#WSO2 Microservices Server (MSS)

WSO2 Microservices Server is a lightweight high performance runtime for hosting microservices.

WSO2 MSS is one of the highest performing lightweight microservices frameworks. The following graphs show the throughput & memory consumption characteristics of MSS against other microservies frameworks.

##Getting Started

It is really easy to define & deploy a microservice using WSO2 Microservices Server. You simply need to annotate your service and deploy it using a single line of code. Check the following [Hello-Service] (samples/helloworld) sample.

####pom.xml This pom file inherits from mss-lite-parent/pom.xml. It provides a way of setting up things quickly with minimum amount of configuration. More info.

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <parent>
        <artifactId>mss-lite-parent</artifactId>
        <groupId>org.wso2.carbon.mss</groupId>
        <version>1.0.0-SNAPSHOT</version>
        <relativePath>../../mss-lite-parent/pom.xml</relativePath>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.wso2.carbon.mss.sample</groupId>
    <artifactId>Hello-Service</artifactId>
    <version>1.0.0</version>

    <name>Hello Microservice Sample</name>

    <properties>
        <microservice.mainClass>org.wso2.carbon.mss.example.Application</microservice.mainClass>
    </properties>

</project>

####HelloService.java This is the hello service implementation that uses JAX-RS annotations.

@Path("/hello")
public class HelloService {

    @GET
    @Path("/{name}")
    public String hello(@PathParam("name") String name) {
        return "Hello " + name;
    }

}

####Application.java This is the one-liner to deploy your service using WSO2 Microservices Server.

public class Application {
    public static void main(String[] args) {
        new MicroservicesRunner()
                .deploy(new HelloService())
                .start();
    }
}

###Build the Service Run following Maven command. This will create the uber jar Hello-Service-1.0.0-SNAPSHOT.jar in target directory.

mvn package

###Run the Service You just have to run the following command to get your service up and running.

java -jar target/Hello-Service-1.0.0.jar

###Test the Service with curl Run the following command or simply go to [http://localhost:8080/hello/Microservices] (http://localhost:8080/hello/Microservices) from your browser.

curl http://localhost:8080/hello/Microservices

##Supported Annotations

For defining services, we support a subset of the JAXRS annotations.

###Class level annotations #####@Path Root path for resource methods. All the paths specified in the resource methods will be sub paths of this.

#####@Consumes Default consume media type(s) for resource methods. The resource methods that do not specify @Consume annotation will inherit this consume media type(s).

#####@Produces Default produce media type(s) for resource methods. The resource methods that do not specify @Produce annotation will inherit this produce media type(s).

###Method level annotations #####@Path Endpoint of the resource method relative to @Path of the container resource class.

#####@Consumes Media type(s) that the method can consume. This overrides the class level @Consumes media types.

#####@Produces Media type(s) that is produced by the method. This overrides the class level @Produces media types.

#####@GET HTTP GET method. Specify that the resource method supports HTTP GET method.

#####@PUT HTTP PUT method. Specify that the resource method supports HTTP PUT method.

#####@POST HTTP POST method. Specify that the resource method supports HTTP POST method.

#####@DELETE HTTP DELETE method. Specify that the resource method supports HTTP DELETE method.

###Parameter level annotations #####@DefaultValue Specify a default value for a resource method parameter. The value will be automatically converted to the corresponding parameter's type.

#####@Context Inject additional objects to a resource method. Currently supports injection of following objects.

• org.wso2.carbon.mss.HttpStreamHandler - This object can be used to stream a chunked request body and process it while the request is streaming.
• io.netty.handler.codec.http.HttpRequest - This object can be used to retrieve HTTP request information. More info.
• org.wso2.carbon.mss.HttpResponder - This object can be used to send HTTP responses. You can make responses more clean way by returning an instance of javax.ws.rs.core.Response or a POJO. See the [StockQuote-Service] (https://github.com/wso2/product-mss/tree/master/samples/stockquote-service) sample.

#####@PathParam /StockQuote/{symbol} to get value of symbol. The value will be automatically converted to the corresponding parameter type and assigned to that parameter.

#####@QueryParam /Students?age=18 to get value of age. The value will be automatically converted to the corresponding parameter type and assigned to that parameter.

#####@HeaderParam To read HTTP request header values. The value will be automatically converted to the corresponding parameter type and assigned to that parameter.

###Lifecycle Callback Methods Support following Java lifecycle callback method annotations.

#####@PostConstruct Invoke by the container on newly constructed service instances after all dependency injection has completed and before transport starts.

#####@PreDestroy Invoke by the container during server shutdown before the container removes the service instance.

For detailed example refer lifecycle sample from here.

###Complete Feature List

• Annotation based definition of microservices
• High performance Netty based transport
• WSO2 Developer Studio based tooling for microservices development starting from a Swagger API definition
• HTTP request & response streaming
• Support for metrics & visualization of metrics using WSO2 Data Analytics Server (DAS) dashboards
• Support for securing microservices
• Integration with rendering engines such as Mustache
• Comprehensive samples demonstrating how to develop microservices based solutions