It's a predefined Datafeed API adapter that uses an HTTP-based UDF protocol designed to deliver data to the library in a simple and efficient way.

tip

This predefined adapter is an example implementation of the JS API. You are not required to implement your datafeed using UDF.

How to start​

You should create a server-side HTTP service that gets the data from your storage and responds to library requests.

Response-as-a-table concept​

Think of data feed responses as tables. For example, a data feed response that includes a symbol list from the exchange may be treated as a table where each symbol represents a row, along with some columns (minimal_price_movement, description, has_intraday e.t.c.). Each column may be an array (it will provide a separate value for each row in a table). Note that there might be a situation when all rows have the same value in the same column. In this case, the column value can be defined as a single value in JSON response.

Example:

Let's assume that we requested a symbol list from the New York Stock Exchange. The response (in pseudo-format) might look like

{
   symbols: ["MSFT", "AAPL", "FB", "GOOG"],
   min_price_move: 0.1,
   description: ["Microsoft corp.", "Apple Inc", "Facebook", "Google"]
}

Here is how this response will look like in a table format.

Symbolmin_price_moveDescription
MSFT0.1Microsoft corp.
AAPL0.1Apple Inc
FB0.1Facebook
GOOG0.1Google

API Calls​

Data feed configuration data​

Request: GET /config

Response: The library expects to receive a JSON response of the same structure as a result of Datafeed API onReady() call.

Also there should be 2 additional properties:

Either s_search or s_group_request should be set to true.

Note: if your data feed doesn't implement this call (doesn't respond or sends 404 error) then the default configuration is being used. Here is the default configuration:

{
    ed_resolutions: ['1', '5', '15', '30', '60', '1D', '1W', '1M'],
    s_group_request: true,
    s_marks: false,
    s_search: false,
    s_timescale_marks: false,
}

Symbol group request​

Request: GET /symbol_info?group=<group_name>

Example: GET /symbol_info?group=NYSE

Response: Response is expected to be an object with properties listed below. Each property is treated as table column, as described above (see response-as-a-table). The response structure is similar (but not equal) to SymbolInfo. Therefore, you should read the description of each field to learn about the details.

Here is an example of data feed response to GET /symbol_info?group=NYSE request:

{
   symbol: ["AAPL", "MSFT", "SPX"],
   description: ["Apple Inc", "Microsoft corp", "S&P 500 index"],
   exchange-listed: "NYSE",
   exchange-traded: "NYSE",
   minmovement: 1,
   minmovement2: 0,
   pricescale: [1, 1, 100],
   has-dwm: true,
   has-intraday: true,
   type: ["stock", "stock", "index"],
   ticker: ["AAPL~0", "MSFT~0", "$SPX500"],
   timezone: “America/New_York”,
   session-regular: “0900-1600”,
}

Notes:

  1. This call will be used if your data feed sent s_group_request: true in the configuration data or didn't respond to the configuration request at all.

  2. In the event that your data feed does not the requested symbol group (which should not happen if your response to request #1 (ed groups) is correct) you may expect a 404 error.

  3. When using this mode of receiving data (getting large amount of symbol data) your browser will keep the data that wasn't even requested by the . If your symbol list has more than a few items, please consider ing symbol search / individual symbol resolve instead.

Symbol resolve​

Request: GET /symbols?symbol=<symbol>

Example: GET /symbols?symbol=AAL, GET /symbols?symbol=NYSE:MSFT

A JSON response of the same structure as LibrarySymbolInfo.

Note: this call will be requested if your data feed sent s_group_request: false and s_search: true in the configuration data.

Request: GET /search?query=<query>&type=<type>&exchange=<exchange>&limit=<limit>

Example: GET /search?query=AA&type=stock&exchange=NYSE&limit=15

A response is expected to be an array of symbol objects as in respective JS API call

Note: this call will be requested if your data feed sent s_group_request: false and s_search: true in the configuration data.

Bars​

Request: GET /history?symbol=<ticker_name>&from=<unix_timestamp>&to=<unix_timestamp>&resolution=<resolution>&countback=<countback>

Example: GET /history?symbol=BEAM~0&resolution=D&from=1386493512&to=1395133512&countback=500

A response is expected to be an object with some properties listed below. Each property is treated as a table column, as described above.

Notes:

  1. Bar time for daily bars should be 00:00 UTC and is expected to be a trading day (not a day when the session starts). The library aligns the time according to the Session from SymbolInfo.

    1. Bar time for monthly bars should be 00:00 UTC and be the first trading day of the month.

  3. Prices should be ed as numbers and not as strings in quotation marks.

    Example:

    {
       s: "ok",
       t: [1386493512, 1386493572, 1386493632, 1386493692],
       c: [42.1, 43.4, 44.3, 42.8]
    }
    {
       s: "no_data",
       nextTime: 1386493512
    }
    {
       s: "ok",
       t: [1386493512, 1386493572, 1386493632, 1386493692],
       c: [42.1, 43.4, 44.3, 42.8],
       o: [41.0, 42.9, 43.7, 44.5],
       h: [43.0, 44.1, 44.8, 44.5],
       l: [40.4, 42.1, 42.8, 42.3],
       v: [12000, 18500, 24000, 45000]
    }

  4. If it is possible, it would be better to handle countback parameter for performance reasons. Basically, if you handle countback, you don't have to worry about ing nextTime, because countBack helps to avoid empty responses for ranges with no data.

How nextTime works​

Consider the following example. The current symbol is AAPL and the chart resolution is one minute. The library requests data in the [2015-04-03 16:00 UTC+0, 2015-04-03 19:00 UTC+0] range. There was no trade on 2015‑04‑03 due to a public holiday. In this case, the library expects the following response from the datafeed:

{
  s: "no_data",
  nextTime: 1428001140000 // 2 Apr 2015 18:59:00 GMT+0
}

nextTime is the time of the closest available bar in the past.

Marks​

Request: GET /marks?symbol=<ticker_name>&from=<unix_timestamp>&to=<unix_timestamp>&resolution=<resolution>

A response is expected to be an object with some properties listed below. This object is similar to respective response in Datafeed API, but each property is treated as a table column, as described above.

If the two_character_bar_marks_labels feature is enabled then at most the first two characters of the label text will be displayed. Otherwise only the first character will be displayed.

{
    id: [array of ids],
    time: [array of times],
    color: [array of colors],
    text: [array of texts],
    label: [array of labels],
    labelFontColor: [array of label font colors],
    minSize: [array of minSizes],
}

Note: this call will be requested if your data feed sent s_marks: true in the configuration data.

Timescale marks​

Request: GET /timescale_marks?symbol=<ticker_name>&from=<unix_timestamp>&to=<unix_timestamp>&resolution=<resolution>

A response is expected to be an array of objects with properties listed below.

Note: this call will be requested if your data feed sent s_timescale_marks: true in the configuration data.

Server time​

Request: GET /time

Response: Numeric unix time without milliseconds.

Example: 1445324591

Quotes​

Request: GET /quotes?symbols=<ticker_name_1>,<ticker_name_2>,...,<ticker_name_n>

Example: GET /quotes?symbols=NYSE%3AAA%2CNYSE%3AF%2CNasdaqNM%3AAAPL

A response is an object with the following keys.

Example:

{
    "s": "ok",
    "d": [
        {
            "s": "ok",
            "n": "NYSE:AA",
            "v": {
                "ch": 0.16,
                "chp": 0.98,
                "short_name": "AA",
                "exchange": "NYSE",
                "description": "Alcoa Inc. Common",
                "lp": 16.57,
                "ask": 16.58,
                "bid": 16.57,
                "open_price": 16.25,
                "high_price": 16.60,
                "low_price": 16.25,
                "prev_close_price": 16.41,
                "volume": 4029041
            }
        },
        {
            "s": "ok",
            "n": "NYSE:F",
            "v": {
                "ch": 0.15,
                "chp": 0.89,
                "short_name": "F",
                "exchange": "NYSE",
                "description": "Ford Motor Company",
                "lp": 17.02,
                "ask": 17.03,
                "bid": 17.02,
                "open_price": 16.74,
                "high_price": 17.08,
                "low_price": 16.74,
                "prev_close_price": 16.87,
                "volume": 7713782
            }
        }
    ]
}

Constructor​

Datafeeds.UDFCompatibleDatafeed = function(datafeedURL, updateFrequency, limitedServerResponse)

datafeedURL​

This is a URL of a data server that will receive requests and return data.

updateFrequency​

This is a frequency of requests that the data feed will send to the server in milliseconds. Default is 10000 (10 sec).

limitedServerResponse​

Optional parameter for configuring the datafeed for truncated server responses. Use this if your data server has a maximum response size. The object has two parameters: maxResponseLength and expectedOrder.