DJ's Weblog

Tarpipe implemented a REST connector a short while ago. This is something that I and others have been wanting for a while now, so it’s great news. The announcement was quite short and didn’t have much detail. I like to see things visually, and I’m guessing others do too, so I decided to write a little handler to receive a sample request from the REST connector to dump it for inspection.

As Bruno showed in the announcement, this is what the REST connector looks like:

It will take whatever values it receives in the title, description and link input fields on the left hand side of the connector, and construct a piece of JSON which it then sends in an application/x-www-form-urlencoded format as a data=<JSON> name/value pair in the message body of an HTTP POST request to the resource specified in the serviceUrl field.

So if we pass the values “DJ’s Weblog” into the title, “Reserving the right to be wrong” into the description, “http://www.pipetree.com/qmacro/blog/” into the link fields, and pass “http://example.org/bucket/” into the serviceUrl field, the following HTTP request is made on the http://example.org/bucket/ resource like this:

POST /bucket/ HTTP/1.1
Content-Length: 218
Content-Type: application/x-www-form-urlencoded
Host: example.org
Accept: */*

data=%7B%22items%22%3A%5B%7B%22title%22%3A%22DJ%27s+Weblog%22%2C%22description
     %22%3A%22Reserving+the+right+to+be+wrong%5Cn%22%2C%22link%22%3A%22http%3A
     %5C%2F%5C%2Fwww.pipetree.com%5C%2Fqmacro%5C%2Fblog%5C%2F%22%7D%5D%7D

(whitespace added by me for readability).

When decoded and pretty-printed, that message body looks like this

data={
    "items":[
       {
           "title":"DJ's+Weblog",
           "description":"Reserving+the+right+to+be+wrong",
           "link":"http://www.pipetree.com/qmacro/blog/"
       }
    ]
}

This is what your app gets to process.

Bruno said that the format was chosen to be compatible with the Yahoo! Pipes Web Service Module, and it sure is — look at this example from the Web Service Module documentation:

data={
    "items":[
       {
           "title": "First Title",
           "link": "http://example.com/first",
           "description": "First Description"
       },
       {
           "title": "Last Title",
           "link": "http://example.com/last",
           "description": "Last Description"
       }
    ]
}

And what about those three output fields on the right hand side of the REST connector? Well, if your app returns a response with JSON in the body — this time not as a name/value pair, but as pure JSON — like this:

{
  "items":[
     {
         "title": "The response!",
         "description": "Long text description of the response",
         "link": "http://example.org/banana/"
     }
  ]
}

then the workflow can continue and you can connect those values in the corresponding title, description and link output fields as input to further connectors.

Happy tarpiping!