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From John Weachock <>
Subject Re: PGA Cache and AJAX/PHP
Date Thu, 18 Jun 2015 12:45:43 GMT
Ahh, yes that makes a lot more sense because the caches seemed very
selective. Thank you!
On Jun 18, 2015 7:08 AM, "Supun Nakandala" <>

> Hi,
> Now you can disable app-catalog data caching in the pga-config.php
> Thanks
> On Thu, Jun 18, 2015 at 4:31 PM, Supun Nakandala <
>> wrote:
>> Hi,
>> In PGA pages are not cached. Only ComputerResource and
>> ApplicationInterface entities are cached. I decided to cache those data in
>> order to improve the performance PGA. When we retrieve experiment data we
>> get only the resource host id and application id s. We don't get the names
>> of them which are required in the UI. So this ends up creating multiple API
>> calls to back end to resolve the names. This becomes problematic in showing
>> search and browse results as it takes a long time.
>> Currently it is not possible to disable caching but you can reduce the
>> cache invalidation time in pga_config.php.  I will change the code such
>> that it is possible to disable caching.
>> Sorry if this caused you trouble
>> Supun
>> On Thu, Jun 18, 2015 at 1:01 PM, John Weachock <>
>> wrote:
>>> I was running into a lot of issues recently with the PGA returning
>>> cached copies of pages. Is there any way to disable the cache for
>>> development or shorten the time-to-live for cached pages?
>>> Thanks!
>>> On Jun 17, 2015 3:19 PM, "Douglas Chau" <> wrote:
>>>> Hello Devs,
>>>> Nothing that requires immediate attention, but I thought I would
>>>> document some of my hurdles while working on adding a feature to the PGA
>>>> case anyone else encounters similar issues. So there are two takeaways: be
>>>> wary of PGA caching results, and be careful of boolean variables passed
>>>> through AJAX being treated as strings in PHP.
>>>> I was working on the admin interface that allows a gateway admin to
>>>> turn on/off the visibility of a resource to regular users. The page before
>>>> was only a dummy page with a bunch of buttons for each resource. I added
>>>> some AJAX functionality to the current buttons so that when one is switched
>>>> on/off a call is made to a PHP controller method that resides in
>>>> AdminController.php; that call then invokes a utility function within
>>>> CRUtilities.php which does the actual calling to the the Airavata API to
>>>> update the compute resource description with the new boolean value that
>>>> reflects the button's on/off state. So basically, the button just updates
>>>> boolean field in the compute resource description. Sounds simple enough.
>>>> To make sure everything was working, I wrote some sanity checks to
>>>> print the before and after states of the compute resource description to
>>>> the browser (using javascript's console.log() function). For the record,
>>>> used the *CRUtilities::register_or_update_compute_resource *method to
>>>> do the actual updating of the compute resource and then the
>>>> *CRUtilities::get_compute_resource* method to check the results. So
>>>> strangely and surely, when I got the results back and printed them to the
>>>> screen, the changes were not reflected; the compute resource object’s
>>>> fields were completely unchanged. But, the even stranger thing was that
>>>> after periods of time, the object fields would change. Huh?... This lead
>>>> on a wild goose chase to see if there was something I forgot in the
>>>> airavata backend code, or if there was some composer command I forgot to
>>>> call, and so on. I looked through the CRUtilities code more carefully and
>>>> found that the *CRUtilities::**register_or_update_compute_resource* method
>>>> actually returns the compute resource when it succeeds. I tried printing
>>>> this return value to the screen and discovered that the changes were
>>>> happily reflected in these results but still not in the results of the
>>>> other *CRUtilities::get_compute_resource *method. Why? With some more
>>>> stumbling around, I discovered that the
>>>> *CRUtilities::register_or_update_compute_resource* method actually
>>>> gets it’s resulting resource description by calling the
>>>> *Airavata::getComputeResource* method and not the getter method
>>>> already provided in CRUtilities; so the succeeding results actually come
>>>> directly from the airavata backend. And finally, after looking carefully
>>>> the *CRUtilities::get_compute_resource* method, I found that this
>>>> method actually returns a cached version of the resource if available,
>>>> which explains why none of the changes were immediately reflected but did
>>>> after a period of time.
>>>> If you did not follow all that, the takeaway is,
>>>> *CRUtilities::get_compute_resource* returns a cached version of the
>>>> resource, so if you ever make an update and are trying to check the results
>>>> to see if they have changed, use the return value of the
>>>> *CRUtilities::**register_or_update_compute_resource *instead; the
>>>> results of *CRUtilities::get_compute_resource* will deceive you into
>>>> thinking the change did not go through. I guess that makes sense, but may
>>>> not be so apparent to newcomers to the PGA code.
>>>> Also, if any of you ever try passing boolean values from AJAX to PHP,
>>>> when PHP get’s the POST/GET results, it will take your original boolean
>>>> types and covert them to strings. So if you passed in boolean true, PHP
>>>> will get it as string “true”. And of course, if you are eventually setting
>>>> a boolean field to the string “true”, PHP always evaluates a string to
>>>> boolean true unless it is something that is considered empty by PHP (i.e.
>>>> “” or “0”). So if you need to do this, make sure the values are converted
>>>> back to boolean. See these links for more detail:
>>>> I hope this was all somewhat clear. And at the least, I hope this helps
>>>> anyone who may eventually work on the PGA code.
>>>> Thanks,
>>>> Doug
>> --
>> Thank you
>> Supun Nakandala
>> Dept. Computer Science and Engineering
>> University of Moratuwa
> --
> Thank you
> Supun Nakandala
> Dept. Computer Science and Engineering
> University of Moratuwa

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