I am developing an iphone application and I don't know which would be the best approach to sync data between the application and a server.
I'd like to work with data in my application even if there is no internet connection, and sync the data when the device reconnects.
First I thought of using a local database, but I have no idea how to sync the records. At least, I can't imagine an easy way to do it.
How could I sync a local database to a remote one?
Should I think in using files (like json or xml) to store my data instead?
How would I sync files?
Thanks.
Related
I'm using core data in our iOS universal application and want the ability for the user to back their data up to our server. So they can log in with another device and pull down that data to that device. Has anyone got any advice on this? I want to analyse the data at the server to synchronise information with our stores as well, so the data must be readable via the server end as well.
I want to send the entire core data store over in one push, so will be an XML mashup of entities from the core data store that will be deciphered on retrieval.
How can I do this?
Have accomplished this using GDataxml to build the xml string and push it through a web service at the server end. Performance is great.
Your duplicating some iCloud functionality here. Why not leave the cloud storage and retrieval to iCloud and then when the app starts, synchronise with your server
I have a task at hand to create a iphone app which is required to do the following.
the app should get the data entered by the user and store it into a remote server database.
other app user can see the data in the remote database.
store login information of the user using the app so as to keep track of what information as uploaded and by who
the thing that i would like to know.
1) What SQL server database is best to accomplish the task.
2) what format is best to retrieve the information from the database.
3) how to send the data from the iphone to the remover server database to it can store the data.
i read up on SQLite and found out that this particular database is a offline which stores the data locally so it cannot be viewed by other used. i wan to use a SQL database which can be accessed remotely.
1) What SQL server database is best to accomplish the task.
For implementation on server side, you can implement any server database, it does not matter. For implementation on iphone device, you have to implement SQLite database, which will provide storage locally.
2) what format is best to retrieve the information from the database.
You can retrieve data using XML or JSON format which will be parsed in device and can be stored in SQLite database, it is the easiest way to transfer data between client and server.
3) how to send the data from the iphone to the remover server database to it can store the data.
You can send data from iphone to server in XML/JSON format or by passing parameters in POST or GET request method then this format is parsed on server side and store data on server database.
For all this, you will require to implement API on server side, which will be the interface between server and device.
I know you mention SQL specifically, but is this a requirement or just a choice based on what most other people are doing? I ask because personally I would give serious thought to using a NoSQL database (document store) like couchdb for such a task. Deploying couch means you often don't need server side application layer at all, the way you will for a SQL based solution.
You talk to couch using HTTP which is perfectly suited to the ASIHTTPRequest library for example. Fetching data is usually a GET request and storing documents is done with PUT. All the data in or out comes back as JSON so a good JSON library will make life easier.
The combination of couchdb and the 2 libraries linked above, makes developing a data driven application really, really easy.
That's how I would do it ...
If you really need to stick with SQL, then as Jignesh says, use whatever database you like and implement a suitable API in the server side language of your choice. You can transfer the data however you like although JSON would still get my vote as a relatively light protocol that remains human readable.
You can use a cloud-enabled database service, like windows azure.
I want to have on-the-device database for my iphone app. It concerns with the data, which comes from dictionary consisting of 200.000 things and their definitions. It is only related with text-type data as appeared. My questions:
1- Does SQLite hold all of these data?
2- When the client downloaded my app, he/she will also have the db in his/her device. Does app store allow me to update my app's db and upload my new release? (i don't know these issues well by the way)
3- And can any client, who downloaded my app, hack and obtain my database? Is there any prevention methods? Is SQLite resilient enough against these?
1- Does SQLite hold all of these data?
Yes, SQLite can cope with this amount of data.
2- When the client downloaded my app,
he/she will also have the db in
his/her device. Does app store allow
me to update my app's db and upload my
new release? (i don't know these
issues well by the way)
The general approach is to store the SQLite database in your application bundle and then copy the database into the application's document directory on the device when the application is first run. On subsequent updates to your applciation, you should check if the database within the document directory is the same version and update it if necessary. See the existing Run NSBundle from the documents folder question/answer for more information on this.
3- And can any client, who downloaded
my app, hack and obtain my database?
Is there any prevention methods? Is
SQLite resilient enough against these?
It's fairly trivial to open up an app (the deployment package is just a zip file after all), so yes, it will be possible to obtain access to your database data. Unfortunately there's no easy way around this that I'm aware of. (You could I suppose download the data from a server when you first run you app, but it'll still be accessible on a jailbroken device.)
Sometimes, you just have to bite the bullet and accept the fact that your data is going to be ripped off.
1) sqllite can definitely hold that amount of data.
2) You can put up an option of refreshing the database in your app. That can be used to sync the local db with the server copy. Updated db can also be added with the new version of the app.
3) You can encrypt your local db using SQLCipher for protecting your application db against hacks.
I want to develop a CRM iphone app. I think there are 2 methods to deal with the data store, one is using the Sqlite(but it can not share datas with others ?), the other method is using the webservice(let the app CURD data by one web application), I want to know which is better?
I think the question is not about having one or the other, you could have both: Webservices to expose a central server somewhere where common data is stored and your local SQLite database where a copy of this data is stored. This allows you for fast search etc. instead of contacting some remote server that may or may not be on-line.
If you want to share your data then you have to store your data in webdatabase otherwise store in sqlite
you can store your data in sqlite for fast access and when you want to share that time you can send it to webservice and retrive when you need to see more data
I'm looking into building an application which works just as well offline as it does online. Since the application cannot communicate with the server while in offline, there is some level of synchronization which needs to take place.
What are some good tools to read about and start thinking about when planning offline operations with synchronization for your iPhone?
What tools would I have to create on my own, versus tools that apple already provides to help with this particular issue?
I've been working on an app that handles this exact behavior for the last 2 months or so. It has a small subset of functions which are online only and a large set of functionality that is offline/online.
I'm using sqlite for local storage as suggested here with a modified version of the sqlitepersistentobjects library. The base version of sqlitepersistentobjects is not thread safe so watch out if you are using it. (check out objectiverecord in: objectivesync for a thread safe alternative but be prepared to dig into the code). If you are willing to develop for the 3.0 sdk then core data is another possibility for a sqlite library.
The overall architecture is simple enough I have modeled local storage using sqlite and remote interaction using objective resource against a rails app and REST api. It can use either xml or json for data serialization.
When an object is modified locally the change is first saved to the sqlite database record for that object and then added to a queue which is serialized and stored in the local sqlite db as well. (The queue can then be processed at any time)
If there is a connection available any queued local changes are deserialized and added to an NSOperationQueue which then processes them in the background.
In order to make this all work I've subclassed NSOperation so that it can support several types of remote queue operations - create, update, delete essentially using objective resource to make the remote requests.
The nice thing about using NSOperationQueue and NSOperation is that they handle the background threading for you so I'd highly recommend having a look at the apple docs for those classes and also at the apple threading guide.
When the application loads there is a bit of remote checking done and processed in the background to pull down the latest data - although to be honest I am still changing the way this behaves a bit.
That's a quick overview of what I've had to deal with so far...hope it helps a little.
there are plenty of application on the app store which rely on both online as well as offline data
what you should really be doing is on start of your app, run a background thread (which runs silently so your user never sees any delay). this thread downloads the latest data from your server and pushes it into your local database (sqlite is the best choice)
make sure you implement some kind of data versioning so that your app only downloads data which is actually changed since last download - else you would unnecessarily be downloading the entire dataset which can be quite huge (depending upon your app requirements)
also make sure to test for internet connectivity when doing this. if no internet is available, alert the user for sure
this way you get the best of both worlds. users when away from internet can still use your app with their local sqlite data
in iphone os 3.0 apple has introduced push services - where you can simply "PUSH" your data instead of doing a "PULL" however this is not available in the current iPhone OS (2.x.x)
Push is probably not a viable option here, since the amount of data you can push is miniscule, and basically comes back to "tell my app to make a server call". We use an online/offline model in Satchel. Whenever we have to communicate with the server, we bundle that communication (a URL and possibly some POST data) and store it to a database. If we're online, we pull it right back out, send it, and when we get a valid response back, we remove the record from the database. If we're offline, those rows build up, and the next time we ARE online, they get sent out. This is not a workable model in all situations, but can be adapted to most.
In 3.0, you've got access to CoreData, which is a great data management tool. Other than that, the NSURLXXX family is your friend.
I would store all the information I gather while offline in a SQLite database. Then, on user 's request, you can SYNC all the stored information with a server using HTTP or a custom TCP/IP protocol you can come up with.
I have been using this approach on Palm OS applications for almost 10 years now, and they do work very effectively.
As far as I know, the only "tool" you will have to accomplish this is plain old OBJECTIVE-C with Cocoa Touch. Although you could use some TCP/IP C++ libraries that will make your life easier if you decide to implement your own protocol.
Wonder if you have considered using a Sync Framework to manage the synchronization. If that interests you can take a look at the open source project, OpenMobster's Sync service. You can do the following sync operations
two-way
one-way client
one-way device
bootup
Besides that, all modifications are automatically tracked and synced with the Cloud. You can have your app offline when network connection is down. It will track any changes and automatically in the background synchronize it with the cloud when the connection returns. It also provides synchronization like iCloud across multiple devices
Also, modifications in the Cloud are synched using Push notifications, so the data is always current even if it is stored locally.
Here is a link to the open source project: http://openmobster.googlecode.com
Here is a link to iPhone App Sync: http://code.google.com/p/openmobster/wiki/iPhoneSyncApp