From which side to approach JAVA EE?

Question

Java

A number of tasks on the server java fell on my head. There is no one to solve them except for me so far :( I don’t want to blurt out on stackoverflow.
I know Java core because I myself am an android. I don’t disdain books, but I haven’t been able to choose a specific one yet.
Tell me the sequence of study, in stages.
Thank you

Answer 1

The sequence of study by stages:
The first and decisive stage, at which the student realizes what exactly is called JEE (that it is not so much about a specific version of some binaries that can be downloaded from the Oracle website if you accidentally click on the wrong button, but on specification stack, each has at least a few implementations, etc.)
and according to the results, it is determined where to start, in the light of the tasks that have fallen down. Most likely, you will have to start with what containers are, in particular CDI, and providers, in particular the persistence API, aka JPA, aka ORM (what is it, what is called an application server, and what is a servlet container, or, roughly , what is the difference between, for example, Wildfly and Tomcat, how Hybernate relates to them and what the hell came up with Spring), and also what modules and profiles are. Understanding the fundamental architecture of JEE, even if only superficially, is the basis, without which any further training will be a useless mumbling of incomprehensible mantras.
Stage two, in which the student chooses a specific JEE sect, joins it and rewrites the apartment in the name of the guru. Yes, yes - in JEE everything is exactly like in life. There is only one specification, but, of course, there is a sea of ​​"most correct" implementations... When you come to start with one of them (perhaps, the tasks that have fallen down already somehow concretize the choice). In any case, the stage ends with the download and installation (first locally, to poke your finger, then on the servers) of some server / servlet container, database server and deployment and launching the first HelloWorld JEE application according to the tutorial and with the help of a large number of such and such mother (because you have to deal with configurations, descriptors, access rights and other settings, which are all completely obvious when you already understand, but look like magic when you step on them for the first time).
The third stage, the most dramatic one, at which the question “why is it all necessary” can bring the student to a nervous breakdown when he tries to “quickly” finish the newly launched HelloWorld to the functionality he needs. At this stage, all sorts of JMS, JAX-RS, JAAS and other incomprehensible things that flickered at the first stage are recalled, previously "unimportant nuances" of the language, like ClassLoader or serialization, suddenly turn out to be key, etc. etc. This is the most important and longest stage of learning. It can be considered passed when: A. grown to the size of an elephant with one leg and three trunks HelloWorld comes the understanding that in JEE you can’t just take it and finish it off the bullshit ... even if it seems that you can, retribution will still come. B. tried different databases, different implementations and updates of some specifications, different IDEs and plugins for them, and everything is useless - nowhere, even in paid tools, there is a button "make everything Feng Shui", and, finally, V. the student understands that all this HER crap was invented with with one single purpose - to prevent the use of what is done "so that it somehow works", leaving only "done right". Of course, it is impossible to win this battle, but on the other hand, you can fight for a long and interesting time with various hacks, esoteric frameworks, and up to instrumentalization of bytecode... there is no limit to fantasy. This is the essence of learning JEE - to understand how to do it right, and how - to yourself. that all this ITS crap was invented with one single purpose - to prevent the use of what was done "so that it somehow worked", leaving only "done correctly". Of course, it is impossible to win this battle, but on the other hand, you can fight for a long and interesting time with various hacks, esoteric frameworks, and up to instrumentalization of bytecode... there is no limit to fantasy. This is the essence of learning JEE - to understand how to do it right, and how - to yourself. that all this ITS crap was invented with one single purpose - to prevent the use of what was done "so that it somehow worked", leaving only "done correctly". Of course, it is impossible to win this battle, but on the other hand, you can fight for a long and interesting time with various hacks, esoteric frameworks, and up to instrumentalization of bytecode... there is no limit to fantasy. This is the essence of learning JEE - to understand how to do it right, and how - to yourself.
The next stage already, in fact, does not apply to training - this is practice. On it, the survivors begin to build the application architecture from scratch, choose solutions within the framework of the set of technologies offered by EE, constantly thinking about scaling, fault tolerance of these solutions, etc. etc. The main thought at this stage: "Damn, how could I have done differently before" ...