Update paper to reflect iOS 11.3 Beta 1 changes.

Author: tomayac

bibliography.bib

@@ -1,7 +1,7 @@
 %% This BibTeX bibliography file was created using BibDesk.
 %% http://bibdesk.sourceforge.net/
 
-%% Created for Thomas Steiner at 2018-01-18 04:19:25 +0100 
+%% Created for Thomas Steiner at 2018-01-31 13:42:12 +0100 
 
 
 %% Saved with string encoding Unicode (UTF-8) 
@@ -367,3 +367,12 @@ @misc{chrome2018useragent
 Title = {User Agent Strings},
 Type = {Blog},
 Year = {2018}}
+
+@misc{mondello2018safari,
+Author = {{Ricky Mondello}},
+Howpublished = {\url{https://twitter.com/rmondello/status/956256845311590400}},
+Journal = {Twitter},
+Number = {Jan 2018},
+Title = {@rmondello on Twitter: ``iOS 11.3 and macOS 10.13.4 include Service Workers---a~powerful specification that allows background scripts to power offline web applications. i\textsc{os}~11.3 also consults Web App Manifest when adding web apps to the home screen''},
+Type = {Blog},
+Year = {2018}}

index-sheet.pdf

@@ -134,9 +134,9 @@
 and---together with Web App Manifests---allow users to \emph{install \textsc{pwa}s}
 to their devices' home screens.
 Service Workers being a Web standard, support has landed in several
-stand-alone Web browsers---among them (but not limited to)
+stand-alone Android Web browsers---among them (but not limited to)
 Chrome and its open-source foundation Chromium, Firefox, Edge, Opera,
-\textsc{uc}~Browser, Samsung Internet, as well as preview versions of Safari.
+\textsc{uc}~Browser, Samsung Internet, and---eagerly awaited---i\textsc{os} Safari.
 In this paper, we examine the \textsc{pwa} feature support situation in \emph{Web Views},
 that is,\ \emph{in-app Web experiences} that are explicitly \emph{not} stand-alone browsers.
 Such in-app browsers can commonly be encountered in chat applications like WeChat or WhatsApp,
@@ -204,8 +204,9 @@ \subsection{History of Progressive Web Apps}
 and---together with Web App Manifests~\cite{caceres2017manifest}---allowed
 users to actually \emph{install \textsc{pwa}s} to their devices' home screens
 with proper operating system integration~\cite{kinlan2017a2hs}.
-Other browsers like Mozilla Firefox, Microsoft Edge, Opera, \textsc{uc}~Browser, Samsung Internet,
-Apple Safari Technology Preview, and several browsers more followed in implementing Service Workers.
+Other Android browsers like Mozilla Firefox, Microsoft Edge, Opera, \textsc{uc}~Browser, Samsung Internet,
+and---eagerly awaited---Apple Safari on i\textsc{os},
+as well as several browsers more followed in implementing Service Workers.
 Now, even multinational companies like Twitter
 or trivago bet on \textsc{pwa}~\cite{gallagher2017twitterlite,twg2017trivago},
 as well as giant national players like Tencent News or Sina Weibo in China~\cite{zhu2017pwa}.
@@ -280,17 +281,13 @@ \section{Background on Web Views}
 each having their own benefits and drawbacks.
 In the following, we describe the options on the two popular
 mobile operating system Android and i\textsc{os}.
-At time of writing (January 2018), Safari on i\textsc{os}
-does not support Service Workers and thus \textsc{pwa}s yet,
-albeit work on implementing them has started, and
-first versions of Safari Technology Preview on Apple's
-desktop operating system mac{os} have enabled
-Service Workers by default~\cite{davis2017safari}.
-In the spirit of Progressive Enhancement~\cite{champeon2003progressiveenhancement},
-where new features will just be used when they are available,
-and in the hope of Service Workers landing on the i\textsc{os} platform
-in the not too distant future,
-we nevertheless describe the Web View situation on i\textsc{os} as well.
+While Android had enjoyed Service Worker support for as long as 2014~\cite{cooney2014chromium},
+at time of writing (February 2018), Safari on i\textsc{os}
+for the first time supported Service Workers
+in Beta versions of i\textsc{os}~11.3~\cite{mondello2018safari}.
+The implementation is still incomplete and several bugs exist, but in the spirit of
+Progressive Enhancement~\cite{champeon2003progressiveenhancement}
+the situation is expected to improve over time.
 
 \subsection{Web Views on Android}
 
@@ -414,9 +411,6 @@ \subsection{Parallelisms on the Two Operating Systems}
 share cookies, permissions, \emph{etc.}
 with the particular system's main browser.
 Solely Android's Trusted Web Activity so far has no i\textsc{os} equivalent yet.
-If (or rather as soon as) Apple catches up with implementing Service Workers,
-our findings will be applicable on i\textsc{os} as well,
-according to the parallelisms described in this section.
 
 \section{Detecting \textsc{pwa} Features}
 \label{sec:pwa-feature-detector}
@@ -589,7 +583,8 @@ \subsection{Feature-Detecting Various \textsc{pwa} Features}
  'Offline Capabilities': 'caches' in win,
  'Push Notifications': 'pushManager' in reg,
  'Add to Home Screen': doc.createElement('link')
- .relList.supports('manifest'),
+ .relList.supports('manifest') &&
+ 'onbeforeinstallprompt' in win,
  'Background Sync': 'sync' in reg,
  'Navigation Preload': 'navigationPreload' in reg,
  'Silent Push': 'budget' in nav &&
@@ -634,28 +629,52 @@ \subsection{Implementation Details}
 which, rather than using a~\texttt{WebView},
 displays Web content in a~\texttt{CustomTabsIntent}.
 Despite the exact same underlying browser engine (Chrome/65.0.3310.3),
-the more powerful \texttt{CustomTabsIntent}-based in-app browser
+the \texttt{CustomTabsIntent}-based in-app browser
 clearly wins the \textsc{pwa} feature competition.
-For non-domain experts we note that the \texttt{WebView}
+For non-domain experts we note that on Android the \texttt{WebView}
 can be easily spotted by looking for the string
 ``wv'' in the displayed user agent~\cite{chrome2018useragent}.
+The corresponding i\textsc{os} screenshots, likewise
+based on the same underlying browser engine (Safari~11.1),
+can be seen in \autoref{fig:facebook-ios-safari11_1} with a~\texttt{WKWebView} displayed in Facebook 
+and in \autoref{fig:twitter-ios-safari11_1} with an \texttt{SFSafariViewController}
+displayed in Twitter.
 
 \begin{figure}[t]
  \centering
- \includegraphics[width=.5\columnwidth,frame]{pwa-feature-detector-wechat-android-chrome65}
- \caption[\textsc{pwa} Feature Detector running in WeChat.]{
- \textsc{pwa} Feature Detector running on Android~8.1.99 in the app WeChat
- in a~\texttt{WebView} based on Chrome~65.}
- \label{fig:wechat-android-chrome65}
+ \begin{subfigure}[t]{0.475\columnwidth}
+ \includegraphics[width=1\columnwidth,frame]{pwa-feature-detector-wechat-android-chrome65}
+ \caption[\textsc{pwa} Feature Detector running in WeChat.]{
+ In WeChat in a~Chrome~65 based \texttt{WebView}.}
+ \label{fig:wechat-android-chrome65}
+ \end{subfigure} 
+ \quad
+ \begin{subfigure}[t]{0.475\columnwidth} 
+ \includegraphics[width=1\columnwidth,frame]{pwa-feature-detector-twitter-android-chrome65}
+ \caption[\textsc{pwa} Feature Detector running in Twitter.]{
+ In Twitter in a~Chrome~65 based \texttt{CustomTabsIntent}.}
+ \label{fig:twitter-android-chrome65}
+ \end{subfigure}
+ \caption{\textsc{pwa} Feature Detector running on Android~8.1.99.} 
 \end{figure}
 
+
 \begin{figure}[t]
  \centering
- \includegraphics[width=.5\columnwidth,frame]{pwa-feature-detector-twitter-android-chrome65}
- \caption[\textsc{pwa} Feature Detector running in Twitter.]{
- \textsc{pwa} Feature Detector running on Android~8.1.99 in the app Twitter
- in a~\texttt{CustomTabsIntent} based on Chrome~65.}
- \label{fig:twitter-android-chrome65}
+ \begin{subfigure}[t]{0.475\columnwidth}
+ \includegraphics[width=1\columnwidth,frame]{pwa-feature-detector-facebook-ios-safari11_1}
+ \caption[\textsc{pwa} Feature Detector running in Facebook.]{
+ In Facebook in a~Safari~11.1 based \texttt{WKWebView}.}
+ \label{fig:facebook-ios-safari11_1}
+ \end{subfigure} 
+ \quad
+ \begin{subfigure}[t]{0.475\columnwidth} 
+ \includegraphics[width=1\columnwidth,frame]{pwa-feature-detector-twitter-ios-safari11_1}
+ \caption[\textsc{pwa} Feature Detector running in Twitter.]{
+ In Twitter in a~Safari~11.1 based \texttt{SFSafariViewController}.}
+ \label{fig:twitter-ios-safari11_1}
+ \end{subfigure} 
+ \caption{\textsc{pwa} Feature Detector running on i\textsc{os}~11.3 Beta~1.} 
 \end{figure}
 
 \section{Results and Discussion}
@@ -710,6 +729,17 @@ \section{Results and Discussion}
  \end{center}
 \end{figure}
 
+\begin{figure}[t]
+ \renewcommand{\figurename}{Table}
+ \begin{center}
+ \centerline{\includegraphics[width=.65\columnwidth,trim=4.3cm 16.4cm 4.3cm 1.5cm, clip]{ios-results.pdf}}
+ % https://docs.google.com/spreadsheets/d/18xaJeIrfaA-8wNucK7IDQMfr5LHjsBcey4lHF3Pkd1o/edit?usp=sharing
+ \caption{\textsc{pwa} feature support situation on i\textsc{os} for both \texttt{WKWebView} (Facebook)
+ and \texttt{CustomTabsIntent} (Twitter).}
+ \label{table:safari}
+ \end{center}
+\end{figure}
+
 \subsection{Discussion of the \texttt{WebView} Results}
 
 Table~\ref{table:webview} unsurprisingly shows that the more mature
@@ -856,10 +886,11 @@ \section*{Acknowledgements}
 
 \begin{figure*}[b]
  \begin{center}
- \centerline{\includegraphics[trim=.5cm 13.75cm .5cm .5cm, clip]{index-sheet.pdf}}
- \caption{Index sheet with all tested device screenshots showing both \texttt{WebView}s
- and \texttt{CustomTabsIntent}s running in different applications.
- High-resolution screenshots available at \url{https://photos.app.goo.gl/FdRsGOgtgNfvRIKB2}.}
+ \centerline{\includegraphics[width=\paperwidth, trim=0cm 2.5cm 0cm 0cm, clip]{index-sheet.pdf}}
+ \caption{Index sheet with all tested device screenshots showing Android \texttt{WebView}s and
+ \texttt{CustomTabsIntent}s, as well as i\textsc{os} \texttt{WKWebView} and \texttt{SFSafariViewController},
+ running in different applications.
+ Higher resolution screenshots are available at \url{https://photos.app.goo.gl/Kh3DyhpL6Q58G7tn1}.}
  \label{fig:indexsheet}
  \end{center}
 \end{figure*}