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Introduction

For some properties of your DMS objects managed by yuuvis® Momentum, you might want to allow only certain string values that are defined in a catalog. One possible way to implement such a custom validation is the usage of a webhook dms.request.objects.upsert.database-before that is calling the CATALOG Service. In this tutorial, you will be guided through the set up of such an example webhook consumer service. It verifies that the value of a certain string property is contained in a specified catalog. Thus, this webhook service will provide an extra validation layer for object import and/or update.

Requirements

In this tutorial, we'll create a Spring Boot Service using Java, meaning the requirements for the proejct project are derived from Spring Boot. Thus, a JDK version 1.8 or later and Maven 3.2 or later are required. 

Also Furthermore, a running instance of a Catalog-the CATALOG Service is required, as well as the existence of the catalog within the system, that will be checked againsta global catalog against which the example webhook checks the property values.

The object property , which should be validated, must also exist be defined in the system scheme global schema that is available in all tenants.

Setting up the Webhook Service

To implement the processing of incoming metadata using our example webhook service, we need to configure an endpoint within a controller class of our Webhook Service. In this instance ValidationWebhookRestController. The URL we define between class with the corresponding validation endpoint. In the example code block below, we define the class ValidationWebhookRestController with the method validateObjectProperty. The URL defined in the RequestMapping annotation of the controller class and the PostMapping annotation of the endpoint method will need to find its way into be referenced in the system hook configuration of our yuuvis® Momentum system as shown later in this article. We will also define a method the method propertyValidationService.validateObject for working with the incoming metadata, which we will call from is called within our endpoint method.

@RestController
@RequestMapping("/api/dms/request")
public class ValidationWebhookRestController
{
    @Autowired
    private PropertyValidationService propertyValidationService;

    @PostMapping(value = "/upsert", produces = {"application/json"})
    public Map<String, Object> validateObjectProperty (@RequestBody Map<String, Object> dmsApiObjectList,
                                                	   @RequestHeader(value = "Authorization", required = true) String authorization) throws HookException {
        this.propertyValidationService.validateObject(dmsApiObjectList, authorization);
        return dmsApiObjectList;
    }
}

Creating the Validation Service for

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Incoming Metadata

This is the core of the heart of our example webhook consumer service. Create the class propertyValidationService and annotate it as @Service. This indicates that it holds the business logic and will communicate with the repository layerREPOSITORY service.

First we will set Within the class, we firstly specify the object property name, which we want to validate. After that Secondly, we specify the name of the wanted catalog must be specifiedcatalog against which we want to validate.

final String propertyId = "[Name of property]";
final String catalogueName = "[Name of catalog]";

Then Now we will implement our method validateObject for metadata handling method validateObject. Here, we will iterate through the imported or updated object and search for the requested property . When by using a method from the utility class PropertyUtils. If the property is found, it and the authorization token will be is send to the private validation method validateProperty together with the authentication token.

public void validateObject(Map<String, Object> dmsApiObjectList, String authorization) throws HookException
    {
        String propertyValue = null;

        //Get object properties and send for validation
        List<Map<String, Object>> newObjectList = (List<Map<String, Object>>) dmsApiObjectList.get("objects");

        for (Map<String, Object> newObject : newObjectList) {
            propertyValue = (String) PropertyUtils.getPropertyValue(newObject, propertyId);
            validateProperty(propertyValue, authorization);
        }
    }

The way of getting the right property is by using the class PropertyUtils.utility class PropertyUtils providing the above referenced method getPropertyValues we implement as follows:

public static Object getPropertyValue(Map<String, Object> object, String propertyId)
    {
        @SuppressWarnings("unchecked")
        Map<String, Object> properties = (Map<String, Object>)object.get("properties");

        return getValue(properties, propertyId);
    }

  

private static Object getValue(Map<String, Object> properties, String propertyId)
    {
        @SuppressWarnings("unchecked")
        Map<String, Object> property = (Map<String, Object>)properties.get(propertyId);
        if(property != null)
        {
            return property.get("value");
        }
        return null;
    }

The validateProperty method shown in the next code block is a private method within our example service. It ensures that the string given property String as propertyValue is not empty or null and then proceeds to create and send a HEAD request for validating the property using the given catalog name. On a Each successful response it logs the success of the result and finishes is logged and the import or update of the object is finished. In case of a failed validation, the method throws a HookException as defined below.

private void validateProperty (String propertyValue, String authorization) throws HookException {
        //Validate property with catalogue entry
        if (propertyValue != null) {
            if (!propertyValue.isBlank()) {
                String url = "http://catalog/api/catalogs/" + catalogueName + "/" + propertyValue;

                HttpHeaders headers = new HttpHeaders();
                headers.set("Authorization", authorization);

                HttpEntity requestEntity = new HttpEntity<>(null, headers);

                try {
                    ResponseEntity<Void> response =
                            this.restTemplate.exchange(url, HttpMethod.HEAD, requestEntity, Void.class);

                    if (response.getStatusCode().is2xxSuccessful()) {
                        LOGGER.debug("Property [" + propertyValue + "] validation was successful");
                    } else {
                        throw new HookException("Catalogue [" + catalogueName + "] does not exist or property [" + propertyValue + "] does not match any catalogue entry.");
                    }
                } catch (HttpStatusCodeException e) {
                    if (HttpStatus.NOT_FOUND.equals(e.getStatusCode())) {
                        throw new HookException("Catalogue [" + catalogueName + "] does not exist or property [" + propertyValue + "] does not match any catalogue entry.");
                    } else {
                        //Error handling
                        throw new HookException("Something went wrong.");
                    }
                }
            } else {
                throw new HookException("The property [" + propertyId + "] is empty.");
            }
        } else {
            LOGGER.debug("This object does not have the property: " + propertyId);
        }
}

On a failed response the service throws a HookException from a custom HookException classThe following code block shows the definition of the HookException realized in the custom class HookException.

public class HookException extends Exception
{
    private static final long serialVersionUID = 1L;

    public HookException(String message)
    {
        super(message);
    }

    public HookException(String string, Throwable exception)
    {
        super(string,exception);
    }
}

Webhook System Configuration

In the systemHookConfiguration.json file, add the folowing following configuration (SpEL) and save it to the configuration server. Here In this configuration, we will specify the type of our validation webhook dms.request.objects.database-before and its URL http://validationWebhook/api/dms/request/upsert. Also here we will set We also specify the predicate for triggering of the webhook's initialisation. In this example, we want our webhook to be activated when if an object is being imported or updated and that has the property "Name" assigned.

{
	"enable": true,
	"predicate": "spel:properties['Name']!=null && (properties['Name']['value'])!=null",
	"type": "dms.request.objects.upsert.database-before",
	"url": "http://validationWebhook/api/dms/request/upsert",
	"useDiscovery": true
}

Summary

In this tutorial we went through the steps of creating and configuring a webhook service for validating object properties using catalogsa catalog. Find the complete code project described in this tutorial in this GitHub Repository.
>> GitHub