Develop Reference

How to simulate browser login in Android using API

I want to make an android app which will login to my web application using rest API. In browsers we have a concept of cookie which servers use to identify/maintain session with the users.
In Android how would we accomplish it ? I heard that there is a concept of token which is sent by server in response(first time when credentials are validated) and Android app have to send it to server every time it tries to access a resource(protected). So, what is the better way of doing it ?
Do we need to validate the token again and again when the client requests for a resource ?

Honestly, I can't think of a better way of doing this. Token based authentication seems to be pretty standard when dealing with RESTful APIs. Is there any reason you can't do that?
If you don't want to change the server code, then this could be simulated by adding a cookie header to every request you send. But this is basically the same thing that you mentioned above, just not as clean.
And the browser is already sending a token to be validated again and again. Every request has a cookie header that gets validated through your web application on every request, so this isn't a big deal at all.
And, you don't need anything Android specific to accomplish this. In whatever http library you're using I'm sure there is a method you can called or something you can override in order to set custom headers. Use that to set either your cookie header or token header on every request that you need to make.

How can mobile app get a JSON form to create a new record in Rails web service?

I have a model User in Rails app. It is restful with 7 actions in UsersController. When accessed using a browser,
GET http://mydomain.com/users/new
will get a form to fill information on the new user. What should an Android app get? Should it also get a html form, fill it then send back the html? Can it get a JSON response from the new action in UsersController or maybe skip this step all together? How should this work?

If Android app is a client of your backend service it should have its own layouts/forms etc. Then, after collecting all necessary information from user you can send a response to server using JSON, in example:
POST http://mydomain.com/users/new
{"name":"Anrnold","password":"I<3steroids"}
If you want to display custom form retrieved dinamically from server you can pass form's fields and generate form on android device programatically. But why would you want to do that?
Everyting you need to know about json is here: json.org. I also recomend Gson

Pass parameters Using HTTP request

Hi i am new to android programming and i would like to know how to call a web service and pass parameters to the web service to obtain the return result in form of an XML.
I previously used Ksoap lib and SOAP request but thats not working correct so now i am trying the HTTP method.
Please Help

You will want to read up on the Apache HttpClient.
Beyond that its a matter of making sure the device and server are generating messages that the other side can correctly parse.
Is the server an existing service? Or are you designing that as well?

check the following in which you will use HTTP post request & you will get response in the form on XML
Android HttpPost: how to get the result

RESTful RAILS and Android HttpRequests

I am currently working on building an Android app for my Rails backend.
I created api_tokens_controller to create an api_token when user logs in from Android using HttpPost and save that token both in Rails user table and Android shared preferences. I was able to verify this.
I am trying to send the api_token as params[:api_token] from my Android app with every subsequent request after initial log in and have Rails verify:
In User.rb:
def self.authenticate_with_api_token(api_token_from_mobile)
user = find_by_api_token(api_token_from_mobile)
if user.nil?
return nil
else
return user
end
end
if user exists, then send other data as JSONObjects.
I am running into trouble conceptually here. I am now trying to have the Android app go to
...:3000/users and HttpGet user data as JSONObjects. The problem is that I don't know how to send the api_token from Android app to Rails in HttpGet. I am assuming that since it is RESTful, my HttpRequests have to correspond to the way rails routes work.
Questions:
Is it possible to send in JSONObject of params[:api_token] from android app to Rails in HttpGet?
Do my HttpRequests have to correspond to the RESTful way Rails works or can I just only use HttpPost?
Thanks

If I understand you correctly, then you just want to add the API token to as a URL parameter if using GET, so something like:
...:3000/users.json?api_token=token
This will put the api_token in the params hash just the same as POST data would be. The RESTful way would be to use GET for retrieving data from the API and using POST to send data, i.e. changing data on your backend but if you are going to be returning a user with the request then GET is the correct method to be using anyway.

I'm a former Ruby on Rails developer myself.
I agree with Tom that you can just pass in the api_token as a parameter with an HTTP GET.
For your second question, I'd say that the RESTful way is to use all the HTTP Verbs for the different actions that you can take in the API. You could change your routes to use HTTP POST and then supply extra parameters to differentiate between say Create and Update (to emulate a PUT). However, I don't think that's the way forward.
However, the good news is that whether you use HttpClient or HttpUrlConnection in your Android app, you will have access to the different HTTP verbs you need. For HttpClient, it is actually different classes like HttpGet, HttpPost, HttpPut and HttpDelete which you then configure by supplying URL and other parameters. For HttpUrlConnection, you just call it like so:
setRequestMethod("PUT");
Here's the relevant documentation on HttpUrlConnection:
HttpURLConnection uses the GET method by default. It will use POST if setDoOutput(true) has been called. Other HTTP methods (OPTIONS, HEAD, PUT, DELETE and TRACE) can be used with setRequestMethod(String).

How to perform client-server communication with android app? Can I use servlet on server side or do I need to implement web service?

I am developing an android app where a user has to enter his login details for authentication...the app will then check username and password entered by user on server and will act accordingly..so how to pass these login details to server..and do I need to implement web service on server side or can use servlet?
Can anyone please tell me which Web Service should I use for the above purpose...also I need to send other data from my client app to server, process it on server and give back the reply to client app...also how to implement a web service? Are there any tools for it? Any tutorials would be of great help.
Thanks in advance...

well, to send data to the server you can use HttpPost and HttpGet requests.
and as you need to get results from the server then, yes you'll need a web service.

You can use servlet (or) webservice, any service, as long as it can be accessed through URL. Make sure the servlet/webservice returning XML/JSON (one of these two formats are preferred, you need to code your servlet/service to return response in one of these formats) response when you hit the URL in internet explore. Once you make sure URL is returning data, then
1) In your app, using HTTPClient, invoke the URL
2) You will get either XML/JSON
3) If it JSON, use in buit JSONObject to parse the response and get the data
If response is XML, use either SAX/Dom parsing to parse the response.