I'm developing an Android application, typically with a fairly small database (hundreds to a thousand or so main entries, plus similar order of magnitude in joined tables) populated by the user. There is also a file associated with each main entry, but those are kept separate, and not part of this question.
In my current prototype, the structured data is stored in a SQLite database in the usual way, and synced between devices by uploading the file to an Application Folder on Google Drive. This allows me to avoid having to provide any user storage, which is something I hope to stick to.
Storing files here also has the happy side effect that I can access them via JavaScript code in a web page using the Google Drive API. But JavaScript interacting with a remote SQLite file is an incredibly ugly thing to attempt. (Downloading the database server-side and handling it there is another option which sounds not great either.) I am wondering if anyone has any recommendations of the best practice approach here, given I would like to have a web-based version of the app accessing the same data.
The obvious most sensible idea seems to be
Exporting from SQLite to some other structured format XXX (like XML, JSON, CSV, ...) first, uploading that XXX file to Google Drive, so that JavaScript can straightforwardly interact with it, and then on sync reimporting this XXX data back into SQLite.
though I'm happy to hear any criticisms/improvements on this idea.
I'm mainly interested in best-practice recommendations of efficient ways to approach these problems. Question: What file format XXX would be good; and do you have any recommended methods for (a) exporting and importing in Java from SQLite to XXX, (b) interacting in preferably client-side JavaScript with a remote Google Drive file in format XXX? (If maintaining server-side code to interact with XXX is substantially better practice do say.)
It depends on how many clients your app will manage
Exporting from SQLite to some other structured format XXX (like XML, JSON, CSV, ...) first, uploading that XXX file to Google Drive, so that JavaScript can straightforwardly interact with it, and then on sync reimporting this XXX data back into SQLite.
IMHO, this is quite a bad idea for quite a few reasons:
If multiple users try to change data at the same time, you will have a tough problem managing all those data entries and possible conflicts
Providing direct access to your data layer is ALWAYS a bad idea since any client can wipe out all your data
If you have very few users or are making it as a personal project, you can stick with SQLite.
Kripken, the developer of Emscripten (the C/C++ to Javascript LLVM compiler) has compiled the SQLite Library to Javascript to make the sql.js library. You can find it on GitHub. There's also a demo page of sql.js
But if you have a lot of users, you might want to use Firebase by Google. It gives you a database and a REST API to use it. There are libraries to access Firebase from different programming languages too.
Cheers!
Related
I have been tasked with researching technology for generating a dynamic report with charts & visuals.
There are countless BI tools available and online solutions that fit the bill, however, the customers have considerable IT restrictions preventing the installation of applications or sharing data across the internet.
One solution I've dreamed up is to serve up an HTML document for offline consumption in a browser. With javaScript bundled in & data added dynamically prior to sending to the client, I believe this would be possible in much the same way a website functioning offline is possible.
How feasible is this? If it's possible, what technologies are recommended? So far I've considered building this using AngularJS since an SPA could mimic a one-page report well & javaScript bundling is readily available.
Are there better solutions? Which?
May be your clients will be okay with providing them files by SFTP. Say, if you are not using a database and are ok with building charts based on files, you can try to provide end users with the files (txt, csv, xml...). Then you will be able to execute client-side code with no server needed. You may even go for some open-source Javascript libraries for data visualisation like D3. All you have to do is to allow local file access for user's browser.
Otherwise you need a local server. I would recommend you to use Python python's SimpleHTTPServer or node.js may fit you.
I have a simple audio sequencer application using javascript and HTML5. The goal of the application is to let users make a beat and save it so other people can open it up, add on to it, then re save. The issue I'm having is the save/open feature. How Do I add this? Or at least where can I start looking fro this solution?
If you are asking for an only-JS solution to this:
Opening Files
You can use the FileAPI to open the files from your users local machine, as long as its your users who are selecting the files manually(you are not digging into the file system yourself).
Here is nice demo for this functionality: http://html5demos.com/file-api
Saving Files
However, saving files was a W3C recommendation that got ditched so your only choice here is to allow your users to download the file. See this relevant question I made some time ago
If I were doing this for a class or prototype I might use PUT or POST requests to save the beat sequence in json form to a web server. When it's time to save your work, take your beat sequence data, convert from a js (I presume) object to a json string and PUT it to an appropriate url on your server. Give it a name and use the name in the url path, like "myserver.com/beats/jpbeat1.json".
When you want to retrieve that beat, issue an HTTP get to the url you saved. You can, of course also maintain and rewrite a directory page in json or html, or you can just navigate the directory offered by your web server. Most developers will think this crude, I imagine, but in a race for time, crude can be good if it meets the requirements.
Choose a web server, the easiest one for you. I might use Amazon S3. Costs money, but available to the internet, has authentication, security features, and supports http GET, PUT of static files. There are many other site hosting services.
For a local install, I might use Node.js. Also very easy to set up to serve static content. For example, the Express framework has static content service and easy examples how to set it up if you are comfortable with Javascript. With Node, you can make the site a bit fancier, by writing server side code to maintain an index, for example. Any real world implementation would require at least some server side code.
There are many other choices. Most developers would want a database, but you don't have to have one if simple files are ok for your class project. It all depends on your requirements.
I hope those ideas are helpful.
I'm building a small offline application that requires a simple data table (a contacts list). Something I can save to and read from.
I've looked into a few libraries and they all seem to only store data for the current session, and not into a file e.g. a fake sql database.
Can anyone point me towards the right technologies to use?
I'm planning to interact with the data table with a basic html form and JavaScript.
EDIT: Would switching to a different technology like Java be more fitting for my needs? Still not able to find a workable solution to hook up to HTML other than setting up a vagrant environment and hooking up to a MySQL db with php.
Modern browsers contain localStorage, that can store data (permanently) inside user's browser (similar to COOKIES). Usually there is ~5MB (but may differ or may be completely disabled).
if (localStorage) {
db_data = JSON.parse(localStorage.getItem('db'));
//... modify db_data
localStorage.setItem('db', JSON.stringify(db_data));
}
(for JSON use JSON2 library: https://github.com/douglascrockford/JSON-js )
I have a simple offline html5/javascript single-html-file web application that I store in my dropbox. It's a sort of time tracking tool I wrote, and it saves the application data to local storage. Since its for my own use, I like the convenience of an offline app.
But I have several computers, and I've been trying to come up with any sort of hacky way to synchronize this app's data (which is currently using local storage) between my various machines.
It seems that chrome allows synchronization of data, but only for chrome extensions. I also thought I could perhaps have the web page automatically save/load its data from a file in a dropbox folder, but there doesn't appear to be a way to automatically sync with a specific file without user prompting.
I suppose the "obvious" solution is to put the page on a server and store the data in a database. But suppose I don't want a solution which requires me to maintain apps on a server - is there another way, however hacky, to cobble together synchronization?
I even looked for a while to see if there was a vendor offering a web database service - where I could, say, post/get a blob of json on demand, and then somehow have my offline app sync with this service, but the same-origin policy seems to invalidate that plan (and besides I couldn't find such a service).
Is there a tricky/sneaky solution to this problem using chrome, or google drive, or dropbox, or some other tool I'm not aware of? Or am I stuck setting up my own server?
I have been working on a Project that basically gives you versioned localStorage with support for conflict resolution if the same resource ends up being edited by two different clients. At this point there are no drivers for server or client (they are async in-memory at the moment for testing purposes) but there is a lot of code and abstraction to make writing your own drivers really easy... I was even thinking of doing a dropbox/google docs driver myself, except I want DynamoDB/MongoDB and Lawnchair done first.
The code is not dependent on jQuery or any other libraries and there's a pretty full features (though ugly) demo for it as are well.
Anyway the URL is https://github.com/forbesmyester/SyncIt
Apparently, I have exactly the same issue and invetigated it thoroghly. The best choice would be remoteStorage, if you could manage to make it work. It allows to use 3rd party server for data storage or run your own instance.
I am working on a Google Gadget that will collect some data through Google API's. What I am getting stuck on is how to collect the data and then save it somewhere to be processed later. The final idea being that I would run the gadget on my own computer it would collect the data and then save it to somewhere on my own computer. (I guess I want to emphasize that this is, for now, a small personal project and does not necessarily need fancy server scripts, I want to be able to run this all on my PC running XP).
Is there a pure Javascript way to save a file on a computer?
Can I use other languages besides XML, HTML, and Javascript to add functionality to my Google Gadget?
Edit: The goal of this is to be able to log how many of my contacts are signed into gchat over a period of time. I decided on a Gadget because that was the only way I could figure out how to access that information. Any other ways to approach this idea are welcome!
No, Javascript alone cannot save a file automatically. And be careful, javascript is affected by the no cross domain rule. If you're hosting the project on your own computer, why bother writing a complex Google Gadget?
I suggest a simple PHP script, and MySQL, if you like, to store the data. By itself, PHP should be more than enough to run most tasks. If you would like me to add in more info about this, please tell me what type of task.
In increasing order of flexibility:
The options object is almost certainly the easiest approach - not really designed for that kind of usage but I suspect it would be fine for your use case.
On windows you could use system.filesystem to get hold of the WScript FileSystemObject which you can then use to create files and write to them.
Also see the Google desktop API blog for embedding an SQLite database in your gadget (looks pretty easy).