Signavio challenge

signavio/thought-process.md

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+Looks like I need to parse the file, process data while parsing and prepare it for fast reading.
+
+Let's start with reading the data first.
+
+One consideration, from the task details, I am not sure should I create a service for this,
+but since it says that other components need to read from this one, looks like web service is a valid option.
+I will create micro micro-service.
+
+I will use standard web service code structure (controller, service, model).
+It is not necessary in this case, but if project grow up just a bit,
+it would be helpful to have clean design.
+
+I will be using Lombok to avoid boilerplate code in controller, service and model classes.
+
+Introducing ActivityCsvParser to read CSV file.
+Having enhancement so it is not only reading CSV, but collecting activities by Case ID.
+I am doing this to avoid multiple iteration through the list of parsed items.
+
+I did intuitive way implementation with following steps:
+reading activities, grouping, finding all variants and finding top variants,
+but it is not performing well (takes around 150ms to finish).
+
+After getting proper inner analysis, I noticed that ObjectMapper was taking more time than Gson
+for translating object to Json string, so I replaced it.
+
+Also, I noticed that first run is taking much more time than any following run.
+That makes sense since in first run, Java is initializing all the necessary classes.
+Any following run is dramatically faster. And real case scenario would be
+this service to be running and other services to call it.
+So I created performance test "ProcessIntelligencePTest"
+where I am calling function 100 times and calculate the average time.
+
+While looking for the best solution, I had idea to cache the response in the very beginning.
+That idea make service works much better in non cached scenario,
+since Java initialized all the classes necessary while running first caching method.
+I will leave it, just to make performance better.
+
+Later on, I had to remove the feature of mapping cases while reading CSV file,
+since I am reading CSV file only once and use it as a database.
+I am doing this to make solution according to task description.
+
+On second thinking about solution, I would say that "component"
+that would be interacting with this service might be another class,
+so I am removing micro-service approach and making this solution
+as a class ("ProcessIntelligence.java") to avoid over-engineering.
+It is very easy to create micro-service if necessary.
+
+I copied provided CSV file into standard Java resource folder,
+where I believe it belongs, so if you want to change input data,
+please use resource folder for that. 
+
+### How to run
+You can run solution once, by executing command:
+`gradlew run` on Windows or `./gradlew run` on Linux
+
+### Notes
+If you are changing any code, and you want to build the project (`gradlew clean build`),
+please run command `gradlew spotlessApply` before building
+since I am using plugin to avoid non formatted code to be pushed.