Communication between two renderers?

[sdiverdi]

My app has two browsers, and each browser has its renderer helper subprocess. I'd like to send a message directly from one renderer to the other. I know I can use SendProcessMessage to go from renderer->browser and then browser->renderer. Is there some way I could use SendProcessMessage (or something else) to go renderer->renderer instead?

[magreenblatt]

Communicating directly between renderers is not allowed for security reasons.

[sdiverdi]

Can you elaborate? I don't understand what the security implications are. Is it more secure to go renderer->browser->renderer?

[magreenblatt]

Renderer processes are sandboxed and have access to minimal information, access to which is controlled by the browser process. Different renderers are often different origins. Allowing a renderer for one origin to access data specific to another origin would be a security issue, particularly if one of the renderer processes was compromised.