Table Of ContentTowards the quality improvement of cross-platform
mobile applications
Matias Martinez, Sylvain Lecomte
Univ Lille Nord de France, F-59000 Lille, France,
Universite´ de Valenciennes et du Hainaut Cambre´sis,
Laboratoire LAMIH - UMR CNRS 8201
59313 Valenciennes Cedex 9
[email protected]
7
1
0
2 Abstract—During last ten years, the number of smartphones A currentchallenge for business enterprises,software com-
and mobile applications has been constantly growing. Android, panies, and independent mobile developers is to choose the
r iOS and Windows Mobileare three mobile platforms that cover
a targetplatformsfortheirmobileapplications.Tocoveralarge
M almostallsmartphonesintheworldin2017.Developingamobile number of users, companies and developers aim at releasing
app involves first to choose the platforms the app will run, and
then to develop specific solutions (i.e., native apps) for each their mobile apps on the three mentioned platforms. More
2
chosen platform usingplatform-related toolkitssuch as Android platforms targeted involves to potentially reach more users
SDK. A cross-platform mobile application is an app that runson and, thus, to increase the impact on the market.
]
E two or more mobile platforms. Several frameworks have been However, nowadays, creating a cross-platform application
proposed to simplify the development of cross-platform mobile
S as we mentioned, implies the development of one native
applications and to reduce development and maintenance costs.
s. Theyarecalledcross-platformmobileappdevelopmentframeworks. application for each platform to target. Thus, companieshave
c However,toourknowledge,thelife-cycleandthequalityofcross- to afford the cost of two or more development processes
[ platformsmobileapplicationsbuiltusingthoseframeworkshave of their cross-platform apps. It has a monetary impact and
not been studied in depth. Our main goal is to first study the
2 also affects the project organization: e.g., a company must
processesofdevelopmentandmaintenanceofmobileapplications
v find specialized developers for targeting each platform, the
built using cross-platform mobile app development frameworks,
7
focusing particularly on the bug-fixingactivity. Then, we aim at developmentdurationforeachplatformcouldbedifferentand
6
definingtools for automated repairing bugsfrom cross-platform it could exist technical limitations and differences between
7
6 mobile applications. platforms, such as permission policies.
0
. B. Cross-platform mobile app development
1 I. INTRODUCTION
frameworks
0
A. Context
7 During last years, researches and industry sectors have
1 Studies estimate that currently in 2017, there are 2 billions both focused on proposing solutions for developing mobile
:
v smartphonesin the world1 andthis numberwill increase 50% applications to overcome the mentioned problematic. One of
i the next 5 years. Smartphones are mobile devices that run themainobjectivesofthosesolutionsistoreducethecostand
X
software applications such as games, social network (Face- time of developing and maintaining mobile applications.
r
a book,Twitter) and bankingapps. A native mobile application From the academic research community, Perchat et al.
isanappbuilttoruninaparticularmobileplatform.Currently, [22, 23] proposed a framework that allows the integration of
therearethreeplatformsthatdominatethesmartphonemarket: cross-platformcomponentsin anyapplication(iOS, Android),
Android (from Google), iOS (from Apple) and Windows with the goal of soften the difference between each mobile
Mobile (fromMicrosoft). A large number of applicationsthat platform. Le Goaer et al. proposed Xmob [11], a technology-
run on those platforms are available in application stores. neutral domain-specific language (DSL) intended to be cross-
For instance, Google Play, the official app store of Android compiled to produce native code for a variety of platforms.
applications, has more than 2 millions apps available to Fromthe industryside,Phonegap(a.k.a.ApacheCordova)2
download. from Adobe is a frameworks to build mobile applications
A cross-platform mobile application is an application that using CSS3, HTML5, and JavaScript source code. The code
targets more than one mobile platform. A manner of building is embedded on a skeleton native app, which interprets and
this kind of apps is, for example, to develop a native appli- executes the app code on the specific device. This kind of
cation created for running on Android devices (built using applicationsarecalledHybridmobileapplicationsduetheyare
Java technology) and another native application built (using conformedbybothnative(e.g.,JavafortheAndroidskeleton)
Objective-C language) for iOS devices. and not-native (e.g., HTML) code.
1https://www.statista.com/statistics/330695/number-of-smartphone-users-worldwid2het/tps://cordova.apache.org
Another cross-platform mobile app development frame- In 2009, the engineer team of Facebook has built the first
works is Xamarin3. It makes it possible to do native Android, mobile application of Facebook using an hybrid approach: a
iOSandWindowsdevelopmentinC#.Developersre-usetheir web-based application (i.e., HTML5 technologies) wrapped
existingC#code,andsharesignificantcodeacrossdeviceplat- on native platforms code such as iOS and Android. By
forms. For example, Evolve4 a conference event management those days, the Facebooks engineers highlighted that this
app,wasdevelopedusingXamarinandis around15,000lines development approach let them leverage much of the same
of code: the iOS version contains 93% shared code i.e., C# code for iOS, Android, and the mobile web. Furthermore,
(the remain 7% iOS specific code) and the Android version the approach also allowed them to iterate on experiences
contains90%sharedcode.5Sharingcodemeanstoreduceboth quickly by launching and testing new featureswithout having
develop and maintenance cost. Frameworks as Xamarin or toreleasenewversionsoftheapps[4].However,overtime,the
React-Native6 are know as Cross-compiled approaches: their Facebook engineersrealized that users had more expectations
receiveasinputanapplicationwritteninaparticularnot-native intermsofspeedanduserexperience[10]. Forthosereasons,
programminglanguageand transformit to a native codefor a they decided to re-write from scratch the native Facebook
particular mobile platform. app for iOS, and later the native app for Android platform.
In this section we have listed some cross-platform mobile Unfortunately,the engineers rapidly realized that recompiling
app developmentframeworks, but mobile developers can find oneverycodechangewasslow,andseparatesetsofskillswere
many more options according to their needs. needed to build for iOS and Android, having as consequence
aslowerproductdevelopmentandanincreaseofdevelopment
C. Developing cross-platform mobile apps costs [4].
Cross-platformdevelopmentframeworksarebuiltforsaving In 2015, the adoption of Reach Native framework brings
development effort and money, and for making more agile the engineer team the possibility to overcome those lim-
the developmentprocess by havinga single team building the itations. React Native is a learn-once-run-everywhere app
whole solution. Researches have conducted different studies developmenttool, started as a hackathonprojectin 2013.In a
about cross-platform development frameworks such as com- nutshell, React-Native allows developersto write components
parisonbetweenthem[3,5,6,9,19]orwithwebbasedmobile in JavaScript language,which are convertedto native compo-
apps[1].However,toourknowledge,nopreviousstudieshave nents for iOS and Android platforms. Nowadays, Facebook,
investigatedtheproblematicandchallengesofmaintaincross- Instagram and Airbnb are examples of cross-platform mobile
platform mobile apps built using those frameworks. apps developed using React-Native7.
This brief story shows that the development of cross-
D. Our research objectives platformmobile apps is a challenge,even for one of the most
valuable companies in the world.
Our main goal is to study the quality of cross-platform
mobile apps built using cross-compiled frameworks such as III. LONG-TERMRESEARCH OBJECTIVES
Xamarin or React-Native. We envision studying how devel-
Inthissectionweproposethreeobjectivesforunderstanding
opers build and maintain cross-platform mobile applications
and improving quality of mobile applications. We focus on
built using those frameworks, and how bugs are fixed during
studying application developed using cross-platform mobile
theapplicationlife-cycle.Moreover,we aimatdefininganew
development frameworks, particular on Xamarin and React-
generation of automated repair approaches for repairing bugs
Native, maintained by Microsoft and Facebook, respectively.
on cross-platform applications.
We choosethose two frameworksdueto theyareopen-source
To our knowledge, this research would be the first at
and well-documented (manuals, forums and white-papers).
studying and understanding the development, maintenance
A. Studying development of cross-platform apps
and automated repair processes of cross-platforms mobile
applications. We consider our research will have a strong First,weplantocomparetheprocessesofdevelopingcross-
impact on the industry of software development, specially platformsusingCross-compileddevelopmentframeworkswith
for mobile developmentcompanies which base their business respect to the development of native apps using tools for
model on the development of cross-platform apps. that propose (Xcode, Android Studio). For instance, we plan
to study the learning curve of those frameworks. Then, we
II. CASE STUDY: HISTORYOF FACEBOOK MOBILE plan to study how a framework manages the differences
APPLICATION between platforms and how those differences impact on the
app development and on the app’s capabilities. Finally, we
Inthissection,wepresenta casestudythatsummarizesthe
plantostudywhethertheuse ofthose frameworkshelps, asit
different strategies adopted by Facebook developers to build
isexpected,tohavefastertime-to-market,increasecomponent
the Facebook mobile apps.
reuse, decrease cost, etc. Those research goals focus on the
3https://www.xamarin.com developmentphase of applications.The nexttwo manlyfocus
4https://github.com/xamarinhq/app-evolve on the maintenance phase.
5https://goo.gl/eqj1ml
6https://facebook.github.io/react-native 7https://facebook.github.io/react-native/showcase.html
B. Studying the maintenance of cross-platform applications sub-components of the development platforms, for example,
Forms Labs8 project provides a set of new controls for Xa-
The second goal is to study the maintenance of cross-
marin. Secondly, we found ‘toy’ projects done for testing the
platform applications. The main research question we plan to
developis:“Areappsgeneratedusingthoseframeworkseasier development platforms9 and other projects with examples10.
Those projects have usually few lines of code and do not
tomaintainthatthosegeneratedusingtraditionaldevelopment
representrealmobileapps.Asconsequence,forimplementing
of native apps?”. In particular, we are interested in studying:
the tool for mining cross-platform mobile projects, we need
a) whatare the mostfrequentbugsthat appearin those cross-
to a) define more precise and complex queries (using, for
platformsapps, b) how bugs look like, c) how bugs are fixed.
instance, the Github API11); b) define heuristics for filtering
C. Repairing bugs on cross-platform apps not desired projects (plug-ins, examples, etc.).
Third, we are interested in automated repair those bugs.
B. Studying bugs and fixes of mobile apps
Based on the knowledge from studying development and
maintenance phases of cross-platforms apps, we will focus Our goal is to create a taxonomy of frequent bugs from
onapproachesthathelpsdeveloperstoovercometheproblems mobile apps developed by our target developers frameworks.
emergedfromtheirapps.Weenvisionpresentingtodevelopers For doing that, we plan to mining bug fixes and related
suggestions and candidate patches to fix bugs at the level of information from: a) issues from report systems such as
source code. In case of Xamarin, which most parts of the Bugzilla, Github issues, etc; b) bug fix commits from our
code are developed in C#, we aim at defining an approach mobile apps corpus; c) questions and responses posed on
that generates C# code repairs. forumssuchasStackOverflow.Onceweidentifybugs,weplan
tocreateabugbenchmarktobeusedforevaluatingautomated
IV. PROPOSED EXPERIMENTS
program repair approaches.
In this section we discuss how we plan to carried our the
Our intuition is there are two kinds of bugs on mobile
experiments for targeting each research goal mentioned in
apps developedusing cross-platformmobile app development
Section III.
frameworks. First, a mobile app could fail due to a bug in
A. Creating a mobile apps corpus its code. For example, derefrencing a null pointer, an infinite
loop, or a wrong method call12. Secondly, a mobile app
We plan to study open-source apps mobile application to
could fail due to a bug presents inside the cross-platform
understandandcharacterizethedevelopmentandmaintenance
mobileappdevelopmentframeworksusedto builttheapp.For
of cross-platform mobile applications. We plan to create a
example, the bug 45311 on Xamarin Android project13 is a
corpus of mobile apps developed using the frameworks we
common bug in Java: given a class field name javaUrl, and
target (i.e., Xamarin and React-Native). For that, we plan to
a formal argument from a method also called javaUrl, then
explore and mine code repositories platforms such as Github
theassignmentjavaUrl =javaUrl;doesnotaffectthefield.
as we have previously done for understanding the bugfixing
The fix consisted on adding the this keyword on the left-part
activityofJavaapplication[14,16].Hence,themainchallenge
of the buggy assignment14.
istoidentifyprojectsbuiltusingcross-platformmobileappde-
The complexityand constantevolutionof mobile platforms
velopment frameworks from other kind of projects, including
such as Android or iOS, and the large diversity of mobile
native mobile apps.
devices in the wild involve that cross-platform mobile app
For mining projects, we plan to build a tool for retrieving
development frameworks must evolve at the same speed,
candidates mobile applications. This tools will carry out two
involving the potential creation of new bugs. In the case of
steps: in the first one it queries the hub sites such as Github
React-Native, which is open-source, Facebook has a develop-
forretrievingprojectsfromtheirmeta-data(e.g.,projectname,
ment team with around 20 developers [10] for evolving the
description, language). For example, using the query:
framework (which includes the addition of new mobile plat-
https://github.com/search?q=xamarin+in%3Areadme%2Cdescrfipotrimons,+nlaenwgufaegateu%re3sA,acn%d2b3u>fiyxpien=gR).eSpousrpitroirsiiensgly,the external
communityalsoparticipateontheevolutionoftheframework:
we retrieve from Github candidate Xamarin projects that: in February 2016, more than 50% of the commits came from
a) are written in C# (language used to build Xamarin apps); external contributors (not employers of Facebook).
b) contains the word ‘Xamarin’ in the project descriptions or Thestudyofbugswillallowustoidentifythemostfrequent
in the README.md file. bugs present on mobile apps for each development platform
Inthesecondstep,thetoolwillparseandanalyzethesource and to define a taxonomy of defect class.
code of each retrieved project to confirm if it is a mobile
app built using the development platform we target (in our 8https://github.com/XLabs/Xamarin-Forms-Labs
exampleXamarin).Theformerstepisimportantforremoving 9Example:https://github.com/TheRealAdamKemp/Xamarin.Forms-Tests
false positives. For example, the previous query returns more 10Example:https://github.com/conceptdev/xamarin-samples
11https://developer.github.com/v3/
than 8800 projects. After manually analyzing the results we
12Example:https://goo.gl/1WDnC7
concluded that there are two kind of projects we are not 13https://bugzilla.xamarin.com/show bug.cgi?id=45311
interested in analyzing. First, some projects are plug-ins and 14https://goo.gl/p0F9cq
C. Automated repair bugs of mobile apps increase in energy consumption, even if the final application
is a real native application.
Recent years, researchers have proposed approaches for
Hybridmobileapps:Malavoltaetal.[12]havefocusedon
automaticallyrepairbugssuchas[8,18,24].Test-basedrepair
analyzinghybridmobileapps(e.g.,thosethatusesPhoneGap)
repairapproaches[8]usetestsuiteascorrectnessoracles,i.e.,
available on the app store Google Play and their meta-data
they are used as proxies of the program specification. In a
(i.e., user ranking and reviews). One of their finding is that
nutshell, those approaches receive as input a buggy program
the average of end users ratings for both hybrid and native
p andits test suite ts, whichhas, atleast, onefailing testcase
apps are similar (3.75 and 3.35 (out of 5), respectively).
(due to the presence of the bug). The approaches produce,
Mining repositories: Previous works such as [16, 20]
when it is possible, a modified version of p which passes all
have studied and classified bug fix from open-source project
tests from the suite ts. Each repair approach applies a set of
repositories. Our goal is to carry out similar experiments but
repair actions, which are source code changes done to create
focusing on repositories of mobile apps.
a candidate repair.
Automated software repair: During last ten years several
Our goal is to define a platform for repairing functional
bugs from mobile apps built with Xamarin. The platform will approaches have been proposed to repair C bugs such as [8]
or Java bugs such as [24]. The buggy programs that conform
re-implement state-of-the-art repair techniques. For instance,
evaluationbenchmarksaretypicallylibrariesorcommand-line
tore-implementtheapproachGenProg[8](whichtheoriginal
(console) applications.
implementationtargetsC code)we need:1) a toolfor parsing
source code of the buggy mobile app; 2) a tool for manipu-
VI. THREATSTOVALIDITY
lating and transforming the parsed code for synthesizing the
candidate repair; 3) a correctness oracle (e.g., test suites) In this section we list possible threats to our research. One
which decides if a candidate repair is correct or incorrect. thread is to not find ‘meaningful’ open-source mobile app
We have already implemented GenProg for repairing Java projectsforcreatingtheevaluationcorpus.Weareinterestedin
code[17].There,weusedthetoolSpoon[21]forparsingand mobileappsa) with an largenumberof commitsto studyand
manipulatingsource code,and JUnit framework15 for running characterize how developers build and maintain applications.
the test suite from the program to repair. To implement a b) that use diverse components and functionalities from the
version of GenProg for repairing buggy mobile apps built underlyingplatform.Anotherthreadistheimpossibilitytofind
with Xamarin, we could use, for instance, Roslyn16, an open- meaningful and frequent bugs from issue tracking systems,
source C# compilers with rich code analysis APIs. Then, bugreports,commits,wikis,etc.Finally,state-of-the-artrepair
for validating correctness of candidate repairs, as for all approaches need correctness oracles such as test suite for
test-based repair approaches, the repair approach needs a validatingcandidatepatches.A threadfacingrepairingmobile
test-suite related to the buggy mobile application. Xamarin apps is to not find open-source project containing (good
provides a testing framework called Xamarin.UITest17 that quality) test suite. This issue does actually affect the whole
allowsprogrammerstowriteandexecutetestsinC#andNUnit automated repair discipline [15].
for validating the functionalityof iOS and AndroidApps. So,
ourimplementationwouldneedtoexecutethosetestcasesfor VII. CONCLUSION
validating candidate repairs.
Thedevelopmentandmaintenanceofcross-platformmobile
apps have particular challenges, different from those related
V. RELATEDWORK
to desktop or web apps. Cross-platform mobile app devel-
Cross-platform mobile app development opment frameworks have emerged with the goal of simplify
frameworks: In addition to open-source development frame- the development of cross-platform mobile apps, reduce the
works such as PhoneGap, Xamarin and React-Native, aca- development,maintenancecostsandthetime-to-marketofthe
demicresearchers[11,22,23]proposedsolutionswiththegoal apps. Our research focuses on understand the maintenance
of simplify the developmentof cross-platforms applications. process of those apps with the goal of producing tools for
There are severalworksthat classify, compareand evaluate improving the quality of mobile applications.
cross-platform mobile application development tools [3, 5, 6, Acknowledge: The ELSAT2020 project is co-financed by
9, 19] to build hybrid mobile and native apps. Our goal is theEuropeanUnionwiththeEuropeanRegionalDevelopment
to empirically study the life-cycle of mobile apps built using Fund, the French state and the Hauts de France Region
some of those tools, such as Xamarin or React-Native. Council.
Empirical studies of Cross-platforms mobile apps:
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