Data Synchronization between mobile and webserver - iphone

How would you implement a data synchronization solution that ensures data on a mobile device and web server are in sync.

Take a look to this tutorial (part one and part two), basically what they do is add a timestamp attribute storing the last modifications. It is developed to synchronize with the parse.com backend service but it is extendable to any backend.

We use a Unix-Timestamp in our company for this. The Server is comunicating with us in json over tls and client is using AsyncSocket. For Web-Server (https) you can take for example a REST-service and ASIHTTP for client. But our solutions are used for client independent services, so if you have only access with IOS/OS X it's maybe easier to use other solutions for direct synchronization :)

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securing a WCF service for consumption by iphone

I have a WCF service that needs to be secured to be consumed by an iphone app. I would like to know what my options are. I looked around the net and found that using SSL or api key or username/password over SSL is an option but I wasn't able to find any links about how to properly implement them for consumption by an iphone app. I'd really appreciate if someone could point me to the right direction.
Configure the WCF service for basicHttp binding and transport security. To make the client side of things work, you will need to implement an NSUrlConnection delegate. The phone will then be able to authenticate correctly. You can use the Keychain to store the user's credentials.
Stay away from the WS-* protocols that are typically turned on by wsHttp binding. These greatly increase the complexity of the XML you need to read and/or generate.
Although the phone can receive and send XML, it's not nearly as convenient as in .NET. You might want to consider a simpler serialization format such as JSON. This will require the use of webHttp binding.

Alternative to building a proper web service for iPhone app to consume

I am in the process of scoping the development of an iPhone app for a client. Among other things, the app will allow users to browse through and place orders on specific (tangible) products.
The client has a website that currently does a similar thing and due to their limited budget and the fact that the website runs on a third-party proprietary platform which they have no control over, we are investigating possible alternatives to building a web service.
On the website, user registration and authentication, as well as order placing is done through POST requests via secure HTTP. The response is always a formatted HTML page which will contain strings indicating whether the request was successful or not, and if there was an error, what the error is etc.
So provided I can replicate the POST requests on the phone, and parse the HTML responses to read the results of each request, do you think this is an acceptable alternative to building a web service to handle this?
Apart from the possibility of pages changing (which we can manage) and the fact that I will probably have to download and parse a relatively large HTML response, are there any other drawbacks to this solution and is there anything else that I might be missing?
Many thanks in advance for your thoughts.
Cheers,
Rog
You could create an intermediary server that will communicate with the client server, and on it expose some REST web services with json (small overhead and easy to handle) responses that will be consumed by the iPhone app.
So, you're going to parse HTML and formulate POSTs off a third-party server, and pray that they don't even so much as rename a form field.
Your question is in two parts:
Do I think that a miracle is an acceptable solution? I don't.
Do I think that aside from the fact a miracle is required, are there any other drawbacks? None that I can think of.
You didn't ask, but this is a terrible course of action. Two suggestions.
I spy an assumption that the providers of the third-party platform aren't interested in enabling third-party applications by providing an API. They have a very good business reason for this, which is that it promotes platform lock-in. Reach out to their support department and have a talk with them.
You have to sell the client on building an intermediary web service. To at least try to mitigate the damage that changes on this third-party platform can do to your app, I recommend that you build and operate a proxy that receives requests from your applications, and proxies them over to the third-party platform. You should build into this client-server protocol a means for returning "we are in maintenance mode, go away" messages to apps, for that inevitable day when the third-party server changes something that breaks your app (they swapped the billing and shipping address pages, for instance) and you have to rush through an update through Apple to deal with it.
The proxy could be written in something more flexible and easy to bash stuff out in, such as PHP, Python, Perl, or Ruby. It could be hosted at Amazon in a micro instance.
p.s. This question is inappropriately tagged objective C.
HTML is the worst because of parsing (1-2secs per page), memory, and changes, but you already know that. Check in advance that ALL the data you need is exposed on the HTML.
If you use an intermediary server you are moving work elsewhere and you have another server to maintain. I would only do that if memory is an issue. Check How To Choose The Best XML Parser for Your iPhone Project for memory/performance/xpath support. libxml2 is a good option, but it depends on your needs. And maybe you'll want to check ASIHTTPRequest features before using the SDK.
I think utilising the web language of JSON would contribute to the diminishing of the parsing time. By building a REST service that, when sent a GET request, returns the correct information for easy sorting, you could then display the output a lot faster than that of parsing straight HTML.
I prefer JSON over XML, but everyone has their personal preference. You should look at a few very good libraries that are built specifically for parsing purposes of both XML and JSON.
For XML I recommend using the inbuilt libxml parser. Albeit, this can sometimes deem very difficult to use. A simple Google search will bring up a heap of results that relate specifically to what parser should be used depending on what task is to be completed.
As for a JSON parser, I recommend SBJSON. I am currently using it one of the biggest projects I have undertaken and it is definitely working perfectly for my use.
If you need a good way to connect to a RESTful web service, you should try LRResty.
Don't go for a parsing solution on the iPhone for 4 reasons:
Server can change their design and break your application (AppStore submition is long) + They can also detect that the request are sent from an application based on user agent which you have to update the application to change it.
Some of the requests might be made thru Javascript so you not only have to parse (X)HTML but also Javascript request (which can be in the form of XMLHttpRequest, but don't have to)
Long term evolution of the mobile market : maybe your client want (or will want) an application for android, Blackberry, Bada OS (Samsung), Symbian (Nokia/ OVIStore), Java Mobile or Windows Phone 7?
Of course network traffic, Memory and CPU needed to parse HTML (look the time it takes to the browser to do it?)
Regarding the traffic, if the application will not have a huge traffic you can home-host your proxy. Or you can find some provider to host it for you. I guess you won't need more than a couple of Megabytes of storage but maybe traffic. For less than 100€/year you can find some with unlimited traffic (like OVH Pro plan or Infomaniak). But if you want to go Java have a look at Google App Engine : you pay only if your traffic is important and if your application generate many CPU Cycles. If not : you don't have to pay. And it's hosted on Google server : reliable.
If the client is open, you could consider the paypal API.

Cross platform WCF service

I want to use a WCF service and consume it using all the mobile platforms iPhone, android, Blackbery, Nokia etc'
Whats my best strategy for using those clients with a WCF service. it will have to be secured of course.
Thanks
amit
I disagree with SOAP and JSON. Use RESTfull service with POX (plain old xml). It will be most probably supported by all platform. Mobile phones can have limited SOAP stack implementations and JSON is usually used with browsers. My friend has BlackBerry and he continuously complains about its support for JavaScript.
To secure your service use HTTPS.
Use a SOAP or JSON endpoint. Most platforms will have support for these (or it'll be easy to find libraries). JSON is more web oriented (Javascript) but will work in other situations as well.
Mono supports WCF so maybe their iPhone and Android will support it as well.
Totally agree with #Ladislav on not expecting clients to be able to consume SOAP. Seems like SOAP stacks are lacking unless your client is native .NET or Java. Your clients will thank you by allowing them to choose JSON (web clients) or XML (system integration). Secure via HTTPS and basic auth or an API key.
If you already have an existing infrastructure of WCF services that you want to aggregate, or adapt, for downlevel clients you could put that POX (or 'REST') service in front of them and let it handle mapping protocols and formats for you. e.g. HTTP/S to TCP/IP and XML or JSON to SOAP.
The upside is that you will make it easier for downlevel clients to consume your services. The downside is that you've added an extra layer, which will cause complexity. Some tools, like WCF Routing Service (free) or Apigee (commercial), coupled with a solid automated deployment proces can help mitigate this complexity.
To build a REST service that supports XML or JSON, create your service with this template, it's designed for .NET 4.0. From there you can configure endpoints that respond in XML or JSON and let your client tell the service what response type it wants.
EDIT You can also have the service respond in a default format to reduce every client having to specify what format.
<standardEndpoints>
<webHttpEndpoint>
<standardEndpoint name="" defaultOutgoingResponseFormat="Json"/>
</webHttpEndpoint>
</standardEndpoints>

iPhone app and server communication

We have a web-based BI reporting product. We have exposed certain webservices which mainly return html content and do authentication.
We are in a initial process of developing an iPhone App, which will interact with these services and get data on iPhone.
There are couple of things we need to make sure before we start with the actual development process...
1) Should we use SOAP or REST (Will have to write the server part in Java) for the communication between iPhone and our web-application?
2) If we use SOAP, Can you suggest something, which will effectively create web services stubs in Objective-C.
3) In either case (SOAP or REST), what security mechanism is suggested by Apple?
We want to know your thoughts on the best and effective way communication could be done between iPhone app and backend servers (mostly written in Java)
Thanks in advance.
If it is an option, I'd use REST
Never did it, but may this will help: http://abhicodehelp.blogspot.com/2010/12/handling-soap-with-iphone.html
I'd do any HTTP-Communication using ASIHttpRequest. It is SSL-capable
In my apps I use simple URL requests returning XML / Cocoa-touch plists over https. I guess that's called "REST" -- it's simple and quick to implement. There are long flame-fests over SOAP vs. REST -- I just use this technique and get my apps done :)

What common backend can be accessed securely from an iPhone and Android application?

I'm thinking about creating an application for the iPhone and Android that will need to access a common backend to retrieve account information. Can both access a web service over https? What other way would allow me to have one interface to the backend that is accessible by both?
They both work over http and https which is a common enough protocol. I would suggest you go with a RESTful web service so you expose your service via URI's like http://www.myservice.com/weather/zip/98007 which would return an XML blob that can be parsed by the client.
if you are starting from nothing, i'd definitely go with RESTful service that returns/accepts JSON... there are plenty of libraries for both platforms that will accept JSON and turn it into arrays and dictionaries.
I'd recommend using a RESTful web service backend, which is all standard HTTP and/or HTTPS. If you can use Ruby on Rails, its default scaffolding will get you about 99% of the way there and for the iPhone there is an open source project called ObjectiveResource that will automate your communication with this Rails backend. I haven't investigated yet what options are available on Android but since it is all simple HTTP it should be straightforward. I am not the maintainer of ObjectiveResource but I have contributed some code. You can check it out here:
http://iphoneonrails.com
One good approach I have seen used with other services is to write the backend in such a way that it can feed data back in different types - for Android an XML response is best, but for the iPhone sending back plist data is preferred (though it can also work with XML if required). In both cases it's easier to simply POST updates back to the server than to wrap an update in XML.
Both platforms should be able to use whatever form of authentication you wish to use, the iPhone I know supports all methods of HTTP authentication.