I Implemented two maven project each using spring MVC, Hibernate, Jax-RS service. they have separate configuration, database, controllers, models, services.
I need to combine both the project in such a way that one is work as parent and other should be its child and can access parent services.
If you want to share configuration among projects, you can use a parent pom.
If you want to combine two projects as subprojects of one larger one, you can use modules. Both concepts are described in
https://maven.apache.org/guides/introduction/introduction-to-the-pom.html#Project_Inheritance_vs_Project_Aggregation
If you want to access classes from project in another project, add a dependency in the dependencies section of your pom.
Related
Experts,
I need some expert advice on how to approach the below use case in spring boot.
I need to have a maven multi-module approach to my project.
I need to have a single jar as output of the final build process.
There are to be common modules for controllers, data access and other functionality
Other modules are to be created based on functionality domain for eg a module for Payroll, a module for Admin etc etc.
Each domain functional module will then have their own controllers extending the common controller, exception handler and so on.
Each module will also have its own set of thyme leaf pages.
The reason for following such an approach is we have development in phases and we will be rolling out based on functional modules.
Here are the issues that I can sense using this approach.
Where do I add the spring web dependency? If I add to the parent pom - it gets replicated across the children and there will be port conflict issues as each module loads. the same issue will also be there the moment I add it to two child modules.
How do I build the fat jar which has all the jars from all modules and works as the final deployment?
All the text that I read i can't see anything even close to what I am trying to achieve.
AD1. They will not unless you are trying to setup independent application context in each module. Of course you can do that(it might be complicated but I believe it's achievable), but for me it's an overkill. Personally I think it's better to have one application context and rely on scanning components that are present in classpath.
AD2. The structure in maven might be a little bit complicated and overwhelming at first glance but it makes sense. Here's how I see it:
Create a parent module that will aggregate each module in project and will declare library/plugin dependencies for submodules.
Create 1-N shared submodules that will be used in other modules. With come common logic, utils, etc.
Create 1-N submodules that will be handling your business logic
Create an application submodule that creates application context and loads configuration and components from classpath
Create a submodule that will be responsible for packaging process, either to war, jar, uber-jar or whatever else you desire. Maven jar plugin should do that for you. For executable uber-jar, you have dedicated tool from spring.
Now you can choose three ways(these ways I know) of loading your modules.
1. Include some modules in maven build based on the build configuration via maven profiles and let spring IoC container load all the components he finds in the classpath
2. Include all of the modules in maven build and load them depending on spring active profiles - you can think about it as of feature flag. You annotate your components or configuration class with #Profile("XYZ") telling spring IoC container whether to instantiate component or not. You will need (most flexible solution) to provide a property file which tells spring which profiles are active and thus which modules should be loaded
3. Mix of these two above.
Solution 1 pros:
build is faster (modules that are not included will be skipped during build)
final build file is light (modules that are not included are... not included ;))
nobody can run module that is not present
Solution 1 contras:
project descriptor in maven may explode as you might have many different profiles
Solution 2 pros:
it's fairly easy and fun to maintain modules from code
less mess in project descriptor
Solution 2 contras:
somebody can run module that is not intended to be run as it's present in classpath, but just excluded during runtime via spring active profiles
final build file might be overweight - unused code is still present in code
build might take longer - unused code will be compiled
Summary:
It's not easy to build well structured project from scratch. It's much more easier to create a monolith and then split it into modules. It's because if you already created a project, you've probably already identified all the domains and relations between them.
Over past 8 years of using maven, I honestly and strongly recommend using gradle as it's far more flexible than maven. Maven is really great tool, but when it comes to weird customization it often fails as it's build capabilities rely on plugins. You can't write a piece of code on the fly to perform some custom build behaviour while buidling your project, you must have a dedicated plugin for doing that. If such plugin exists it's fine, if it's not you will probably end up writing your own and handling its shipment, so anyone in your company can easily perform project build.
I hope it helps. Have fun ;)
I want to be sure what is the best practice for project structure while using microservice architecture.
All microservices can be created as a new maven/gradle project or as a subproject/module.
I think dependency inheritance, project repository should be taken into account.
Due to the nature of the microservices, any service can has a different technology but still most of the services can have same dependencies(e.g. spring-boot)).
Another issue is that should team fetch all services or just a service which will be worked on? so repository structure also will be affected by the structure.
The main reasons to have a multi-module project is to manage dependencies (in the maven sense) between the different modules (and build them together in the right order). Your microservices may call each other, but are not dependent on each other in the Maven sense. So I would not use multi-module projects for them.
Nevertheless, you can define a parent pom for your microservices that defines common configuration and dependencies.
I don't recommend you to have a single project with multiple microservices of different technologies.
If you use Java as a programming language you can have a master project and use it as a parent in your microservices projects. Also, you can have common libraries as dependencies of your microservices projects.
If you want to do a microservices with different technology I recommend you to have a repository for each microservice.
Choosing this option you can deploy and versioning each microservice when you do changes in its code and not when you have changes in another microservice.
I have created a service builder project (Gradle type) in Liferay7 called register-user. There is another service builder project called register-organization. I have a situation where one of the service builders depends upon other. However, i am not able to figure out where to put the dependency of one into another. Is there is any way to do that?
With each servicebuilder project you create from the template, you get two projects, e.g. register-user-api and register-user-service. The -service project depends on the -api project and has the dependency noted in its build.gradle. Look it up and use exactly the same notation to make any other project depend on register-user-api.
The situation changes if both projects do not live in the same workspace: In that case you'll need your own repository (e.g. proxy for Maven Central) where you publish your own modules. Then you can just declare a standard dependency for your modules.
I read a lot of posts regarding the ways to use spring-boot-starter-parent in a spring boot project.
Essentially, I read posts (Spring documentation also talks about this) describing two ways to do this
To use spring-boot-starter-parent as the project parent directly. It gives us the benefits of having the dependency management as well as the plugin management.
The other way is to import the spring-boot-starter parent in the project pom (we may need this in case we already have a parent pom for the project).
It allows us to get the benefits of dependency management but not the plugin management)
I am creating a new Maven multi module project. Ideally I would like to have my own custom parent and also get all the benefits of using the Spring-boot-starter-parent.
I was wondering if it made sense to create a custom parent for my maven projects. This parent would in turn be a child of the spring-boot-starter-parent.
If I am not missing anything, this way I could get the benefits of having the dependency management and plugin management from spring-boot-starter-parent and at the
same time have a custom parent for all my projects where I could define some other common dependencies or if needed override the dependencies defined in the
spring-boot-starter-parent which would then be inherited by all my projects.
Does this design make sense or am I missing something.
What are the drawbacks of this approach?
There are no drawbacks -- this is exactly what you're meant to do if you want a multimodule spring-boot project. However, consider this: typically multi-module projects have all modules versioned together, released together, and dependant on each other. This rarely makes sense in a group of spring-boot modules, which are typically of the micro-service style and which require independent evolution. So, you should question your need for a multi-module project at all.
I have question towards a best practice for configuration of persistence and cache (2nd lvl) within a maven multi module project with spring/jpa/ehcache.
Only a single datasource is needed.
Lets assume
I have 3 domain maven modules containing only the entities:
core_domain
customers_domain (dependency core_domain)
products_domain (dependency core_domain)
I also have 3 integration modules containing repositories:
core_integr
customers_integr (dependency customers_domain, core_integr)
products_integr (dependency products_domain, core_integr)
Now these modules MAY eventually be combined into a single WAR.
One approach might be to define all persistence,transaction and caching configuration in the core_integr module. But this does not cleanly allow configuration per module. It's possible, but not clean.
Is it possible to have a persistence.xml and ehcache.xml per integration module? preferably while keeping spring configuration in the core_integr module.
OR
Do you really need to separate the spring config fully with multiple entitymanagers, persistence_units and cachemanagers all working against the single datasource?
Any advice is welcome.