User Guide¶
The datareservoirio library provide access to DataReservoir.io,
and is a native Python experience. The following features are supported through the
Python API:
Manage series (time series or sequences):
Access existing series
Create and upload new series
Edit and append to existing series
Delete series
Manage metadata
Set metadata
Edit existing metadata
Delete metadata
Browse and search for series based on metadata
All of the above functionality are exposed as high-level methods in the
Client class. The general workflow can be summarized as:
Authenticate
Instantiate a new
client(usingClient)Go… Data is waiting for you!
Data Structures¶
DataReservoir.io works with two fundemental data structures; series and metadata. These data structures and their Python representations are explained below.
Series¶
A series is a one-dimensional sequence with numeric values (64-bit float) and unique indecies (64-bit integer). (Consequently, each numeric value is natively represented with 128-bits.) Each series is assigned a unique identifier TimeSeriesId (guid) for convinient access. Furhtermore, a series can be enriched with metadata.
For time series the index is interpreted as nanoseconds since epoch (1970-01-01 00:00:00+00:00), i.e. support for nanosencond resolution.
pandas.Series objects maps perfectly to this paradigm.
datareservoirio is designed around pandas.Series as it
accepts and returns series data in this format.
Higher dimensional data, such as tables (dataframes), can be broken down to one-dimensional series’, see Cookbook for examples.
Metadata¶
Metadata is a set of key-value pairs that can be associated with one or more series. The purpose of metadata is to enrich series data with essential information such as units, origin, description, etc. The same metadata can also be used to search and find series data later.
DataReservoir.io employs a “schemaless” metadata store. That is, there are no minimum requirements and you can basically add anything your heart desires. However…
“With great power comes great responsibility!”
—Uncle Ben
But, that responsibility is left to the user/app/service that uses DataReservoir.io. Simply because one-size does not fit all!
Metadata entries are organized using namespace and key. A namespace
can be thought of as a table and key is the row index. Then a row can have
any number of arbitrary number of columns. (Note that rows in a table do not
have to share the columns!). This resembles “table storage” paradigm for those
who are familiar with that.
Thus, a namespace and key combination uniquely defines a metadata
entry in DataReservoir.io. (That is, you can only have one entry in the
entire system with a given namespace and key combination). In addition,
each entry is also assigned an alias MetadataId (guid) that can be used for
direct and convenient access.
A table-like representation may look like this:
Namespace: vessel.electrical |
|||
|---|---|---|---|
Keys |
Units |
Vendor |
Type |
Voltmeter A |
V |
Company S |
|
Thermometer Z |
C |
Analog |
|
Best practices¶
DataReservoir.io won’t enforce a particular schema when it comes to metadata, but we can suggest smart ways of approaching it.
One simple yet effective way of creating a hierarcy and taxonomy is to use
“period” seperated names as namespace. E.g.:
vessels.galactica.electrical
service.context.sensors
application.streams
We found that this approach is rather easy to visualize and maps well to the physcial world.
What is it NOT for¶
Despite its flexibility, DataReservoir.io has its limitations when it comes to metadata; it is NOT a general purpose database that you can dump anything in to and it is not designed to keep track of complex hierarchical information. The query capabilities are also kept simple and efficient by design.
For very advanced use cases, it may be advisable to employ a purpose built database solution (that compliments DataReservoir.io for your application).