android asynchronous interaction with server

Question

I'm developing a client-server android application, which makes use of REST protocol.

Basically I upload a picture to the server first and then process it on a server and then update the status of this picture in android application (from new to processed);

so the user needs to press "refresh" to receive the renewed list of processed pictures from the server...

I'm surely don't like it...

is it possible to have some sort of callback after the server has completed processing? I think i'm looking for somewhat like... ajax, in other words, the server needs to trigger the event of updating the list, not users "refresh" button pressing. I also don't wan't to ask server every ~2 seconds after sending the picture if it's been processed or not ... i think there must be more elegant solution.

What is the correct way to implement such a functionality?

I can change both server and android parts of an application

thank you in advance!

Use this answer (http://stackoverflow.com/questions/3696986/how-can-i-send-an-http-response-using-only-standard-network-libraries) to learn how to send responses for your requests (if you don't know). And then simply create and send response like "PROCESSING", "DONE" etc — Semyon Danilov, Aug 08 '13 at 15:13

tyczj · Answer 1 · 2013-08-08T15:01:01.383

0

This is what Google Cloud Message is for, the server notifies a device or devices that there is new stuff to get from the server. the phone makes the call to the server to get all the new information and process it

Another option is using xmpp, take a look at asmack

edited Aug 08 '13 at 15:01

answered Aug 08 '13 at 13:55

tyczj

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Or she can can notify a device or devices that there is new stuff from HER server.=) – Semyon Danilov Aug 08 '13 at 14:01
Isn't it an unnecessary complication? – Semyon Danilov Aug 08 '13 at 14:04
its not really any different than using xmpp, probably more reliable because everything is handled by google – tyczj Aug 08 '13 at 14:07
i tried this approach already, and i'm sorry, but GCM doesn't really work... ie it's not stable - doesn't send messages right away, often sends with delay (receiving messages after hours...) – tania Aug 08 '13 at 14:42
@tania We use it at my job sending out thousands of push messages daily and we have not problems. another option is xmpp – tyczj Aug 08 '13 at 14:48
Added xmpp library that I use – tyczj Aug 08 '13 at 15:01

score 0 · Answer 2 · edited May 23 '17 at 10:31

You can use droidQuery to perform an Ajax request with similar syntax to Javascript. It is highly configurable, so check the javadocs for help (if you have used Javascript, you will catch on really fast). The call will run in a background thread, but the callback methods will be called on the main thread. Here is an example of how to do a post that gets a JSON response:

$.ajax(new AjaxOptions().url("http://www.example.com")
                        .type("post")
                        .dataType("json")
                        .data(bitmap_bytes)
                        .context(this)
                        .success(new Function() {
                            @Override
                            public void invoke($ droidQuery, Object... params) {
                                JSONObject json = (JSONObject) params[0];
                                //handle json response. Also see $.map(JSONObject) for parsing
                            }
                        })
                        .error(new Function() {
                            @Override
                            public void invoke($ droidQuery, Object... params) {
                                AjaxError e = (AjaxError) params[0];
                                Log.e("$", "Error: " + e.status + ": " + e.error);
                            }
                        }));

If you want to add a progress spinner, droidProgress is a droidQuery Extension, and can very easily be integrated with droidQuery.

Also, you can see how to convert a Bitmap to a byte[] at converting Java bitmap to byte array.

android asynchronous interaction with server

2 Answers2