Can you store an sqlite database remotely on a server? I am building an iphone app and all the tutorials seem to store the sqlite database on the iphone itself...
That is not advisable, as you will quickly run into concurrency problems. I would use a traditional RDMS such as MySQL or PostegreSQL in such a case.
SQLite has a useful page explaining when to use it. It says:
If you have many client programs
accessing a common database over a
network, you should consider using a
client/server database engine instead
of SQLite.
I agree with Matthew Flaschen, but if you really want to, you can connect to a sqlite db throuth an ssh tunnel. If multiple clients prefer mysql postgresql.
Related
I would like to give a web app with a PostgreSQL database 100% offline functionality. In an ideal case the database should be completely replicated in the browser per user, and synchronized when online. So that the same code can be used to talk to both the offline and online database. I know this is possible with PouchDB and CouchDB, but have not found a solution that works with PostgreSQL. Is this at all possible?
Short answer: I don't know of anything like this that currently exists.
However, in theory, this could be made to work...(long answer:)
Write a PostgreSQL backend for levelup (one exists for MySQL: https://github.com/kesla/mysqldown)
Wire up pouch-server to read/write from your PostgreSQL db using pouchdb's existing leveldb adapter (which in turn will have to be configured to use your postgres backend). Congrats, you can now sync data using PouchDB!
Whether an approach like this is practical in reality for your application is a different question you'll have to answer.
You may be wondering, for example, "will I be able to sync an existing complex schema with multiple tables to the client with this approach?" The answer is probably not - the mysqldown implementation of leveldown uses a single MySQL table with three fields: id, key, and value (source), and I imagine any general-purpose PostgreSQL adapter would be similar (nothing says you can't do a special-purpose adapter just for your app though!).
On the other hand, if you were to implement a couchdb-compatible API (or a subset- you may not need attachments, for example) over your existing database schema, there's nothing stopping you from using PouchDB on the client to talk directly to that as if it were an actual CouchDB - just pop in the URL and call replicate()! Implementing the replication protocol might be a fair bit of work, since you'd need to track revisions and so on somewhere - but again, technically not impossible!
There are also implementations of levelup's backend storage that are designed for browsers. See level.js, which could be another way to sync between a server-side Postgres levelup backend and the browser.
TL;DR: There's tons of work being done around Javascript databases right now. Is syncing with Postgres impossible? probably not. Would it be a lot of work? Definitely. Worth it? Who knows, but it would be cool.
Without installing PostgreSQL on the client? No. Obviously you can cache data for offline use, but an entire RDBMS+procedural languages in Javscript, no.
I've been researching now for couple of days about this matter but with no luck.
I am learning iOS development with the plan of developing iPhone app mainly. Now this app will mimic the behaviour of my PHP site.
The question: Can I interact from my iPhone app directly with my tables to load and/or insert new data? if not mySQL then which database is used to host the data for CRUD operations? JSON objects? if yes, then how?
As you can see I am really unaware of the way and hope that some light should be shed on storing and retreving data from existing database or what I need to host new database to use with iPhone.
The "best" and easiest way (for me anyway) is to use CoreData.
CoreData is a data management system. You set up some objects and relationships in it and then interact with those (use fetch requests to retrieve them and stuff).
CoreData then manages a datastore (most often a SQLite DB) which it uses to store the objects and relationships etc...
Using CoreData removes the necessity of a DBA and a lot of the complex DB logic and stuff.
A good tutorial to look at is this one...
http://mobile.tutsplus.com/tutorials/iphone/iphone-core-data/
I bought this book though...
http://www.amazon.co.uk/Pro-Core-Data-Professional-Apress/dp/1430236566/ref=sr_1_2?s=books&ie=UTF8&qid=1358773284&sr=1-2
and found it extremely useful for everything from starting out to the more advanced stuff.
When used properly, CoreData makes it VERY easy to use and manipulate persistent data.
YES, You can interact from your iPhone app directly with your tables to load and/or insert new data; Check the next tutorial - interact with your MySQL/PHP server http://www.scott-sherwood.com/ios-5-uistoryboards-a-practical-example/
CoreData is good but limits to access to just iDevices.
I use couchdb, means a copy is stored in the cloud with auto syncing between cloud and devices allowing for web updates and also Android
I am looking for a tutorial on how to make an iPhone app that fetches data from and writes data to a MySQL database. I've seen some other threads saying that I should make an abstraction layer so as not to connect directly to the database from my app, but I'm not sure of how to actually go about doing this. Does anyone know of any tutorials that involve creating an abstraction layer for a MySQL database or connecting a MySQL database to an iPhone app?
To clarify, I am looking for a secure method that wouldn't allow people to sniff out my MySQL host, username and password. It seems like the libraries that connect directly to MySQL from the iPhone all have this problem, but please correct me if I'm wrong.
This is a really good tutorial that covers how to communicate with MySQL from an iPhone app using PHP:
http://www.raywenderlich.com/2941/how-to-write-a-simple-phpmysql-web-service-for-an-ios-app
I know only one library, which makes possible connection from iPhone to MySQL. This is port of official MySQL C libraries created by Karl Kraft.
Author published also small portion of samples, which describes how to use this library.
UPDATE (Karl Kraft's broken link)
Instead of link above, I used an archived copy.
not up to date, but this tutorial helped me a lot:
http://codewithchris.com/iphone-app-connect-to-mysql-database/#connectiphonetomysql
Here http://blog.iosplace.com/?p=30 is a snippet that uses the original mysql client lib, and here http://www.karlkraft.com/index.php/2012/01/ is a link to a 3rd-party connector.
Here is a nice tutorial on how to connect to a database using web service layer.
From a practical perspective you could connect directly to a database from an iphone because that is a client server transaction. The problem is that you would need to expose your database server an issue that many would find very disturbing, because you would expose your server which hold your most valuable resource "your data". Of course you can implement and could be a good solution for rather small projects. But you would need to implement the layer which it would be used to connect on the iOS app, adding more complex to the matter.
Using a web service is more reliable even from the iOS developer, because there is a very extensive api for using web service, which offer great functionality (asynchronous transactions, threads management,JSON Mapping, XML Mapping) to name a few.
Use the library OHMySQL. It copes with MySQL through MySQL C API.
I am trying to access a remote MySql database from my iPhone application. I googled, but I can't find anything that works. Can any one suggest a clear way to do this?
Since the iOS SDK does not contain any API's that can access a MySQL database, you have two options:
Implement whatever is necessary in order to talk to a MySQL database engine.
Talk to an application sitting in between your iOS application and your MySQL database.
Of the two, nbr. 2 is by far the easiest, and the normal way to do that is to set up a web service somewhere that you can talk to.
You will have to implement web service methods for whatever kinds of operations you need to perform on your MySQL database.
Exactly how to talk to that web service, and exactly how to talk to the MySQL server from your web service, those are separate questions.
I have been interested in working with a MySQL database in my iPhone or Mac projects. How is a connection performed in Objective-C?
I only had a bit of experience with PHP, but heck, that is a bit too different =/
Check this tutorial for connectivity with SQLite.
You will not be able to connect to MySQL directly from the iPhone. You must use some intermediate layer such as a Web application with PHP.
So, you will have something like this:
iPhone POSTING a request to the WebServer using HTTP
Web Server connecting to the MySQL database
Web Server returning data to the iPhone (XML, plain text)
iPhone processing the data
You can use this technique to query and insert/update/delete data.
Once I found this library for MySQL, and I am aware how it works.
It's a much better option not to deal directly with MySQL, but use Apple's Core Data API.
It allows you to manage an relational database without having to write SQL. It's very fast, very useful. Good stuff.
Try absrd which recycles connections across concurrent threads (queues).
If you want to connect to a MySQL database, use MySQL's Connector/C API library which, as Objective-C is a strict superset of C, you can use without any issues. I helped someone with the installation of it here.