Office web apps are now getting more and more popular with the SharePoint 2013 environment. In native SharePoint environment when you click on a document it will open in a office online (OWA) based on configuration.
But it you a writing a SharePoint Hosted app or a Provider Hosted app; you might wonder how to open it in office web apps and what is the URL you are going to use it.
You can use JSOM and SharePoint REST services to archive this.
Frist you need to send a REST request by mentioning file name.
You should carefully give the sever relative file name for this operation. regardless of app type (Provider hosted or a SharePoint Hosted ) file name it coming with app web url
Absolute File Url
Relative File Url
Depending on the App type either you need to use the RequestExecutor or normal rest approach.
Using RequestExecutor in Provider Hosted Apps
if the LinkingUrl available it indicates it can be open via office web apps. LinkingUrl some times returns direct web app url ; thus you don’t need to create the Url by amending items but some times it returns absolute document Url. mentioned approach will be suits for both occasions.