HTML5 Web Messaging
What is Web Messaging?
- Web messaging is an API which was introduced in WHATWG HTML5 draft specification.
- It allows the documents to communicate with one another across the different origins or the source domains.
Attributes
| Attributes | Description |
|---|
| data | It contains the string data. |
| origin | It contains the domain name and the port. |
| lastEventId | It contains a unique identifier for the current message event. |
| source | It contains a reference of the original document window. |
| ports | It contains the data that is sent by any message port. |
Cross-document message
A new web browsing context is required to be created before a cross-document message is sent by creating a new iframe or window.
Data is sent by using postMessage() which has two arguments as follows:
message – the message that is required to be sent.
targetOrigin – the name of the origin.
Channel messaging
Channel messaging is a two way communication between the browsing context. They are used for communication across multiple origins.
MessageChannel and MessagePort Objects
There are two ports which are created internally while a messageChannel is created. The two ports are used to send data and forward it to another browsing context.
postMessage() - the throw channel posts the message.
start() - the data is sent.
close() -the ports are closed.
