JSON requests for local apps

[Ali-Khatami]

I added a few properties (with proper comment documentation) and modified the registerApps method to allow a container developer to specify whether or not they would like to load "local" apps (apps hosted on the same domain as the container) through JSON vs JSONp through the use of allowLocalDomainJSON=true. There is also the ability to specify what the domain check will use via localDomain.

Modifying localDomain allows a developer to do something as follows:

Container URL: https://sub.greatdomain.co.jp
APP URL: https://f2app.greatdomain.co.jp

F2.init({ allowLocalDomainJSON: true, localDomain: "greatdomain.co.jp" });

Container URL: https://sub.greatdomain.com
APP URL: https://f2app.greatdomain.com

F2.init({ allowLocalDomainJSON: true, localDomain: "greatdomain.com" });
....

• Modified/Added logic in F2.registerApps to read containerConfig properties allowLocalDomainJSON and localDomain to determine whether to request an app via JSON or JSONp

[ilinkuo]

Uh, is this really necessary to expose as an option? Why not make the loader smarter -- try a local app as JSONP and if that fails, try as JSON, and if that works, set a field in the appConfig to use JSON.

But I don't really see what this "feature" gains except possibly faster prototyping. All f2 apps really need to be able to respond to JSONP in order to work on other domains.. Making them also respond to JSON would usually be an additional burden. Now, if you only want apps to work on your own domain, then that's a legitimate use of this feature, but in that case, it's a property of the app rather than the container, and should be in the app manifest rather than in the app config.

[markhealey]

This definitely has implications for the F2 spec because this means the AppManifest takes on 2 forms—with and without the JSONP function wrapper.

Separately, jQuery used to have logic in the $.ajax function to automatically switch to json from jsonp if the request URL was on the same base domain—I think it's still there. Long/short is, if we add this support, I think the internal loader should make the on-the-fly switch to json using POST.

More details here:
http://forum.jquery.com/topic/make-json-vs-jsonp-request-depending-on-url

[Ali-Khatami]

If all developers want to support multiple formats great, the intention of the allowLocalDomainJSON parameter was to not force developers to support JSON and JSONp. Also it should be noted that the container developer is the one in control of these parameters and also controls the local apps, which means it should be their decision whether or not they want to use JSON, not F2s decision.

At the very least you would need to provide the localDomain parameter if you want F2 to be smart enough to check the domain and determine or you will run into issues with apps on a different sub domain than the container.

I should also add that developers who host apps or containers that request apps, or are requested, across continents would probably not be in favor of F2 attempting the transmission of json then going to jsonp after (every second/millisecond counts).

Those are my justifications for adding the functionality that I did. I am certainly open to more discussion on this.

@markhealey - I haven't seen any evidence of jQuery making the switch automatically from json to jsonp. I'm sure we could through together some test cases though.

[brianbaker]

@markhealey, @Ali-Khatami - jQuery will perform an XHR request when the protocol/host/port matches instead of doing a jsonp request. This can be seen in Chrome if you download the basic app template (http://docs.openf2.org/app-development.html#get-started). Here's the source code for it: https://github.com/jquery/jquery/blob/master/src/ajax.js#L442 The 'jsonp' transport delgates off to the 'script' transport, and the 'script' transport only applies to cross domain requests (https://github.com/jquery/jquery/blob/master/src/ajax/jsonp.js#L78 https://github.com/jquery/jquery/blob/master/src/ajax/script.js#L30)

[markhealey]

Nice sleuthing. So, @brianbaker, is the only thing we're missing here the lack of POST support?

[markhealey]

@Ali-Khatami, would this commit 28053bc work for your needs?

https://github.com/OpenF2/F2/blob/issue41/sdk/src/container.js#L550

Basically, I added a check on the manifestUrl defined in the AppConfig to see if it's "local" or not. If the manifest URL is local, the $.ajax.type is set to POST during F2.registerApps().

(Since I added 3 new private methods, I also updated the SDK docs in the issue41 branch.)

[markhealey]

Also, my test case was:

• Download the basic app template
• Replace the _appConfigs variable in index.html with this one.

[Ali-Khatami]

Closing this based on Mark's test cases.

[markhealey]

Wait, so you undid my changes in my proposed commit? Or not…?

[Ali-Khatami]

I probably shouldn't have closed this issue seeing as how you have changes to change local requests to POST. I just deleted this pull request because I deleted the repo a while ago. Sorry about the confusion. Let me know how you want to proceed.

[markhealey]

Opened #59 to track this enhancement.