I am writing an android application that needs to work both offline and online. In order to do that I need to get mysql database from external server and save that db to phones localdatabase so it can be read from there if user has no connection. Is it possible and if so, how can I do it?
Refer the following thread in which I have mentioned javascript frameworks which can be used to store data locally. The frameworks are using the standard local storage mechanism but they make it easier to store/retrieve and also make it portable across many platforms (this again depends on selection on the framework).
What to Use for PhoneGap Database Storage
Although you still need to load data from server.
This sounds like you need to write an API which does CRUD operations on a database.
There is no trivial way to simply do this directly with MySQL - you'll have to write one.
There are frameworks designed specifically for this, for example FRAPI: http://getfrapi.com/
Related
I have a web applications that stores data in a MySQL database on-line. It also retrieves data using PHP code, performs calculations on the server and sends the result back to the user.
Data it's quite simple: names, descriptions, prices, VAT, hourly charges that are read from the database and manipulated on the server side.
Often client work in environments where the internet connection is poor or not available. In this case I would like the client to be able to work offline: enter new names, descriptions, prices and use the last VAT to perform calculations. Then synchronise all data as soon as a connection is available.
Now the problem is that I do not know what is the best way or technologies for achieving this. Don't worry, I am not asking to write code for me. Can you just explain to me what is the correct way to build such a system?
Is there a simple way to use my online MySQL and PHP code locally?
Should I save the data I need in a local file, rebuild the calculation in JavaScript, perform them locally and then synchronise the data if database is available.
Should I use two MySQL database, one local and one online and do a synchronisation between the two when data is available? If yes which technology (language) shall I use to perform this operation?
If possible, I would like an answer from PHP coders that worked on a similar project in the past and can give me detailed information on framework structure and technology to use. please remember that I am new to this way of writing application and I would appreciate if you can spare few minutes and explain everything to me like if I am six year old or stupid (which I am!)
I really appreciate any help and suggestion.
Ciao,
Donato
There are essentially 3 ways to go:
Version 1: "Old school": PHP-Gtk+ and bcompiler
first, if you not have done so already, you need to separate your business logic from your presentation layer (HTML, templating engines, ...) and database layer
then adapt your database layer, so that it can live with an alternative DB (local SQlite comes to mind) and perform synchronisation when online again
Finally use PHP-Gtk+ to create a new UI and pack all this with bcompiler
Version 2: "Standard": Take your server with you
Look at Server2Go, WampOnCD and friends to create a "double clickable webserver" (Start at Z-WAMP)
You still need to adapt your DB layer as in Version 1
Version 3: "Web 2.x": Move application from server to browser
Move your application logic from the server side (PHP) to the client side (JS)
Make your server part (PHP) only a data access or sync layer
Use the HTML5 offline features to replace your data access with local data if you are offline and to resync if online
Which one is best?
This depends on what you have and what you want. If most of your business logic is in PHP, then moving it into the browser might be prohibitingly expensive - be aware, that this also generates a whole new class of security nightmaares. I personally do not recommend porting this way, but I do recommend it for new apps, if the backing DB is not too big.
If you chose to keep your PHP business logic, then the desicion between 1 and 2 is often a quiestion of how much UI does your app have - if it's only a few CRUD forms, 1. might be a good idea - it is definitly the most portable (in the sense of taking it with you). If not, go with 2.
I have worked with similar system for ships. Internet is expensive in the middle of the ocean so they have local web servers installed with database synchronization via e-mail.
We also have created simple .exe packages so people with no experience can install the system or update system...
I've developed an application that I would like to use meteor.js for real time updates (I want to enhance but not change my program, for example when a user adds a comments make it update in real-time ) . Problem is meteor.js uses node.js (so javascript as server-side code). I use LAMP stack, Is it possible to get PHP to feed data into meteor.js from mysql.
Meteor is more than just an 'interactive webapplication'-builder or javascript framework. The idea is to have only one programming language (besides HTML/CSS for markup) to do all the work. Basically it creates a 'remote server' (in the clients browser) it can push data to and at the same time it publishes various API's to the users system. The data passed through these API's / connections has a specific structure which has to be adhered at all time.
Meteor is built around NodeJS, which makes it hard (if not impossible) to run it without this backend. Sure you can try to mimic the backend using PHP, but it would be a waste of time. Reading your question you'll be better of using a javascript framework like jQuery or Prototype. Unlike Meteor you will need to do the AJAX calls (POST & CallBack) yourself, but you can actually decide which backend you want to use yourself (including PHP / MySQL).
If you want to do this anyway you need to check the Meteor & NodeJS source code to see what the minimum requirements are to make Meteor run under PHP. The PHP stack has to interpret the commands Meteor sends and receivers, but this won't be an easy task.
You can use comet (or reverse ajax) for realtime updates.
Trying to marry node.js with PHP doesn't sound like a worthwhile path to go down. If someone insisted on using a system like Meteor.js, yet with a PHP back-end, it would make more sense to look at AngularJS which is mainly the client side.
Of course, that is different technology stack. If someone really insisted on the blending, one could consider using server side sockets to interact with PHP Web services; and/or use mongodb and/or mysql-node to interact with the same databases.
I released a meteorite package that interacts with a Wordpress site that has the Wordpress JSON API. A quick fix. For now.
Comes with a backend call that will return the raw data, or a publication that stores the posts using their id's instead of a randomly generated mongoid. And some basic templates to get you started including a Session variable that keeps track of the currently selected post.
I'm working on it a lot more and will eventually have a version that directly makes mysql calls from node so you won't need php or Wordpress; just the ability to access the mysql database (which can be remote, with the appropriate configuration, or on the same machine).
There have been many questions along these lines but I'm struggling to apply them to my scenario. Any help would be be greatly appreciated!
We currently have a functioning mySQL database hosted on a website, data is entered from a website and via PHP it is put into the database.
At the same time we want to now create a python application that works offline. It should carry out all the same functions as the web version and run totally locally, this means it needs a copy of the entire database to run locally and when changes are made to such local database they are synced next time there is an internet connection available.
First off I have no idea what the best method would be to run such a database offline. I was considering just setting up a localhost, however this needs to be distributable to many machines. Hence setting up a localhost via an installer of some sort may be impractical no?
Secondly synchronization? Not a clue on how to go about this!
Any help would be very very very appreciated.
Thank you!
For binding Python to MySql you could use HTSQL:
http://htsql.org
You can then also query your MySQL DB via http requests, either from AJAX calls or server-side e.g. cURL (and of course still have the option of writing standard SQL queries).
There is a JQuery plugin called HTRAF that handles the client side AJAX calls to the HTSQL server.
The HTSQL server runs on localhost as well.
What OS would you be using?
How high-performance does your local application need to be? Also, how reliable is the locally available internet connection? If you don't need extremely high performance, why not just leave the data in the remote MySQL server?
If you're sure you need access to local data I'd look at MySQL's built-in replication for synchronization. It's really simple to setup/use and you could use it to maintain a local read-only copy of the remote database for quick data access. You'd simply build into your application the ability to perform write queries on the remote server and do read queries against the local DB. The lag time between the two servers is generally very low ... like on the order of milliseconds ... but you do still have to contend with network congestion preventing a local slave database from being perfectly in-sync with the master instantaneously.
As for the python side of things, google mysql-python because you'll need a python mysql binding to work with a MySQL database. Finally, I'd highly recommend SQLalchemy as an ORM with python because it'll make your life a heck of a lot easier.
I would say an ideal solution, however, would be to set up a remote REST API web service and use that in place of directly accessing the database. Of course, you may not have the in-house capabilities, the time or the inclination to do that ... which is also okay :)
Are you planning to run mysql on your local python offline apps ? I would suggest something like sqlite. As for keeping things in sync, it also depends on the type of data that needs to be synchronized. One question that needs to be answered:
Are the data generated by these python apps something that is opague ? If yes (i.e. it doesn't have any relations to other entities), then you can queue the data locally and push it up to the centrally hosted website.
This is not a codefix question but please help me where possible.
I am developing an application which needs to store information in a database. This information needs to be stored off-device for security reasons (patient data).
I have explored using PHP as a bridge to the external MySQL database hosted locally via WAMP, however I have recently been informed of servlets and also of SQLite.
As I am learning these technologies under a limited time frame I need to know which to invest my time into to get the job done as easily as possible. I have no experience with any query language but I did get a simple login screen to work on Android using PHP and MySQL on WAMP using HTTP post/fetch within android.
Also, is it possible to store the information in SQLite within android and write that data to a server, which can then load the SQLite database again on re-launch?
Many thanks for your time!
From our expericence these kind of services need to work offline if possible. Both 3g and especially wifi has been unreliable in several occasions.
You do good if you save the data locally in e.g. sqlite database but be warned the data can get wiped on OS update or software update.
Also try to write your changes/additions in batches and servr updater can send all the batches that are not yet on the server. this way it's more reliable if you miss updates.
These kind of interfaces to another systems take a lot of time in testing. Consider getting a new timeframe in advance.
You will find more about Android connection to MySQL here
I was wondering if there is any kind of alternative to MySQL DB's.
It would be great if I could use MySQL db's but i don't want to ask the user to create a db as they'd find it to complicated and give up (non-web savvy target market). I cant store the data on one of mine remotely as there is just too much data and that's asking for trouble.
Also, the target market for my product are people that use one host. This host they use does not allow users to create MySQL db's. So I'm looking for an alternative where I can store personal data for the users to read and write. Maybe something that PHP can read and write to?
Any suggestions?
Is it possible to have a normal DB (Microsoft access DB file) on the server and PHP read/write to that?
What about SQLite?
SQLite is a software library that implements a self-contained, serverless, zero-configuration, transactional SQL database engine. SQLite is the most widely deployed SQL database engine in the world.
sqlite is your choice:
In contrast to other database management systems, SQLite is not a separate process that is accessed from the client application, but an integral part of it.
http://php.net/manual/en/book.sqlite.php