Pencil Code Reference > urls

urls the structure of the Pencil Code server

How Pencil Code stores your data

The web server for the Pencil Code editor has a simple design.

• There is a single HTML file (internally called editor.html) that does all the work. All pencilcode.net/edit/... URLs actually resolve to this same static file.
• That page makes HTTP GETs to pencilcode.net/load/... to load the actual text of programs.
• And it makes HTTP POSTs to pencilcode.net/save/... to write the text of the programs.

Here is a summary of the special URL patterns on Pencil Code that deal with files saved in a user's directory.

Loading and storing your own data

You can also load and save your own data on the Pencil Code server.

Your files are limited to about one megabyte, so Pencil Code is not a good server for photos or other media: for those, you should use an external service such as Imgur or Soundcloud or Youtube, and link to those services using absolute URLs.

When saving your data, rememember to follow the Pencil Code terms of service. In particular, do not flood the service with more than a megabyte of data: Pencil Code is not a bulk storage service, and using it as one would unfairly deny resources to other students. If you try to host spam or copyrighted content or bulk data that are too large, we may remove the data, or limit or block access.

Pencil Code is good for storing small text or data files for your application. If you save data, you can use file extensions like .txt or .json or .xml to indicate the data type.

You can post to the load and save urls using jQuery as follows.

In JavaScript:

$.get('/load/dir/filename',
  function (m) {
    console.log('loaded', m);
  }
);

$.post('/save/dir/filename',
  { key: '012', data: 'my data' },
  function (m) {
    console.log('saved and got', m);
  }
);

In CoffeeScript, the equivalent code:

$.get '/load/dir/filename', (m) ->
  console.log 'loaded', m

$.post '/save/dir/filename',
  key: '012'
  data: 'my data'
  (m) ->
    console.log 'saved and got', m

JSON response format

When loading a file via /load/, the response is formatted as JSON. For example, if you view pencilcode.net/load/first, you will see the following JSON data (though not indented nicely):

{
  "file":"/first",
  "data":"speed 2\npen red\nfor [1..25]\n  fd 100\n  rt 88\n",
  "auth":true,
  "mtime":1385737227432,
  "mime":"text/x-pencilcode;charset=utf-8"
}

The data of the file is encoded in a string under the "data" field, and all the other fields are metadata.

The "meta" field, when present, is used with Pencil Code programs without an file extension which to store non-default language or library choices (the choices under the "gear menu" in the editor).

Access keys and turtle methods

To save data in an account, you may need an access key.

Every account has a different access key. Note that the keys are not a high-security measure - they are akin to a school combination lock, mainly to discourage accidental or casual saving over somebody else's data. To get the access key that allows programs to save data into your own account, you should be logged in, and then you can run the following function, using the turtle library:

console.log(save.loginCookie().key)

Heed the terms of service when using keys: please do experiment with keys, but do not interfere with another students work by hacking their keys or overwriting their data. Pencil Code is a learning community. We do not require students to learn bulletproof security measures before storing their data, so please respect their work and support these novices.

The turtle library also includes simplfied load and save methods that unwrap the metadata for you:

load 'myfile', (txt) -> write 'got', txt
save 'myfile', 'saved at ' + new Date

If you run a program while logged in, the save method will use your cookie to provide the key automatically.

Other useful URLs

The Pencil Code server also supports a few other useful URLs.