Windows Phone 7 - how to send files from/to the app?

Question

I'm trying to write the most basic application for windows phone 7 and want to be able to send files (specifically XML in case that changes anything) to my app. Currently I have a WCF service setup so I can send push notifications through it. The problem is that there is a limit on the amount of raw data I can send via a push notification.

My solution to this is to send the initial push notification (either tile or raw) to alert my application that I want to send a file to it and then make the app somehow communicate with a server (everything is on my personal computer btw - I'm just trying to figure out how things work) - from which the app will recieve/download the files.

What is the easiest way to accomplish this? Note that I'm not concerned with security or anything like that.

Clarification - the question is essentialy: how do I transfer files from/to a server to/from the phone? Assume everything else was handled - the app is up and running and the user has given or will give permissions to every possible thing he may give his permission to.

Answer 1

Unfortunately, the total size of a push notification (including HTTP headers) is 1kb. This means that it can't be used to send large amounts of data.

Instead of sending the whole file, send a notification (raw or toast—as appropriate) which should be treated by the application as a trigger to go and retrieve the new file/data/whatever from the server. It may also be worth checking for new messages when your app starts. However, if when you start the app it will notify the server that it is ready to receive raw notifications and such messages will be sent indicating new content is available, it may be unnecessary to add this extra check.

To transfer files to/from the phone you will need to use either HttpWebRequest or WebClient as this is the only way to use HTTP on the device and HTTP is the only protocol currently available to transfer data.

While WebClient may appear to be easier to use than HttpWebRequest it is less flexible and will automatically perform it's callback on the UI thread and if you're downloading files in the background you almost certainly don't want this.

There is no way to transfer files to/from a conencted PC and have them exclusively available to your app.

Answer 2

First of all: you won't be able to do this approach automatically - the user will have to open your app to do that because WP7 SDK doesn't allow your app to run on background/start automatically once a push notification is received.

The only way to communicate with your server, at this point in time, is web services. If I were you, I would check for new information available once the app is started, if there is new info, I would call one or more web services which would return me all the information that I need. If you want, you can use a timer to check for information periodically.

As I said, it will only work while your app is running (check the app lifecycle if you don't know it yet), WP7 doesn't allow apps to run in background, that is a serious limitation IMHO.

Good Luck, Oscar

Answer 3

You can use the WebClient class and the DownloadStringAsync method in order to download data from a web service . A good example of this is Scott Guthrie's Twitter app from MIX10 .

George

Answer 4

Maybe a little bit off topic but when I was thinking about file sharing in my WP7 app, I found two approaches:

1. Integrate an app with Dropbox
2. Use advanced explorer for WP7