Consuming a WCF REST service from Android is very slow

I have a WCF REST service built with C# and it returns an image as part of a CPU intensive operation. The client is running on Android (Java) By default, it will return a text JSON object that looks something like this:

{"d",[9,0,77,12,11,...]}

Those are they bytes of the image. Fine. However, all the solutions for decoding this JSON are intolerably slow. I've tried Gson, Jackson, and the built-in Android JSONObject class. I have no idea why they are so slow.

As an alternative solution, I have my REST service return a GUID, 开发者_Go百科and then that GUID can be used by the Android client to go to a regular URL that serves up the image as a regular binary stream, via an MVC controller.

This works well, and it fast, and is pretty easy to handle on the Android side. However, it does feel like a bit of kludge and kind of a violation of the REST design principles.

Am I missing something here? Is there a better way to do this?

How about your REST service return a Redirect 303 with a Location header that has an URL that points to the image? Or why not just return the bytes directly from the first URL?

As far as RESTful or not, returning a JSON encoded image is not exactly in the spirit of the REST self-descriptive constraint.

Just make sure the endpoint that returns the image stream of bytes, actually uses an image/* media type in the content header.

Well, on of your main problems is trying to transmit binary data using a text format. Most if not all java json libraries will try to recognize the type of the field. It'll take a long time if there's a lot of fields.

Yeah, streaming it directly is a lot faster. Maybe you can use XML since it supports binary or blob data.

As Darrel wrote above, if the URL computes and returns an Image, simply return that Image with an appropriate content-type, for e.g., as a PNG image. Transmitting the image encoded within JSON is a strange choice, to say the least.

There is a great talk about developing rest client application on android form Google IO 2010.

http://www.youtube.com/watch?v=xHXn3Kg2IQE

This session will present architectural considerations for developing RESTful applications on the Android platform. It focuses on design patterns, platform integration and performance issues specific to the Android platform.

A great resource and must watch.