7 ms·

When to Rewrite from Scratch – Autopsy of Failed Software

240 points by perseus323 10y ago

coldtea 10y ago
>The development officially began in Summer of 2012 and we set end of January, 2013 as the release date. Because the vision was so grand, we needed even more people. I hired consultants and couple of remote developers in India. Well, that's already a warning sign. If you don't have the talent to do the rewrite, consultants and remote developers in India are only going to make things worse.
- deleted 10y ago
  [deleted]
- perseus323 10y ago
  We began early April and we had more FT in-house developers than remote resources. The only reason we got remote workers because it was next to impossible to find good developers. We initially had a terrible experience with remote workers and it didn't work out at all. But we learned from our mistakes and made it work later on. When I left the company, 100% of its development (i.e. maintenance) is done offshore.
- copperx 10y ago
  Wasn't the rewrite was a technical success despite warning signs? The customer simply didn't want to adopt the shiny new software.
  - perseus323 10y ago
    The rewrite was a technical success. But we missed real business opportunities and completely underestimated the effort of building a new system while maintaining the legacy one in parallel. In short, we didn't prioritize and miscalculated big time :-) The customer confidence in us had eroded because we weren't responding to their new feature requests in the legacy system. Plus their management didn't want to take any risks since the new system offered to new features to them and only benefited us.
    - skj 10y ago
      What about responding to their feature requests... in the new system? ! Then they'd have the motivation to make the switch.
      - chris_wot 10y ago
        That's the problem. From my reading of the article, their client was, probably legitimately, concerned with the risk of a cutover to a new and unproven system. To implement a new system the client always needs to do UAT. That's actually a drain on their resources, and if they have a working system it is far better to have incremental changes made and a regular set if bug fixes than to launch a new system, then find a raft of new bugs or unexpected changes that need to be fixed anyway. Existing systems allow enterprises to operate effectively. New systems almost always cause unexpected disruption to a business regardless of efficiencies gained from the new system. And most IT systems are to support the objectives if the business, they aren't the actual objective if the business. A software development company can lose sight of this because it IS the objective of their business :-)
        perseus323 10y ago
        Good point. The UAT was definitely one of the reasons. It was several Excel spreadsheets long and scheduling it was a pain :-) Also, it was a hosted service and client saw no value to them- just the pain. There was risk of service outage during the upgrade that would have had resulted in the loss of revenue. Also, the client had to provision extra resources to run Cassandra/SOA servers. In short, it was a lot of work for them with no benefit to them.
      - perseus323 10y ago
        We tried that and that's how we eventually got them to switch - 2 years later. The client required a feature to start 'live sessions' with mobile subscribers whenever they were active on the network (made or received a call) and support for multi-level menus. The original architecture was transactional and they understood its limitations. The rewrite used SEDA and we were having latency issues, gc and memory issues handling live sessions with SEDA. So we had to do another upgrade to switch from SEDA to Actor based model that worked. The next upgrade was small and incremental compared to the first one very and we had the system ready by the time contract was finalized.
  - aytekin 10y ago
    There is no way to know if it was a technical success since it was never used by real customers. It might be full of bugs and bad decisions. In fact, by default unused code should be assumed to be full of bugs and problems. That's the reason behind the success of continuous integration and deployment. At least bad code stay hidden for a very short time and needs to be fixed before other things can be built on top of it.
  - pjc50 10y ago
    "The operation was a success, but the patient died"
- eganist 10y ago
  > If you don't have the talent to do the rewrite, consultants and remote developers in India are only going to make things worse. I don't think this is necessarily a given, but I see where you're coming from with the overall perspective. To get closer to the point of the post: unless there are truly solid and unavoidable blockers, e.g. substantial architectural defects that just can't be resolved without a major rework, a rewrite of any capacity should probably be off the table. Although I'm sure there are others that I have no insight into, the only "successful" commercial rewrite I can think of would be Windows Vista, and that only made that version of Windows somewhat releasable. Even then, that wasn't a total reboot even of the project; it was a partial rewrite off of a different codebase with as much code salvaged from the original project as possible (the initial Longhorn builds on top of the XP codebase were a total trainwreck, driving the partial reboot on top of Server 2003's codebase instead). They still needed two service packs to make Vista stable, and it took an entire subsequent major release (7) to right the ship, so to speak.
  - chris_wot 10y ago
    There would be nothing preventing a rewrite of core subsystems. Vista, despite it being a disaster for Microsoft, was only problematic because of changes made to the UX. Actually Vista is interesting. For all its problems, it's actually an impressive upgrade - whilst there was development chaos due to a lack of focus, a new management team was able to significantly focus in on what needed to be done and hundred of improvements were made under the hood. Microsoft rewrote their TCP/IP stack from scratch and included important system administration tools like an improved logging system, performance and reliability tools, a vastly improved desktop window manager, a new graphics driver model called WDDM and a raft of new kernel security measures. These rewrites weren't rewrites of the entirety of Windows, but instead Windows was increasingly modularised and entire subsystems were rewritten. Whilst Vista was a disaster and had some real problems I don't think it was because of rewriting subsystems, I think it was due to UX changes. Interestingly, Windows 7 was an amazing success and in fact built on Windows Vista, but again focused on modularisation and leveraging the work done in Vista. My hypothesis that major UX changes caused Microsoft to stumble in Windows is born out by Windows 8 - which was even more stable and performed better than Windows 7, but was rejected in the market because of insane UX decisions. So a major rework can be done, but if you are going to do this then I suggest that major changes to UX should be done after the rework. I don't think you can avoid major rework though. Without some of the things I highlight above, there is no way Microsoft would be able to improve their code or implement features that actual make sense!
chris_wot 10y ago
This is one of the reasons I love working on LibreOffice. I think most people acknowledge that LibreOffice is a pretty decent office suite. But it is just over 30 years old now and it has acreted massive amounts of legacy code, some questionable design decisions and in terms of often trying to track it in version control it can be a nightmare if you go back far enough. But it would definitely be a mistake to rewrite it from scratch. There are millions of users who rely on it, and it's a massive code base that runs on three major operating systems - four if you include Android. Instead, the LibreOffice developers are slowly working through refactoring the code base. They are doing this quietly and carefully, bit by bit. Massive changes are being done in a strategic fashion. Here are some things: * changed the build system from a custom dmake based system to GNU guild - leading to reduced build times and improving development efficiency * the excising of custom C++ containers and iterates with ones from the C++ Standard Template Library * changing UI descriptor files from the proprietary .src/.hrc format to Glade .ui files * proper reference counting for widgets in the VCL module * an OpenGL backend in the VCL module * removal of mountains of unneeded code * cleanup of comments, in particular a real push to translate the huge number of German comments to English * use of Coverity's static analysis tool to locate thousands and thousands of potential bugs most of which have been resolved * a huge amount of unit tests to catch regressions quickly This has allowed LibreOffice to make massive improvements in just about every area. It has also allowed new features like tiled rendering - used for Android and LibreOffice Online, the VCL demo which helps improve VCL performance, filter improvements which has increased Office compatibility and allowed importing older formats, a redesign of dialogue boxes, menus and toolbars which has streamlined the workflow in ways that make sense and are non-disruptive to existing users, and many more improvements which I probably don't know about it has slipped my mind. But my point is - if LibreOffice had decided to do a rewrite it would have been a failure. It is far better to refactor a code base that is widely used than to rewrite it, for all the reasons the article says.
pg_bot 10y ago
The only cases where I've seen rewrites work are when the software fails to consistently complete the task it was written to do. A lot of software is garbage but gets the job done. When you encounter hot spots its best to slowly refactor until you get the system where it needs to be. Lots of little changes mitigate risk, and it is easier to track down bugs if you make a mistake.
fallous 10y ago
Unfortunately this is a lesson that often has to be learned the hard way when you have a lead or team that lacks experience/wisdom. If you can survive that educational expense, you end up much better for it but it's painful nonetheless. Aesthetics are never a legitimate reason to replace a functioning system with something else. I do not care how it offends the eye, the mind, the ear, or any other sensation you have... if it does not have a fundamental functional problem your best option is to maintain or plan an incremental rolling replacement that is tightly scoped at each step. For large systems that do present functional problems, identify the egregious offenders in that system, abstract the entities/behaviors most responsible, and replace-in-place in a Ship of Theseus fashion. Despite how familiar you believe you are with a monolithic or complex inter-dependent system, you will discover how much you don't actually understand about how it works as a whole if you try and re-implement in its entirety.
- tonyarkles 10y ago
  I perpetually love the references to Ship of Theseus, and find it particularly applicable to this problem. You mention fundamental functional problems, and I'd like to add something: sometimes it's not a functional problem, but a changeability problem. The code functions fine, but the process of adding a new feature is incredibly painful. I've done big-bang partial rewrites of systems before, quite successfully, but I've got a Ship of Theseus rule of my own that I follow: no new features during the rewrite, and no missing features. The first example that comes to mind was a rather complicated front-end application that had become a total spaghetti disaster. It had been written using Backbone, and from my research it fit the Angular model of things quite well. I took a pound of coffee with me out to the cabin for a weekend, and rewrote the whole frontend. Side-by-side. I started with the first screen, and walked through every code path to populate a queue of screens that were reachable from there. Implement a screen, capture its outbound links, repeat. Nothing changed, but everything changed. The stylesheet was gnarly too, but I left it 100% untouched. That comes later. By keeping the stylesheet intact, I (somewhat) ensured that the new implementation used identical markup to the old system. The markup was gnarly too, but keeping it identical helped to ensure that nothing got missed. 48-72ish hours later, I emerged a bit scraggly and the rest of the team started going over it. They found 1 or 2 minor things, but within a week or so we did a full cut-over. The best part? Unlike the article, clients had no outward indication that anything had changed. There was no outcry, even though about a quarter of the code in the system had been thrown out.
ereyes01 10y ago
Ill-fated code rewrite crusades often seem to be linked with the Second System Effect (https://umich.instructure.com/files/884126/download?download_frd=1 https://umich.instructure.com/files/884126/download?download... ... page 55). Excerpt: An architect's first work is apt to be spare and clean. He knows he doesn't know what he's doing, so he does it carefully and with great restraint. As he designs the first work, frill after frill and embellishment after embellishment occur to him. These get stored away to be used "next time." Sooner or later the first system is finished, and the architect, with firm confidence and a demonstrated mastery of that class of systems, is ready to build a second system. This second is the most dangerous system a man ever designs. When he does his third and later ones, his prior experiences will confirm each other as to the general characteristics of such systems, and their differences will identify those parts of his experience that are particular and not generalizable. And from the OP, frill by frill :-) I wanted to try out new, shinny technologies like Apache Cassandra, Virtualization, Binary Protocols, Service Oriented Architecture, etc. To OP's credit, he took a step back and learned from his mistakes. Also related... Second System Effect may not only apply for your second system ever. It may also bite you designing the second system in a new problem domain you're unfamiliar with. I can admit I've built a few second systems in my time ;-)
- Terr_ 10y ago
  I hope/like-to-think that the second-system that focuses on architectural-features is better than the second-system that focuses on new user-features. Stuff like "no global variables" or "actually use database transactions" or "support UTF-8"...
  - kinghajj 10y ago
    "Remember that time zones are a thing and not everyone is in America/Los_Angeles..."
    - kuschku 10y ago
      That’s why I personally love most european companies, as most just assume UTC.
whichdan 10y ago
Part of me was really hoping that some startup had written an MVP in Scratch and was seeing how far it could scale.
rdtsc 10y ago
Software is re-written most often for political reasons, namely for new developers to leave a mark, and put a good line in their resume. Everyone likes to read "designed and implemented" on a resume than "maintained and fixed annoying bugs here and there". We know what looks better, managers know who they'd move to the next round, and so on. The only thing is, if there is no software to be written software developers will always find a reason to write software. Because they get paid full time, usually above what other professions get paid, to well, ... write software. I think other reasons such as "it is slow, outdated, not written in <latest-language-fad>, bad UI", are often brought up and used as excuses. But underlying reasons are a lot more personal and subjective.
hibikir 10y ago
I rewrote from scratch once, after much deliberation and was successful. In my case, I had some extremely good reasons: The original codebase was build using good old waterfall, where neither programmers nor testers had ever met a user in their life. So all the things that are good about working software kind of go out the window: There are a lot of abstractions in the code, but they didn't match the user's mental model, or helped in any way. My users didn't like the software at all. It might have me their requirements in theory, but not in practice. The team that had built the application was pretty much gone, nobody that had any responsibility in any design decision was still in the company. I actually had managed to get access to people that actually used the software, and people that supported those users, so relying on them, I was able to get a model of the world far better than the original developers ever did. 300K lines of Java, written over three years by 10+ developers were rewritten by a team of two in three months. All the functionality that anyone used was still there, but actually implemented in ways that made sense for user workflows. I'd not have dared a rewrite had the situation been better though: Working code people want to use trumps everything.
- danieltillett 10y ago
  I have always felt that if you need more than 3 developers and 12 months then the software is too big and the scope needs to be cut down. Better a small program that does one thing well than a monolith that does everything badly - why do we never learn from the UNIX philosophy.
  - mafro 10y ago
    I think what you're referring to is what the kids call "microservices".
- auxbuss 10y ago
  Three months = 60 working days. Two devs, so 120 working days. 300k lines of code. So, 2500 lines of production code rewritten per day. Sustained for three months. No holiday. No days off. And this code was tested to be equivalent of the old code. So, let's say, being conservative, another 2500 lines of test code per day. (It's a lot more that, of course, in most cases.) So 5000 lines of working, tested code per day. Plus, the team of two were checking in with the users to make sure everything was hunky dory. And the new team was designing a new "model of the world far better than the original developers ever did". I'd have gone along with that bullshit until the final sentence: Working code people want to use trumps everything. No, no, young ninja, rock star, Jedi: Working maintainable code trumps everything.
peterbotond 10y ago
I have incrementally refactored large codebases by committing to a guide of which constructs to replace with what, what is the final goal and writing test cases. Once the guide was seen beneficial by other developers, rather they were forced to use it, they were surprised how well that worked. All this was behind the scene from the customer and updates bugfixes were going out. Re-write may be the answer sometimes, many times, a well thought incremental re-factoring guide is an easier path.
_navaneethan 10y ago
"Incremental change is always better for testability and validating the existing features" - from 97 things every programmer should know
hinkley 10y ago
I no longer believe in rewrites. I used to believe that every company gets one rewrite, but only because I have seen that most places have the patience and the stamina for a little bit less than a single rewrite, but I was on the fence about whether they were a good idea anyway. Trouble is, I could never put my finger on why, other than that it never seemed to fix the problem. It was a bit like moving to a new city to start over and finding out you brought all your problems with you. In the last couple of years I have begin to figure out what I know in a way I can articulate. The people who have the skills and discipline to take advantage of a rewrite don't need a rewrite. It's a short distance from that skill set to being able to break the problem down and fix it piece by piece. They just need permission to fix key bits, one bite at a time, and they've probably already insisted on the space to do it, although they may be clever enough never to have said it out loud. They just do it. Then you have the people who don't have the skills and discipline to continuously improve their code. What the rewrite buys them is a year of nobody yelling at them about how crappy the code is. They have all the goodwill and the hopes of the organization riding on their magical rewrite. They've reset the Animosity Clock and get a do-over. However, as the time starts to run down, they will make all of the same mistakes because they couldn't ever decompose big problems in the first place, and they lack the patience to stick with their course and not chicken out. They go back to creating messes as they go, if they ever actually stopped to begin with. Some of them wouldn't recognize the mess until after its done anyway. In short, people who ask for a rewrite don't deserve a rewrite, and would squander it if they did. It's a stall tactic and an expensive dream. The ones who can handle a rewrite already are. They never stopped rewriting. Now, I've left out all of the problems that can come from the business side, and in many cases the blame lies squarely with them (and the pattern isn't all that different). In that case it might take the rewrite for everyone to see how inflexible, unreasonable and demanding the business side is, and so Garbage In, Garbage Out rules the day. But the people with the self respect to not put up with it have moved on, or gotten jaded and bitter in the process.
- raverbashing 10y ago
  I definitely agree A rewrite is more useful when the original project is irrevocably doomed (bad/obsolete framework, needs a new language, etc) Most of the time you can refactor the original code
cdevs 10y ago
I'm facing this at work and wanting to rewrite, updates are to slow when one small change needs 1000 other changes in spaghetti code in piles of scripts... Difference is we can roll our users over as they renew and in a year after release all new customers and old will have the same software. Only about 2000 users not as big as a scale as the story here.
Ace17 10y ago
A lack of design skills and code-cleaning skills can mislead you into thinking "the code needs to be rewritten from scratch". However, as the new code grows, you're going to need badly these very skills anyways.
hoodoof 10y ago
The new Software Development Manager always wants to rewrite the code from scratch. That's the way it's always been. I like that the guy who wrote this post had the courage to admit that he was motivated partly by the desire to play with new tech. reply
deleted 10y ago
[deleted]
craigvn 10y ago
I think there are only two reasons to rewrite. 1) When you need to support a different platform, ie we have a Windows Desktop app and want a Web or Mobile or Mac. 2) When the code base is so bad adding any new features creates many time more bugs.
wink 10y ago
Interestingly I've hardly seen this 'rewrite' vs 'no rewrite' debate regarding to microservices, with all the talk about them. In theory it shouldn't be more work (as they are supposed to be so small) than some refactoring in your old (big) piece of software, and you can even rewrite it in a different language.
pramalin 10y ago
Survived a complete rewrite for a client just now. The previous team blindly relied on a single method from Spring framework's RestTemplate for every rest service calls with SAP backend. ResponseEntity<T> exchange(String url, HttpMethod method, HttpEntity<?> requestEntity, Class<T> responseType, Object... uriVariables) throws RestClientException (ref: https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/client/RestTemplate.html https://docs.spring.io/spring/docs/current/javadoc-api/org/s...) This forsed them to create object models structured to match the complicated and inconsitent request and response JSON strings that SAP used, instead of creating the objects modeled after the business domains. The result was no surprise was a disaster and the client wasted five months with them and I had to redo and complete the project still on time. I still see many teams make their function signatures in Java so convoluted like below and don't know what hit them. interface ToDoService { ListToDoResponse listToDo(ListToDoRequest request) throws ListToDoException; AddToDoResponse addToDo(AddToDoRequest request) throws AddToDoException; .. and so on .. }
- mikevm 10y ago
  Can you shed some light on how to best solve this problem? I'm pretty much in the same boat with a restful service I depend on.
erikb 10y ago
That guy really has a done a rewrite and then got it back to the point where it is used. That is what I felt when reading the article. Many people just rewrite and then complain that their rewrite never gets used. So they don't draw the important conclusions and the next time they will try it again. If you really push yourself, your team and the users to using the rewrite and getting it back on track with the original solution, then you have to go through all the disappointments of your rewrite not being better than the original, the real pains you induce in your users, and solve so many problems you've never signed up for solving because you didn't know that the old, ugly solution actually solved these as well. The pain of reading, understanding and fixing/improving the old, ugly solftware is never that painful. And the value is much more immediate since your users already use and know the old software.
mtrn 10y ago
I don't believe in rewrites. But I believe in the evolution of the understanding, what a system is supposed to do and how to do it. A customer might have a lofty web-scale vision, the first version is built with all scaling and no maintenance in mind. You are then faced with a decision: carry along the visionary nightmare and get almost no real work done, because the system itself is in the way, or rewrite the system with a fresh, minimal approach, focusing on a valuable target. The point being: Software requirements evolve and sometimes, writing a first version of the software is the spec itself. Just as with specs, you can try to scavenge all good things from the previous version for the next one - and actually getting better over time, despite being in a rewrite mode.
freework 10y ago
> The development officially began in Summer of 2012 and we set end of January, 2013 as the release date. This is the problem right there. In my experience, successful rewrites only happen when they get done quickly. If you know exactly what you're re-writing, you can get it done within a few days. If you have no idea what you're doing and think it'll take more than a week, it will probably end in failure. The truth is, I re-write code almost every day in my programming life. I usually don't realize I'm rewriting something until after the fact.
DonHopkins 10y ago
"While parts of code were bad, we could have easily fixed them with refactoring if we had taken time to read and understand the source code that was written by other people." This is the thing. Many people just HATE and REFUSE to read other people's code. Maybe they just don't teach code reading and reviewing in computer science classes, but they should. Printing it out on paper and reading it away from the computer is helpful, but a lot of people write code for wide screens that doesn't print out well, or they just don't give a shit and it looks terrible even on the screen. And some people just don't have the stomach for reading through a huge pile of pages, or think that's below their station in life. But reading code is one of the best most essential ways to learn how to program, how to use libraries, how to write code that fits into existing practices, how to learn cool tricks and techniques you would have never thought of on your own, and how to gain perspective on code you wrote yourself, just as musicians should constantly listen to other people's music as well as their own. I just don't feel safe using a library I haven't at least skimmed over to get an idea of how it's doing what it promises to do. There are ways to make reading code less painful and time consuming, like running it under a debugger and reading it while it's running in the context of a stack and environment, looking at live objects, setting breakpoints and tracing through the execution. Code reading and reviewing is so important, and it should be one of the first ways people learn to program, and something experienced programmers do all the time. And of course as the old saying goes, code should be written first and foremost for other people (preferably psychopaths who have your home address, photos of your children, and your social security number) to read, and only incidentally for the computer to execute.
- stevetrewick 10y ago
  >Maybe they just don't teach that in computer science classes, but they should. Should they? This seems like a classic conflation of computer science with programming. Perhaps the reason this important craft skill is not taught in CS is because it has nothing to do with complexity classes, automata theory, etc. Programming != CS
  - DonHopkins 10y ago
    They aren't the same, but they aren't mutually exclusive either. I think all computer scientists should learn to program, and learning to program requires getting over your distaste of reading other people's code. I doubt a pure academic "computer scientist" who doesn't like to get their hands dirty reading or writing code because they look down on it as a "craft" is going to be of much use on the types of projects we're discussing that require rewriting or refactoring existing code.
chrisan 10y ago
What are everyone's thoughts on rewriting in order to simplify your developer overhead with the likes of React? We are a small shop and have a non-game app for html, ios, and android. The non-public (used by less than 30 people) backend has two management interfaces in, you might want to sit down for this, Adobe Flex. There are 2 full time developers (1 backend/flex/html and 1 ios/html) and 1-3 part time (android/ios) contractors depending on workload/deadlines. Everyone is pretty siloed with mostly 1 additional cross over app. I have read articles similar to this as well as worked with some greybeards that carry this philosophy of staying the course and righting the ship rather than jumpin. However, this siren's song of React is luring me in with their philosophy of "learn once, write anywhere"[0]. Instead of siloed developers we'd simply have developers that would feel comfortable in [management interface/html/ios/android] [0]: https://facebook.github.io/react/blog/2015/03/26/introducing-react-native.html https://facebook.github.io/react/blog/2015/03/26/introducing...
- douche 10y ago
  Sometimes, you've got to dump the old stuff because it is just too painful to make changes on. I've rewritten more than a couple of projects that I inherited from less than competent outsourced contractors... Number one, these projects mostly didn't work, and had so many bugs that I'm not sure how it was ever shipped software that somebody paid for. Number two, it was all the worst kind of WebForms and Visual Basic monstrosity. I'm sure its possible to write non-terrible code with WebForms that looks good, but I've never seen it, and it was a matter of a couple weeks to burn it down and build a proper MVC application instead. My only regret there is that I waited too long to rewrite, and wasted a few months battling the manure pile of the old version and trying to improve it incrementally.
bernardlunn 10y ago
True story. Similar start. A couple of enterprise customers, kludgy old code. Changeability was the problem. Decision made for total rewrite. Budget no probs, team of 10 allocated. I was the guy who sold the deals. Wanted to assess if we had a disaster on our hands. Asked CTO to explain how team was constructed. Here is how the conversation went: Me: tell me about the team CTO: well it is actually all being built by two guys. Me: That's crazy. We have a 10 person team. CTO: Actually I lied, it is actually all being built by one guy. Before you get me fired, let me explain. One guy just builds prototypes to keep all those idiotic requests from management. Me: I knew the guy. Fastest damn developer on the planet CTO: we just throw his code away. The other guy who we don't let you meet actually writes the code that works. You see nothing for weeks, then it emerges and works beautifully. Me: what do you do with the other 8 guys? CTO: give them make work to keep them out of the way. The system was a market success for a long time.
- nyir 10y ago
  That's fascinating, was everyone involved in on the deal, or how did they manage to keep that under wraps?
CraigJPerry 10y ago
I want to try a re-write project at least once in my career. I've been thinking about how I might tackle it: The legacy system components are unlikely to have ideal boundaries (unless you're insanely lucky) due to organic growth. So step 1, identify key boundaries and implement them as libraries / micro services / whatever makes sense. Step 2, identify the highest value component to refactor - that might not be the part that makes the system go better for the users, it might be tackling the bit generating most support noise so you can free up more dev resource. Begin the refactoring with a release, the new component begins life as a shim between the component interface and the legacy component, calling out to the legacy component for all features initially but as functionality is migrated to the new component it gradually uses the legacy component less and less. You can always release at any time and you'll have a system using new code where it's written and falling back to old code where not. Lather, rinse, repeat. Key challenges I see during the refactoring are managing state during the refactoring of complex behaviors of the original component. It may lead to a private interface which is more granular but only exposed to the new replacement component. Interesting stuff for sure.
sferoze 10y ago
I recently faced the decision whether to rewrite I took over a rails + angular 1 codebase from another developer who left the company. I would be working on the project for few months. I rewrote the entire app with Meteor + React in few weeks. Best decision I ever made. Even though the app has same features, customers say the app is faster, has less bugs, and overall feels more solid. Security is also better because of the pub/sub system. It also gave me a chance to fully understand the ins and outs of the database and how the app works. I can also develop features much faster with Meteor + React than with Rails + Angular 1. So time spend re-writing is saved by enabling faster feature development.
brudgers 10y ago
Jeff Meyerson's interview with David Heinemeir Hanson [DHH] includes rewriting software. It discusses the reasons rewrites have a bad reputation and the difference between rewriting because "it's not my code/language/idiom" and declaring "technical bankruptcy" as an extension of the technical debt metaphor. Agree with DHH or not, he's thought deeply about a lot of software development tropes. http://softwareengineeringdaily.com/2016/01/13/the-evolution-of-rails-with-david-heinemeier-hansson/ http://softwareengineeringdaily.com/2016/01/13/the-evolution...
- dham 10y ago
  I listen to every DHH interview I can but his view on a rewrite is different than others that do rewrites. There is no "second system" per say in his world. He leaves the old system up for people that still think it works just fine. Instead of messing up the old versions with upgrades, they leave them up and if a customer wants to go to new version that is "rewritten" they can.
tekism 10y ago
"and changed our protocols to binary, all at the same time. " What does the author mean by that statement?
jv22222 10y ago
This is why all developers should build their own framework from scratch in their spare time... It scratches the itch and helps one appreciate existing software.

240 points by perseus323 10y ago

>The development officially began in Summer of 2012 and we set end of January, 2013 as the release date. Because the vision was so grand, we needed even more people. I hired consultants and couple of remote developers in India. Well, that's already a warning sign. If you don't have the talent to do the rewrite, consultants and remote developers in India are only going to make things worse.

deleted 10y ago
[deleted]
perseus323 10y ago
We began early April and we had more FT in-house developers than remote resources. The only reason we got remote workers because it was next to impossible to find good developers. We initially had a terrible experience with remote workers and it didn't work out at all. But we learned from our mistakes and made it work later on. When I left the company, 100% of its development (i.e. maintenance) is done offshore.
copperx 10y ago
Wasn't the rewrite was a technical success despite warning signs? The customer simply didn't want to adopt the shiny new software.
- perseus323 10y ago
  The rewrite was a technical success. But we missed real business opportunities and completely underestimated the effort of building a new system while maintaining the legacy one in parallel. In short, we didn't prioritize and miscalculated big time :-) The customer confidence in us had eroded because we weren't responding to their new feature requests in the legacy system. Plus their management didn't want to take any risks since the new system offered to new features to them and only benefited us.
  - skj 10y ago
    What about responding to their feature requests... in the new system? ! Then they'd have the motivation to make the switch.
    - chris_wot 10y ago
      That's the problem. From my reading of the article, their client was, probably legitimately, concerned with the risk of a cutover to a new and unproven system. To implement a new system the client always needs to do UAT. That's actually a drain on their resources, and if they have a working system it is far better to have incremental changes made and a regular set if bug fixes than to launch a new system, then find a raft of new bugs or unexpected changes that need to be fixed anyway. Existing systems allow enterprises to operate effectively. New systems almost always cause unexpected disruption to a business regardless of efficiencies gained from the new system. And most IT systems are to support the objectives if the business, they aren't the actual objective if the business. A software development company can lose sight of this because it IS the objective of their business :-)
      - perseus323 10y ago
        Good point. The UAT was definitely one of the reasons. It was several Excel spreadsheets long and scheduling it was a pain :-) Also, it was a hosted service and client saw no value to them- just the pain. There was risk of service outage during the upgrade that would have had resulted in the loss of revenue. Also, the client had to provision extra resources to run Cassandra/SOA servers. In short, it was a lot of work for them with no benefit to them.
    - perseus323 10y ago
      We tried that and that's how we eventually got them to switch - 2 years later. The client required a feature to start 'live sessions' with mobile subscribers whenever they were active on the network (made or received a call) and support for multi-level menus. The original architecture was transactional and they understood its limitations. The rewrite used SEDA and we were having latency issues, gc and memory issues handling live sessions with SEDA. So we had to do another upgrade to switch from SEDA to Actor based model that worked. The next upgrade was small and incremental compared to the first one very and we had the system ready by the time contract was finalized.
- aytekin 10y ago
  There is no way to know if it was a technical success since it was never used by real customers. It might be full of bugs and bad decisions. In fact, by default unused code should be assumed to be full of bugs and problems. That's the reason behind the success of continuous integration and deployment. At least bad code stay hidden for a very short time and needs to be fixed before other things can be built on top of it.
- pjc50 10y ago
  "The operation was a success, but the patient died"
eganist 10y ago
> If you don't have the talent to do the rewrite, consultants and remote developers in India are only going to make things worse. I don't think this is necessarily a given, but I see where you're coming from with the overall perspective. To get closer to the point of the post: unless there are truly solid and unavoidable blockers, e.g. substantial architectural defects that just can't be resolved without a major rework, a rewrite of any capacity should probably be off the table. Although I'm sure there are others that I have no insight into, the only "successful" commercial rewrite I can think of would be Windows Vista, and that only made that version of Windows somewhat releasable. Even then, that wasn't a total reboot even of the project; it was a partial rewrite off of a different codebase with as much code salvaged from the original project as possible (the initial Longhorn builds on top of the XP codebase were a total trainwreck, driving the partial reboot on top of Server 2003's codebase instead). They still needed two service packs to make Vista stable, and it took an entire subsequent major release (7) to right the ship, so to speak.
- chris_wot 10y ago
  There would be nothing preventing a rewrite of core subsystems. Vista, despite it being a disaster for Microsoft, was only problematic because of changes made to the UX. Actually Vista is interesting. For all its problems, it's actually an impressive upgrade - whilst there was development chaos due to a lack of focus, a new management team was able to significantly focus in on what needed to be done and hundred of improvements were made under the hood. Microsoft rewrote their TCP/IP stack from scratch and included important system administration tools like an improved logging system, performance and reliability tools, a vastly improved desktop window manager, a new graphics driver model called WDDM and a raft of new kernel security measures. These rewrites weren't rewrites of the entirety of Windows, but instead Windows was increasingly modularised and entire subsystems were rewritten. Whilst Vista was a disaster and had some real problems I don't think it was because of rewriting subsystems, I think it was due to UX changes. Interestingly, Windows 7 was an amazing success and in fact built on Windows Vista, but again focused on modularisation and leveraging the work done in Vista. My hypothesis that major UX changes caused Microsoft to stumble in Windows is born out by Windows 8 - which was even more stable and performed better than Windows 7, but was rejected in the market because of insane UX decisions. So a major rework can be done, but if you are going to do this then I suggest that major changes to UX should be done after the rework. I don't think you can avoid major rework though. Without some of the things I highlight above, there is no way Microsoft would be able to improve their code or implement features that actual make sense!

chris_wot 10y ago

This is one of the reasons I love working on LibreOffice. I think most people acknowledge that LibreOffice is a pretty decent office suite. But it is just over 30 years old now and it has acreted massive amounts of legacy code, some questionable design decisions and in terms of often trying to track it in version control it can be a nightmare if you go back far enough. But it would definitely be a mistake to rewrite it from scratch. There are millions of users who rely on it, and it's a massive code base that runs on three major operating systems - four if you include Android. Instead, the LibreOffice developers are slowly working through refactoring the code base. They are doing this quietly and carefully, bit by bit. Massive changes are being done in a strategic fashion. Here are some things: * changed the build system from a custom dmake based system to GNU guild - leading to reduced build times and improving development efficiency * the excising of custom C++ containers and iterates with ones from the C++ Standard Template Library * changing UI descriptor files from the proprietary .src/.hrc format to Glade .ui files * proper reference counting for widgets in the VCL module * an OpenGL backend in the VCL module * removal of mountains of unneeded code * cleanup of comments, in particular a real push to translate the huge number of German comments to English * use of Coverity's static analysis tool to locate thousands and thousands of potential bugs most of which have been resolved * a huge amount of unit tests to catch regressions quickly This has allowed LibreOffice to make massive improvements in just about every area. It has also allowed new features like tiled rendering - used for Android and LibreOffice Online, the VCL demo which helps improve VCL performance, filter improvements which has increased Office compatibility and allowed importing older formats, a redesign of dialogue boxes, menus and toolbars which has streamlined the workflow in ways that make sense and are non-disruptive to existing users, and many more improvements which I probably don't know about it has slipped my mind. But my point is - if LibreOffice had decided to do a rewrite it would have been a failure. It is far better to refactor a code base that is widely used than to rewrite it, for all the reasons the article says.

pg_bot 10y ago

The only cases where I've seen rewrites work are when the software fails to consistently complete the task it was written to do. A lot of software is garbage but gets the job done. When you encounter hot spots its best to slowly refactor until you get the system where it needs to be. Lots of little changes mitigate risk, and it is easier to track down bugs if you make a mistake.

fallous 10y ago

Unfortunately this is a lesson that often has to be learned the hard way when you have a lead or team that lacks experience/wisdom. If you can survive that educational expense, you end up much better for it but it's painful nonetheless. Aesthetics are never a legitimate reason to replace a functioning system with something else. I do not care how it offends the eye, the mind, the ear, or any other sensation you have... if it does not have a fundamental functional problem your best option is to maintain or plan an incremental rolling replacement that is tightly scoped at each step. For large systems that do present functional problems, identify the egregious offenders in that system, abstract the entities/behaviors most responsible, and replace-in-place in a Ship of Theseus fashion. Despite how familiar you believe you are with a monolithic or complex inter-dependent system, you will discover how much you don't actually understand about how it works as a whole if you try and re-implement in its entirety.

tonyarkles 10y ago
I perpetually love the references to Ship of Theseus, and find it particularly applicable to this problem. You mention fundamental functional problems, and I'd like to add something: sometimes it's not a functional problem, but a changeability problem. The code functions fine, but the process of adding a new feature is incredibly painful. I've done big-bang partial rewrites of systems before, quite successfully, but I've got a Ship of Theseus rule of my own that I follow: no new features during the rewrite, and no missing features. The first example that comes to mind was a rather complicated front-end application that had become a total spaghetti disaster. It had been written using Backbone, and from my research it fit the Angular model of things quite well. I took a pound of coffee with me out to the cabin for a weekend, and rewrote the whole frontend. Side-by-side. I started with the first screen, and walked through every code path to populate a queue of screens that were reachable from there. Implement a screen, capture its outbound links, repeat. Nothing changed, but everything changed. The stylesheet was gnarly too, but I left it 100% untouched. That comes later. By keeping the stylesheet intact, I (somewhat) ensured that the new implementation used identical markup to the old system. The markup was gnarly too, but keeping it identical helped to ensure that nothing got missed. 48-72ish hours later, I emerged a bit scraggly and the rest of the team started going over it. They found 1 or 2 minor things, but within a week or so we did a full cut-over. The best part? Unlike the article, clients had no outward indication that anything had changed. There was no outcry, even though about a quarter of the code in the system had been thrown out.

ereyes01 10y ago

Ill-fated code rewrite crusades often seem to be linked with the Second System Effect (https://umich.instructure.com/files/884126/download?download_frd=1 https://umich.instructure.com/files/884126/download?download... ... page 55). Excerpt: An architect's first work is apt to be spare and clean. He knows he doesn't know what he's doing, so he does it carefully and with great restraint. As he designs the first work, frill after frill and embellishment after embellishment occur to him. These get stored away to be used "next time." Sooner or later the first system is finished, and the architect, with firm confidence and a demonstrated mastery of that class of systems, is ready to build a second system. This second is the most dangerous system a man ever designs. When he does his third and later ones, his prior experiences will confirm each other as to the general characteristics of such systems, and their differences will identify those parts of his experience that are particular and not generalizable. And from the OP, frill by frill :-) I wanted to try out new, shinny technologies like Apache Cassandra, Virtualization, Binary Protocols, Service Oriented Architecture, etc. To OP's credit, he took a step back and learned from his mistakes. Also related... Second System Effect may not only apply for your second system ever. It may also bite you designing the second system in a new problem domain you're unfamiliar with. I can admit I've built a few second systems in my time ;-)

Terr_ 10y ago
I hope/like-to-think that the second-system that focuses on architectural-features is better than the second-system that focuses on new user-features. Stuff like "no global variables" or "actually use database transactions" or "support UTF-8"...
- kinghajj 10y ago
  "Remember that time zones are a thing and not everyone is in America/Los_Angeles..."
  - kuschku 10y ago
    That’s why I personally love most european companies, as most just assume UTC.

whichdan 10y ago

Part of me was really hoping that some startup had written an MVP in Scratch and was seeing how far it could scale.

rdtsc 10y ago

Software is re-written most often for political reasons, namely for new developers to leave a mark, and put a good line in their resume. Everyone likes to read "designed and implemented" on a resume than "maintained and fixed annoying bugs here and there". We know what looks better, managers know who they'd move to the next round, and so on. The only thing is, if there is no software to be written software developers will always find a reason to write software. Because they get paid full time, usually above what other professions get paid, to well, ... write software. I think other reasons such as "it is slow, outdated, not written in <latest-language-fad>, bad UI", are often brought up and used as excuses. But underlying reasons are a lot more personal and subjective.

hibikir 10y ago

I rewrote from scratch once, after much deliberation and was successful. In my case, I had some extremely good reasons: The original codebase was build using good old waterfall, where neither programmers nor testers had ever met a user in their life. So all the things that are good about working software kind of go out the window: There are a lot of abstractions in the code, but they didn't match the user's mental model, or helped in any way. My users didn't like the software at all. It might have me their requirements in theory, but not in practice. The team that had built the application was pretty much gone, nobody that had any responsibility in any design decision was still in the company. I actually had managed to get access to people that actually used the software, and people that supported those users, so relying on them, I was able to get a model of the world far better than the original developers ever did. 300K lines of Java, written over three years by 10+ developers were rewritten by a team of two in three months. All the functionality that anyone used was still there, but actually implemented in ways that made sense for user workflows. I'd not have dared a rewrite had the situation been better though: Working code people want to use trumps everything.

danieltillett 10y ago
I have always felt that if you need more than 3 developers and 12 months then the software is too big and the scope needs to be cut down. Better a small program that does one thing well than a monolith that does everything badly - why do we never learn from the UNIX philosophy.
- mafro 10y ago
  I think what you're referring to is what the kids call "microservices".
auxbuss 10y ago
Three months = 60 working days. Two devs, so 120 working days. 300k lines of code. So, 2500 lines of production code rewritten per day. Sustained for three months. No holiday. No days off. And this code was tested to be equivalent of the old code. So, let's say, being conservative, another 2500 lines of test code per day. (It's a lot more that, of course, in most cases.) So 5000 lines of working, tested code per day. Plus, the team of two were checking in with the users to make sure everything was hunky dory. And the new team was designing a new "model of the world far better than the original developers ever did". I'd have gone along with that bullshit until the final sentence: Working code people want to use trumps everything. No, no, young ninja, rock star, Jedi: Working maintainable code trumps everything.

peterbotond 10y ago

I have incrementally refactored large codebases by committing to a guide of which constructs to replace with what, what is the final goal and writing test cases. Once the guide was seen beneficial by other developers, rather they were forced to use it, they were surprised how well that worked. All this was behind the scene from the customer and updates bugfixes were going out. Re-write may be the answer sometimes, many times, a well thought incremental re-factoring guide is an easier path.

_navaneethan 10y ago

"Incremental change is always better for testability and validating the existing features" - from 97 things every programmer should know

hinkley 10y ago

I no longer believe in rewrites. I used to believe that every company gets one rewrite, but only because I have seen that most places have the patience and the stamina for a little bit less than a single rewrite, but I was on the fence about whether they were a good idea anyway. Trouble is, I could never put my finger on why, other than that it never seemed to fix the problem. It was a bit like moving to a new city to start over and finding out you brought all your problems with you. In the last couple of years I have begin to figure out what I know in a way I can articulate. The people who have the skills and discipline to take advantage of a rewrite don't need a rewrite. It's a short distance from that skill set to being able to break the problem down and fix it piece by piece. They just need permission to fix key bits, one bite at a time, and they've probably already insisted on the space to do it, although they may be clever enough never to have said it out loud. They just do it. Then you have the people who don't have the skills and discipline to continuously improve their code. What the rewrite buys them is a year of nobody yelling at them about how crappy the code is. They have all the goodwill and the hopes of the organization riding on their magical rewrite. They've reset the Animosity Clock and get a do-over. However, as the time starts to run down, they will make all of the same mistakes because they couldn't ever decompose big problems in the first place, and they lack the patience to stick with their course and not chicken out. They go back to creating messes as they go, if they ever actually stopped to begin with. Some of them wouldn't recognize the mess until after its done anyway. In short, people who ask for a rewrite don't deserve a rewrite, and would squander it if they did. It's a stall tactic and an expensive dream. The ones who can handle a rewrite already are. They never stopped rewriting. Now, I've left out all of the problems that can come from the business side, and in many cases the blame lies squarely with them (and the pattern isn't all that different). In that case it might take the rewrite for everyone to see how inflexible, unreasonable and demanding the business side is, and so Garbage In, Garbage Out rules the day. But the people with the self respect to not put up with it have moved on, or gotten jaded and bitter in the process.

raverbashing 10y ago
I definitely agree A rewrite is more useful when the original project is irrevocably doomed (bad/obsolete framework, needs a new language, etc) Most of the time you can refactor the original code

cdevs 10y ago

I'm facing this at work and wanting to rewrite, updates are to slow when one small change needs 1000 other changes in spaghetti code in piles of scripts... Difference is we can roll our users over as they renew and in a year after release all new customers and old will have the same software. Only about 2000 users not as big as a scale as the story here.

Ace17 10y ago

A lack of design skills and code-cleaning skills can mislead you into thinking "the code needs to be rewritten from scratch". However, as the new code grows, you're going to need badly these very skills anyways.

hoodoof 10y ago

The new Software Development Manager always wants to rewrite the code from scratch. That's the way it's always been. I like that the guy who wrote this post had the courage to admit that he was motivated partly by the desire to play with new tech. reply

deleted 10y ago

[deleted]

craigvn 10y ago

I think there are only two reasons to rewrite. 1) When you need to support a different platform, ie we have a Windows Desktop app and want a Web or Mobile or Mac. 2) When the code base is so bad adding any new features creates many time more bugs.

wink 10y ago

Interestingly I've hardly seen this 'rewrite' vs 'no rewrite' debate regarding to microservices, with all the talk about them. In theory it shouldn't be more work (as they are supposed to be so small) than some refactoring in your old (big) piece of software, and you can even rewrite it in a different language.

pramalin 10y ago

Survived a complete rewrite for a client just now. The previous team blindly relied on a single method from Spring framework's RestTemplate for every rest service calls with SAP backend. ResponseEntity<T> exchange(String url, HttpMethod method, HttpEntity<?> requestEntity, Class<T> responseType, Object... uriVariables) throws RestClientException (ref: https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/client/RestTemplate.html https://docs.spring.io/spring/docs/current/javadoc-api/org/s...) This forsed them to create object models structured to match the complicated and inconsitent request and response JSON strings that SAP used, instead of creating the objects modeled after the business domains. The result was no surprise was a disaster and the client wasted five months with them and I had to redo and complete the project still on time. I still see many teams make their function signatures in Java so convoluted like below and don't know what hit them. interface ToDoService { ListToDoResponse listToDo(ListToDoRequest request) throws ListToDoException; AddToDoResponse addToDo(AddToDoRequest request) throws AddToDoException; .. and so on .. }

mikevm 10y ago
Can you shed some light on how to best solve this problem? I'm pretty much in the same boat with a restful service I depend on.

erikb 10y ago

That guy really has a done a rewrite and then got it back to the point where it is used. That is what I felt when reading the article. Many people just rewrite and then complain that their rewrite never gets used. So they don't draw the important conclusions and the next time they will try it again. If you really push yourself, your team and the users to using the rewrite and getting it back on track with the original solution, then you have to go through all the disappointments of your rewrite not being better than the original, the real pains you induce in your users, and solve so many problems you've never signed up for solving because you didn't know that the old, ugly solution actually solved these as well. The pain of reading, understanding and fixing/improving the old, ugly solftware is never that painful. And the value is much more immediate since your users already use and know the old software.

mtrn 10y ago

I don't believe in rewrites. But I believe in the evolution of the understanding, what a system is supposed to do and how to do it. A customer might have a lofty web-scale vision, the first version is built with all scaling and no maintenance in mind. You are then faced with a decision: carry along the visionary nightmare and get almost no real work done, because the system itself is in the way, or rewrite the system with a fresh, minimal approach, focusing on a valuable target. The point being: Software requirements evolve and sometimes, writing a first version of the software is the spec itself. Just as with specs, you can try to scavenge all good things from the previous version for the next one - and actually getting better over time, despite being in a rewrite mode.

freework 10y ago

> The development officially began in Summer of 2012 and we set end of January, 2013 as the release date. This is the problem right there. In my experience, successful rewrites only happen when they get done quickly. If you know exactly what you're re-writing, you can get it done within a few days. If you have no idea what you're doing and think it'll take more than a week, it will probably end in failure. The truth is, I re-write code almost every day in my programming life. I usually don't realize I'm rewriting something until after the fact.

DonHopkins 10y ago

"While parts of code were bad, we could have easily fixed them with refactoring if we had taken time to read and understand the source code that was written by other people." This is the thing. Many people just HATE and REFUSE to read other people's code. Maybe they just don't teach code reading and reviewing in computer science classes, but they should. Printing it out on paper and reading it away from the computer is helpful, but a lot of people write code for wide screens that doesn't print out well, or they just don't give a shit and it looks terrible even on the screen. And some people just don't have the stomach for reading through a huge pile of pages, or think that's below their station in life. But reading code is one of the best most essential ways to learn how to program, how to use libraries, how to write code that fits into existing practices, how to learn cool tricks and techniques you would have never thought of on your own, and how to gain perspective on code you wrote yourself, just as musicians should constantly listen to other people's music as well as their own. I just don't feel safe using a library I haven't at least skimmed over to get an idea of how it's doing what it promises to do. There are ways to make reading code less painful and time consuming, like running it under a debugger and reading it while it's running in the context of a stack and environment, looking at live objects, setting breakpoints and tracing through the execution. Code reading and reviewing is so important, and it should be one of the first ways people learn to program, and something experienced programmers do all the time. And of course as the old saying goes, code should be written first and foremost for other people (preferably psychopaths who have your home address, photos of your children, and your social security number) to read, and only incidentally for the computer to execute.

stevetrewick 10y ago
>Maybe they just don't teach that in computer science classes, but they should. Should they? This seems like a classic conflation of computer science with programming. Perhaps the reason this important craft skill is not taught in CS is because it has nothing to do with complexity classes, automata theory, etc. Programming != CS
- DonHopkins 10y ago
  They aren't the same, but they aren't mutually exclusive either. I think all computer scientists should learn to program, and learning to program requires getting over your distaste of reading other people's code. I doubt a pure academic "computer scientist" who doesn't like to get their hands dirty reading or writing code because they look down on it as a "craft" is going to be of much use on the types of projects we're discussing that require rewriting or refactoring existing code.

chrisan 10y ago

What are everyone's thoughts on rewriting in order to simplify your developer overhead with the likes of React? We are a small shop and have a non-game app for html, ios, and android. The non-public (used by less than 30 people) backend has two management interfaces in, you might want to sit down for this, Adobe Flex. There are 2 full time developers (1 backend/flex/html and 1 ios/html) and 1-3 part time (android/ios) contractors depending on workload/deadlines. Everyone is pretty siloed with mostly 1 additional cross over app. I have read articles similar to this as well as worked with some greybeards that carry this philosophy of staying the course and righting the ship rather than jumpin. However, this siren's song of React is luring me in with their philosophy of "learn once, write anywhere"[0]. Instead of siloed developers we'd simply have developers that would feel comfortable in [management interface/html/ios/android] [0]: https://facebook.github.io/react/blog/2015/03/26/introducing-react-native.html https://facebook.github.io/react/blog/2015/03/26/introducing...

douche 10y ago
Sometimes, you've got to dump the old stuff because it is just too painful to make changes on. I've rewritten more than a couple of projects that I inherited from less than competent outsourced contractors... Number one, these projects mostly didn't work, and had so many bugs that I'm not sure how it was ever shipped software that somebody paid for. Number two, it was all the worst kind of WebForms and Visual Basic monstrosity. I'm sure its possible to write non-terrible code with WebForms that looks good, but I've never seen it, and it was a matter of a couple weeks to burn it down and build a proper MVC application instead. My only regret there is that I waited too long to rewrite, and wasted a few months battling the manure pile of the old version and trying to improve it incrementally.

bernardlunn 10y ago

True story. Similar start. A couple of enterprise customers, kludgy old code. Changeability was the problem. Decision made for total rewrite. Budget no probs, team of 10 allocated. I was the guy who sold the deals. Wanted to assess if we had a disaster on our hands. Asked CTO to explain how team was constructed. Here is how the conversation went: Me: tell me about the team CTO: well it is actually all being built by two guys. Me: That's crazy. We have a 10 person team. CTO: Actually I lied, it is actually all being built by one guy. Before you get me fired, let me explain. One guy just builds prototypes to keep all those idiotic requests from management. Me: I knew the guy. Fastest damn developer on the planet CTO: we just throw his code away. The other guy who we don't let you meet actually writes the code that works. You see nothing for weeks, then it emerges and works beautifully. Me: what do you do with the other 8 guys? CTO: give them make work to keep them out of the way. The system was a market success for a long time.

nyir 10y ago
That's fascinating, was everyone involved in on the deal, or how did they manage to keep that under wraps?

CraigJPerry 10y ago

I want to try a re-write project at least once in my career. I've been thinking about how I might tackle it: The legacy system components are unlikely to have ideal boundaries (unless you're insanely lucky) due to organic growth. So step 1, identify key boundaries and implement them as libraries / micro services / whatever makes sense. Step 2, identify the highest value component to refactor - that might not be the part that makes the system go better for the users, it might be tackling the bit generating most support noise so you can free up more dev resource. Begin the refactoring with a release, the new component begins life as a shim between the component interface and the legacy component, calling out to the legacy component for all features initially but as functionality is migrated to the new component it gradually uses the legacy component less and less. You can always release at any time and you'll have a system using new code where it's written and falling back to old code where not. Lather, rinse, repeat. Key challenges I see during the refactoring are managing state during the refactoring of complex behaviors of the original component. It may lead to a private interface which is more granular but only exposed to the new replacement component. Interesting stuff for sure.

sferoze 10y ago

I recently faced the decision whether to rewrite I took over a rails + angular 1 codebase from another developer who left the company. I would be working on the project for few months. I rewrote the entire app with Meteor + React in few weeks. Best decision I ever made. Even though the app has same features, customers say the app is faster, has less bugs, and overall feels more solid. Security is also better because of the pub/sub system. It also gave me a chance to fully understand the ins and outs of the database and how the app works. I can also develop features much faster with Meteor + React than with Rails + Angular 1. So time spend re-writing is saved by enabling faster feature development.

brudgers 10y ago

Jeff Meyerson's interview with David Heinemeir Hanson [DHH] includes rewriting software. It discusses the reasons rewrites have a bad reputation and the difference between rewriting because "it's not my code/language/idiom" and declaring "technical bankruptcy" as an extension of the technical debt metaphor. Agree with DHH or not, he's thought deeply about a lot of software development tropes. http://softwareengineeringdaily.com/2016/01/13/the-evolution-of-rails-with-david-heinemeier-hansson/ http://softwareengineeringdaily.com/2016/01/13/the-evolution...

dham 10y ago
I listen to every DHH interview I can but his view on a rewrite is different than others that do rewrites. There is no "second system" per say in his world. He leaves the old system up for people that still think it works just fine. Instead of messing up the old versions with upgrades, they leave them up and if a customer wants to go to new version that is "rewritten" they can.

tekism 10y ago

"and changed our protocols to binary, all at the same time. " What does the author mean by that statement?

jv22222 10y ago

This is why all developers should build their own framework from scratch in their spare time... It scratches the itch and helps one appreciate existing software.