RSS

Monthly Archives: April 2011

MonoCross – The Technology

Many of you have expressed an interest in the details of the MonoCross technology. The intent of this post is to do that, but only at a high level. I won’t be conducting a bit-by-bit tour of the pattern in this post, since the source is available for review by interested persons in the Project on Google Code. So if this narrative piques your interest, please go check out the details there.

A Little History

It started about two-and-a-half years ago when we were heavy into iOS development using Objective-C. At that time we started to hear from more and more clients that were interested in cross-platform applications. At the time we saw HTML 5 and WebKit as the best option, (as many large organizations still do today). Having done so much native development up to that point gave us a unique perspective on the capabilities of HTML 5, and we quickly realized that there were many things it did well– but there were other things that it did not do as well. The HTML 5 frameworks available for mobile development at the time were limited, and the same rich user experience that was available in native iOS applications was difficult to achieve. We also learned that although HTML 5 provided for offline applications using the cache manifest specification, there were still significant use-cases that required more sophisticated offline capabilities than were available in the browser.

As we were diligently working to solve cross-platform problems with HTML 5 we discovered MonoTouch, and a whole new possibility emerged. We had been working with C# and .NET for years, and the foundation of our mobile practice was in Windows Mobile development in CE and .NET CF. Within a few days of downloading the evaluation we had ported several client projects from .NET CF into MonoTouch, and were able to prove the concept of code portability. For the first time in my career I was seeing true code-reuse in heterogeneous platforms — it was very exciting! When Novell announced Mono for Android we immediately joined the beta, and began to put together our vision for cross-platform mobile development.

Code Portability

I’ve been in software a long time, and since before I joined the profession people have been talking about code re-use and portability, but the discussions have been largely theoretical. Most large enterprise software organizations tend to create homogeneous development environments. “One Language, One Platform” has been the mantra of most shops because its easier to manage things that way. You settle on a single technology stack, and build your applications on it. The organization also dictates the infrastructure needed, and the devices that will be supported, and most of those decisions are made after the technology stack is chosen.

Then Apple came along with the iPhone — then Google with the Android, and these organizations started having these decisions made for them by their employees. This consumerization trend has turned corporate IT on its head. The status-quo is no longer sufficient. “One Language, One Platform” doesn’t work anymore in the rapidly changing world of mobility. Suddenly these enterprises were facing problems they’d never had before. Supporting multiple, heterogeneous platforms had become a necessity, but very few organizations had the expertise to do so because of their homogeneous platform strategies of the past.

Fortunately for most of my clients, who have already made significant investments in C# and .NET as their language and platform of choice, Mono provides a compelling path forward. Those theoretical discussions around layered architectures and re-use of code became real, and the benefits apparent in this new world order. With MonoTouch and MonoDroid we could clearly demonstrate that the millions of dollars spent on existing applications could be leveraged and brought to these new platforms; and with the application of a few proven enterprise design patterns, significant modules could be shared across them all.

.NET Developers now had a choice. They could deliver native applications in MonoTouch and MonoDroid, or they could deliver web applications using HTML 5 and ASP.NET– but a new choice was also available. From our experience delivering HTML 5 applications with ASP.NET and PhoneGap, we saw a new pattern emerging. Native device integration could be achieved in HTML 5 via JavaScript interface, and custom URI schemes. Now developers could build applications across the hybrid spectrum, delivering as much or as little native vs. web functionality as their use-case required. Web techniques could be used where they were strongest, and native techniques where they excelled. Not only had Mono enabled cross-platform development in C# and .NET, it had enabled cross-architecture development.

Code Portability

This code portability model has become the foundation upon which we have built the MonoCross pattern. The core principles of code-reuse not only across platforms, but across architectures became our rallying cry. It remains our vision moving forward.

Coding Across Platforms & Architectures

This realization of code portability across both the platform and architecture dimensions was exciting, but we knew there were some practical problems that still needed to be solved. Most business and data access code could be ported and shared easily. We had proven this in our initial experiments with MonoTouch. But the UI paradigms exposed by the various native SDK’s were decidedly different. Beyond that we had to solve the problem of workflow and navigation. How do you enable cross-architecture development when the fundamental construction of application screens varies so much between web and native implementations? Finally we needed to provide a mechanism to handle changes to objects that were in-play, and successfully communicate changes from the UI to the shared application.

Separating the UI

The solution to the mismatch in UI paradigms was obvious. We needed to provide for fully customized views in the presentation layer, while sharing as much of the other application code as possible.

Separating the UI

To accomplish this we settled on a modified Model-View-Controller pattern that uses a separated view-interface to loosely couple the View and Controller. As long as the custom view implements the correct interface, the shared Controller code can interact with it as needed.

Defining Application Workflow

We also needed a mechanism to define the application workflow in a manner that would easily translate from native to web-based architectures — this was an absolute necessity in achieving our vision of cross-architecture portability. We knew we needed to provide for stateless navigation to support web architectures, but needed a way to accommodate the event-driven application interaction model in the native platforms. We settled on a URI template navigation model in the shared application. This model provides for seamless integration in web scenarios, while exposing hooks to the native views to initiate actions in the shared controllers. Controllers are registered with one or more URI endpoints that follow RESTful design principles to enable multiple workflow paths, and full CRUD data operations.

NavigationMap.Add("", new CategoryListController());
NavigationMap.Add("{Category}", new BookListController());
NavigationMap.Add("{Category}/{Book}", new BookController());

The Navigation Map is shared across platforms, and the use of a URI-based navigation scheme further extends the MonoCross architecture to support URI-based device API’s, web links, and deep-linking to other MonoCross applications by registering your own custom URI schemes.

MonoCross Containers

Much of our work of late has been continually refining the container concept in MonoCross. A container is a platform/architecture specific executable that runs a MonoCross application. The container is where calls between the shared application, (i.e. Model and Controllers), are marshalled to and from the platform specific UI implementation, (i.e. Views). The purpose of the abstract MXContainer class is to provide the base interface and implementation that is extended to each specific platform target. These concrete containers, one per platform, mitigate much of the mismatch between platform UI paradigms. They serve as an application wrapper, message broker, and utility interface, and are a critical component to the MonoCross pattern.

Handling Changes

To achieve the necessary communication of changes, including validation and CRUD operations, we settled on an Observer pattern on the container to notify the shared controllers of changes to the model. The MXContainer implements a NotifyViewModelChanged() method that is exposed to the Views.

private static void NotifyViewModelChanged(IMXView view, object model)
{...}

While this pattern is working well in our current client implementations, we’re exploring a move toward a pseudo-MVVM pattern to achieve synchronization of model changes in the shared application. This is actively evolving as we speak, and input from qualified contributors is welcome.

Moving MonoCross Forward

We continue to refine and evolve the pattern– and we want your help! So visit the MonoCross project, and get involved. The current roadmap is published there, and there is plenty of opportunity to help us take this into the future. Suggestions are welcome, and our hope is to build a vibrant community around MonoCross. So come join us!

Advertisements
 

Tags: , , ,

iPad in Business – Apple Features Medtronic

Apple just posted a feature in the iPad in Business section of apple.com featuring Medtronic. You can view the post here.

So congrats to the Medtronic team!

 
3 Comments

Posted by on April 7, 2011 in Mobile Development, Mono

 

Tags: , ,

Mono for Android Released

Mono for Android was released on Wednesday! Congrats to the team at Novell for this tremendous accomplishment! I have many clients who have been waiting for this, and plan to roll out several apps in the coming months.

Now we can deliver their iOS apps using MonoTouch into production on Android.

People are really starting to get excited about this in the enterprise, but it’s truly only the beginning.

 
Leave a comment

Posted by on April 7, 2011 in Android, Mobile Development, Mono

 

Tags: ,

 
%d bloggers like this: