Monday, June 23, 2014

our journey with cordova-cli

Hey folks !

So we are back with a new post.This time would rather prefer to tell you a kinda story of how we fought we with cordova-cli and finally captured it in our captivity :P :P
Yeah .. Its time to celebrate .. But the success is at very initial stage right now.Getting stucked up with cli was disheartening, but conquering it was heartwarming :D

So to start, we aimed to make the various cordova cli commands work for sugar.All we knew was that we had to push some changes in the cordova-cli package.So quickly searched up where the cordova-cli code lied and downloaded it.Well, to our surprize, the cli code was nothing but a pointer to cordova-lib which was actually the backbone.So downloaded lib too ! But where do the both meet ? How to make them work together ? Though we had some documentation in the readme of cordova-lib.. but ahh .. it didn't work as expected.Spent days to figure what was wrong.Finally after hours of research, found a way to work around.

so let me get you know how we fixed up the things to let our changes in our local directory reflect in the cli on the terminal. The first was the discovery of ~/.cordova directory from where the library code for all the platforms is fetched once downloaded from their respective urls.This is the directory which enables us to copy the templates when we issue the cordova platform add command.Next, the correct linking between cordova-cli and cordova-lib,for this we had to go into cordova-cli directory and issue the npm link from there for cordova-lib.Once cordova-lib is there in the cordova-cli/node_modules then the changes done in directory cordova-cli/node_modules/cordova-lib  get it reflected on terminal.But we have to be cautious to remove the cordova executable file from usr/lib/bin directory which may be residing there from earlier installation of cordova-cli.Lastly to get a feel of our changes we move to cordova-cli/bin and run the cordova executable file present there.

Now let me take you through the digging we have done in the cordova-cli code. Firstly the executable that we run inside the bin folder of cordova-cli, simply calls cli.js of cordova-cli with process.args ( the arguments we provide) , the cli then calls for cordova-lib.js of cordova-lib in node_modules.Obviously apart from the cordova-lib, we do need a few other node dependencies as well.

Cordova-lib.js defines various files to be used with different commands - see here. So for the cordova commands, we are directed to the cordova.js inside cordova-lib/cordova.There different modules which eventually cater to our various category of commands like create, platform add etc are added.

For cordova create command, create.js in cordova-lib simply makes a new project with the specified directory name,id and app name but with no specific platform. To add a platform we issue ' cordova platform add <platform name >'. This calls for the platform.js.It looks in platforms.js [note a difference of 's' in platforms ;-) ] to see if there is an entry for the specified platform.If not it issues an error, else it downloads the platform's library from the url specified in platforms.js.Its only when the command is issued first time for the specified platform that cli downloads it else ~/.cordova/lib/<platform>/<version> is referred for the platform project template.The 'create' file in ~/.cordova/lib/<platform>/<version> /lib folder contains the platform specific script to add the files from the platform's library to the cordova project.

Once the platform has been added to the project, we then need to build project after coding up our logic in the app.For this the build command is broken into two parts, prepare and compile.The prepare part copies all the updated parts from the global www folder - projectDirectory/www to the native platform's www folder - projectDirectory/platform/<platform name>/www, it also updates the app name, package name,icons etc and installs and uninstalls the plugins through plugman.Once the relevant web stuff has been added to the native platform compile part then runs a script using superspawn.js which converts the web stuff to the native platform package.

So as far as today we are building upon the build command and hope to finish it soon :-)

A visual representation of all explained above can be found below ..

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