I really love Grails but I was wondering how to get the performance benefits of Groovy 2.
The question is how to configure the development and production environments in order to get that "close to Java" performance boost.
So, if I setup:
* JDK 7
* Groovy 2 (indie JAR to use invokedynamic)
* Grails 2.2
are there any guidelines in order to really speed my webapp out-of-the-box?
And do I need to do any re-factoring in my Grails webapp codebase? I mean that dependency injection stuff like referencing services in controllers should be statically compiled or should I keep writing code as the docs say?
ps: I guess Groovy #CompileStatic and Grails might be a relevant question...
It depends on what might be slowing your web application down :) I know "it depends" is so often the answer, but it's still true.
Anyway, I've asked around and it seems that Grails and invokedynamic won't go together just yet. The reloading agent needs updating and there may be problems with the cglib/asm libraries used by Hibernate.
Regardless, internally Grails is making more and more use of #CompileStatic (for the stuff that wasn't already written in Java), so unless your app is doing a lot of work itself, you're unlikely to see a big boost with invokedynamic.
It would be useful to have some official information on this, but it's not out there right now.
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I have been given a project to work on, and I know that in order to make efficient progress I need a good mental model of how things work together. I am supposed to be using an IDE of my choice, as well as Maven and Apache Tomcat to compile and build the project. I can do that, but the program is not fully functional, and because I don't understand how all the software works together, debugging is difficult. I have spent a lot of time researching how these things work, and what they do, but I am still not understanding. I know that Maven handles the dependencies, but I do not really understand what that means. I am confused by what Tomcat technically is, but I understand that it is needed to run dynamic programs. Beyond that, I do not understand how it works, or what it does. I also do not understand what happens between the IDE to the Tomcat server, as in, what is connecting them and how do I get my changes to affect what I see in my browser? Thank you!
Very short.
Maven builds your code by compiling the sources you write into byte code which the Java Virtual Machine can run, and include code written by others that your code needs. This is a good thing.
Tomcat has your compiled code (which needs to be in the form of a webapp) deployed to it, after which it can be run if appropriately invoked.
How the compiled code gets from your machine after Maven builds it, into Tomcat varies depending on the need of the team doing it, but during development this is often facilitated by your IDE - this typically also makes it easier to debug.
If at all possible, I would suggest finding a local mentor which can help you getting started because there is a lot of moving parts your need to have a basic understanding of.
The closest thing I've found is their Elasticsearch Plugins and Integrations
page, which doesn't help. I was following their out of date tutorial to make a "hello world" plugin, but I can't find any documentation on the classes used. Is there a page with information on what each class does, or do I have to look at the code to figure it out on my own?
To quote elastic search developer Adrien Grand(jpountz) "No, there is no guide about writing plugins and the API is actually quite unstable. The plugin API is mainly a way for us to provide additional functionality through plugins so that we do not have to fold everything into a single release artifact that would be quite huge. Some community membors have writter plugins by taking inspiration of existing plugins but we do not want to commit on a stable API for plugins as this might prevent us from improving other areas of elasticsearch."
The only real way of learning about developing a plugin is trying to find something similar and modifying it to suite your needs. Developing anything remotely complex will require an extensive knowledge of the ES codebase. I suggest you look into some plugins developed by jprante to get started.
What are the current downsides of Gradle? I have been researching different build tools but I haven't seen anything that seems to point out problems with Gradle as of October 2014. I have seen things a bit dated saying that Gradle users are on the bleeding edge. Is that still true or has Gradle reached decent point of maturity? (As far as I know, in terms of ide integration it might be more mature than others). Searching "why not use gradle" doesn't really help and "problems with gradle" shows people getting help (a plus). Most of what I have read were build tool comparisons and newer ones didn't list any flaws of Gradle.
Having not really used gradle except with libgdx projects I can't confirm issues presented in old comparisons still exist, but it seems like they don't.
The one thing I have seen that might be a problem is that it is "slow". If slowness is really an issue please explain how slow and what are the impacts.
Another somewhat reasonable downside is that people need to learn it to use it. To a person knowing how to use 0 tools this isn't really a problem and for others, it seems that Gradle is well documented and easy enough to learn.
I understand there are complications with switching and making sure the build still fully works so I am not asking what are the downsides of switching to gradle specifically but more generally why not use it now in a new project?
Looking for non opinionated reasons/problems.
I am currently using Gradle as part of Android Studio, and its working decently. For me I had a HUGE headache getting started because the default settings of Gradle requires internet connection for the initial build (I assume it was for updates) and it fails to build if it can't make communication with the internet the first time. (so there are some Firewall issue you might need to work around) So the only 'Con' I have to add is that Firewalls can be a problem with initial set up of Gradle.
We are evaluating reactor library for using it in our project. Our project was backed by spring context. So we needed a tool to build event-driven application which has the spring support.
Also our main area of focus was on ability to composing sequence of asynchronous events (Streams & Promises). In certain other use cases we might be in need of publisher/subscriber model or running long running processes asynchronously.
As I was evaluating, I noticed some of the following the latest released reactor-spring version is v1.1.3 with dependency on reactor-v1.1.3 which we could use.
But I also noticed the there’s reactor-v.2.0.0 (under development) which had quite a bit of changes especially in the area of Streams and Promises.
Please suggest me if it is a good idea for going with reactor-v1.1.3 with spring support or should we wait for reactor-v2.0 if we have to use more of Streams and Promises.
If we go ahead with reactor-v1.1.3.RELEASE how much code changes might be needed to get ourselves upgraded to v2.0.0.
I also wanted to check if we have any branch of ‘reactor samples’ for reactor-v1.1.3/v1.1.4. As of now I could see only one master branch available which has been updated to use reactor-v2.0.
Do we have the reactor API for latest release v1.1.4. Currently the API (https://reactor.github.io/docs/api/) points to Reactor 1.1.0 Release.
Where can I find the reactor-core-2.0.0 codebase? I am finding difficult to locate.
As I am new to this library, please feel free to correct me if any of my mentioned points/questions were incorrect. Thanks.
If you're starting new development, definitely go with Reactor 2.0. It's mainly the substantial improvements in the Stream and Promise APIs which resulted in having to bump the major version number. Differences in the rest of the codebase are pretty minimal. Converting between 1.1 code and 2.0 code requires some package renaming and a few tweaks here and there (like eliminating the use of the Deferred object in Stream 1.1).
The other major change that justifies a major point release bump is the implementation of the Reactive Streams specification. It's out of the scope of this question to discuss it further but it is an important part of Reactor moving forward. Being able to natively integrate with Akka Streams, Ratpack, RxJava, and other libraries that already (or will shortly) implement Reactive Streams is a huge benefit to Reactor 2.0.
The reactive-streams branch contains the code for Reactor 2.0. M1 is coming shortly and we'll start the process of updating the samples, though as you've noticed, some components like Spring support have already had to be bumped to Reactor 2.0 since they're relied on in some major almost-production applications.
I am not sure if the title of the question is correct, but please read the question.
I have been working on C/C++ for most part of my work life (close to 11 years). we only had C/C++ source/header files and all dependencies were managed by Makefiles. things were simple and manageable.
for the last 1.5 years i have shifted to Java domain. and i feel extremely irritated that most difficult aspect of working with anything new is the dependency managers. e.g. maven, leiningen, builder, sbt, etc etc etc.
whenever i download anything new from the open source world, there is a significant amount of time to be spent to just to setup the compilation, build, run environment. that too when i am using eclipse. why can't all the dependencies be placed along with the software to be downloaded?? why the tools like maven,leiningen, etc must make a separate internet connection to download the dependencies. i know that maven forms a local repository and should be able to find the dependency locally as it downloads whole internet anyway, but why is this model used. I am behind a firewall and not everything is accessible, and the tools fail to download dependencies. i am sure the same situation is there in most work environments.
recently i started with clojure, and boy it has been a pain to get eclipse configured for clojure. leiningen is supposed to be some magic which must be used with any clojure development. sometimes it feels learning leiningen is more important than learning concepts of clojure. i downloaded so called 'standalone' jar file for leiningen as 'self-install' was not working for me. but it fooled me. as soon as i run 'lein' command it is making an internet connection and trying to download somethings. WHY? it wont even print the help menu without connecting with the internet. WHY? there is no way i can fulfill its demands without bypassing my internet firewall, as i dont know, and no one can tell me what all things this guy wants. there is simply no other way.
And every one seems to be inventing their own. Java had ant which was simple, and went to Maven, some project uses Ruby based Builder, Clojure has leiningen, Scala has sbt. Go has something else. WHY? Why we need this added complexity in a world already full of complexity. why cant there be just one tool.
All you experts in Java technology please excuse my rant. I am sure this question will be downvoted and closed as from someone who is not trying hard enough to understand the things. But please believe me i have spend enough hours battling with this unnecessary complexity.
I just want to know how others get around this, or am i the only unfortunate one facing these issues.
I guess this question cannot accept an answer. I humbly can provide you with elements, hopefully they will help you get some perspective on the problem.
There are mainly 2 problems I identify with Java build systems:
some of them are declarative while others are using scripts
the fragmentation of the Java tools for building and exercising control is tied to people and Java stewardship of the space, not so much the technological choices.
Maven is the paramount of a method of defining your build using a formal grammar in a standard manner. Your pom.xml file contains a lot more than just your build : it is the identity of your artifacts, the project metadata, the modules and the plugins brought in. It treats with particular attention of the declaration of the dependencies and repositories.
Maven is declarative.
For a certain population of programmers, this is great, and they don't create new projects very often. It works well over time, it consolidates the build nicely.
Ant is a different system where you define tasks that will execute, chained in a particular order. All the definitions are made using XML and in effect, you are writing scripts and declaring how they will be stitched together.
Buildr (full disclosure: I am a committer there) is a build system which was created off the frustration of dealing with the inefficiency of the declarative approach for cases where the build needed to do additional steps and complex testing and the rigidity of using XML for a build. It is script-based, enforcing conventions over configuration (expecting a few good defaults, but letting you drive if you need to change things).
I am not familiar with Gradle and SBT but I think they extend and build on this approach, from what I heard.
So this gives you I hope a better picture of the landscape in terms of build tools.
The reason why no standard build tool emerged is probably tied to the fact Sun didn't push one with Java. Eventually, I think they adopted Ant (I have some most JSR jars being built with it). There also has been some products built in this space over extending some of those build systems ; there is always going to be a huge difference between people being paid to maintain code rather than doing it on the side.
And well, people argue. Build systems are a great way to start a flame war. We have a hard time agreeing on a standard though some of the common elements are now settling well around the Maven artifacts.
As for the need to download the Internet over and over again, it's a rather long story but here are a few things that may trigger the need for an unnecessary download:
any of the dependencies using SNAPSHOT will try to get the latest snapshot. This is a great scheme but it takes its toll. You might depend on something that depends on a snapshot, and get a download because of that.
Maven doesn't redownload the artifacts but sometimes checks md5. This is easy to fix, just use the -O option from the command line.
Tools like Buildr were built around fixing this issue once for all. First off, you only download what you said you would. Second, no connection is made again unless you asked for it. By default, Buildr doesn't play the transitive dependencies game though you can ask for it, but you have to do it explicitly.
I hope this was informative and that your journey in Java land becomes less painful going forward.