Extending Accelerator APIs

Through the use of Insights Enterprise custom APIs the accelerator APIs can be extended or enhanced.

Within a custom API, the Accelerator get* functions can be called locally. However the input/output format must be taken note of as it is structured in a way that supports distributed queries and aggregations.

Use cases

In the example below we will simply add a column at both the DAP and the aggregator, however some common use cases are:

• Reformat the data to structure for a dashboard render
• Append a second reference table in a way that is not natively supported by the get* APIs
• Run more complex analytics on top of first stage aggregations of getStats

Structure of accelerator APIs

To understand how to best make use of the Accelerator APIs it is necessary to know the inputs and outputs. It is also worth understanding what happens within each of the Accelerator get* APIs at a high level,

The structure of the accelerator APIs on a DAP is as follows:

get*:{[args]]

    /Validate arguments
    /Adjust arguments
    /Query data
    /Transform data
    /return to aggregator

    :(data;args)
    }

This means it accepts a dictionary (same as if querying from a gateway)

However, it returns at the DAP level a two item list:

- `data` the queried data from this DAP as a table
- `args` the argument dictionary with any adjustments applied

At the Aggregator level all get* APIs are serviced by one join function.

fsiJoin:{[returns]

    /Unpack returns variable
    /Join data
    /Transform data
    /Return

    :data
    }

Here the fsiJoin is taking a single argument, which is a variable length nested list of structure:

((data;args);(data;args);(data;args))

which is a list of outputs from each DAPs.

The return data is the joined table.

Using accelerator APIs in own custom APIs

Therefore with the above in mind a custom API making use of this could be built like so:

At the DAP

myAPI:{[args]

    out:getTicks[args];

    data:first out;
    args:last out;

    data:update DAPColumn:.z.p from data;

    :(data;args)

At the aggregator

myJoin:{[returns]

    data:fsiJoin[returns];

    :update aggColumns:.z.p from data
    }

These custom APIs will need to be registered with the SG as per the custom API guide

Packaging

The above custom API enhancements should be packaged separately to the Accelerator packages, and loaded in by referencing them in the DAP/Aggregator as described in the Insights Enterprise documentation.