It is common knowledge that it is possible to use web applications only if a connection to the Internet exists. The limitation is that one cannot browse documents, or check e-mail or use other web applications when offline. It is also a fact that heavy web applications have stretched the web browser capacity beyond its limits and created a compelling need for a new space on the desktop.
Need for Offline Web Applications
The need for offline access and bringing web applications to the desktop for local storage and data access when disconnected, has been engaging the attention of many computer professionals for quite a few years.
Despite WiFi and availability of high-speed broadband network, computer users are not always connected to the critical online applications and data – particularly when traveling or commuting to workplace or otherwise engaged. The provision for offline access will lend additional dependability and extended reach to web applications.
A web application with offline access capabilities will definitely mean faster and improved performance even when disconnected from the Internet. Offline web applications means two essential parts – cloud synchronization and local storage capability. In the foreseeable future, the market will be agog with many new offline products and tool kits for almost every type of developer.
Offline Web Applications – Data and Server Specification
Most Web applications need to interact with a server. It is therefore the job of the application developer to ascertain the offline status using the available APIs. An offline user must see the exact functionality of the web application while offline, though the browser is interacting with a small local server instead of the datacenter.
The HTML 5 specification offers two–way proposal for offline web applications - a SQL-based data based API for purposes of local storage of data and an offline application HTTP cache to facilitate application availability even when the user is disconnected to the network.
SQL database in HTML 5 is capable of storage of structured data - thus enabling storing e-mails locally and a cart in a shopping site. The striking feature is the interacting API with this database is asynchronous and therefore there is no locking up of user interface.
HTTP Cache Mechanism in offline web applications
An offline application HTTP cache mechanism ensures availability of Web applications even when the user ceases to be connected to the network. It is interesting to know that the application cache mechanism also enables to cache from the server a group of files matching a common prefix and also for scripts to dynamically add and remove entries from the cache.
Apart from these APIs, HTML 5 also defines an online attribute on the Navigator object to enable the user determine whether online at any given time.
The facility to place frequently accessed data on a user's local machine will mean increased productivity, meaningful performance gains and enlarged application capabilities. It is evident that just as a network proxy might cache frequently accessed web pages, the local web application proxy will be ready with all critical data on the local machine.
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