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The tutorial Preprocessing Metadata using Webhooks provides a general example on how to configure and set up your own webhook service. A more specific example controller class for a webhook service for our concrete use case is provided in the code block below. For each object imported with a binary content file, the MD5 digest of the corresponding content is calculated. Since an internal endpoint of the REPOSITORY service has to be called, the webhook service must run within the yuuvis® Momentum Kubernetes cluster.
As defined on lines 2 and 5, the webhook service will be available via the URL /api/process/checkcontent. This endpoint accepts the import request body containing all object's metadata, and the request headers (line 6).
Especially in the case of a batch import, it is necessary to iterate over the individual objects (line 13) as the repository can only retrieve the content of one object at a time. For each individual object, the existence of an assigned binary content file is checked (line 17, 19). The binary content file is retrieved from the repository (starting on line 28) and its MD5 digest is calculated (line 47). The value is printed to the console (line 55).
Depending on the MD5 digest value, it would be possible to manipulate the individual object's metadata. However, in this example, the metadata remain unchanged. The objects from the request body are returned without any manipulation (line 66).
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@RestController
@RequestMapping("/api")
public class WebhookRestController
{
@PostMapping(value = "/process/checkcontent", produces = "application/json;charset=UTF-8", consumes = "application/json")
public ResponseEntity<?> checkContent(@RequestBody final Map<String, Object> dmsApiObList, @RequestHeader HttpHeaders incomingHeaders) throws Exception
{
try
{
String authorization = incomingHeaders.getFirst(HttpHeaders.AUTHORIZATION);
List<Map<String, Object>> apiObjectList = (List<Map<String, Object>>)dmsApiObList.get("objects");
for (Map<String, Object> apiObject : apiObjectList)
{
String objectId = (String)getMap(getMap(apiObject, "properties"), "system:objectId").get("value");
boolean hasContent = apiObject.get("contentStreams") != null && ((List)apiObject.get("contentStreams")).size() > 0;
if (hasContent)
{
Map<String, Object> requestObject = new LinkedHashMap<>();
LinkedList<Map<String, Object>> requestList = new LinkedList<>();
requestList.add(apiObject);
requestObject.put("objects", requestList);
// @formatter:off
String md5Digest =
restTemplate.execute(
"http://repository/api/dms/objects/" + objectId,
HttpMethod.POST,
(ClientHttpRequest requestCallback) -> {
if (StringUtils.hasLength(authorization))
{
requestCallback.getHeaders().add(HttpHeaders.AUTHORIZATION, authorization);
}
requestCallback.getHeaders().setContentType(MediaType.APPLICATION_JSON);
requestCallback.getBody().write(this.objectMapper.writeValueAsString(requestObject).getBytes("UTF-8"));
},
new ResponseExtractor<String>()
{
@Override
public String extractData(ClientHttpResponse response) throws IOException
{
if (response.getStatusCode().is2xxSuccessful())
{
// calculate MD5 Hash
return DigestUtils.md5DigestAsHex(response.getBody());
}
throw new IllegalStateException("error in getting content: " + response.getRawStatusCode() + " " + response.getStatusText());
}
}
);
// @formatter:on
System.out.println("for objectId[" + objectId + "] the md5-digest of content is[" + md5Digest + "]");
}
}
}
catch (Throwable e)
{
return new ResponseEntity<>(e.getMessage(), HttpStatus.UNPROCESSABLE_ENTITY);
}
// just return input no changes
return new ResponseEntity<Map<String, Object>>(dmsApiObList, HttpStatus.OK);
}
} |
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