Google android notification downloads

Before we can send a push message we must first subscribe to a push service. Subscribing returns a subscription object, or subscription. The subscription is a critical piece of the process to send push messages. It tells us, the developer, to which push service we should send our push messages remember, each browser will provide their own push service.

The subscription also details which client the push service should route the messages to. Finally, the subscription contains the public key to encrypt the data so that it is delivered securely to the user.

It is your job to take this subscription object and store it somewhere on your system. For instance, you might store it in a database attached to a user object.

In our examples, we will log results to the console. First, we need to check if we already have a subscription object and update the UI accordingly. We should perform this check whenever the user accesses our app because subscription objects may change during their lifetime. We need to make sure that it is synchronized with our server. If there is no subscription object we can update our UI to ask the user if they would like receive notifications.

It's best practice to call the subscribeUser function in response to a user action signalling they would like to subscribe to push messages from our app. In the above example we call the subscribe method on the pushManager and log the subscription object to the console. Notice we are passing a flag named userVisibleOnly to the subscribe method. By setting this to true , the browser ensures that every incoming message has a matching and visible notification.

If the user doesn't accept the permission request or there's another error, the promise rejects. We add a catch clause to handle this, and then check the permission property on the notification global object to understand why we can't display notifications. Let's look at how to send a push message to the browser using the Web Push Protocol.

The Web Push protocol is the formal standard for sending push messages destined for the browser. It describes the structure and flow of how to create your push message, encrypt it, and send it to a Push messaging platform. The protocol abstracts the details of which messaging platform and browser the user has. The Web Push protocol is complex, but we don't need to understand all of the details. The browser automatically takes care of subscribing the user with the push service.

Our job, as developers, is to take the subscription token, extract the URL, and send our message there. FCM recently adopted the Web Push protocol.

Here's how:. For example, the manifest could look like this:. To get FCM to push a notification without a payload to your web client, the request must include the following:.

A production site or app normally sets up a service to interact with FCM from your server. Check out the Web Fundamentals documentation for more information. We can test push messaging in our app using cURL.

We can send an empty message, called a "tickle", to the push service, then the push service sends a message to the browser. If the notification displays, then we have done everything correctly and our app is ready to push messages from the server. You can send a message to Firefox using the same cURL command, but without the Authorization header:.

It's relatively easy to get a push message to the user. However, so far the notifications we have sent have been empty. Chrome and Firefox support the ability to deliver data to your service worker using the push message.

Let's first look at what changes are needed in the service worker to pull the data out of the push message. When we receive a push notification with a payload, the data is available directly on the event object. In order to send data, the push message must be encrypted with the key information from the subscription object.

As with anything related to encryption, it's usually easier to use an actively maintained library than to write your own code. We are using Mozilla's web-push library for Node. This handles both encryption and the web push protocol, so that sending a push message from a Node. The first argument is the the subscription object.

The second argument is the payload. The third is an options object that contains various options to configure the message. See the documentation for details. While we recommend using a library, this is a new feature and there are many popular languages that don't yet have any libraries. Here is a list of some available web-push libraries for various languages.

If you do need to implement encryption manually, use Peter Beverloo's encryption verifier. We now have all the client side components in place, so let's create a simple server-side script using Node. This example passes the subscription object, payload, and server key into the sendNotification method. It also passes in a time-to-live, which is the value in seconds that describes how long a push message is retained by the push service by default, four weeks. The Web Push Protocol has been designed to respect the user's privacy by keeping users anonymous and not requiring strong authentication between your app and the push service.

This presents some challenges:. At a minimum, this provides a stable identity for the application server, though this could also include contact information, such as an email address. You can see how to do this in the web-push node library :.

You'll know if it has worked by examining the endpoint in the resulting subscription object; if the origin is fcm. Let's look at these new headers in detail. A JWT is a way of sharing a JSON object with a second party in such a way that the sending party can sign it and the receiving party can verify the signature is from the expected sender. The structure of a JWT is three encrypted strings, joined with a single dot between them.

The JWT Header contains the algorithm name used for signing and the type of token. The Signature is the result of joining the encoded header and payload with a dot then encrypting the result using the VAPID private key you created earlier. The result itself should be appended to the header with a dot. There are a number of libraries that will take the header and payload JSON objects and generate this signature for you.

The signed JWT is used as the Authorization header, with "WebPush" prepended to it, and looks something like the following:. There are a few things to point out here. Also notice the dots separating the JWT header, payload, and signature.

When you are sending a notification with encrypted data, you will already be using the Crypto-Key header, so to add the application server key, you just need to add a comma before adding the above content, resulting in:. It contains the subject your email address and the generated Public and Private keys. The library takes care of encrypting the message, generating and signing the JWT, and adding the Authorization and Crypto-Key headers to the request.

See the web-push documentation for more information on how to use the library. While it's relatively simple to get notifications up and running, making an experience that users really value is trickier. There are also many edge cases to consider when building an experience that works well. Notifications should be timely, precise, and relevant. By following these three rules, you'll keep your users happier and increase their return visits.

Timely — The notification should display at the right time. Use notifications primarily for time-sensitive events, especially if these synchronous events involve other people. For instance, an incoming chat is a real-time and synchronous form of communication another user is actively waiting on your response. Calendar events are another good example of when to use a notification to grab the user's attention, because the event is imminent and often involves other people.

Precise — Offer enough information so that the user can make a decision without clicking through to the web page. Because users often give notifications only a quick glance, you can make their lives easier with a well-chosen title, description, and icon. If possible, make the icon match the context of the notification so users can identify it without reading. Relevant — Make notifications relevant to the user's needs. If the user receives too many unimportant notifications, they might turn them all off.

So keep it personal. If it's a chat notification, tell them who it's from. Avoid notifications that are not directed specifically at the user, or information that is not truly time-sensitive. For instance, the asynchronous and undirected updates flowing through a social network generally do not warrant a real-time interruption.

Don't create a notification if the relevant new information is currently on screen. Instead, use the UI of the application itself to notify the user of new information directly in context. For instance, a chat application should not create system notifications while the user is actively chatting with another user.

To show notifications we need to prompt the user to give permission. But when is the best time to do that? Geolocation offers a good example of where we can look at people's experience with its prompts.

Although geolocation is a great API, many sites immediately prompt the user for their location the instant that the page loads. This is a poor time to ask. The user has no context for how to make an informed decision about allowing access to this powerful piece of data, and users frequently deny this request.

Acceptance rates for this API can be as low as six percent. However, when the user is presented with the prompt after an action such as clicking on a locator icon, the acceptance rate skyrockets. The same applies to the push notifications.

If you ask the user for permission to send push notifications when they first land on your site, they might dismiss it.

Once they have denied permission, they can't be asked again. Case studies show that when a user has context when the prompt is shown, they are more likely to grant permission. Another pattern that works well is to offer a very subtle promotion area on the screen that asks the user if they would like to enable notifications.

Be careful not to distract too much from your site's main content. Clearly explain the benefits of what notifications offers the user. It's not unreasonable for a site to send the user lots of important and relevant updates.

However, if you don't build them correctly, they can become unmanageable for the user. A simple technique is to group messages that are contextually relevant into one notification. For example, if you are building a social app, group notifications by sender and show one per person. If you have an auction site, group notifications by the item being bid on. The notification object includes a tag attribute that is the grouping key. When creating a notification with a tag and there is already a notification with the same tag visible to the user, the system automatically replaces it without creating a new notification.

Not giving a second cue is intentional, to avoid annoying the user with continued beeps, whistles and vibrations. To override this and continue to notify the user, set the renotify attribute to true in the notification options object:. If the user is already using your application there is no need to display a notification.

You can manage this logic on the server, but it is easier to do it in the push handler inside your service worker:. The clients global in the service worker lists all of the active push clients on this machine. If there are no clients active, the user must be in another app. We should show a notification in this case. If there are active clients it means that the user has your site open in one or more windows. The best practice is to relay the message to each of those windows.

When a user clicks on a notification we may want to close all the other notifications that have been raised by your site. In most cases you will be sending the user to the same page that has easy access to the other data that is held in the notifications. We can clear all notifications by iterating over the notifications returned from the getNotifications method on our service worker registration and closing each:. If you don't want to clear all of the notifications, you can filter based on the tag by passing it into getNotifications :.

You could also filter out the notifications directly inside the promise returned from getNotifications. For example, there might be some custom data attached to the notification that you could use as your filter-criteria. Window management on the web can often be difficult. Think about when you would want to open a new window, or just navigate to the current open tab.

When the user clicks on the notification, you can get a list of all the open clients. You can decide which one to reuse. The code above looks for the first window with visibilityState set to visible. If one is found it navigates that client to the correct URL and focuses the window.

If a window that suits our needs is not found, it opens a new window. So far, we've been assuming the user is around to see our notifications. But consider the following scenario:. That scenario is a poor experience for the user. The notification is neither timely or relevant.

Our site shouldn't display the notification because it's out of date. The value of this parameter must be a duration from 0 to 2,, seconds, corresponding to the maximum period of time for which FCM stores and tries to deliver the message. Requests that don't contain this field default to the maximum period of 4 weeks.

If the message is not sent within the TTL, it is not delivered. In other words, FCM guarantees best effort for messages that must be delivered "now or never". However, because such messages are never stored, this provides the best latency for sending notifications. What should you do if the user can get the same notification in multiple places, such as in a chat app?

We don't want to display redundant notifications that have been removed elsewhere, but you currently have to display a notification to the user.

Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4. For details, see the Google Developers Site Policies. I use the same code for updating a notification layout which contains two ProgressBars and four TextViews with a frequency of msms.

Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Asked 10 years, 3 months ago. Active 3 years, 8 months ago. Viewed 14k times. Splitusa Splitusa 1, 7 7 gold badges 31 31 silver badges 51 51 bronze badges. Add a comment. Active Oldest Votes. Yep, you're publishing too many notifications. Sounds good. Would you happen to have some sample code or just an idea of how I can implement it?

Well, just add an int variable and before publishProgress, e. Show 1 more comment. Builder context ; mBuilder. Lalit Umbarkar Lalit Umbarkar 7 7 silver badges 13 13 bronze badges. MartinPfeffer Thanks. Edited accordingly. Sakiboy Sakiboy 6, 7 7 gold badges 49 49 silver badges 63 63 bronze badges.

Still, this is not enough if the download servers are too fast. VSG24, huh? It's not the "too fast" servers fault, it's probably your code, to be honest. I hope this answer will be helpful for other newbies like me. For fast downloads. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown.

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