# Architectual question: Engine with all common models **URL:** \ **Category:** Rails\ **Created:** [April 7, 2009, 3:02pm UTC](https://www.ruby-forum.com/t/architectual-question-engine-with-all-common-models/164929 "2009-04-07T15:02:40Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![tuktuk](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/77aa72/32.png) [@tuktuk](https://www.ruby-forum.com/u/tuktuk)\ **Post date:** [April 7, 2009, 3:02pm UTC](https://www.ruby-forum.com/t/architectual-question-engine-with-all-common-models/164929/1 "2009-04-07T15:02:40Z")
I am maintaining a large Rails application, that consists of several “interfaces”: 1. The web interface (figures) 2. Import of data from external providers 3. Export of data to a large range of customers It seems to me quite bloated to have all the code from 2) and 3) inside the web-application, since they functionally have nothing in common. The only reason for them being there, is that they also need the business rules implemented in the models. Enter Rails 2.3 and Engines… I am thinking about restructuring the application the following way, and my question regards whether this is a sound idea. i) Make a Rails engine, consisting only of all models, that are shared by two or more of the above “interfaces” ii) Split my current application into 3 seperate applications - each only containing what is nessecary for its own uses: 1a) Web interface should only keep: Controllers, Views, Mailer-“models” (and other dependent files in e.g. lib) 2a) Import of data should only keep code needed for the import 3) Same as 2a) All three of them should then add the “model-engine” in their vendor folder. I am not sure if Engines were meant to be used like this - but somehow it fits in my mind. Any thoughts on this? - Carsten ---
**Author:** ![tuktuk](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/77aa72/32.png) [@tuktuk](https://www.ruby-forum.com/u/tuktuk)\ **Post date:** [April 12, 2009, 11:46am UTC](https://www.ruby-forum.com/t/architectual-question-engine-with-all-common-models/164929/2 "2009-04-12T11:46:04Z")
I allow myself to bump this question just once, since I believe, that it is quite relevant at the moment, considering the release of Rails 2.3 - Carsten ---
**Author:** ![tuktuk](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/77aa72/32.png) [@tuktuk](https://www.ruby-forum.com/u/tuktuk)\ **Post date:** [April 13, 2009, 1:45am UTC](https://www.ruby-forum.com/t/architectual-question-engine-with-all-common-models/164929/3 "2009-04-13T01:45:35Z")
Carsten G. wrote: > I am maintaining a large Rails application, that consists of several > “interfaces”: > > 1. The web interface (figures) > 2. Import of data from external providers > 3. Export of data to a large range of customers > > It seems to me quite bloated to have all the code from 2) and 3) inside > the web-application, since they functionally have nothing in common. The > only reason for them being there, is that they also need the business > rules implemented in the models. > […] > ii) Split my current application into 3 seperate applications - each > only containing what is nessecary for its own uses: > […] I am not 100% sure that I’m correctly understanding the current structure of your app, but if I am, my advice is this: you have one application, accessible through multiple channels. Keep it that way – since it’s one application, it probably shouldn’t be broken down any further from the user’s point of view. Just keep everything modularized well enough that the interfaces don’t have much coupling to the models. (Of course, Phlip is liable to say something totally different, and if he does, you should definitely listen to him, not me.) ## Best, Marnen Laibow-Koser removed\_email\_address@domain.invalid [http://www.marnen.org](http://www.marnen.org) ---
**Author:** ![tuktuk](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/77aa72/32.png) [@tuktuk](https://www.ruby-forum.com/u/tuktuk)\ **Post date:** [April 13, 2009, 4:20am UTC](https://www.ruby-forum.com/t/architectual-question-engine-with-all-common-models/164929/4 "2009-04-13T04:20:12Z")
One issue with splitting the application into 3 will be consistency of deployment. If the models in the engine change you need to at a minimum run all the tests in all 3 systems, and possibly make updates, then find the time to deploy all 3. I know these situations are solvable, but I don’t think it’s worth introducing them if you strive to keep all your interfaces (web, import, export) well separated. You could add something like app/importers and app/exporters and treat them like “controllers” for the alternate interfaces. Also, the use of modules and namespaces can be useful for situations likes this. On Apr 12, 6:45 pm, Marnen Laibow-Koser \ **Author:** ![tuktuk](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/77aa72/32.png) [@tuktuk](https://www.ruby-forum.com/u/tuktuk)\ **Post date:** [April 13, 2009, 2:05pm UTC](https://www.ruby-forum.com/t/architectual-question-engine-with-all-common-models/164929/5 "2009-04-13T14:05:26Z") Marnen: > you have one application, accessible through multiple channels. > Keep it that way – since it’s one application Andrew: > One issue with splitting the application into 3 will be > consistency of deployment > You could add something like app/importers and app/exporters > and treat them like “controllers” for the alternate interfaces. These are good points, both of you, and they made me think some more about the layout of my application. What really bothers me is that, right now, all import code is started by executing “script/runner Janitor.perform\_daily\_tasks”, where Janitor is a class defined in the model folder. This means, that the “Janitor code” is automatically loaded by Rails, adding code to each mongrel that has nothing to do with the web interface. I think I will try to convince my colleague, that do the app/importers & app/exporters approach. It seems the right way. Thanks a bunch both of you. - Carsten