Worklight and Cloudant Integration
Daniel González 270007DFU9 Comments (2) Visits (6975)
Worklight and JSONStore
IBM Worklight is a framework that enables developers to build hybrid and native mobile applications for many prevalent environments, such as Google's Android and Apple's iOS mobile operating systems. Part of the value of using this framework is having powerful APIs for solving key problems across the board.
For example, one common problem many developers face while crafting their mobile experience is securely managing data for offline use between their clients and the server. One of the APIs provided by this powerful framework to aid in such a scenario is called JSONStore. It provides an easy to use API, industry standard AES 256 bit data encryption, indexing of key fields for fast look up times, works with JSON formatted data and provides support for hybrid (Android, iOS, Windows Phone 8 and Windows 8) and native (Android and iOS) environments.
There is a great deal of information available to get started with these technologies. Some areas worth looking into before you continue reading:
Going back a couple of years you would see many companies investing heavily in their on premise infrastructure. These entities had to buy many servers based on estimates of how much traffic they expected to receive. They also had to contract system administrators to manage these servers, while ensuring an acceptable level of performance, security and scalability. Furthermore, typically you would need expensive software on top of that.
Fast forward to today and many companies are taking an entirely different approach to their infrastructure. These entities are preferring to pay others to manage key parts of their infrastructure (e.g. databases) so they can spend most of their capital on their core business (e.g. making their product better).
IBM has been investing heavily in simplifying tasks so companies can focus on what's really important to their bottom line, while at the same time reducing costs. It's easy to spot this trend when looking at recent acquisitions.
Cloudant is one of those companies recently brought into the IBM family. It's a NoSQL managed database that scales vertically across many servers located in various locations across the globe. It's powered by the open source database called Apache CouchDB. Many of the core Cloudant developers are active contributors to the open source project.
There's a plethora of information available to help you get started with this revolutionary Cloud as a Service solution:
Goal and scope
The goal of this article is to show how one could work with both Cloudant on the backend and Worklight's JSONStore API on the client. There are many ways of keeping data on the backend (e.g. MySQL, MongoDB). There are also many ways of keeping data on the client (e.g. HTML5 LocalStorage, SQLite). The article presumes the reader has evaluated the various alternatives and has picked Cloudant and JSONStore. There are many reasons why developers would pick those two technologies, for example, a key feature of Cloudant is scalability and an important feature of JSONStore is security.
It's also imperative to mention that every application is different. You may have to tweak some of what you learn here in order to meet your requirements. Most of the content aims to be very generic and many not apply to all situations.
Let's imagine we're creating an application for a list of contacts. The data would look like the following in table form:
and like the following in JSON form:
You must go to cloudant.com and create an account. After you have done that, login to your account and go to the control panel (
Next you need to add a database, call it
If you don't want to bother with security while learning, you may go into the people database and modify the permissions to allow
You may also add some data via the
If you don't have one already, you must create a Worklight Project and a Hybrid Application. After you've done that you may add environments such as: Android, iOS, Windows Phone 8 and Windows 8. Since JSONStore is an optional feature make sure you enable it as shown in the documentation.
You will be using the JSONStore initialization API to create two collections. You can think of collections as different tables inside a database.
The first collection will store the data we care about, let's call it the
The values for
The second collection will keep track of the last time we have successfully communicated with the backed, let's call it
The value for
You may want to take advantage of the Adapters as listed in the Server-side portion of the IBM Worklight Getting Started Modules in order to communicate with the backend. Alternatively, you could contact the Cloudant API directly using an XMLHttpRequest API like dojo.xhr and jQuery.ajax. There are many advantages to using Adapters which are mentioned in the documentation. One key advantage is security; for example, you can keep authentication data and tokens inside the context of the adapter in the server, and protect the adapter with security tests.
You need a way of applying changes made on the backend. We call this operation pull, but there's no single API for this. You use a couple of different APIs to achieve this with maximum flexibility. The first part of the algorithm is to ensure that the collections affected by the operation have been initialized.
After the collections have been properly initialized we can begin to load changes. One approach is to contact the
After we get the changes, need to either perform an update using JSONStore's
After all the changes have been handled, the
It's worth mentioning that you may want to follow a slightly different approach here based on your application's requirements. For example, you may want to use views to get only a portion of the data. Also, you may not want to get the documents directly from the
It is assumed that all local-only changes have been sent to the server before the pull algorithm explained above is executed. An algorithm to send all local-only changes to the backend is described below.
Documents with local only changes are called dirty documents when using the JSONStore API. When you perform operations such as
The first thing we must do is make sure that the collections being used are initialized. After that we can call JSONStore's
Note that we have all the data for the document in the value for the
Based on the value of the
If the document was added on the client, we simply call the Cloudant API to add the document on the server too. The API uses the POST HTTP verb and takes the data representing the document in the body of the request. We get back an
If the document was removed on the client, we simply call the Cloudant API to add the document on the server too if the document exists on the server (that is, it has an identification number (
The dirty document is then passed to JSONStore's
If the document was replaced locally but does not contain an identification number (
During the course of this post we have talked about Worklight and pointed to valuable resources for learning the framework. We also introduced Cloudant, shared learning resources and created a new database using their web based control panel. We also talked through possible algorithms developers can use to keep data on the client, while receiving and sending changes to a Cloudant database.