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Using REST APIs from the Device

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When using the REST APIs from a mobile device, a common pattern is to store the registrationIds of the registrations associated with the device in local storage. This enables you to update tags and channel information with a single update call.

Because mobile connections are not always reliable, it is best to avoid creating a new registration without being able to store the registrationId in local storage. This can result in the device registering multiple times, causing duplicate notifications. You can achieve this by using the Create Registration ID and Create or Update Registration REST APIs.

The first API returns a registrationId without actually creating a registration. When the ID has been securely stored on the device storage, the device can call the Create or Update Registration API.

Important

In order to keep the device local storage in sync with the hub, even in the event of loss of local storage data, it is suggested that you delete all registrations with the current channel (that is, the ChannelURI, device token, or GCM registrationId) every time local storage is not initialized.

The following Javascript code creates a registrationId using jQuery:

var createRegistrationId = function() {
        var registrationPath = hub.hubPath + "/Registrations";
    var serverUrl = hub.endpoint + registrationPath
        + "?api-version=2015-01";

    var token = getSelfSignedToken(serverUrl,sasKeyValue,
        sasKeyName, 60);

    var deferred = $.Deferred();
    $.ajax({
        type : "POST",
        url : serverUrl,
        headers : {
            "Authorization" : token
        },
    }).done(function(data, status, response) {
        var location = response.getResponseHeader("Content-Location");
        deferred.resolve(location);
    }).fail(function(response, status, error) {
        console.log("Error: " + error);
        deferred.reject("Error: " + error);
    });
    return deferred.promise();
};

The create or update operation (“upsert”) is a simple PUT call on the returned location. You can construct the registration XML body in the same way as described in the Using REST APIs from a Backend section.

The following Javascript code example demonstrates an “upsert” operation:

var updateRegistration = function(location, registration) {
    var registrationPayload = buildCreatePayload(registration);
    var serverUrl = location;

    var token = getSelfSignedToken(serverUrl, sasKeyValue,
        sasKeyName, 60);

    var deferred = $.Deferred();
    return $.ajax({
        type : "PUT",
        url : serverUrl,
        headers : {
            "Content-Type" : "application/atom+xml",
            "Authorization" : token,
        },
        data : registrationPayload
    }).done(function(data, status, response) {
        var location = response.getResponseHeader("Content-Location");
        deferred.resolve(location);
    }).fail(function(response, status, error) {
        console.log("Error: " + error);
        deferred.reject("Error: " + error);
    });
    return deferred.promise();
};