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July, 2013

We just published an Android sample application to Google Play. The application demonstrates the usage of various Backendless APIs for some real-world use-case you may be implementing in your app. The application allows anyone to take a picture or use one from the gallery, upload it to the server and associate the picture with a point on the map (tag). Users can browse uploaded pictures by moving/zooming the map. For any picture/tag you can see a list of comments and submit your own comment as well. The application source code specifically demonstrates how to handle the following use-cases:

  • User registration and login
  • User login with Facebook or Twitter accounts
  • Retrieving a list of geo points and plotting them on the map
  • Taking a picture with the device’s camera
  • Selecting a picture from the device’s gallery
  • Uploading/Downloading images to/from Backendless
  • Establishing relational mapping between uploaded images and submitted comments
  • Using Data Service to submit and load user comments

You can find the app in Google Play if you search for “Endless Tagging” or simply follow the link below:
https://play.google.com/store/apps/details?id=com.backendless.examples.endless.tagging

The source code of the application is available in our GitHub repository:
https://github.com/Backendless/EndlessTagging-Android

Posted in Android, Examples

In this blog post we review the process of setting up and developing an iOS application capable to receive Apple Push Notifications. We also review the functionality of publishing a push notification through Backendless.

Creating App ID

  1. First we are going to create an App ID for the application which will receive Push Notifications. Login to Apple Developer Member Center. Click on “App IDs” in the “Identifiers” section. Use the plus sign “+” button to create a new ID:
  2. When prompted enter App ID Prefix. Make sure it is descriptive enough so you recognize it later when you return to the Member Center.
  3. Select Explicit App ID in the “App ID Suffix” section and enter the same bundle ID which you will be using in the application:
  4. In App Services select the services which the application will use and click “continue”:
  5. Make sure that Push Notifications are enabled and click “submit”. This will conclude the App ID creation for the app:

Creating Certificate Request

Push Notifications require a certificate which will be used on a device by the means of a provisioning profile. Also the same certificate (transformed to the Personal Information Exchange – .p12 format) will be used by Backendless to publish Push Notifications. If this makes little sense, do not worry, you will need to perform these steps only ones and then can move on to code and using the APIs.

  1. In order to create a certificate a Certificate Signing Request (CSR) must be issued. To create a CSR, open Keychain Access and select Keychain Access >> Certificate Assistant >> Request a Certificate from the main menu:
  2. Enter your email address and Common Name (leave the CA Email Address field empty), select “Saved to disk” and click “Continue”:
  3. Select a directory where to save the file and click Save.

Generating an SSL Certificate for Push Notifications

The CSR file created in the section above will be used to create an SSL Certificate. That certificate will then be used by Backendless to publish push notifications.

  1. Return to Apple Developer Member Center and select “All” under “Certificates”. Click the plus button “+” to add a new certificate:
  2. Select certificate type – there are two options Development and Production. For now select “Apple Push Notification service SSL (Sandbox)”:
  3. Select the App ID created earlier in these instructions:
  4. Next you will see the instructions for generating a CSR which you have already created by now. Click Continue to proceed to the next step.
  5. Select the CSR file created and saved to the disk earlier and click Generate:
  6. The certificate is ready now, click “Download” to download it:
  7. Add the certificate file to Keychain Access.
  8. Open Keychain Access and locate the certificate in the “My Certificates” section:
  9. Right click on the certificate and select the Export option:
  10. Save the certificate in the p12 format:
  11. Enter a password for the certificate. Make sure to make a record of the password – you will need to use it later in the instructions when you submit the certificate to Backendless:
  12. Enter your Mac OS X account password to confirm the action. At this point you have a certificate for Push Notifications.

Configuring Backendless App with the Certificate

Since Backendless provides the actual server-side integration for delivering Push Notifications for your application, it needs to have access to the certificate you created above. The steps below provide the instructions for uploading the certificate into Backendless:

  1. Login to Backendless Console at: https://backendless.com/develop and create/select an application which you will use on the server-side:

  2. Click Manage > App Settings. Locate the Mobile Settings section and upload the .p12 certificate created earlier. Make sure to enter the same password you used when created the certificate:

  3. Now your Backendless server is ready to publish Push Notifications.

Creating Provisioning Profile

  1. Login to Apple Developer Member Center and select “All” under Provisioning Profiles. Click the plus button “+” to create a new profile:
  2. Select the “iOS App Development” profile type:
  3. Click Continue. On the next screen select the App ID which was created earlier:
  4.  Click Continue. Select the users/certificates which will be included into the profile.
  5. Click Continue. Select the devices to include into the profile.
  6. Click Continue. Enter a name to assign to the profile and click Generate:
  7. Download the profile:
  8. Start XCode and open Organizer. Select the Provisioning Profiles section and add the profile you generated/downloaded:

Creating App in XCode

Finally all the setup is done and we can proceed to the fun part – creating an app in XCode and writing some code.

  1. Open XCode and create new “Single View Application”.
  2. Enter “pushNotificationSample” as the Product Name. Also provide your organization name and company identifier. Since the bundle ID we used when creating App ID earlier was “com.backendless.pushNotificationSample”, you should use “com.backendless” as the “Company Identifier”:
  3. Once the application is created, open Targets > Build Settings > Code Signing > Code Signing Identity and select the provisioning profile created earlier:



  4. At this point you should add Backendless SDK to your project. This includes adding Backendless library and its dependencies. Additionally, you will need to copy/paste Backendless Application ID and Secret Key into the code. For detailed instructions on how to do that, please follow the Backendless Quick Start Guide for iOS.
  5. Open AppDeletage.m. The following code registers the device with Backendless and Apple Push Notification Service:

    If the registration goes through, the following method is automatically called with the device token passed as the argument:

    Otherwise, if the registration fails, the following method is called with the argument of the underlying error:

    In case of the successful registration, the device is ready to accept published Push Notifications. When a notification is delivered to a device, the following method is invoked when the app is running.
  6. In order to send a Push Notification from a device, use the following code:

Publishing Push Notifications from Backendless Console

  1. Open Backendless Console at https://backendless.com/develop and select the Messaging section.
  2. Enter the text of the notification message in the “Message text” area, also make sure to specify the headers:
    1. “ios-badge”:”X”, where X is the number for the badge update
    2. “ios-alert”:”alert message text”
    3. “ios-sound”:”URL of the sound file”For a list of all supported headers, see the Publish Push Notification section in the documentation.
  3. Click the “iOS Devices” checkbox.
  4. Click Publish. The Push Notification will be delivered to all registered iOS devices:
  5. To see a list of the registered devices use the Devices tab. You can also send a push notification to specific devices. In order to do that, select the devices using the checkboxes and then click the “Selected devices” option under “Push Notification” section:

Blocks are a powerful C-language feature that is part of Cocoa application development. They are similar to “closures” and “lambdas” you may find in scripting and programming languages such as Ruby, Python, and Lisp. For a more in-depth review of blocks, see “a short practical guide to blocks”. A Backendless user has recently asked us about the ability to handle asynchronous APIs via block-based callbacks. Since this is a very reasonable request, we added support for blocks and it is available in the latest version of the Backendless SDK for iOS. Below is an example of using the new feature with the user registration and login APIs (btw, the feature is available for ALL Backendless APIs):

By the way, here is an example of code that does the same thing, but synchronously:

The example below demonstrates the usage of block callbacks with the Data Service API in order to:

  • Persist a complex type (an instance of class Weather)
  • Find an object by ID
  • Finding first and last instances
  • Deleting an object by its objectId

If you prefer to use the synchronous (blocking) API, the follow code does the same thing as the example above (but synchronously):

Enjoy!

Posted in Examples, iOS

Differentiating user behavior in an application by roles is a very common practice. Indeed, as long as you have different workflows in the application, it is likely each workflow would be associated with a specific user role. Take for an instance a mobile application to reserve a taxi. One of the user types (roles) is a client making a reservation, another one is a taxi driver for whom the reservation is dispatched to. Users in either role will have a separate login form, they will access the same data (reservation), but will see different aspects of it. Another example may be an application coordinating appointments with a gym’s private trainer. One user role in such an app is going to be the trainees coming to the gym for the workouts and another one are the trainers with whom people make appointments. In these apps users in different roles are likely to have different entry points into the application (different login forms) as well as different access level to the applications’ data.

Backendless simplifies roles-based access to data through a flexible permission system. Each role may have its own set of permissions either granting or denying access to various Backendless resources like data tables, messaging channels or media streams. The API provides a way to associate a user with a particular role. Once a user is linked to a role, any restrictions that the role has will automatically apply to the API operations made in the user’s session.

The example reviewed in this post demonstrates the roles-based data access concept. The example is an Android application. It defines two Backendless roles – ReadOnlyRole and ReadWriteRole. The first role has the read-only access to data, the second one has unlimited permissions. There are also two login forms – when a user logs in using the first form, his account is associated with the ReadOnlyRole. When the user logs in using the second form, the account is associated with ReadWriteRole. Once the user logs in, they see a screen where they can see and enter to-do tasks. Users who log in with the ReadOnlyRole will not be able to enter new tasks, while the other ones can create new to-do items. Please follow the instructions below to configure and run the example. The complete source code of the example is available in the Backendless GitHub account.

  1. Open Backendless Console to create a new application or select an existing one.
  2. Click the “Users” icons in the vertical menu on the left and select the “User Properties” section to adjust the properties. In this application we will use the “name” property as the identity:
  3. The next step is to define the roles for the application. To do that click the “Security & Restrictions” section. You should see a list of the built-in user roles available in the application. Click the “Add Role” button to add two user-defines roles: ReadOnlyRole and ReadWriteRole.

  4. Now create a data table for which we will adjust the role permissions. Go to the Data section and create the ‘Task’ table:
  5. Adjust the table schema by adding the ‘message’ column.
  6. At this point we have two custom user-defined roles and a data table. Now we need to modify the permissions policy between the roles and the data table. To do so, make sure you are in the “Schema and Permissions” screen (Data section). Click the ‘Roles Permissions’ link at the table ‘Schema and Permissions’ view. Override the default permission values so they look as shown in the screenshot below:
  7. Now that the server side is configured, all we need is to copy the application ID and the secret key into the applications’s source code (the values must be pasted into Defaults.java):
  8. Run the app. Use any arbitrary username and password – the app will automatically register the user if an account cannot be found. This is done to simplify the app and show the core of what we wanted to demonstrate without added complexity.
    1. Login to the READWRITEROLE form.
    2. Add a few todo tasks.
    3. Switch to the READROLE form and login there.
    4. You should see a list of tasks created in step B.
    5. Try adding a new tasks – you should see a toast notification informing about the error.

We start a new blog series called “Highlight Reel”. Today Backendless highlight reel comes to you from Irving, Texas. We have a chance to chat with EtherGloo founder Durga Dash about app development and his mobile application “SwarmLocal”.

Thanks for taking the time to chat with us, Durga. So, where are you located?

Irving, Texas

Good to be in neighborhood. Please tell us a little about yourself and your background. What were you doing before?

I did my Masters from Ohio State University in Electrical Engg. Also hold down a full-time job at a software company managing the network infrastructure for their datacenter.

Tell us about the app you have running on Backendless.

SwarmLocal was envisioned during the 2011 Occupy Wall Street protests and then the Arab Spring movements. The goal was to create a service that could leverage the power of the anonymous collective in close proximity by allowing real time communication. Inspired by the behavior of bees in a swarm and hence the name SwarmLocal. To that end the ‘swarms’ in SwarmLocal are mobile and the users anonymous. The app is free and available at AppStore and Google Play.

Cool idea. How long have you been developing apps? Is it your first app?

I have been developing apps for about 5 years. My first two apps were for Windows Mobile. Contraction Timer and BugPhone.

What was the biggest challenge in development?

One of the big challenges in development was being able to broadcast real time audio and video from mobile devices and having a backend that can scale to support it. There are not too many solutions out there currently.

      

Please take us through the process of decision making and options for your applications’ backend.

As far as being able to support broadcasting real time audio and video there not many existing services out there. Especially ones that integrate with native code on the different end user devices.

How did you come across Backendless BaaS platform?

I was attending a mobile developers meetup in Dallas and one of the presenters was Mark Piller. He did a presentation on Backendless backend as a service. I was at that time looking for a solution that would do the heavy lifting on the backend and let me focus on the user front end, so Backendless seemed like a perfect fit for my needs.

What Backendless features do you use in your application?

Currently we use the media services API to broadcast real-time audio and video from iOS devices.

What do you like the most in Backendless as a Backend as a Service platform?

  • Easy and elegant administration panel;
  • Well documented API’s and examples;
  • I was able to reach out to Backendless support and even make feature requests which were added pretty quickly;
  • At the end of the day it is very simple to use. And I like to use tools that make it really simple and do the heavy stuff behind the scenes.

Which issues do you expect to be covered by Backendless for you in the future?

From my perspective, I would like to see the Media Services API extended to more platforms and not just iOS. Also the ability to manipulate live streams to add/insert custom content from the admin panel.

What are your plans for the future?

  • Allow live streaming across multiple mobile platforms.
  • Give users the ability to encrypt their messages.
  • Spread out to other platforms, beyond iOS and Android.

What do you do when you aren’t busy working? Any favorite hobbies?

I have a three year old daughter who is a time sink. Other than that working on SwarmLocal and my new passion for boxing.

Do you have any advice for people who create their first apps?

I did write a blog that I hope will help other indie developers on their journey to writing their first app. It can be found here.

Well, best wishes, Durga. We appreciate sharing your thoughts with us.

P.S. If you have a production app running on Backendless, please drop us a line at community@backendless.com. We will be glad to present you in our highlight reel.

A quick heads-up for everyone – we just opened up a discussion forum available at: https://backendless.com/product/forum/.

The rule of thumb is to use the Community Support site for bug reports, feature and improvement suggestions and the use the forum for all other conversations.

 

Posted in Status