Eric lippert - Amazon Web Services

Check Box for the AcceptBroadcast field. Our new UI will be as
follows
Subscribing Channels
We’ll put in a Clicked handler for the Subscribe button and update
the client side code as follows:
- In MainPage.xaml, we add the following statement to be able to
access the new ChannelSub table
As we can see, we have added a new table called ChannelSub and
added the following Insert Script.
function insert(item, user,
request) {
var channelTable = tables.
getTable(‘ChannelSub’);
channelTable
.where({ channel:
item.channel })
.read({ success:
insertChannelIfNotFound });
function insertChannelIfNotFound
(existingChannels) {
if (existingChannels.length >
0) {
request.respond(200, existingChannels[0]);
} else {
request.execute();
}
}
}
private IMobileServiceTable channelSubs =
App.MobileService.GetTable();
- The Subscription button click handler is as follows
private async void SubscribeButton_Click(object sender,
RoutedEventArgs e) {
await channelSubs.InsertAsync(new ChannelSub
{
MyId = MyIdTextBox.Text,
AcceptBroadcast = AcceptBroadcastCheckBox.IsChecked.
Value,
Channel = App.CurrentChannel.Uri
});
}
The script checks the table to see if the requested Item’s Channel
URI already exists, if not, it inserts the new Channel Subscription
requests.
Sending out Push Notifications based on Type of
Subscription
Now that we have subscription information with us, let’s modify
the notification logic so that:
a. Users not subscribed to Broadcasts do not receive notifications
without a To ID and the ones who are subscribed, get all requests
b. Instead of lobbing the Notification back to where it came from,
if it has a To ID, send to that subscription ONLY.
On the server, we’ll have to setup the Insert script such that it
doesn’t allow duplicate subscription requests.
To achieve the above two, we update the code with the Insert
script of the FakeTweetMessage as follows:
function insert(item, user, request) {
request.execute({
success: function() {
request.respond();
sendNotifications();
}
});
function sendNotifications() {
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