Python: Google App Engine , JavaScript Channel API to call back end

Question

Hi I am quite new to java script and i am looking a working example to call back ends using java script channel API . I do not have any idea about channel API . Can anyone provide me a working example

Sorry, I voted to close this before I saw the reference to backends. My apologies. — Drew Sears
– Drew Sears, Commented Nov 28, 2011 at 17:51

Moishe Lettvin · Accepted Answer · 2011-11-28 14:57:24Z

3

If you're asking how to get a message from the backend to a javascript client: you can't send messages from a backend server to a channel created on a frontend server. This is because the app version number is included in the channel token, and backends have a different app version than frontends. You could, however, implement a servlet in your backend that calls createChannel and returns it to your frontend for inclusion in javascript that your frontend renders.

If you're trying to send a message to a backend from your javascript code, you won't be able to use XmlHttpRequest directly because of the same-origin policy (this assumes your clients are rendered from a non-backend instance). You could get around this using JSONP, or by routing XHR requests from your frontend to your backend in a frontend servlet.

answered Nov 28, 2011 at 14:57

Moishe Lettvin

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2 Comments

Kalanamith Over a year ago

I have a back end handler which fetch URLs . I am looking a way to call it via an ajax Handler. That is my goal

Kalanamith Over a year ago

and i am looking for a python example

pradeek · Accepted Answer · 2011-11-28 08:11:56Z

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Did you see the docs? Java / Python

answered Nov 28, 2011 at 8:11

pradeek

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3 Comments

Kalanamith Over a year ago

Im Using python not java . it didnt specify anything about backend urls though used URL;s

pradeek Over a year ago

See this : netgamix.wordpress.com/2011/02/15/…

hiroshi Over a year ago

@pradeek the site you mentioned is "a protected blog" and I don't want to login to wordpress.

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