My app is highly data driven, and needs to be frequently updated. Currently the MySQL database is dumped to an xml file via PHP, and when the app loads it downloads this file. Then it loads all the values in to NSMutableArray's inside of a data manager class which can be accessed anywhere in the app.
Here is the issue, the XML file produced is about 400kb, and this apparently takes several minutes to download on the EDGE network, and even for some people on 3G. So basically I'm looking for options on how to correctly cache or optimize my app's download process.
My current thought is something along the lines of caching the entire XML file on to the iPhone's hard disk, and then just serving that data up as the user navigates the app, and loading the new XML file in the background. The problem with this is that the user is now always going to see the data from the previous run, also it seems wasteful to download the entire XML file every time if only one field was changed.
TLDR: My iPhone app's download of data is slow, how would one properly minimize this effect?
I've had to deal with something like this in an app I developed over the summer.
I what did to solve it was to do an initial download of all the data from the server and place that in a database on the client along with a revision number.
Then each time the user connects again it sends the revision number to the server, if the revision number is smaller than the server revision number it sends across the new data (and only the new data) from the server, if its the same then it does nothing.
It's fairly simple and it seems to work pretty well for me.
This method does have the drawback that your server has to do a little more processing than normal but it's practically nothing and is much better than wasted bandwidth.
My suggestion would be to cache the data to a SQLite database on the iPhone. When the application starts, you sync the SQLite database with your remote database...while letting the user know that you are loading incremental data in the background.
By doing that, you get the following:
Users can use the app immediately with stale data.
You're letting the user know new data is coming.
You're storing the data in a more appropriate format.
And once the most recent data is loaded...the user gets to see it.
Related
I am building an application that connects to a mysql database. I set up the data connections and data source (data set) and have begun working on development, going back and forth between adding tables and views to the database and adding forms and components to the application.
I have up to now used the "Configure Data Source with Wizard" wizard to refresh the dataset in the application. Sometimes it takes a couple click throughs to get it to fully load the changes, but that's not the end of the world.
Today, without me knowingly changing anything, when I click on the wizard button, the frame of the wizard opens and closes instantly.
My data is accessible, and the parts of the application already developed work just fine, but I don't know how to add new tables and views to my project. My worry is that something went screwy in one of the auto generated dbDataSet.* files.
I'm happy to provide more information if that will help.
To answer my own question for whomever comes here next:
I came across this solution:
https://stackoverflow.com/a/4749044/7640114
It links to a microsoft.com page that is no longer available, but copies the relevant information. Finding the corresponding files is not hard, but knowing what the wrong Provider is may not be so simple.
Mostly because of a lack of patience, I just went with the second option and deleted the entire folder, which may have been overkill. It worked, and I have access to the wizard again and can continue development, but it also wiped out my workspace layout which I now have to rebuild from my memory.
Win some/loose some. In the end, I suggest being more delicate and removing lines of code from DefaultView.SEView first, and then moving on to trying to delete the file and the folder if nessasary.
In our windows store app we save the files that the users are creating in an epub file, which is a zip archive with file extension .epub
The app is written primarily in HTML and JS, but to handle the writing to the zip archive we use some C# in a helper.
This all works, but I have found that the zip archive can become corrupted if the app suspends whilst writing to the zip, as sometimes when adding a particularly large file to the zip, say a 100mb video file, the operation does not complete in the 5 seconds allowed from oncheckpoint.
Are there any ways that I could avoid this problem? As far as I can see there is just no way to write a large file to a zip and be 100% sure that it won't get corrupted if the app suspends.
I agree with you that there is just no way to write a large file to a zip and be 100% sure that it won't get corrupted if the app suspends.
As far as I know, when an App was suspended, the memory owned by the app will not be released, so you don’t need to worry about the data missing in memory when suspending.
The thing you need to worry is user quit the app before the data was persistent.
But some extra designs may improve some user experience and avoid data losing.
auto-save
For example, persistent the changes when the object was changed by user.
show user saving progress
Using the progress UI to let user know the saving is in-progress and he/she will lost the data if quit the app.
Basically I need to connect a MySql database to an IOS application and save a local copy to the device but i'm confused about which path I should take to do this.
Here is a basic description of the application:
The application is used to replace multiple paper based forms, allowing the user to complete a desired form on an iPad. Once the user has completed the form, the forms data is uploaded to a server.
Some forms have fields where the user is required to 'select' an option (drop down list). These options need to be pulled from a database because the options will be changed regularly.
The application still needs to work if there is no internet connection!
This means that whenever there is a connection the application needs to save a copy of the current database so that any required information to fill out forms is still available even if there is no connection.
In short my question is: What is my best option to save a local copy of a database (or just a few tables) to an IOS application?
You should look into Core Data. If you're trying to keep an updated copy of a couple tables, I would create a Core Data database that contains the information you need for your app and, every time the user uses your app, check to see if there's an internet connection. If there is, use NSURLSession to download the necessary data from the web server, after which you can compare the downloaded data to that which is in your Core Data database. If there are any discrepancies between the two, you can update your Core Data database as needed. This way you will always have a relatively up-to-date copy of your MySQL database.
This is a good tutorial for getting a feel for NSURLSession in case you haven't used it much.
Hope it helps!
I have a node.js application that uses a simple JSON file as the model. Since this is an MVP with very limited data storage needs, I don't want to spend time designing and configuring a MongoDB database. Instead, I simply read from and write to a JSON file stored in /data directory of my Node JS application.
However, on Heroku, the JSON file appears to get reset (to the original file I'd deployed to Heroku) every so often. I don't know why this happens or how to turn off this behavior. Any help would be really appreciated, I need to fix this problem within the next four hours.
Heroku uses an ephemeral file system, so that's why it's going to vanish (every 24 hours, or thereabouts).
If you want to store something, you have to use an external backing store. Adding a free tier MongoDB database shouldn't take more than a few minutes. See here or here for examples.
I have a front-end Access 2007 apllication which talks to MySql server.
I want to have a feature where the application on the user's computer can detect that there is a new version on the network (which is not difficult) and download the latest version to the local drive and launch it.
Does anybody has any knowledge or exprience how this can be done?
Thanks
Do you actually need to find out if there is a newer version?
We have a similar setup as well, and we just copy the frontend and all related files every time someone starts the application.
Our users don't start Access or the frontend itself. They actually start a batch file which looks something like this:
#echo off
xcopy x:\soft\frontend.mde c:\app\ /Y
c:\app\frontend.mde
When we started writing our app, we thought about auto-updating as well and decided that just copying everything everytime is enough.
We have enough bandwidth, so the copying doesn't create any performance problems (with about 200 users).
Plus, it makes some things easier for me as a developer when I can be sure that each time the application is started, the frontend is overwritten anyway.
I don't have to care about auto-compacting the frontend when it's closed (and users complaining that closing the app takes too long...), and I don't have to deal with corrupted frontends after crashes.
#Lumis - concerning the custom icon:
Ok, maybe I should have made this more clear. There is only one batch file, and it's in the same network folder as the frontend.
The users just have links on their desktops which all point to the same batch file in the network folder.
This means that:
future changes to the batch file are easy, because it's only one single
file in one central place
we can change the icon, because
what the user sees is a normal Windows link
(By the way, we did not change the icon. Our app is for internal use only, and I'm working in a manufacturing company, which means that all but very few users are absolutely non-technical and couldn't care less about the icon, as long as it's the same on all machines and they know how it looks like so they can find it quickly on their desktop...)
Tony Toews has one: Access Auto FE Updater
It appears to be free, but I'm not 100% sure.
Lumis's option is solid, however if you want to check the version and only copy the database when their is a new version, have a 'Version' field in a back end table, and a 'Version' constant in a front end module. Keep these in sync with each new production release. Compare the table version against the version in the module when the main form of the front end database opens.
If they don't match, have the database close, but have the database call a batch file as the last bit of code to run as it's closing. The database should finish closing before the batch file begins it's copy process. If needed, place a minor delay in the batch file code just to be sure there are no file locking issues.