How does camunda publish and call the rest service interface

1. How does camunda publish the rest service interface

The Camunda BPM platform itself provides a REST API interface, which can be used to manage and operate various resources and data in the Camunda platform, such as process definitions, process instances, tasks, etc. Therefore, we can package the Camunda REST API into our own REST service interface by writing the Camunda application, so as to provide it to other applications or clients.

Specifically, the following steps can be used to publish the Camunda REST service interface:

1. Start a web application (such as Spring Boot, Java Servlet, Node.js, etc.) in the Camunda BPM platform.

2. Use the Java client library or REST client library officially provided by Camunda BPM to interact with the Camunda platform through the REST API interface to obtain or operate the resources and data in the Camunda platform.

3. Encapsulate the API method in the Java client library or REST client library into a REST service interface, and use a Web framework (such as Spring MVC, Jersey, Restify, etc.) to implement the publishing and routing of REST services.

4. In the published REST service interface, the resources and data in the Camunda platform can be read and modified by means of request parameters and request body. At the same time, the corresponding results and data can be returned to the client through the response body.

It should be noted that publishing the Camunda REST service interface needs to ensure the security and authority control of the Camunda BPM platform to prevent unauthorized access and operations. Therefore, we need to configure corresponding identity authentication, authorization and role authority mechanisms in the Camunda platform to ensure the security and reliability of the REST service interface.

 

2. How does camunda call the rest service interface

In the Camunda BPM platform, you can use Java code or JavaScript script to call the REST service interface. The implementation methods of the two methods are introduced respectively below. 1. Use Java code to call the REST service interface
You can use the Java client library or REST client library officially provided by Camunda BPM to interact with the Camunda platform through the REST API interface, and obtain or operate the resources and data in the Camunda platform. Among them, the REST client library provides the following methods for performing REST requests:

import org.camunda.bpm.engine.rest.RestService;
import org.camunda.bpm.engine.rest.dto.VariableValueDto;
import org.camunda.bpm.engine.rest.util.VariablesBuilder;

import java.util.Map;

public class RestServiceClient {

    private RestService restService;

        public RestServiceClient(RestService restService) {
        this.restService = restService;
    }

    public void executeRestRequest(String url, Map variables) {
        VariableValueDto[] variablesDto = VariablesBuilder.fromMap(variables).create();
        restService.path(url).post(null, variablesDto);
    }
}

In the above code, RestService is a class in the REST client library used to interact with the Camunda platform's REST API. The executeRestRequest method is used to execute a REST request, where the url parameter is the URL address of the REST service interface, and the variables parameter is the variable to be passed to the REST service interface.

2. Use JavaScript script to call REST service interface
You can use JavaScript script in the Camunda BPM platform to interact with the Camunda platform through the built-in REST API interface, and obtain or operate the resources and data in the Camunda platform. The following is a sample code for calling a REST service interface using a JavaScript script:

var xhr = new XMLHttpRequest();
xhr.open(‘POST’, ‘http://localhost:8080/rest/path/to/rest/service’, true);
xhr.setRequestHeader(‘Content-Type’, ‘application/json;charset=UTF-8’);
xhr.onload = function() {
if (xhr.status === 200) {
console.log(xhr.responseText);
} else {
console.error(xhr.statusText);
}
};
xhr.onerror = function() {
console.error(xhr.statusText);
};
xhr.send(JSON.stringify({data: ‘test data’}));

In the above code, the XMLHttpRequest object is used to send a POST request to the REST service interface, and a JSON data object {data: 'test data'} is passed. It should be noted that in order to ensure security, corresponding CORS (Cross-Origin Resource Sharing) settings need to be configured in the Camunda BPM platform to allow requests from specified domain names.