There's a lot of info out there for a newbie like myself when it comes to webservices, I acknowledge that.
However, most of the Google results I've seen tend to be focusing on a specific format or strategy, and all of them different to each other.
As a newbie, I am looking to get more of an overview of the various options open to me, their pros & cons... before I start committing to a specific one.
For example, I have an existing webservice created from a SQL Server source via ASP.net and this by default comes out as a DiffGram. So there are articles that tell me how to parse the diffgram data coming into my Android app, but I still do not know if the diffgram is the best option I should be using in the first place.
Should I, for example be changing my webservice to output JSON ?
Does anyone know of a 101 level tutorial or explanation out there ?
Many Thanks
DiffGram is just another type of XML format. In order to parse the XML data in Android, simply use the XMLFullParse class.
FYI: http://developer.android.com/training/basics/network-ops/xml.html
However if you just want to create a simple data exchange WebService, Json is definitely a better choice. Json is simple, lightweight, easier-to-parse and surely easier to use.
Example:
JsonObject json = new JsonObject(jsonString);
json.put("name", "Michael");
json.put("age", "18");
String name = json.opt("name");
Related
Firstly , this is a java program but not Android.
I write a very simple API to get the DB data in Php like below code:
<?php
$query = "Select * from staff order by staff_name";
$reuslt = $mysqli->query($query);
echo json_encode($reuslt->fetch_object());
Suppose that i can get the JSON object in the following URL easily in Android or Php:
http://localhost/Testing/simpleWebService.php
But how can i get it in Java??
I have searched it in Google but the result seems not what i actually want and useful to me
(Reason is i am quite Junior to Java ,Lack of knowledge in Web Service, not accurate keywords inputted........).
I found sth like Jersey, JAX-RS but i don't think this help and the way to get the JSON from the Web Service is complex like that.
Can anyone help ? Thank you very much!!!!!!
The crux of the matter is that you have to replace the behaviour implemented by PHP's json_encode function in Java ie. you have got to find a way to convert the recordset representation of your data to JSON.
1 approach would be to manually convert your recordset to a collection of POJO's then use Jackson to generate the JSON.
However, there are loads of frameworks that make this easier for you to achieve.
What Java framework are you using as that will constrain your future decisions to some degree? How are you reading from your DB - using JDBC API or using an ORM or other library?
I am writing a RESTful web service using Java which should be able to take as (POST) input an unknown number of parameter name, value pairs. I am thinking what is the best way to achieve this.
The POST input will be JSON with the expected format being:
{"input" :
{ "x" = 1, "y"="Hello, "z"="1.2.3.4",... }
}
The parameter values are expected to be a mix of int/long/float/string etc. The expected behavior is to save this input to the DB and provide it back on request. The tricky part is with the parameter names being unknown, I cannot write getter and setter methods. Is there a simple way for handling this?
Any pointers in the right direction will be very much appreciated. Can I read this as a List? Do I need to write Custom MessageBodyReaders? Is there some other way of achieving this? The only option I can think of is to have these sent as a file and parse it but am hoping that there are simpler/cleaner solutions. Thank you for any pointers...
If all you need to do is save it and make it available on request, why parse it at all? Simply write the json as a string to your database, and return it as a string while setting the response type to "application/json". The one caveat being you're going to have to have some way to identify which json string you want and associate a unique id that you're going to be able to determine when you're requesting the specific json string in the future.
Something worth noting here would be that when you don't parse something, you don't actually know what it is. Even though a lot of modern libraries/frameworks sanitize against sql injection/xss already, it would be worth it to verify that this is being done in your server if you don't already know for sure.
That being said, if you're still feeling as though you need to parse the json, I would look into gson: http://code.google.com/p/google-gson/
I'm new to Java. I want to send an array (ArrayList) of objects over the network via Java Web Service to my Silverlight app. This ArrayList contains custom class objects:
ArrayList<SVNSearchResult> results
so I'm thinking the best way is to serialize this to an XML String and on the Silverlight part, use LinQ to parse it. If there's a better way to send it please let me know. Thanks.
XML is a good fit for this. JSON would be one of the other usual suspects these days.
Whatever format you end up choosing, make sure you get the encoding right.
For a starter, try JSON. It has a network-efficient format, and is supported by any major language in the world.
XML is only my second choice as it is more complicated to generate/parse and is more verbose.
Just wondering which is best here. I want to output data from a table in my DB then put a lot of this data into a html table on the fly on my page. I'm working with Java on the server side. Basically I pull the results form the DB and have the raw data..just what next?
There is a chance I may want to take data from multiple tables in order to combine it into one table for my site.
I retrieve the results of the query from the DB, now do I create a text from it in the form of json which I can parse as json using jquery upon the return of the object to my browser?(kind of a sub question of this question: Is just using a stringbuilder the correct way to make a json object to output?)
Or..
Should I build the HTML as a string and output that to the browser instead?
Which is better and why?
I've built entire pages from JSON data on the client. It reduces the redundancy of repeating HTML and can lead to better performance, depending on the complexity of your HTML.
I had large a catalog that used multiple tabs for different sections. Sending it all to the client as JSON and generating the resulting HTML was way faster than downloading the equivalent HTML.
What you lose, of course, is SEO. Search engines won't be able to see the Javascript-generated output. There are ways around this, using hash URL techniques.
I used to be in favor of generating HTML on the server so that the client can be dumb and simply inject dynamic content. The pragmatic real world advantages for our small team was that we needed to be experts at fewer different technologies. We focused on the middle tier and back end and spent less time on the front end.
Lately, with tools like jQuery, it is easier and easier to do more robust client stuff without having to increase the dev bandwidth much. From a client side, I can say building dynamic HTML from JSON using jQuery isn't that hard.
From the server side, I'm sure there are tools to serialize to JSON. I wouldn't roll your own with StringBuilder. Sorry, I'm not a Java guy so don't have a recommendation.
I'd go with JSON if I knew I had anything more than just static views of the data in mind later on.
But if it's just so that you can see what the result was, and don't care too much for the data then I'd go with the straight forward HTML output.
For actually generating the JSON server-side, there are a number of libraries you can use. org.json is the canonical one, but I prefer Stringtree personally.
JSON stands for JavaScript Object Notation. But how come languages like php, java, c etc can also communication each other with json.
What I want to know is that, am i correct to say that json is not limited to js only, but served as a protocol for applications to communicate with each other over the network, which is the same purpose as XML?
JSON cannot handle complex data hierarchies like XML can (attributes, namespaces, etc.), but on the other hand you don't get the same overhead with JSON as you get with XML (if you don't need the complex data structures).
Since JSON is plain text with a special notation for JS to interpret, it's an easy protocol to adopt in other languages.
It is easy for a JS script to parse JSON, since it can be done using 'eval' in which the JS enginge can use its full power.
On the other hand, it is more complicated to generate JSON from within JS. Usually one uses the JSON package from www.json.org in which an object can easily be serialised using JSON.stringify, but it is implemented in JS so its not running with optimal performance.
So serialising JSON is about the same complexity using JS as when using Java, PHP or any other server side language.
Therefore, in my opinion, JSON is best suited when there is asymmetry between produce/consumer e.g. a web server that generates a lot of data that is consumed by the web application. Not the other way around.
But! When one choses JSON as data format it should be used in both directions, not XML<>JSON. Except for when simple get requests are used to retrieve JSON data.
yes, JSON is also wildly used as a data exchange protocol much like XML.
Typically a program (not written in JavaScript) needs a JSON library to parse and create JSON objects (although you can probably create them even without one).
Your right - it's a light weight data interchange format -- more details at: http://www.json.org
You are completely correct. JSON definition of how data should be formatted. It is more light weight than XML and therefore well suited to things like AJAX where you want to send data back and forth to the server quickly.