tl;dr

Reactive Jersey Client API is a generic API allowing end users to utilize the popular reactive programming model when using Jersey Client. This part of the series describes API, usage and lists all supported reactive libraries.

Reactive Jersey Client API is a generic API allowing end users to utilize the popular reactive programming model when using Jersey Client. This part of the series describes motivation behind creating Reactive Jersey Client.

Although I am not a big fan of sending JSON in other places than in the message body as the entity, for example in query parameter in case of requests, it’s not a rare use-case and the way how it can be solved in JAX-RS 2.0 gives me a nice opportunity to illustrate usage of two new interfaces, ParamConverterProvider and ParamConverter. You can then re-use this approach to inject other media-types or formats your application relies on via @*Param annotations (@MatrixParam, @QueryParam, @PathParam, @CookieParam, @HeaderParam).

Few times I’ve ran into a situation in which I wanted to return only a part of entity I was working with, in my service, to the client-side. Feature that would allow me to send this partial set of fields should not only be driven by my own filtering rules but it also should take into consideration application roles the current user is in. It’s not an uncommon use-case I’d say so in Jersey we’d come up with the Entity Filtering concept that would allow you to do such a thing: sending subgraph of entities from server to client (and vice versa), define your own filtering rules and make sure users get only the fields they are supposed to see.

Since JAX-RS 2.0 you can use Bean Validation to validate inputs received from users and outputs created in your application. It’s a handy feature and in most cases it works great. But what if you’re using also MVC and you want to display custom error page if something goes wrong? Or what if you want to handle Bean Validation issues in a slightly different way than JAX-RS implementation you’re using does? This article will give you some answers to these questions.

Different life-cycles of Jersey 2 and GlassFish 4 arise a question how to make sure that ones GlassFish instance contains always the latest version of Jersey. This question is even more important in case you don’t want to download the nightly/promoted build every-time a new version of Jersey is released but you still want to use the latest and greatest Jersey.

Note: The script below is not compatible with Jersey 2.6 at the moment. I’ll update it as soon as possible.

Common use-case in web-application development is aggregating data from multiple resources, combining them together and returning them to the used as XML/JSON or as a web page. In Java world these (external) resources can be approached via standardized Clients from JAX-RS 2.0. Jersey 2 application can use so-called managed client mechanism that brings a convenient way to create JAX-RS clients and web targets for such resources.

In this article we’ll create a simple Jersey application deploy it in Jetty servlet container and everything will be hosted on Heroku.

Create an Application

To create a skeleton of Jersey 2 web-app that can be run on Heroku from the jersey-heroku-webapp archetype (available since Jersey 2.5), execute the following Maven command in the directory where you want the new project should be located:

mvn archetype:generate -DarchetypeArtifactId=jersey-heroku-webapp \
    -DarchetypeGroupId=org.glassfish.jersey.archetypes -DinteractiveMode=false \
    -DgroupId=com.example -DartifactId=simple-heroku-webapp -Dpackage=com.example \
    -DarchetypeVersion=2.5.1

Adjust the groupId, package and/or artifactId of your new web application project to your needs or, alternatively, you can change it by updating the new project pom.xml once it gets generated.

When you register providers (such as filters and interceptors) in your application they’re associated and applied to each resource method by default. In other words they’re bound globally. For most cases this approach is sufficient but sometimes, especially when you want to use your provider only with a few methods, it’s not enough. JAX-RS 2.0 brings a solution for this situation: Name and Dynamic Binding.

There has been some confusion on StackOverflow lately about how to register JAX-RS resource classes and custom providers in Jersey 2. The main problem seemed to be finding and using correct properties and methods to configure a JAX-RS/Jersey application. In this article I’d like to discuss 3 ways how to configure such an application properly.