Canvas Developer Guide

Getting Started
Using Force.com Canvas
Canvas SDK
Referencing the Canvas SDK
Authentication
Getting Context in Your Canvas App
Cross-Domain XHR
Getting a List of Chatter Users
Posting to a Chatter Feed
Resizing a Canvas App
Implementing Canvas App Events
Using Streaming API in a Canvas App
Debugging in a Canvas App
Using the <select> Tag in a Canvas App
Canvas Apps and Visualforce Pages
Canvas Apps in a Page Layout or a Mobile Card
Canvas Apps in the Publisher
Canvas Apps in the Chatter Feed
Canvas in the Salesforce App
Customizing Your App Lifecycle
Reference
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Cross-Domain XHR

Canvas apps are loaded on a Salesforce page in an iFrame. Therefore, the canvas app (in its own domain) can’t make XHR (XML HTTP request) calls back to the *.salesforce.com domain. You can develop and deploy your own proxies as part of the SDK, however, Canvas provides a client-side proxy written in JavaScript. This proxy enables client-side XHR calls back to Salesforce.

If you use this proxy from the client to make an XHR request, the API forwards the request to the outer iFrame and the request is submitted on your behalf. When the request is complete, the SDK calls the client’s callback function with the results. Here are some examples of how you can make XHR calls:

The SDK supports cross-domain XHR calls, however, it shouldn’t be used to make same-domain calls.

Note