Asynchronous Comparison

Synchronous comparison is used when the response is obtained quickly and where the Delta is returned as part of the response.

However in other cases asynchronous comparison is useful:

If there is a risk of HTTP timeout
When using HTTP or Cloud IO - as the REST service will need to make HTTP requests to retrieve these resources
Using large inputs
When the comparison result is needed somewhere other than where the response is returned
Where progress, logging or resource consumption information is needed
When multiple comparisons can be started at once

XML / JSON Request

Whether using XML or JSON, an asynchronous comparison will use the async element to specify the optional values callback and output.

callback provides a callback URL that the REST service will make a GET request to after the comparison is complete. This is detailed in Callbacks below.
output allows you to specify a location for the result to be written to. For more information see I/O Types

The response will consist of the created Job, and a Location header pointing to where you can poll the Job status.

Request (XML)

XML

<comparison>
  <inputA type="http">
    <uri>http://www.example.com/file1.xml</uri>
  </inputA>
  <inputB type="http">
    <uri>http://www.example.com/file2.xml</uri>
  </inputB>
  <configurationParameters>
    <configurationParameter type="boolean">
      <name>Word By Word</name>
      <value>true</value>
    </configurationParameter>
  </configurationParameters>
  <async>
    <callback>http://www.example.com/comparison-callback</callback>
    <output type="file">
      <path>/Users/exampleUser/Documents/result.xml</path>
    </output>
  </async>
</comparison>

Request (JSON)

JS

{
  "inputA": {
    "type": "http",
    "uri": "http://www.example.com/file1.xml"
  },
  "inputB": {
    "type": "http",
    "uri": "http://www.example.com/file2.xml"
  },
  "configurationParameters": [
    {
      "name": "Word By Word",
      "value": true,
      "type": "boolean"
      }
    }
  ],
  "async": {
    "callback": "http://www.example.com/comparison-callback",
    "output": {
      "type": "file",
      "path": "/Users/exampleUser/Documents/result.xml"
    }
  }
}

Response (XML)

XML

HTTP/1.1 202 Accepted
Location:  /api/xml-compare/v1/jobs/12346124
<job>
    <links>
        <link href="/api/xml-compare/v1/jobs/12346124" rel="self"/>
    </links>
    <creationTime>2018-11-23T10:39:47.742Z</creationTime>
    <jobId>12346124</jobId>
    <jobStatus>STARTED</jobStatus>
    <numberOfStages>0</numberOfStages>
    <progressInPercentage>0.0</progressInPercentage>
    <startTime>2018-11-23T10:39:47.746Z</startTime>
</job>

Response (JSON)

JS

HTTP/1.1 202 Accepted
Location:  /api/xml-compare/v1/jobs/12346124
{
  "startTime": "2018-11-23T10:39:47.746Z",
  "creationTime": "2018-11-23T10:39:47.742Z",
  "jobId": 12346124,
  "numberOfStages": 8,
  "progressInPercentage": 0,
  "jobStatus": "STARTED",
  "links": [{
    "rel": "self",
    "href": "/api/xml-compare/v1/jobs/12346124"
   }]
}

Form Request

When using multipart/form-data, set the parameter async to true.

You can also use the parameters callback and keepResult in a similar fashion to XML / JSON async requests.

CODE

.....
Content-Disposition: form-data; name= "async"
true
--boundary
Content-Disposition: form-data; name= "callback"
http: //www.example.com/comparison-callback
--boundary
Content-Disposition: form-data; name= "output"
/Users/exampleUser/Documents/out.xml
--boundary
 .....

Jobs

For each async comparison a Job is created. The jobs can be read from the /jobs/{jobId} endpoint. For example, you can poll for the Job's status:

Request

CODE

GET /api/xml-compare/v1/jobs/12346124

Response (XML)

XML

<job>
    <links/>
    <creationTime>2018-04-19T10:56:01.644+01:00</creationTime>
    <jobStatus>INPUT_FILTER_CHAIN_B</jobStatus>
    <numberOfStages>77</numberOfStages>
    <pipelineStage>dxp-PRE_FLATTENING-mark-important-attributes.xsl</pipelineStage>
    <progressInPercentage>12.0</progressInPercentage>
    <startTime>2018-04-19T10:56:01.656+01:00</startTime>
</job>

Response (JSON)

JS

{
  "startTime": "2018-04-19T09:56:01.656+0000",
  "creationTime": "2018-04-19T09:56:01.644+0000",
  "numberOfStages": 77,
  "progressInPercentage": 12,
  "pipelineStage": "dxp-PRE_FLATTENING-mark-important-attributes.xsl",
  "jobStatus": "INPUT_FILTER_CHAIN_B",
  "links": []
}

You can see the pipeline is currently running the Input Filter Chain for Input B, but some time later...

Response (XML)

XML

<job>
    <links>
        <link href="/api/xml-compare/v1/results/12346124" rel="result"/>
    </links>
    <creationTime>2018-04-19T10:56:01.644+01:00</creationTime>
    <finishedTime>2018-04-19T10:57:24.095+01:00</finishedTime>
    <jobStatus>FINISHED</jobStatus>
    <numberOfStages>77</numberOfStages>
    <pipelineStage>dxml-clean</pipelineStage>
    <progressInPercentage>100.0</progressInPercentage>
    <startTime>2018-04-19T10:56:01.656+01:00</startTime>
</job>

Response (JSON)

JS

{
  "startTime": "2018-04-19T09:56:01.656+0000",
  "creationTime": "2018-04-19T09:56:01.644+0000",
  "finishedTime": "2018-04-19T09:57:24.095+0000",
  "numberOfStages": 77,
  "progressInPercentage": 100,
  "pipelineStage": "dxml-clean",
  "jobStatus": "FINISHED",
  "links": [
    {
      "rel": "result",
      "href": "/api/xml-compare/v1/results/12346124"
    }
  ]
}

...the comparison is now finished - with a HATEOAS link available to view result information.

Job Model

The Job contains the following objects:

Object	Description
`creationTime`	ISO 8601 timestamp of the time the Job was created.
`startTime`	ISO 8601 timestamp when the comparison started. Depending on the number of queued jobs, there may be significant time between `creationTime` and `startTime`
`finishedTime`	ISO 8601 timestamp of when the comparison finished.
`comparisonTime`	Time in ms the comparison took, as a string - e.g. "123 ms".
`jobStatus`	An enumeration of the state of the comparison. States include: QUEUED STARTED INPUTS_LOADING_A INPUTS_LOADING_B INPUT_FILTERS COMPARISON_RUNNING OUTPUT_FILTERS SAVING FINISHED FAILED CANCELLED
`jobId`	The ID of the Job
`numberOfStages`	Number of stages in the pipeline, as an integer.
`pipelineStage`	The current pipeline stage of the comparison.
`progressInPercentage`	Percentage of progress in the pipeline, as an integer. Note: numbers are approximate, and are based on the number of stages in the pipeline. Individual stages will vary in length of time they take to complete.
`links / link`	HATEOAS links containing a `href` URI and a `rel` describing its meaning. A rel of "cancel" indicates you can use `HTTP DELETE` to cancel the Job, whereas "result" indicates the endpoint you should call `GET` on to receive result information.
`output`	Specifies where the result has been output to.
`error`	Contains error information if an error happened. See Errors Page for more information.

When using Cloud I/O output will contain the Cloud I/O information provided minus the client ID / secret information for security reasons, for example:

XML

<output type="s3">
    <region>EU-WEST-1</region>
    <bucket>DeltaXML-Bucket</bucket>
    <fileName>output.xml</fileName>
</output>

If not using Cloud I/O for the output, then it will contain a uri and size (which provides the result size in bytes - as an integer). For example:

XML

<output type="http">
    <uri>http://localhost:8080/api/xml-compare/v1/downloads/12346124</uri>
    <size>390</size>
</output>

If the comparison failed, an error element will contain details of the failure, including a stack trace which can help diagnose the issue. The size of the result is reported in terms of bytes.

A GET request to the output uri will then complete the asynchronous lifecycle:

Request

CODE

GET /api/xml-compare/v1/downloads/123456

Response

CODE

HTTP/1.1 200 OK
<root xmlns:deltaxml="http://deltaxml.com/ns/well-formed-delta-v1" deltaxml:deltaV2="A!=B">
  <child deltaxml:deltaV2="A=B">...</child>
  <child deltaxml:deltaV2="A!=B">...</child>
</root>

Note

If the pipeline POST request specified an output file location, the output file will be available at that location after a successful asynchronous comparison. A GET request from the downloads resource will merely provide the same file from that location.

Cancelling a Job

Jobs can be cancelled while they are queued or running, this is indicated through a HATEOAS link in the Job info, for example:

Response (XML)

XML

<job>
    <links>
        <link href="/api/xml-compare/v1/jobs/12346124" rel="cancel"/>
    </links>
    <creationTime>2018-04-06T11:31:20.863+01:00</creationTime>
    <jobStatus>QUEUED</jobStatus>
    <numberOfStages>0</numberOfStages>
    <progressInPercentage>0.0</progressInPercentage>
</job>

Response (JSON)

JS

{
  "creationTime": "2018-04-06T11:31:20.863+01:00",
  "numberOfStages": 0,
  "progressInPercentage": 0,
  "jobStatus": "QUEUED",
  "links": [
    {
      "rel": "cancel",
      "href": "/api/xml-compare/v1/jobs/12346124"
    }
  ]
}

It is invoked by using a DELETE request to the specified Job:

Request

CODE

DELETE /api/xml-compare/v1/jobs/3

The response will be the Job, note the jobStatus is now CANCELLED:

Response

XML

<job>
    <links/>
    <creationTime>2018-04-06T11:31:20.863+01:00</creationTime>
    <jobStatus>CANCELLED</jobStatus>
    <numberOfStages>0</numberOfStages>
    <progressInPercentage>0.0</progressInPercentage>
</job>

Response

JS

{
  "creationTime": "2018-04-18T13:19:31.989+0000",
  "numberOfStages": 0,
  "progressInPercentage": 0,
  "jobStatus": "CANCELLED",
  "links": []
}

Result Files

In an asynchronous comparison, by default a comparison's result file will be deleted after doing a GET request on the Job's 'downloads' resource. This can be changed by setting the boolean parameter keepResult to true when making the comparison request.

A comparison's result file can also be deleted through a HTTP DELETE request to the jobs 'downloads' resource. This will be indicated by a change of the Job's status to DELETED. Further GET requests to this Job's 'downloads' ID will produce a HTTP 204 status code.

Note

If the output has been specified to be uploaded to a cloud service, it won't be deleted regardless of a DELETE request.

Request

CODE

DELETE /api/xml-compare/v1/downloads/123456

Response (XML)

XML

<result>
    <status>DELETED</status>
</result>

Response (JSON)

JS

{
    "status": "DELETED"
}

Callbacks

If the user registered a callback URL with the comparison request, the REST service will attempt an HTTP GET to that URL on completion of the comparison.

In this example the callback URL "http://www.example.com/comparison-callback" was registered in the comparison request - we will add a request parameter of jobIf which allows the Job resource to be located:

Request

CODE

GET http://www.example.com/comparison-callback?jobId=12346124