This question has been brought up a ton, but I have not found a clear answer. I'd rather not take the JS injection approach, because I feel that I should not have to...
Basically what I'm doing is making an Android application that will act as an offline counterpart to a web site. When synced up, it will pull any changes to the sites html, JS, and CSS files if needed. Then while offline, it will display that in the WebView.
I want to be able to pull data from the form as if it were online, but pull it from the WebView and save it into a DB on the device. Then, when back online, the application will sync that data to the actual web site database.
I know how to get this to work with GET, but I'd much rather pull sensitive in with a POST.
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We are currently starting work on a project which consists of a website, plus Apps for Android, iOS and (yes) Windows phone.
The apps are identical on all three platforms, and are relatively simple, at least in theory.
They need to provide offline access to the content on the site. This is static content, so is a set of .html pages plus assets (images, css, javascript, etc.).
They need to be able to periodically update the content automatically, when an internet connection is available.
Any external links should open in the user's internet browser rather than within the app.
The app should not display any browser 'chrome' (e.g. address bar, etc.).
It seems like Cordova is a good way to go with this (though I'm open to other suggestions). However, I'm having difficulty finding any information about how to proceed.
For point 1, the way I'd imagine it working is that the app loads some form of web view pointing to file://path/to/site/index.html. Assuming the site uses relative URLs for all internal links and assets this should be sufficient to provide a fully browsable offline version of the site. The app will ship with a static export of the current site.
For point 2, I imagined that the Cordova app would occasionally run a synchornisation process, which would essentially be a number of web requests to the website's API to find out if there is new content. It would then download any new files, placing them in the file structure referred to in point 1, overwriting existing files. (For the purposes of this question, I don't care if that temporarily puts the site in an inconsistent state.)
Point 3 sounds trivial, but I'm not sure if it is. Would target="_blank" be enough? Or a bit of JavaScript to trigger some Cordova action when the link is clicked? We control the way the HTML is generated, so we can insert additional markup for offline use, if necesssary.
Can anyone offer any advice about how to handle an automatically-updating local static site in this manner? Is it even possible?
Cordova mostly does store your html files in an app and the shows the index.html (Or an other page if you define it) in an WebView.
The cool thing here is that Cordova will also provide an API to call Device APIs from JS.
Cordova does not automatically reload you html files and assets into the app. For that you would need to release a new App or you simply reload just the Data in your App and you control all of that in JavaScript.
If you do not need any Device APIs I would recommend you take a look at ServiceWorkers for caching and reloading files.
With some HTML Tags you can also create a really App like behavior after pressing "Add to homescreen".
Best Regards
Marc
My question will be really long but I encourage you to read through everything as it will be used for an honest, good cause. Or you can skip to the highlighted questions part.
Let me introduce myself first, I am an independent web application developer here in the Philippines and I work for a non-profit organization where we help less fortunate people by providing IT solutions and services for free. I have a working web application that has dynamic registration forms where users can enter their data online. I developed this application with responsive UI using bootstrap's grid system. But being here in the Philippines, there are remote areas where the target clients don't have access to the internet 24/7, and bringing laptop or desktop computers is a pain because of the terrain and rivers that we need to cross to reach these remote areas.
Now, together with my team, we are thinking of a way to use our mobile phones, mostly androids to create a mobile app version of our web application. Where it can download the registration form (html) when we are connected and then use it even without internet connection.
Ideally the situation should be:
1. Launch the app from my mobile, and while connected to the internet, download the html forms needed from our web application.
2. Travel to remote areas, use the mobile application to encode the native's information offline. (I heard its possible to save it locally to sqlite db)
3. Go back to the headquarters and sync with the online web application to pass all the information gathered and thats it.
Having said all that, I have 3 questions:
1. What should I use to create a mobile app that can display html forms downloaded from the internet?
2. How can I save the data locally (within the phone)? I heard about sqlite db but I am not sure if it will work with my situation.
3. How can I sync the locally saved data to the online web application?
This is more like a survey application. You dont need the html here. You design your question definitions in xml or json. You may have multiple types of question like Text Answer Question, Single Choice Multiple Option Question, Multiple Choice Multiple Option question, Image Question, QR Code Question, GPS Coordinate Question etc etc. You design these questions in json or xml and put them in server. For example
{
questionSetName: "Question Set 1",
question:[{
questionText: "What is your name ?",
questionType: "TextAnswer"
},
{
questionText: "Which one console below do you own ?",
questionType: "SingleChoiceMultipleOption",
options:["PS4", "XBox", "Steam Console"]
}]
}
Now for your mobile client:
When online user will want to download questions for later offline surveys. so user send a request to server for available question sets. then will pull these file from server (in case of android through some HttpClient like OkHttpClient) and put them in sd card. The server will implement rest apis for question lists and downloading individual question sets.
The application will check if files are present in a certain folder (your app designated folder) in the sdcard. The file names will be the list of the questions.It will parse the json or xml and render question windows accordingly, for example for text question a label with the question text and a text box for answer, for single choice multiple options a set of option buttons, for image questions open the mobile camera etc.
When filling up (answering) the questions you save the answers and question number and flush them in a json file. and put the answer files in another directory (you need some sort of identification).
later on upload the answer files to server.
The server side will require the following rest apis :
1. List of Question Sets of a user (from db ??)
2. An api (webservice) to download a set of questions.
3. An api to upload an answer sheet for a question.
4. user management of course.
Hope this helps.
I'm developing a simple Android App where the user must fill in a very complex form, for which I believe it's much easier to use an HTML form than an Android Activity with tons of TextViews.
The data collected by the form must be sent to some remote database, and the application must be able to work offline.
I thought of two alternatives, the question is: which one would be better?
Let a WebView load a remote website with an offline manifest
Let a WebView load a local website in assets folder
My second question is related to the storage when offline, and once again I have two options, and I don't know which one is better:
Using the HTML5 local storage, and let HTML + javascript send data to the server when online again
Let my Android app catch the form data, and handle everything the Android way.
Any input will be very helpful. Thanks in advance.
Regarding the first question: depends on how often will you need to update your form. An online cached form can be updated quickly, while bundled pages are only updateable together with the app, and you will need to consider that both legacy and new clients can connect to your server at the same time (users will procrastinate updating).
Another aspect is portability. Do you envision an iOS version of your app, or perhaps a mobile site? If yes, then an HTML5 solution is definitely more portable. Also, debugging an app which is entirely HTML or entirely native is usually easier than a hybrid one -- you can stay within a single debugger.
Perhaps, one drawback of using HTML local storage inside WebView is that the data you save will be in a kind of a "black box" -- you will not be able to back it up easily.
[Added later] OK -- one drawback of putting your site into assets folder is that you'll have to use file: scheme in order to access it. This can lead to some cross-origin loading access related issues if you will try to mix your bundled content with content from the web. Check these WebView settings for example: setAllowFileAccessFromFileURLs, setAllowUniversalAccessFromFileURLs, setMixedContentMode.
I just finished reading few some sparse tutorials on caching/offline and about making an Apps responsive when the user is not connected to the internet. It was quite interesting cause I have being wondering how some Apps have being doing that cause I was thinking it was some database manipulation.
I am relatively new to the caching mechanism and I really want to implement it in my next project cause I am still learning.
The few tutorials I have read talks about caching static files like pictures, .css files, .js files etc
My question is this;
**Question 1**
How do I cache Dynamic Files e.g I have an Apps when a User want to view their profile, I normally implement it by sending an Ajax request to the server to populate the profile page with pictures and other profile details (texts). How Do I cache these texts and pictures since they are dynamic?
**Question 2**
I am using different page (index.html, profile.html) JQuery Mobile mechanism, will this affect caching in any way because I have to refresh the page every time I am navigating to a new page so as to show my styling correctly?
This question may sound really noob but I really want to learn and I have read a lot about caching but these question were not addressed. I just hope somebody helps. thanks...
Answer is given based on my knowledge so far.
1) You can store / cache things with localStorage It's preety basic so won't take a lot of time or coding or mechanism to implement. Profile data, image as encoded string can be saved in localSorage. First you will save the profile data in localStorage. Then next time after app starts you can load data from the localStorage and also in the mean time you can make a async ajax call to server to check if data is modified. If so, then you can bring that data again and update localStorage.
2) If you use localStorage then page transitions won't be a matter until you reach the localStorage size limit of 5 mb.
I'm a Webdev beginner, have been learning some Python/PHP/Javascript and want to help a friend of mine with a project.
She's conducting a large scale survey of old houses/windows, and fills in forms (similar to Google Forms). However, she doesnt always have 3G coverage on her phone, so she wants some way of uploading the data when she gets online, and she wants to be able to upload photos and attach these to the forms.
I've found a javascript-library which makes use of html5 localstorage, but I havent understood if localstorage also accepts file uploads? Also, when you have submitted one form you would need internet access to open up the form again to submit another form.
Are there libraries or projects around that would help me with some of this, so I dont have to reinvent the wheel?
This is going to be very difficult to do with a web app. Your going to have to rely on something like AJAX to send the data and if it times out store in local storage and keep retrying every few minutes, because a web app has no access to anything like checking the wifi status etc.
Also that there is a limit to the size you can use in html5 local storage:
What is the max size of localStorage values?
, this is not going to work if you want to hold onto photos.
This would require a native or minimum a hybrid app (like phonegap) to store the data on the actual device in a file or SQLite database. This way you can store what you like, have access to the status of the internet connection and even have prompts to appear on the screen (when the app is in the background) to remind her that there are still some that need to be uploaded.
It will be much more reliable and stable this way
You can create an app which stores the data (form) in the Local DB (ie SQLite) of the App.
Once she is online (mostly wifi) she can start uploading the data.