Couchbase Java SDK with Rx-Java

A neat thing about Couchbase Java SDK is that it is built on top of the excellent Rx-Java library, this enables a reactive way to interact with a Couchbase server instance which is very intuitive once you get the hang of it.

Consider a very simple json document that I intend to store in Couchbase:

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1	{"key":"1","value":"one"}

and a Java class to hold this json:

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public class KeyVal {     private String key;     private String value;       ... }

The following is the code to insert an instance of KeyVal to a Couchbase bucket:

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JsonObject jsonObject = JsonObject.empty().put("key", keyVal.getKey()).put("value", keyVal.getValue()); JsonDocument doc = JsonDocument.create(keyVal.getKey(), jsonObject); Observable<JsonDocument> obs = bucket                 .async()                 .insert(doc);

The return type of the insert is an Observable, so if I needed to map the return type back a KeyVal I can use the extensive mapping support provided by Observable class.

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Observable<KeyVal> obs = bucket                 .async()                 .insert(doc)                 .map(jsonDoc ->                     new KeyVal(jsonDoc.id(), jsonDoc.content().getString("value"))                 );

Other API's follow a similar pattern, for eg. to retrieve the saved document:

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bucket                 .async()                 .get(id)                 .map(doc ->                         new KeyVal(doc.id(),                                 doc.content().getString("value")));

If you are interested in exploring this sample further, here is my github repo with a working example - https://github.com/bijukunjummen/sample-karyon2-couch

References:

• Couchbase Java SDK: http://docs.couchbase.com/developer/java-2.1/java-intro.html
• Rx-Java: https://github.com/ReactiveX/RxJava
• An excellent and concise article on Rx-Java provided at the Couchbase site: http://docs.couchbase.com/developer/java-2.0/observables.html

Spring boot static web resource handling for Single Page Applications

Javascript build tools like gulp and grunt truly boggle my mind, I look at one of the build scripts for these tools and find it difficult to get my head around it and cannot imagine writing one of these build scripts from scratch. This is where yeoman comes in, a very handy tool that quickly allows one to bootstrap a good starter project using any of the myriad combination of javascript build tools.

I wanted to explore an approach which Spring framework recommends for handling static web resources, which is to use these very capable build tools for building the static assets and using Spring for serving out the content once the static assets are built into a distributable state.

My approach was to use yeoman to generate a starter project, I chose the gulp-angular as my base and quickly generated a complete project, available here. I was able to expand this template into a fairly comprehensive angularjs based single page application which delegates back to Spring based REST calls to service the UI.

The steps that I followed are the following, mostly copied from the excellent sample created by Brian Clozel:

If you want to follow along the end result is available in my github repo.

1. Define two modules, the "client" module to hold the generated yeoman template and a "server" module to hold the Spring Boot application.
2. Hack away on the "client" module, in this specific instance I have created a simple angularjs based application
3. I am using maven as the java build tool so I have a wrapper maven pom file which triggers the javascript build chain as part of the maven build cycle, then takes the built artifacts and creates a client jar out of it. The static content is cleverly placed at a location that Spring boot can get to, in this instance at the classpath:/static location.
4. In the "server" module client is added as a dependency and "server" is set to be run as a full-fledged spring-boot project
5. Serve out the project from the server module by executing:
   
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   1	mvn spring-boot:run

Conclusion

Spring Boot has taken an excellent approach to providing an asset pipeline for static web resources which is to not interfere with the very capable build tools in the Javascript universe and providing a clean way to serve out the generated static content.

Working with Spring-Cloud and Netflix Archaius

Background

Spring Cloud provides all the tools that you require to create cloud ready microservices. One of the infrastructure components that Spring-Cloud provides is a Configuration server to centralize the properties of an application, however it is possible that you that you may be using other solutions to manage the properties. One such solution is Netflix Archaius and if you work with Netflix Archaius there is a neat way that Spring-Cloud provides to integrate with it.

Integration With Archaius

Spring Cloud provides a Spring Boot Auto-configuration for Archaius which gets triggered on finding the Archaius related libraries with the application. So first to pull in the Archaius libraries, which can be done through the following dependency entry in the POM file:

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<dependency>     <groupId>com.netflix.archaius</groupId>     <artifactId>archaius-core</artifactId> </dependency>

Not that the version of the dependency need not be specified, this information flows in from the dependency management information in the parent POM’s.
With this new library in place, Archaius Configuration, all that now needs to be done is to define Spring beans which extend Apache Commons Configuration AbstractConfiguration class and these would automatically get configured by Spring Cloud. As an example consider the following AbstractConfiguration which has one property in it:

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@Bean public AbstractConfiguration sampleArchaiusConfiguration() throws Exception {     ConcurrentMapConfiguration concurrentMapConfiguration = new ConcurrentMapConfiguration();     concurrentMapConfiguration.addProperty("testkey", "testvalue");     return concurrentMapConfiguration; }

That is essentially it, this property should now be visible as an Archaius property and can be accessed along these lines:

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1	DynamicPropertyFactory.getInstance().getStringProperty("testkey", "").get()

Also there are a few more neat features provided through Archaius integration in Spring-Cloud:

1. The Spring managed properties are visible as Archaius properties
2. An endpoint(/archaius) is provided by Spring-Cloud where all the registered archaius properties can be viewed

Conclusion

Spring Cloud natively provides all the tools to write a Cloud Ready microservice, however it is possible that the way to configure the centralized properties may be via Netflix Archaius, if that is the case Spring Cloud enables this neat way to integrate with Archiaus.