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Defensive programming archivos - AwakeDeveloper AwakeDeveloper Linus Torvalds: "Most good programmers do programming not considering they expect to get paid or get unctuousness by the public, but considering it is fun to program"   Skip to content HomeSix weightier blogs well-nigh programming and wiry Tag Archives: Defensive programming No comments Defensive Programming and Resilient Systems   By admin December 15, 2016 December 19, 2016LawmakingQuality Although you have ripened your software with TDD and your using has 100% coverage. It is likely which there will be some bugs in production environment, due to Murphy’s Law: “Anything that can possibly go wrong, does” As pragmatic programmers, we have to be hair-trigger with our lawmaking and our programming way, but sometimes this is not enough, and we have to try to baby-sit our using of the production bugs, in wing our system should survive failures. In my opinion, It is increasingly important goof quick than the user or consumer is waiting for any response of our using which never happens, besides it is very important to snift when the system fails, due to the error can be unprotected and fixed, moreover an email or flipside kind of alarm could be sent  in order to start to research what problem has happened. Assertions In my wits as developer in variegated Companies, when you have to do a report for some people, you have to create a file, you have to save it in some directory and perhaps, that directory is not still created or the using did not have permissions to write in it. So the process will goof and an issue will be opened. For this reason, the unexpected conditions should be checked and Assertions (asserts) can be used. In our case, with an interjection or flipside kind of verification well-nigh the directory and permissions would have avoided the previous issue. In the bookLawmakingComplete Second Edition, there are some rules regarding assertions that you should take in account: That an input parameter’s value falls within its expected range (or an output parameter’s value does) That a file or stream is unshut (or closed) when a routine begins executing (or when it ends executing) That a file or stream is at the whence (or end) when a routine begins executing (or when it ends executing) That a file or stream is unshut for read-only, write-only, or both read and write That the value of an input-only variable is not reverted by a routine That a pointer or element is non-null That an variety or other container passed into a routine can contain at least X number of data elements That a table has been initialized to contain real values That a container is empty (or full) when a routine begins executing (or when it finishes) That the results from a highly optimized, complicated routine match the results from a slower but unmistakably written routine An example of a groovy interjection would be the following:InterjectionExample Java public void riseWrongReportAssertion(){ File emptyReportDirectory = new File(DIRECTORY_NAME) log.info "Before assert..." try{ predicate emptyReportDirectory.canWrite() }catch (AssertionError ex){ log.warning "Directory can not be write" // First option: Fix the problem emptyReportDirectory.setWritable(Boolean.TRUE) // Second option: Raise a precondition exception //throw new PreconditionException("Directory can not be written") } log.info("After assert...") } 123456789101112131415      public void riseWrongReportAssertion(){         File emptyReportDirectory = new File(DIRECTORY_NAME)        log.info "Before assert..."        try{            assert emptyReportDirectory.canWrite()        }catch (AssertionError ex){            log.warning "Directory can not be write"            // First option: Fix the problem            emptyReportDirectory.setWritable(Boolean.TRUE)            // Second option: Raise a precondition exception            //throw new PreconditionException("Directory can not be written")        }        log.info("After assert...")    }   On the one hand, if you want to use assertions in variegated places of your code, you can generalize your solution, this is an specific example. On the other hand, be shielding with the assertions in production environment, they can reduce the performance of your application.Full-lengthdisablingFlipsidesituation, that I have seen during my career, has been when you deploy a particular minutiae which has been included in a  key component. If it is not working properly and you can not deactivate it. A good practice, which you can use to stave downtimes in your system, is full-length disabling, although it is not the clearest solution. This technique consists in including an if statment in order to excute or not a part of lawmaking depends on any configuration. Example:Full-lengthDisabling Example Java // do first deportment if(genericDao.retrieveConfigurationProperty("activateNewDevelopment")){ //do some deportment } else { //do flipside deportment } // do increasingly deportment 12345678910111213 // do first actions if(genericDao.retrieveConfigurationProperty("activateNewDevelopment")){     //do some actions } else {    //do flipside actions } // do increasingly deportment   If you ask me, the configuration should be in the database, considering you can transpiration it without deploying the using again. The other possibility is to use a properties file, but in this specimen you would need to reboot your using server, which  would produce a downtime.Zestfulsystems Other problem, which you can find in production environment, is when you have a process which never finishes and you have no alarms or alerts. So… How can I know that the process has failed? Maybe somebody reminds you which you have a report who nobody has received or maybe not. Hence It is very important to manage if a process should have finished. In this way, you can add an zestful or timeout, when the process is running although it should have achieved successfully. Then you can research quickly, what it happens so as to fix the problem and restore the service. During this article, we have talked well-nigh alarms, alerts and reports systems. All of them should be out our using to work when our system has failed, otherwise the IT team would not visualize whether the system is working or not.Flipsidefeatures of the Logs should be: Readeable (By human or machine) Do not indulge unravel lines (New appenders Log4j2 or Logback can be configured to show the info in one line) Do not mix variegated information Show the important information (user ids, emails….) Split the logs well-nigh the variegated services Use daily rollings Integration with other systems Currently, scrutinizingly all the using or sites are working with microservices or they have to connect to other services or databases. For these cases the health checks are very important, due to they snift whether the provider services are falling or not. Depending on their responses, the using will be deployed or not. In addition, when your are unfluctuating with a provider service or database, you are going to slosh their responses, and perhaps the data, which they provide, are not the weightier for your using or they are wrong, so you can create a vallation where you can validate and transform the data. With the new data your system will work properly scrutinizingly always. If your system detects an error data, you must decide what the system does with that data. In theLawmakingComplete book, the tragedian proposes some techniques which can help you to decide : Return a neutral value: Sometimes the weightier response to bad data is to protract operating  and simply return a value that’s known to be harmless. Substitute the next piece of valid data: When processing a stream of data, some circumstances  call for simply returning the next valid data. If you’re reading records  from a database and encounter a corrupted record, you might simply protract reading  until you find a valid record. Substitute the closest legal value: In some cases, you might segregate to return the closest  legal value, as in the Velocity example earlier. This is often a reasonable tideway  when taking readings from a calibrated instrument. The thermometer might be calibrated  between 0 and 100 degrees Celsius, for example. Log a warning message to a file: When bad data is detected, you might segregate to log a warning message to a file and then protract on. This tideway can be used in conjunction with other techniques. Call an error-processing routine/object:Flipsideapproach is to centralize error handling  in a global error-handling routine or error-handling object. The wholesomeness of this  approach is that error-processing responsibility can be centralized, which can make  debugging easier. Display an error message wherever the error is encountered: This tideway minimizes  error-handling overhead; however, it does have the potential to spread user  interface messages through the unshortened application, which can create challenges when  you need to create a resulting user interface. Shut down: Some systems shut lanugo whenever they snift an error. This tideway  is useful in safety-critical applications. In conclusion, we have to know which there will be bugs in production environment, but as pragmatic programmers we have to try to reach a system without downtimes and bugs, for these goals, the defensive programming tools are very important. However, if the bugs happen, try to solve it as soon as possible. Although you use defensive programming,please you do not forget to alimony on using  S.O.L.I.D, lawmaking reviews, tests and TDD. References: Joaquín Engelmo – Programación defensiva y sistemas resilientes en el mundo real 8 formas de mejorar tu vida gracias a los LogsLawmakingComplete Second Edition Tagged   Defensive programming Search for: Search Últimos TweetsNew vendible has been published: awakedeveloper.xyz/en/code-qua… I hope that it likes you Please provide your feedback! :D pic.twitter.com/puChPxDBLrOctober 15, 2017 2:05 pmGood tutorials for improving your javascript skills awakedeveloper.xyz/javascript/…December 23, 2016 4:30 pmMy new post well-nigh defensive programming and resilient system has been published: awakedeveloper.xyz/code-qualit… I expect your feedback!! :DDecember 15, 2016 5:45 pm Recent Posts How to reservation an Exception with Spock Javascript weightier practices: Good tutorials Defensive Programming and Resilient Systems Software engineer and knowledge Refactoring and GoodLawmakingCategoriesLawmakingQuality Javascript Unit Testing Martin Fowler: "Any fool can write lawmaking that a computer can understand. 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