HTTP

DSS can read data stored on HTTP or HTTPS servers. This “remote” dataset can only be used as input in DSS.

Warning

When using a HTTP dataset “as-is”, data will be fetched from the HTTP source each time you access this dataset in Explore or Charts and the sample needs to be refreshed.

Quite often, you’ll want to use the Download recipe to cache the contents from the HTTP server.

The HTTP (with cache) dataset is a shortcut that allows you to quickly create a download recipe and its associated “files in folder” output dataset

By default, the download recipe will still check the HTTP server for updates when its output folder is rebuilt. This behavior can be disabled.

Creating a HTTP dataset

  • From the Flow or datasets list, click the “New dataset” button and select “Network > HTTP”
  • Enter the URL(s) to download, one per line.
  • Click on Test to download the first URL and detect format and schema

Remote URL definition

A remote source can be defined by a HTTP or HTTPS URL. HTTP/HTTPS URL may only reference a single remote file, and wilcard expansion patterns are not recognized in them.

Remote URL definitions can contain optional inline authentication credentials and non-default network ports.

URL Downloaded files (single source)
http://HOST/stats/20140102.log 20140102.log
http://USER:PASSWORD@HOST:8080/stats/20140102.log 20140102.log

Partitioned HTTP dataset

It is possible to partition a HTTP dataset. Unlike with other kinds of files-based datasets, you do not partition a HTTP dataset by specifying folder patterns. That is because a HTTP dataset is not enmuerable.

When partitioning is enabled for a HTTP dataset:

  • Remote files are downloaded from origin servers one partition at a time, each time a sample is computed, or a recipe based on this dataset is run
  • A set of expansion variables are available to include in the URL to choose remote file names from partition values.
  • The source definition screen contains an additional input field “Preview partition” to define which partition is used when “Testing” the dataset in the dataset definition screen
  • The source definition screen contains an additional input field “Partitions list” to manually set the list of possible partitions. This is used when trying to list partitions from the sample screen, from the metrics screen, or when using the “All available” partition dependency.

The expansion variables are the regular %Y, %M, %D, %H and %{dimension_name} that you use in other partitioned datasets.

Warning

Expansion variables in download recipes are different

Example

The following defines a HTTP dataset based on a web server that contains a file for each US state:

  • Create a new HTTP dataset
  • Click on activate partitioning, add a discrete partition dimension named “state”
  • Set https://my-website/data/%{state}.csv as the URL
  • Set “AZ” as the preview partition
  • Optional: Set “AL,AZ ….. WY” as the partitions list
  • Test and create

Given the above definitions, whenever you access partition “NJ”, the HTTP dataset will only fetch the URL https://my-website/data/NJ.csv.