I am developing an Android App. I read about RESTful Webservices and decided to use that for my app. But I have doubt about REST Client
After reading many article I understood that
I can directly write code to make HTTP request from android
App as given in Connenting To Network OR
I can write code to develop the RESTful client OR
I can use some already developed Third Party lib like RESTDroid
I am not able to decide should directly write code to make the HTTP request as suggested by developers guide or i should follow the rest client model.
What is the advantage of using rest client over directly making HTTP request ( or can say using non-RESTful Client) ?
I am new to android and REST architecture. Please correct me if I am wrong.
This is quite a broad answer but I will divide it in 2 parts:
1) Rest and non-Rest clients:
In my experience I have not seen any REST client except the browsers
the industry trimmed part of the original REST specification and created improved HTTP clients/services and called them REST which(most of them) are not different than any ordinary HTTP library.
So for Android you will get ordinary HTTP Clients with various features but the REST part you will need to code it yourself.
2) What is better to use
Clearly I would not advise to write your own HTTP client as it is far from trivial job to do.
I would not advise to use Retrofit for a really RESTful service as it is not good for that. You better build something on top of OkHttp or extend Volley or Jus which is my creation and it will support basic HATEOAS implementations from version 0.7.0 and optimized pipeline and memory utilization from version 1.0.0 (follow it on github :)
Related
I'm new to android, I'm trying to build an android app that is a front for a web portal. For example, Airbnb. They have a website, but they also have an android app that, using it's own layout, will show listings from their website.
There are many websites that teach how to or even directly convert your website to android apps. However, this will result in an app that loads too slowly and is unresponsive due to CPU usage.
Could anyone share any tutorial/guide to learn how to do this myself?
Million thanks.
To actually load data from a web server you're gonna need and API which usually delivers the proper date using JSON or XML format so that you can properly parse and display that data. Building this API is in it self a complete course on its own.
But connecting to and requesting data from the API is usually done using some networking libraries. These are some of the better know libraries for this purpose.
OkHttp: A complete library with a set of tools for handling network connections and HTTP requests.
RetroFit:Type-safe HTTP client for Android and Java by Square, Inc. which is built on top of OkHttp.
Async-Http-Client:
The Async Http Client library's purpose is to allow Java applications
to easily execute HTTP requests and asynchronously process the HTTP
responses. The library also supports the WebSocket Protocol. The Async
HTTP Client library is simple to use.
There tons of other good libraries.
its called webservices
Through android you get data in form of json from a web server and then return in custom view as you want.
Follow this link hope it will help
Step by Step Method to Access Webservice from Android
you would have to write an API/Web service or use if already exits to fetch data from web server. Basically the concept is that, the website itself must be pulling data from some database, so write an API which would fetch the data from same API and return JSON data and consume the API from your android app.
If you know PHP refere to this for the help :http://www.codeproject.com/Articles/267023/Send-and-receive-json-between-android-and-php
You can write WebService, in programming it generally refers to a web page(ex. Airbnb), that can be called from your android application which can pass in data to it, or receive data from it.
WebService is basically like a 'method' or 'function' in a normal programming language; except you're calling it over the internet.
The first thing is you have to create a Web Service. The Web Service will be your "bridge" to consume the data from other Website like airbnb or others and return the data to your android through json format for example.
You can create a Web Service using many languages like C#, Java, PHP, etc. I would like to recommend you to use the language that you know the most.
You can try to google this
Cheers
Can anyone explain for me or guide me through the basics that i have to know on how to interact with the server API from Android Application?
Any good website that teaches beginners because am new to this thing and am quite lost
If it is a restful API that you will be interacting with, I would highly recommend using RetroFit.
http://square.github.io/retrofit/
Square have excellent documentation and the examples should be easy to follow. If you get stuck you can always post on here under the Retrofit tag which has a fairly large following.
Volley is also an option.
Use Volley networking library http://developer.android.com/training/volley/index.html
This example shows how to make simple client-server app right now.
Here and here you can read description during making client-server app.
I found those links very useful for me when I started to learn this topic.
Hope it helps.
To get you started I've have a sample app Link which uses Github's REST and fetch the result and display it in android List. It is a basic one without any authentication. Hope this helps.
Recently android has introduced a library to parse json. It is called volley.
Volley offers the following benefits:
Automatic scheduling of network requests.
Multiple concurrent network connections.
Transparent disk and memory response caching with standard HTTP cache
coherence.
Support for request prioritization.
Cancellation request API. You can cancel a single request, or you can
set blocks or scopes of requests to cancel.
Ease of customization, for example, for retry and backoff.
Strong ordering that makes it easy to correctly populate your UI with
data fetched asynchronously from the network.
Debugging and tracing tools.
Tutorial which I used is Volley tutorial for json parsing. Another link is here
Hope this helps you.
I am new to socket programming i have to use socket.io and node.js to connect with my server host in android so can anyone please just describe me the programming example of how to connect to server in android. And if possible please give some help regarding node.js and socket.io. As i have searched everywhere on google but not able to find out the proper example.
Thanks
You can just have your web service be REST base.
Your Android application can just talk to your web server via REST and receive data json or xml whatever you fancy.
So with node.js you should set up routes.
An example would of a route would be
www.example.com/users via GET post would return a list of users either in JSON/XML
For your android application you need a library, I believe there's a built in one already, to make request for certain routes such as www.example.com/users via GET method and write the logic to expect JSON or XML and parse that.
I just googled this:
Android: https://github.com/koush/ion
As for node.js you just have to build route...
I think is would be better:
websocket api to replace rest api?
It actually invalidate my answers sorry, REST and websocket api are different.
I have no clue what problem exactly you have. But you should break your problems down to small part. And google and search for answer for each smaller part which would make your life easier to google.
Get your webservice up first so that your android software can consume stuff, build a prototype and then build a prototype of android app that consume data from that webservice.
The current solution that I have to adopt uses JDBC and stores the user/password of the database inside the android app. That's as far as I'm concerned not a good solution. I would like to implement a mapping layer on the webserver in the middle.
Is there any best practice or recommended strategy for this? Should I use SOAP or JSON or something completely different (because they're well implemented and/or easy to use in Java)?
Are there any mapping tools for postgresql <-> SOAP/JSON/whatever in PHP or will I need to write these scripts by myself?
Any pointers will be greatly appreciated.
Quick version:
Use a web service midlayer running on a public host you control (possibly but not necessarily the database host). Expose public web service methods to do the limited work you want to permit and nothing else.
Related questions:
Driver JDBC PostgreSQL with Android
How to connect to a PostgreSQL server via JDBC in Android?
Implementation options
Personally I'd use a Java application server like Apache Tomcat or JBoss AS 7 and I'd write my web service methods using JAX-RS to produce a nice REST-style API for my app to use. That's what I'm familiar with and it works well, but you have lots of options including implementations of:
REST-like APIs (Java's JAX-RS impls Jersey and RESTEasy, various other langs tools) that use HTTP requests and produce JSON or XML replies.
SOAP with WSDL, the classic "web service" layer. In Java done with JAX-WS among other options. Most languages have tools for SOAP+WSDL but it's kind of crappy to work with especially on intermittently connected devices like mobiles.
XML-RPC if you like pain
There are some JAX-RS quickstarts on the JBoss AS 7 quickstarts list; just search for "JAX-RS". The "kitchen sink" quickstart is useful, though perhaps not ideal if you're not familiar with the basics of JBoss AS 7 and Jave EE 6. Fort the JAX-RS specifics you're better off with a Jersey or RESTEasy tutorial like this or this.
Important considerations
Use HTTPs if possible, and if access isn't to be public use a suitable HTTP authentication scheme like HTTP Basic auth over HTTPs. Any decent web services implementation will offer authentication options or support those of the platform on which it runs. Avoid the temptation to implement your own authentication and user management at the web services layer, you will screw it up; use the auth at the HTTP layer that's already written and tested. This may require the use of something like Apache's mod_auth_pgsql, JBoss AS 7's JDBC security realms, etc. The only case I'd consider not doing proper per-user HTTP auth is where I don't need to separate my users for security reasons, I only care that it's my app accessing the server, ie if my security requirements are quite weak. In this case I'd use a fixed username/password for the whole app and possibly an X.509 client certificate if Android supports them.
Remember that no matter how you secure things, all credentials are either known to the user or can be extracted trivially from a .apk so you still have to assume anybody could access your web service methods, not just your app. Write them accordingly.
Do not just send SQL from your app over a web service call to the server and return the results as JSON. This is horrifyingly insecure, as well as ugly and clunky. Write a web service method for each individual task you want the app to be able to perform and keep the SQL in the server. Remember to use parameterised queries and be careful of other SQL injection risks. These web service methods may use one or more queries to produce a single reply - for example, you might collect a "Customer" record and all associated "Address" and "Contact" records then return the result in a nice JSON object the Android device can consume, saving numerous slow and unreliable network round trips.
No matter what you use, make sure to do your web service calls in a background worker thread and not to block the user interface. Be prepared for timeouts and errors, and for the need for retries. Test your app by simulating intermittent connection loss, high latency, and high rates of packet loss and make sure it remains usable.
Is there a best practise:
It depends on the person. All have their strength and weakness.
I prefer, and I think many but not all will agree on JSON cause it is really easy to use in Android. It's also lightweight and very easy to use in php. Php has methods to convert an array/object to json and back.
It is indeed not recommended to save your postgres data on an android device.
My strategy is usually:
PHP server side with a POSTGRESQL database, using PDO to communicate between my models and the database.
If you are not familiar with PDO(php data objects), I recommend you make yourself familiar with it.
php.net PDO
Android as client, using JSON as method of transfering data from and to.
There are many examples that can help you.
Android has standard libraries to handle json parsing.
See this answer for an example:
example
I'm writing a web-service for Android. The client side will be coded in JAVA and we are planning on using ReST. But, the server supports SOAP, JMS( Java Messaging Service) and Remote Method Invocation (only these). I just want to know if it is possible to return response for a ReST based client from this server.
As far as I know, ReST is not a protocol like SOAP, but I just want to be sure that it can be done before I get started.
Any link to video/tutorial/code will also do.
Thanks in advance.
REST is really just an elegant way to use HTTP for resource access.
HTTP is the protocol.
So if you can process HTTP requests on that server, it's doable.
In a Java EE environment a servlet container is perfect: you can create a WAR based on the Jersey framework.