Global vs Local

Huiqi and I analyze the pros and cons of global/centralized control vs local/distributed control in software projects. The discussion was partly a reaction to an argument I had with my coworker. It's a fun discussion for us and it ended with a poignant moment.

Transcript

The following transcript was automatically generated by an algorithm.

00:00 : i had an argument with danny we're still
00:02 : working on the typescript problem by the
00:04 : way i'm comparing my approach versus if
00:08 : we use nx
00:10 : because i have some problems that i like
00:12 : to solve
00:14 : better and i see when i see how the nx
00:16 : people have done it or it did a poc
00:19 : using nx to do it and i realized that nx
00:23 : collapses all of the dependencies to the
00:26 : one
00:27 : globalpackage.json file which means
00:29 : there's no way to know which modules are
00:32 : dependent on by which sub-projects
00:35 : because all of the sub-projects node
00:37 : modules go into the same package.json
00:41 : but he's trying to argue that that's
00:43 : actually good
00:45 : the sub projects now have this
00:47 : dependency on each other as in if you
00:50 : upgrade some known modules for the
00:52 : purpose of one of the sub projects you
00:54 : could potentially break project b so you
00:56 : want to make sure you retest project b
00:59 : and project c as well
01:01 : well how how would that work to begin
01:03 : with say all this all the project has to
01:06 : use the same version of one dependency
01:08 : say yeah can project use different
01:11 : version of typescript well that okay for
01:14 : the first place yeah for the ones that
01:17 : are frameworks
01:18 : that will have to be the case they will
01:20 : have to all agree on the version the
01:22 : reason why you want to do it is because
01:24 : you want to share type definition across
01:27 : the project right but say different
01:29 : projects have different version of
01:31 : typescript how do how can you make sure
01:34 : that whatever you're sharing are
01:37 : valid for each project if the versions
01:39 : are different it might be easier for the
01:42 : typescript to be the same yeah on all
01:44 : projects
01:45 : but it it also it
01:48 : may not be a problem like because
01:50 : because typescript more or less stays
01:54 : stable
01:55 : with some exceptions so so if if you if
01:58 : you write some code that works
02:00 : differently for one version of
02:02 : typescript versus another version of
02:03 : typescript
02:05 : there has to be a reason like maybe
02:07 : you're using a specific feature of
02:09 : typescript whose behavior has changed
02:12 : over time so if that's the case then
02:14 : you'll have a problem you have to come
02:16 : up with a way to solve it but if that
02:18 : doesn't occur then it's not a problem
02:21 : and if it does happen you can either
02:23 : choose to
02:24 : i'm gonna just sync up all the version
02:27 : also typescript and then we won't have
02:29 : this problem anymore or you can choose
02:32 : to
02:32 : you know what i'm not gonna use that
02:35 : specific feature that causes the problem
02:37 : i'm gonna
02:38 : write the typescript a slightly
02:40 : different way
02:41 : that's an example of i'm gonna loosen
02:44 : the coupling it reminds me of the
02:47 : opinion that one of my coworkers has
02:50 : which is we should avoid using libraries
02:53 : in general
02:55 : because
02:56 : using libraries cause
02:58 : uh version issues right so they they
03:02 : have to like either have the same
03:04 : version or the dependency have to have a
03:06 : lower version so that causes an issue so
03:08 : if you could not use the libraries and
03:10 : just make everything like services
03:13 : you don't have this issue yeah i know
03:16 : it's a very extreme you know opinion
03:19 : but
03:19 : if you think about this if you do want
03:22 : to make everything
03:23 : have the local control and not have to
03:26 : be dependent on all these other things
03:29 : that help you
03:30 : minimize these kind of like uh coupling
03:34 : right i mean of course what he said oh
03:37 : that's a way which is you don't use
03:40 : tennessee
03:41 : you don't use race i mean what are ways
03:44 : right
03:45 : well let's talk about this notion of
03:47 : global control versus local control let
03:51 : me just go over why one would prefer
03:54 : global
03:55 : and why one would prefer
03:57 : local i guess
03:59 : one pro for the local is you could
04:03 : develop each module separately
04:07 : so that
04:08 : they don't have to be dependent on each
04:11 : other say if you want to upgrade one
04:13 : module you don't have to upgrade all of
04:15 : them which is much more work separate
04:17 : teams can work on it
04:19 : yeah i think teams also
04:21 : i'll separate those two things separate
04:24 : teams development
04:25 : make
04:26 : sweep
04:28 : changes
04:30 : separately
04:33 : by module maybe
04:35 : a change
04:38 : is
04:39 : unlikely to
04:41 : affect
04:43 : another module
04:45 : right
04:46 : or a unrelated module
04:49 : right
04:51 : whereas yeah whereas if every every
04:55 : every sub project has to be in sync
04:58 : in terms of the version of a very
05:02 : central library well also if there's a
05:04 : breaking chain if you not like talking
05:07 : about upgrading if you just say you act
05:09 : accidentally break a module it's not
05:12 : like all the modules are broken at the
05:14 : same time
05:15 : the negative
05:17 : effect
05:18 : of a bug
05:21 : is maybe a better product limited you
05:24 : you can find the bugs easily if
05:26 : everything is broken if ever say if all
05:28 : the module depends on the same library
05:31 : then okay this library
05:33 : breaks then obviously everything broke
05:36 : so that's probably appropriate global
05:38 : control
05:39 : it's like
05:40 : because if everything is separately then
05:43 : everything has to be like q8 or
05:46 : separately but if you have
05:48 : central breakages are easy to spot let's
05:52 : say that
05:53 : what are some global pros now
05:56 : um
06:00 : type definition and everything else
06:03 : code
06:04 : less barrier this would be the cons here
06:08 : more barrier
06:10 : to share
06:11 : central breakages are easier
06:14 : global cons is
06:17 : up
06:19 : of central libraries
06:23 : impact
06:24 : unrelated
06:26 : code all right let's think of something
06:28 : else
06:29 : um
06:30 : there's just less overhead
06:33 : coordinating between the modules
06:37 : with the global approach developers
06:40 : might be less thoughtful about
06:42 : modularization
06:44 : maybe
06:45 : an overly hasty
06:47 : with
06:48 : another thing about local cons for local
06:52 : is
06:53 : uh if the dependent
06:55 : relationship between modules sometimes
06:58 : they are like
06:59 : inter two intertwined so if there's like
07:03 : a circular reference or whatever
07:06 : and it's kind of hard to
07:10 : break it into different modules it's
07:12 : like tight coupling
07:14 : yeah tight coupling so
07:16 : sometimes things have to couple so it's
07:20 : kind of hard
07:22 : to
07:23 : break things to modules so you're saying
07:25 : if two two modules
07:28 : are tightly coupled there's
07:31 : there's additional pain associated with
07:34 : that
07:35 : one approach you might take is just
07:38 : merge them into the same module because
07:40 : they they do want to be together right
07:43 : the single responsibility principle
07:46 : it's really about cohesion and coupling
07:49 : we'll dig into like what those things
07:51 : mean exactly but essentially cohesion
07:54 : and coupling are
07:56 : more or less two sides of the same coin
07:58 : coin as how much
08:00 : does the code want to be together
08:04 : how much they're related if you have
08:07 : tight coupling they probably belong in
08:09 : the same module if you try to separate
08:11 : them
08:12 : [Music]
08:13 : then the pain is
08:14 : exacerbated because
08:17 : there's this extra boundary overhead
08:20 : that's associated with the breaking them
08:22 : into separate modules right
08:25 : then anytime one changes the other one
08:28 : has to change as well whereas with the
08:30 : global you will still have pain
08:33 : it's just that we've reduced the
08:35 : boundary overhead
08:37 : right one pro that danny argued for is
08:42 : everyone can expect the same hate
08:44 : behavior maybe that like uniform
08:47 : behavior can be expected because other
08:51 : versions are synchronized
08:55 : local is probably good for very large
08:58 : companies
08:59 : company it's definitely
09:01 : very difficult to do the global approach
09:04 : for
09:05 : a lot of things just because
09:08 : uh so so many people has to coordinate
09:11 : if you want to do the global so what we
09:13 : do is like we do have some coordinator
09:16 : orchestrator app but
09:18 : it's loosely coupled
09:20 : it can like um bring all the sub-modules
09:23 : as libraries
09:25 : just because there are so many
09:27 : sub-modules it's more like a platform
09:30 : it's like oh we have this iphone store
09:32 : right uh you have so many apps like 100
09:36 : of them so you really expect all of them
09:39 : to have the same typescript or angular
09:42 : version but yeah you want
09:45 : certain
09:46 : uniform behavior
09:48 : because of some reason but we just have
09:51 : to first keep those minimal and second
09:53 : just use like either service or whatever
09:56 : other ways but we can't use libraries
09:59 : just because that's that's impossible
10:00 : yeah
10:02 : that makes sense yeah yeah using using
10:04 : an arrest endpoint maybe like every app
10:08 : has to have this kind of rest endpoint
10:11 : or something for other apps to get that
10:13 : information about it that and that's why
10:16 : your co-worker doesn't like to depend on
10:18 : these central libraries because this
10:21 : kernel of incompatibility but that
10:24 : happens at the language level as well as
10:27 : you mentioned
10:28 : one of the times the version of java
10:31 : you're using causes that as well right
10:34 : exactly because that was a system that
10:37 : was created based on using other modules
10:40 : as sub module
10:42 : like like as libraries so they are like
10:44 : directly using their codes now
10:47 : we are
10:48 : upgrading java then the issue uh exposed
10:52 : that was like a non-issue before because
10:54 : every everybody was using the same java
10:56 : version now it's kind of like
10:58 : problematic
11:00 : because people are you start to upgrade
11:02 : their stuff so there's incompatibility
11:05 : yeah
11:06 : yeah with java you use a third-party
11:09 : library you download the compiled
11:11 : version of the library code the creator
11:14 : of the library compiled the code for you
11:17 : into the java bytecode but the problem
11:20 : is the java bytecode is sort of pinned
11:23 : to a specific version of java
11:26 : and that's the problem if they had
11:28 : instead given you their source code and
11:31 : then let you compile the code yourself
11:34 : that might have avoided the problem but
11:37 : the java community does not tend to do
11:40 : things that way with javascript
11:42 : like a language that doesn't have this
11:44 : intermediate compile step all the
11:46 : compilation happens on the fly python is
11:50 : the same way you distribute your source
11:52 : code your original source code there the
11:55 : incompatibility is less likely because
11:59 : it wouldn't break just because you
12:01 : compiled for a different version of the
12:03 : language but breakage can still happen
12:06 : if the source code uses a feature that's
12:09 : not supported by your version of the
12:11 : programming language yeah that's what
12:13 : i'm saying if you have the
12:16 : global control then
12:19 : everything breaks oh version doesn't
12:20 : match it doesn't compile so let me try
12:23 : to resolve it but javascript is like oh
12:26 : everything that kind of works but there
12:28 : are like small things because you use
12:30 : the language feature and it's hard
12:33 : because it looks like it works but it
12:35 : doesn't actually work 100 percent yeah
12:37 : yeah yeah
12:39 : knowing ahead of time versus
12:41 : finding out later
12:43 : i think it's fun to
12:45 : have different opinions
12:48 : yeah yeah
12:50 : it's only fun if you can
12:53 : talk to each other about it and not hate
12:55 : each other
12:56 : sometimes
12:57 : that's not easy to achieve if you can
13:00 : have a atmosphere
13:02 : that that allows like the discussion
13:05 : even when there's strong
13:07 : differences that's very cool well if
13:09 : everybody has an agreement of all these
13:12 : are just trade-offs
13:14 : then things will be better but
13:18 : yeah people tend to get really attached
13:21 : to certain ideas that they believe in
13:24 : and and everybody does that they sort of
13:26 : attach themselves to the idea so if you
13:28 : attack the idea is like you're attacking
13:30 : them if we can get away from that yeah i
13:33 : feel like for me i i guess i understand
13:36 : everything is a trade-off but at the
13:37 : same time i feel like there are things
13:40 : that i think there are like benefit of
13:43 : doing it that way but i don't want to
13:45 : deal with it say if you want me to go in
13:47 : and add a functionality in the code that
13:50 : i don't want to work with then it's it's
13:52 : pretty hard
13:53 : so
13:54 : but i do understand there i mean there
13:57 : is a reason why it's like done this way
14:01 : you can look at it as
14:03 : you're traveling to a foreign country
14:06 : yeah and and for this brief period of
14:09 : time
14:10 : i'm gonna live by their customs
14:14 : that is true but you don't necessarily
14:16 : have to change yourself permanently it's
14:18 : just for this week like when i went to
14:20 : spain uh they they eat dinner at like
14:23 : nine o'clock in the evening
14:26 : and at first i was like i there's no way
14:28 : i would do that but later i was like oh
14:31 : let me just do it it's fine
14:33 : [Laughter]