adds a lot of hardware abstraction, so you can access things like the accelerometer, but in a way that PhoneGap will make work on all devices.

The Argos SDK is fully PhoneGap compatible, so you can create mobile applications with Argos, compile them with PhoneGap and then deploy them through an app store.

Windows 8

I know Microsoft just dropped the use of the “Metro” name for its native tablet apps, but without a replacement I’m going to just keep calling it Metro. Metro is a subsystem of Windows 8 that allows you to build tablet type apps. Similar to iPhone apps, these can only be distributed via the Microsoft Store (or via a very arcane Enterprise distribution system). The intent of these is to define a new modern UX model for Windows applications. These programs run by themselves and can’t be displayed as Windows in the regular Windows desktop. There are two ways to develop these via Visual Studio 2012, either as C#/XAML apps or as JavaScript/HTML applications. PhoneGap doesn’t have Windows 8 support yet, but I would expect to see it down the road.

If you develop a Metro app in JavaScript/HTML in VS 2012, don’t expect it to run anywhere except in the Metro environment. This is standard JS, but the core of the program structure is proprietary and you have to use a number of proprietary native controls to get proper Windows 8 functionality. All that being said, you can leverage a large number of standard JavaScript libraries such as JQuery or HighChart. You can also structure your program to isolate the proprietary parts to keep as much reusable as possible.

To use operating system you need to be a native application and you have to use proprietary controls to access things like the integrated search and the charms. You can probably simulate the command bar via other means.

If you buy a Windows 8 ARM Processor based device, then it only runs Metro or Web apps, it will not run any other type of application. So if you want to participate in this world then you do need to develop for Metro (or rely on a web app). It will be interesting to see if sales of ARM based Windows 8 devices takes off. Microsoft is releasing their Surface tablet in both ARM and Intel processor based versions.

Right now there is a lot of impedance between current laptops/desktops and Windows 8. Metro is really designed for the next generation of hardware and doesn’t work at all well with current hardware. Perhaps it’s a mistake making it compatible with old hardware since it yields a bad experience, but Microsoft’s hope is that as new hardware comes to market, then the Metro experience will greatly improve.

Summary

It seems that applications need the experience of native applications, but want to leverage the portability of Web apps. After all what developer wants to create 4 or 5 different versions of their program? This is leading to new categories of hybrid applications that have large parts written as web apps, but then merged with parts that are created natively to directly interact with operating system and device features. It certainly leads to programmers needing quite a plethora of skills starting with JavaScript/HTML/CSS for Web Apps and Metro Apps, Objective C for iOS and Java for Android.

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The Argos SDK

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Introduction

Argos is a framework for creating mobile SData clients using HTML5, JavaScript and CSS. This was originally developed by the Sage SalesLogix group to create the mobile interface for the Sage SalesLogix Mobile product. However since SalesLogix uses SData as its Web Services interface, this library was created entirely on SData. As a consequence it can be used with any product that supports SData.

As part of our Sage 300 ERP 2012 development we tested Argos on our SData feeds and produced a sample mobile application.

Note: that to run this application on your own system, you need at least the Sage 300 ERP 2012 beta.

Argos SDK

The Argos SDK is open source and available on github:

This includes a JavaScript SData client library that you can use standalone independent of the rest of the SDK along with a sample application that shows Argos running on SalesLogix. The SalesLogix sample application also includes the second sample which shows how to customize the first without requiring code changes to it.

Sage 300 Sample Argos Application

Sorry, the Sage 300 team doesn’t have a github account like SalesLogix right now. However I posted the Sage 300 Sample application and the matching Argos SDK on GDrive here:

Generally you would put these as folders under the c:\inetpub\wwwroot folder. Then you can start the app via: http://localhost/sage300/index-dev.html. (Or substitute your own hostname as needed).

In the Sage300 application there is a runtime folder. This needs to be copied to: C:\Program Files (x86)\Common Files\Sage\Sage 300 ERP\Tomcat\portal\sageERP\runtime. These are the definition files for the SData feeds that this sample uses. After you copy this, you need to restart the “Sage 300 ERP Tomcat” service for them to get read.

CORS

The last gotcha is that the Argos SDK uses Cross Origin Resource Sharing (CORS). This is a mechanism where the server that is serving the HTML can let the browser know its ok to talk to another server. This way the Web Server that serves up the HTML, CSS and JavaScript files can be different than the SData server. Normally this isn’t allowed as it’s considered a severe security threat since it allows malicious programs to send sensitive data to a third server or to send out things like Spam. CORS is an internet standard that provides a way to let the browser know what is ok and what is bad in a secure manner.

As a result, you have to configure the IIS (or whatever web server you use for the static content) to grant access to the SData server. You still have to do this, even if they are the same, since all SData requests from the Argos SDK are CORS validated. The Wiki attached to the Argos SDK on the main Github site above has complete information on this.

But since I’m not exposed to the outside world and don’t usually worry too much about this, I tend to just let CORS say everything is valid with a simple web.config file (in c:\inetpub\wwwroot):

<?xml version=”1.0″ encoding=”UTF-8″?>
<configuration>
<system.webServer>
<handlers accessPolicy=”Read, Execute, Script” />
<httpProtocol>
<customHeaders>
<add name=”Access-Control-Allow-Origin” value=”*” />
</customHeaders>
</httpProtocol>
</system.webServer>
</configuration>

Like I said, don’t just specify “*” like I have for a real situation, but if you are on different networks with a laptop, sometimes this is just easier. Similarly in a real environment, you would want to use https rather than http.

Configuring to Connect to Sage 300 SData Feeds

The key to interfacing to Sage 300 is the development.js file in the configuration folder. To work with Sage 300 it needs to look something like this:

define(‘configuration/development’, [‘Mobile/Sage300/ApplicationModule’], function() {
return {
modules: [
new Mobile.Sage300.ApplicationModule()
],
connections: {
‘crm’: {
isDefault: true,
offline: false,
url: ‘http://localhost/sdata/sageERP/sage300mobiledemo/SAMINC/&#8217;,
virtualDirectory: ‘SDataServlet/sdata’,
json: false
}
},
enableUpdateNotification: true
};
});

The key parts are the virtualDirectory to form the correct SData URLs for Sage 300. Remember that Sage 300 URLs start SDataServlet/sdata rather than just sdata. This is to avoid conflict when we are installed on the same server as Sage CRM. So notice the url: tag doesn’t include SDataServlet and then the virtualDirectory tag does. This will then cause the correct URLs to be formed. If you are having trouble with URLs then the Fiddler tool is great for debugging what is going on.

Note that to work, at least you need to change localhost to the server name you are using. Localhost will only work when running on the same computer.

Setup Quick List

So to summarize setup:

  1. Unzip the two zip files under the c:\inetpub\wwwroot folder.
  2. Add something to c:\inetpub\wwwroot\web.config for CORS.
  3. Copy the sage300\runtime folder to …\portal\sageerp\runtime.
  4. Restart Tomcat
  5. Edit the development.js file if you need to change the hostname.

Hopefully this will get you going fairly quickly.

Create Your Own App

This blog post is already getting a bit long, so I’ll go into more detail on how this sample program works in a future post. However this should be enough to get you started with the Argos SDK Wiki information and a working sample.

The Argos SDK is written in JavaScript and oriented to JavaScript development, so learning JavaScript is crucial. There are many good books on JavaScript as well as many good free web based resources. I like “Eloquent JavaScript” by Marign Haverbeke since it is fairly short and complete.

The Argos SDK relies heavily on the Dojo JavaScript framework. Along with the Simplate library and iUI library. My experience is that you don’t need to know too much about these to work with Argos, but I imagine if you get deep into it, it doesn’t hurt to know something about these.

Summary

One of the goals of SData is to enable the use of common tools across all Sage products. The Argos SDK is an example of this; it is a mobile SDK library for creating mobile applications that use SData to communicate with on-premise Sage applications. Over time you will see more and more of these sort of tools that leverage SData to provide enhanced functionality for a whole range of Sage applications.

Written by smist08

July 21, 2012 at 6:25 pm