Advanced topics

Content negocation in REST mocks

Microcks mocks engine supports Content Negociation for REST APIs based on Accept HTTP header.

So supposed you have defined 2 representations for the same example of a GET /pastry/{name} operation into your API contract:

  • One describing a JSON response like below


  • Another describing a XML response like below


Both samples are matching the same dispatch criterion that is the name part of the URI. However depending on the Accept header of your request, Microcks will return different responses:

$ curl http://localhost:8080/rest/API+Pastry+-+2.0/2.0.0/pastry/Eclair+Cafe
{"name":"Eclair Cafe","description":"Delicieux Eclair au Cafe pas calorique du tout","size":"M","price":2.5,"status":"available"}


$ curl http://localhost:8080/rest/API+Pastry+-+2.0/2.0.0/pastry/Eclair+Cafe -H 'Accept: text/xml'
    <name>Eclair Cafe</name>
    <description>Delicieux Eclair au Cafe pas calorique du tout</description>

Operation parameters constraints

Sometimes it may be important to specify additional constraints onto a Mock operation. Constraints that are related to API behaviour or semantic may be hard even impossible to express with an API contract. Microcks allows you to specify such constraints by editing the properties of a Service or API operation.

Constraints can be put onto Query or Header parameters and are of 3 types:

  • required constraints are forcing the presence of parameter in incoming request,
  • recopy constraints are just sending back the same parameter name and value into mock response,
  • match constraints are checking the value of a parameter against a specified regular expression.

Now imagine you put such constraints onto the GET /pastry operation of your REST API that is secured using a JWT Bearer and should managed tracabelity using a correlation id:


Now let’s do some tests to check Microcks behavior:

$ http http://localhost:8080/rest/API+Pastry/1.0.0/pastry
HTTP/1.1 400 
Connection: close
Content-Length: 65
Content-Type: text/plain;charset=UTF-8
Date: Fri, 13 Dec 2019 19:20:31 GMT
X-Application-Context: application

Parameter Authorization is required. Check parameter constraints.

Hum… Adding the Authorization header…

$ http http://localhost:8080/rest/API+Pastry/1.0.0/pastry Authorization:'Bearer 123'
HTTP/1.1 400 
Connection: close
Content-Length: 89
Content-Type: text/plain;charset=UTF-8
Date: Fri, 13 Dec 2019 19:31:01 GMT
X-Application-Context: application

Parameter Authorization should match ^Bearer\s[a-f0-9]{36}$. Check parameter constraints.

Hum… Fixing the Bearer format and adding the x-request-id header:

$ http http://localhost:8080/rest/API+Pastry/1.0.0/pastry Authorization:'Bearer abcdefabcdefabcdefabcdefab1234567890' x-request-id:123
HTTP/1.1 200 
Content-Length: 559
Content-Type: application/json
Date: Fri, 13 Dec 2019 19:33:52 GMT
X-Application-Context: application
x-request-id: 123

        "description": "Delicieux Baba au Rhum pas calorique du tout",
        "name": "Baba Rhum",
        "price": 3.2,
        "size": "L",
        "status": "available"
        "description": "Delicieux Divorces pas calorique du tout",
        "name": "Divorces",
        "price": 2.8,
        "size": "M",
        "status": "available"
        "description": "Delicieuse Tartelette aux Fraises fraiches",
        "name": "Tartelette Fraise",
        "price": 2,
        "size": "S",
        "status": "available"

Operation parameters constraints are saved into Microcks database and not replaced by a new importation of your Service or API definition. They can be independently set and updated using the Microcks APIs.

Override default headers during tests

Coming soon…

“Advanced topics” was last updated: December 13, 2019
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