Handling a batch REST request in PHP

Question

For a PHP application I am integrating a REST service capable of receiving multiple nested HTTP requests at once. This is identical to the google calendar API: https://developers.google.com/google-apps/calendar/batch

However, I am not sure about the best way to parse this single request into multiple requests. The request to the server (from the Google example) would look like this:

POST /batch HTTP/1.1
Authorization: Bearer your_auth_token
Host: host
Content-Type: multipart/mixed; boundary=batch_foobarbaz
Content-Length: total_content_length

--batch_foobarbaz
Content-Type: application/http
Content-ID: <item1:12930812@barnyard.example.com>

GET /farm/v1/animals/pony

--batch_foobarbaz
Content-Type: application/http
Content-ID: <item2:12930812@barnyard.example.com>

PUT /farm/v1/animals/sheep
Content-Type: application/json
Content-Length: part_content_length
If-Match: "etag/sheep"

{
    "animalName": "sheep",
    "animalAge": "5"
    "peltColor": "green",
}

--batch_foobarbaz

The top section (above --batch_foobarbaz) should be available in the $_SERVER I presume. For the nested requests I clearly cannot use that.

My current action plan would be:

• Create a request class with properties for each header
• Create a request parsing class that parses each single request object
• For the /batch requests a wrapper would be used that splits the batch into multiple smaller request objects, feeding them from the extracted nested requests.
• For all normal/single requests it would simply populate the request with data from the headers. Both nested and single requests would then be handled the same through the request parsing class.

The splitting of the request would be done using an explode() on the boundary. But then? Parse each section using regular expressions to get every key:value? And expect the payload to be wrapped in newlines? Or is there some function / class available that would do this for me?

Any suggestions on how to tackle this is greatly appreciated. The response would also be a multipart/mixed message with responses per request. That way each single request would still use the REST principles.

Answer 1

1) If you absolutely insist on the multipart/mixed style then following old Stack Overflow articles may be useful:

• How do I get just the text content from a multipart email?
• Proper PHP way to parse email attachments from EML format

2) If you can influence the REST API design than it would be easier both for you (the parser) and for your users if you'd support one JSON with batch data on input. The REST API was supposed to simplify things, not to make them more complicated.

For examples look e.g. here (some Google results for "batch rest api" query):

• Jive forum - https://community.jivesoftware.com/thread/257773
• Stack Overflow - Patterns for handling batch operations in REST web services?