Tuesday, November 28, 2017

Spring api docs using swagger


Just want to write a quick post on need for API specifications for your REST services. This is especially important if you are adopting microservices .

How to provide documentation for your api's ?  What information is required and how to provide this information that can be easily understood and used by other teams?   .

This concept is same as WSDL when using a SOAP service , the interesting thing is when ever we want to consume a soap service immediately WSDL comes to mind . But so far I haven't seen this adoption to REST based service . Industry is moving towards a  micro-service model and light weight api's  become ubiquitous this becomes a compelling need.

Swagger comes to the rescue in providing specifications for  defining the interface to the rest service.
https://en.wikipedia.org/wiki/OpenAPI_Specification. Most important thing is when you use a framework like spring you  don't have to understand swagger to the extent of writing them manually . Spring can do that for you .

Here is how you do it

Include swagger library in pom.xml ( version I use in 2.7.0 , you can use the latest )

<dependency> 
 <groupId>io.springfox</groupId> 
 <artifactId>springfox-swagger2</artifactId 
<version>2.7.0</version> 
</dependency>


Enable swagger Configuration . I am using Swagger 2 , use the version that is accepted with in your organization 

@Configuration
@EnableSwagger2
public class SwaggerConfig {                                    
    @Bean
    public Docket api() { 
        return new Docket(DocumentationType.SWAGGER_2)  
          .select()                                  
          .apis(RequestHandlerSelectors.any())              
          .paths(PathSelectors.any())                          
          .build();                                           
    }
}

Now when you start your spring boot application
the api docs are available , it provides all the information for your consumers

http://localhost:8080/v2/api-docs



All these data along with the model objects are now part of my specification . I can share this information with other teams that want to consume my service .

As your application grows and model changes the documentation is automatically reflected with the latest information .

Here is an complete example in github
https://github.com/arun2dot0/simple-rest-service-swagger







Wednesday, November 15, 2017

Spring Integration file processing using DSL


Simple Example of File processing using Spring Integration 

Here is my use case , watch directory for new file and process files of certain format ( e.g *.txt ) . Process them and send to Message queue .

Spring  integration can be used for both file processing and message queue . This blog provides example for  watching file folder for changes and invoking a message

Its elegant and straight forward , example here watches directory in a certain directory and then process the files of type text .


https://github.com/arun2dot0/spring-file-process



Note : Example here will get you started , if you need to implement in load balanced environment , the "AcceptOnceFileListFilter" may not be enough , you will need persistent storage and use "FileSystemPersistentAcceptOnceFileListFilter"

Friday, July 14, 2017

Fun with IOT

Publish -> Analyze -> Utilize


First project that I wanted to try when I looked at GrovePi and the connectors .



Architecture has 3 main components

  • Edge - Get data temperature , light and humid readings and publish to the server
  • Data Platform - Consume the data provided by Edge and store . Provide api to get analysis on the data
  • Client - this can be anything that consumes rest api , mobile app or Alexa ( its fun this way !)


Edge


Raspberry Pi and GrovePi module with the connectors act as the Edge .
Python module continuously  reads the readings every minute and pushes
to the server using Rest api .

You need :  Raspberry and Grove pi with the Grove Sensors for Temp/Humidity ,light and Sound
Github Link : https://github.com/arun2dot0/APIPython


Data Platform


API interfaces to consume the data from edge and store . Developed using Spring Boot
Data can be stored in any db of your choice based on the analytical needs .
This project I have used Redis to store maximum of
100 values to provide simple analytics ( Average and Latest readings) on that data .
Readings are also exposed as rest api .

You need : Cloud setup ( google cloud or aws ) . I setup my server in google cloud . If you need same setup
details are in the github link
Github Link :https://github.com/arun2dot0/metrics-rest-service-redis.git


Client

Rest API exposed can be consumed by mobile app . Its fun to integrate with Alexa to
get the readings . You will find the details in github link

Alexa : you will need to create aws account and code using aws lambda
Github Link :https://github.com/arun2dot0/AlexaSensorDataNodeJS


It's a fun project and just to get hands on IOT . Edge , Platform and Client
are totally decoupled and can be easily changed for a different use case .
Although it's a simple project it get exposure to variety of technologies
Python , Java , Spring Boot , Redis , Node js and AWS Lambda's

Demo



Did you find it useful , did you try it ,  hack it , improve it ?
do share in the comments below