Spring on Felix Seifert

Limit and Offset in Spring Data JPA

Sun, 14 Jul 2019 13:29:21 +0000

Limit and offset are two properties often requested for requesting data out of a database. Implementing them with a SQL query is also not that difficult. In this article I will describe how to achieve this with the magic of Spring Data JPA repositories (without SQL).

The Entity

First, we need a class describing the entities which should be retrieved from the database. We annotate the class with @Entity to mark it as a representative of a database table. The class describes how the table in the database should look like. Each object of this class would be stored as one row in this table (in a relational database).

autobahn-spring: Autobahn|Java and Spring

Sun, 27 Jan 2019 16:24:36 +0000

Are you an enthusiastic user of Spring and do you also want to benefit from the Web Application Messaging Protocol? Even though wamp2spring mainly serves as a router, Spring users often want to create several microservices communicating with each other. A comfortable solution is using the WAMP library Autobahn|Java. This article will describe how to combine Spring and Autobahn|Java.

Create a Controller for WAMP

Autobahn|Java could be implemented as a controller. Therefore, the bean of Spring should be created with the annotation @Controller. Topics and procedures could be handled exactly as described in the article about Autobahn|Java. The methods implementing this should be registered as listeners. This could be achieved in the constructor of the controller.

wamp2spring: Topics and Procedures

Fri, 02 Nov 2018 17:36:02 +0000

wamp2spring offers the option to serve as Web Application Messaging Protocol (WAMP) router publishing on topics and registering remote procedures. The article wamp2spring - Router for WAMP has already described how to set up a router with wamp2spring. In this article, we would learn how the router could publish on topics and register remote procedures. Understanding RPC and Pub/Sub might be quite helpful for creating microservices communicating via WAMP. The different ways of communicating via the protocol are described in the article Web Application Messaging Protocol.

wamp2spring - Router for WAMP

Sun, 21 Oct 2018 14:57:56 +0000

As I am a strong advocate of Spring Boot, I would present you with another way to set up a router for the Web Application Messaging Protocol (WAMP). This is based on the Java library wamp2spring and Spring Boot (you could also use the Spring framework). Besides setting up one or multiple WAMP clients (for example with Autobahn|Java), a router is needed so that the clients could communicate with each other via WAMP. I have already described the idea in the article Web Application Messaging Protocol. Even though there are multiple options for settings, it is quite convenient to set up a router with the default settings. A wamp2spring router itself could register remote procedures, as well as publish on topics, which could be addressed by the wamp clients. This article would present a solution of a router that does not register or publish.