Hi Rene, I will be a bit later today as the family and I are going out now. I will contact you when I return - likely around 2:00 my time (+/-)
Thanks! Jason On Aug 3, 2014 9:27 AM, <[email protected]> wrote: > Thank you Jason. I registered on Skype (rene.heymans). > You can try around noon your time (6PM mine). > Till then. > Regards, René > > On Saturday, August 2, 2014 9:16:29 PM UTC+2, Jason Garber wrote: >> >> We can do a gotomeeting. Perhaps around lunchtime eastern on Sunday? >> On Aug 2, 2014 2:08 PM, <[email protected]> wrote: >> >>> Hello Jason, >>> >>> Thank you very much for your kind and swift offer. I'll do it gladly ... >>> but I need to set-up Skype on my station :-( and register a Skype account. >>> I'm an old-timer and my only contact is Gmail. I have no G+, no >>> Facebook, no Twitter, ... >>> >>> What is your preferred day and time for a Skype call. >>> I live in the Paris-Luxembourg-Brussels time zone. For instance it is >>> now Saturday Aug. 2, 20:05. >>> >>> When you say privately, I suppose a one-to-one call on Skype and I >>> suppose I can easily find your name there. >>> >>> Have a nice Sunday and thanks again, >>> >>> René >>> >>> On Saturday, August 2, 2014 6:35:33 PM UTC+2, Jason Garber wrote: >>>> >>>> Hi Rene, >>>> >>>> I offer to do a skype call with you to review all of this as I have >>>> been there done that and have a crisp understanding of all the working >>>> parts. >>>> >>>> Contact me privately if you want to do this. >>>> >>>> Thanks, >>>> Jason >>>> On Aug 2, 2014 12:32 PM, <[email protected]> wrote: >>>> >>>>> Dear Graham & al., >>>>> >>>>> Congratulations for your software and documentation. I have however >>>>> some difficulties as outlined in the subject caption. >>>>> >>>>> I'm building a case study for an application on an intranet within a >>>>> company where the users would interact with their browser communicating >>>>> with the Apache2/mod_wsgi server (daemon mode + multi-threads). >>>>> >>>>> However I'm afraid I'm misunderstanding some important underlying >>>>> concepts of the architecture. Please allow me to give an example and to >>>>> give you my thoughts - which could go wrong somewhere. >>>>> >>>>> *Part 1:* >>>>> >>>>> I wrote a simple HTML page with a one field input form. >>>>> >>>>> In my `environment` dictionary, I have, among other key/value pairs, >>>>> the following: >>>>> >>>>> REQUEST_METHOD: POST >>>>> REQUEST_URI: /core/my-wsgi-app >>>>> mod_wsgi.callable_object: application >>>>> >>>>> The first two values come obviously from my html <form >>>>> action="core/my-wsgi-app" method="post">...</form>, and the third value is >>>>> the default value in the configuration directive (WSGICallableObject >>>>> application). >>>>> >>>>> In my my-wsgi-app script, I have of course: >>>>> >>>>> def application (environment, start_response): >>>>> [my code here] >>>>> return [response_body] >>>>> >>>>> So all is fine and works well but there is something I don't get (I >>>>> mean I haven't fully assimilated), certainly in a multi-users, >>>>> multi-threads, ... environment. The main question is about the >>>>> WSGICallableObject. >>>>> >>>>> >>>>> The documentation (https://code.google.com/p/modwsgi/wiki/ >>>>> ConfigurationDirectives#WSGICallableObject) says "*The >>>>> WSGICallableObject directive can be used to override the name of the >>>>> Python >>>>> callable object in the script file which is used as the entry point into >>>>> the WSGI application.*" [underlining is mine]. For me the WSGI >>>>> application is the whole application: when finished the target application >>>>> I'm case studying could serve one hundred users, delivering thousands of >>>>> pages built dynamically over hundreds of SQL tables, ... Am I right in >>>>> thinking than one entry point would be fit for such purpose. The size of >>>>> the application is such that I already opted for a daemon configuration >>>>> with multi-threads (I do not wish to have users waiting in a single queue >>>>> because one of them is building a page that takes seconds to assemble). >>>>> >>>>> Having one single callable object seems to give me these only 4 >>>>> options: >>>>> >>>>> 1) Have only one single REQUEST_URI, say /core/my-wsgi-app, where >>>>> only one callable object (function, class, ...) is used under the one and >>>>> same name (application). In such case that callable object is the one and >>>>> only full single entry point to the overall application (thousands of >>>>> pages >>>>> built dynamically) and I must care for checking, authorisation, parsing, >>>>> dispatching, ... and finally assembling the response and returning it. I'm >>>>> wondering if this single script/callable-object could become a bottleneck. >>>>> It is the concern I've just expressed. Of course, Python can handle >>>>> hundreds of function calls and instance calls. This option makes me doubt >>>>> I >>>>> fully understand the mechanism. I call this option N to 1. >>>>> >>>>> 2) Have various REQUEST_URI (even one per page if need be) and in each >>>>> called script, there would be one callable object with the same name >>>>> ("application" as defined in the WSGICallableObject directive). In >>>>> that case, I could create a callable instance of a base class but that >>>>> instance should bear the application name and use the two positional >>>>> arguments passed by mod_wsgi. This option, if used exclusively, seems to >>>>> me >>>>> like a normal "CGI static serving", i.e. one request activates one script >>>>> (the whole logic and dynamism is in the script). This point too makes me >>>>> doubt I understand the real nature of WSGI. I call this option N to N. >>>>> >>>>> 3) One could combine option 1 and 2 to create more dynamism without >>>>> risking the potential (?) bottleneck of option 1 when used alone. I call >>>>> this option N to M (<<N) >>>>> >>>>> 4) There seems to be a possibility to define the WSGICallableObject >>>>> per directory. My understanding is that the REQUEST_URI belonging to a >>>>> directory (and its sub-directories) would use that callable object name. >>>>> This means for instance that any URI of the form /core/section-1/abc would >>>>> have a callable object Application_1, while any URI under >>>>> /core/section-N/... would have a callable object Application_N. I haven't >>>>> tried this directive yet so I may misunderstand its role. >>>>> >>>>> This is my overall understanding but I'm afraid I'm missing something >>>>> fundamental [please note that I'm not an English speaker and I might have >>>>> missed subtleties in the documentation which is quite dense]. I tried to >>>>> picture this in a diagram but I'm not sure I got it right: >>>>> >>>>> M (html requests) -> 1 (http server) -> N x P (mod_wsgi daemons x >>>>> threads) -> X? (Python instance(s) / one per daemon ? I don't know) -> M >>>>> (calls to one object in one URI or to many objects - named the same - in >>>>> many URI ? ) and back to the user via the same route. >>>>> >>>>> I assume that one user html request generates ultimately one call to a >>>>> callable object (give or take) : that's why I use M in toth cases. Is this >>>>> assumption correct ? My dilemma is that I can't understand the spread of >>>>> the load between the 2 extremes: one URI containing the `application` >>>>> callable object (that is eventually called hundreds of times per second) >>>>> or >>>>> many hundreds URI each containing a callable object named `application` >>>>> that all get called much less frequently. >>>>> >>>>> *Part 2:* >>>>> >>>>> As a consequence of this hazy understanding of mine, I wonder why >>>>> can't the name of the callable object be chosen on demand ? >>>>> >>>>> If I refer to PEP3333 (http://legacy.python.org/dev/peps/pep-3333/) I >>>>> understand that: >>>>> " >>>>> *A server or gateway must invoke the application object using >>>>> positional (not keyword) arguments. (E.g. by calling result = >>>>> application(environ, start_response)*" >>>>> >>>>> So my guess is that, still referring to the example at the top, one >>>>> thread in mod_wsgi loads (I wouldn't call this an import) the >>>>> /core/my-wsgi-app script and calls application(environment, >>>>> start_response) >>>>> that has been defined in it. Is this the correct mechanism ? >>>>> >>>>> Could we imagine that mod_wsgi would sometime call my_App (arg1, >>>>> arg2), some other time call your_App (req, resp) or call Small_app (in, >>>>> out) where my_App, your_App, Small_app would be defined because mod_wsgi >>>>> would be able to set dynamically the WSGICallableObject . Imagine >>>>> that in the WSGIImportScript script file, we would have: >>>>> >>>>> def my_App (param1, param2): >>>>> [code here] >>>>> return [my_Response] >>>>> >>>>> def your_App (param1, param2): >>>>> [code here] >>>>> return [your_Response] >>>>> >>>>> def Small_app (param1, param2): >>>>> [code here] >>>>> return [Small_response] >>>>> >>>>> all the functions would be ready to be called. >>>>> >>>>> I suppose that in any case we are limited: >>>>> >>>>> A) by the HTTP protocol (URI given via the action attribute, the >>>>> POST, GET, OPTIONS, ... from the method attribute and the key/value pairs >>>>> from the various input fields); and >>>>> >>>>> B) by directives we could give to configure mod_wsgi. I guess it is >>>>> not the role neither the intend to build some "user logic" within >>>>> mod_wsgi. >>>>> >>>>> *Conclusions:* >>>>> >>>>> 1) Am I correct in my understanding of mod_wsgi as expressed here >>>>> above (Part 1) ? Beware that I could be out of my depth, i.e. talking >>>>> about >>>>> something I don't properly understand. In that case please correct me or >>>>> complement my view. >>>>> >>>>> 2) Do we need to dynamically choose the callable object name for the >>>>> sake of dynamism and multiplicity ? >>>>> >>>>> -> If not, the current set-up is enough. In which case is the >>>>> preceding point ( 1) ) complete and correct ? >>>>> >>>>> -> If yes, how to do it simply and elegantly ? >>>>> >>>>> => Idea 1: create an extra key/value pair (e.g. >>>>> wsgi_callable_object=my_application). It seems cumbersome to me. >>>>> >>>>> => Idea 2: if the URI were to have the form >>>>> /core/my-wsgi-app/_my_application then mod_wsgi could provide: >>>>> REQUEST_URI: /core/my-wsgi-app >>>>> mod_wsgi.callable_object: my_application >>>>> in the 'environment` dictionary because it would strip >>>>> the trailing part beginning with an underscore provided it is told to do >>>>> so >>>>> by a directive; >>>>> otherwise it would behave as now and deliver: >>>>> REQUEST_URI: /core/my-wsgi-app/_my_application >>>>> mod_wsgi.callable_object: application >>>>> >>>>> *Thanks:* >>>>> >>>>> I do realize this is an unusual post (maybe it should find its way in >>>>> the group working on the documentation) but I would be very happy if some >>>>> of you could answer / feedback to me. In any case I do thank you all in >>>>> advance. >>>>> >>>>> René >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "modwsgi" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to [email protected]. >>>>> To post to this group, send email to [email protected]. >>>>> Visit this group at http://groups.google.com/group/modwsgi. >>>>> For more options, visit https://groups.google.com/d/optout. >>>>> >>>> -- >>> You received this message because you are subscribed to the Google >>> Groups "modwsgi" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To post to this group, send email to [email protected]. >>> Visit this group at http://groups.google.com/group/modwsgi. >>> For more options, visit https://groups.google.com/d/optout. >>> >> -- > You received this message because you are subscribed to the Google Groups > "modwsgi" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/modwsgi. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "modwsgi" group. 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