DAX API Overview

For Data Analysts

The DAX API enables Power BI, Excel, and other Analysis Services-compatible tools to query your Olytix Core semantic layer using DAX (Data Analysis Expressions). This provides native integration with Microsoft BI tools while leveraging Olytix Core's unified semantic model.

Key Features

Feature	Description
DAX Query Execution	Execute DAX queries against Olytix Core cubes
XMLA Protocol	Native Power BI connectivity via XMLA endpoint
Metadata Discovery	Expose cubes, dimensions, and measures to clients
Session Management	Stateful connections for Power BI Desktop
IntelliSense Support	Query completions for DAX editors

Architecture

The DAX API translates DAX queries into Olytix Core semantic queries:

Power BI Desktop  -->  XMLA Protocol  -->  DAX Engine  -->  Semantic Layer  -->  Data Warehouse

DAX Parser: Parses DAX syntax into an AST
DAX Translator: Converts DAX concepts to Olytix Core semantic queries
XMLA Handler: Implements XMLA protocol for Power BI connectivity
Metadata Provider: Exposes cube metadata to clients

Concept Mapping

Olytix Core maps DAX concepts to semantic layer constructs:

DAX Concept	Olytix Core Equivalent
Table	Cube
Column	Dimension
Measure	Measure
SUMMARIZECOLUMNS	Query with dimensions and measures
FILTER	Semantic filters
CALCULATE	Modified filter context

API Endpoints

REST Endpoints

Endpoint	Method	Description
`/api/v1/dax/execute`	POST	Execute a DAX query
`/api/v1/dax/validate`	POST	Validate DAX syntax
`/api/v1/dax/functions`	GET	List supported DAX functions
`/api/v1/dax/completions`	POST	Get IntelliSense completions
`/api/v1/dax/cubes`	GET	List available cubes

XMLA Endpoint

Endpoint	Method	Description
`/api/v1/dax/xmla`	POST	XMLA SOAP endpoint for Power BI

Quick Example

Execute a DAX query via REST:

curl -X POST http://localhost:8000/api/v1/dax/execute \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "query": "EVALUATE SUMMARIZECOLUMNS(orders[region], \"Total Revenue\", SUM(orders[amount]))"
  }'

Response:

{
  "columns": [
    {"name": "region", "data_type": "String", "is_measure": false},
    {"name": "Total Revenue", "data_type": "Double", "is_measure": true}
  ],
  "data": [
    {"region": "NORTH", "Total Revenue": 125000.00},
    {"region": "SOUTH", "Total Revenue": 98500.00},
    {"region": "EAST", "Total Revenue": 112000.00},
    {"region": "WEST", "Total Revenue": 87500.00}
  ],
  "row_count": 4,
  "execution_time_ms": 45.2,
  "from_cache": false
}

XMLA Protocol Basics

The XMLA (XML for Analysis) protocol enables Analysis Services-compatible tools to communicate with Olytix Core. XMLA uses SOAP over HTTP with two primary operations:

Discover

Retrieves metadata about cubes, dimensions, measures, and server properties.

<Discover xmlns="urn:schemas-microsoft-com:xml-analysis">
  <RequestType>MDSCHEMA_CUBES</RequestType>
  <Restrictions>
    <RestrictionList>
      <CATALOG_NAME>Olytix Core</CATALOG_NAME>
    </RestrictionList>
  </Restrictions>
  <Properties>
    <PropertyList>
      <Catalog>Olytix Core</Catalog>
    </PropertyList>
  </Properties>
</Discover>

Execute

Executes DAX queries and returns results.

<Execute xmlns="urn:schemas-microsoft-com:xml-analysis">
  <Command>
    <Statement>
      EVALUATE
      SUMMARIZECOLUMNS(
        orders[region],
        "Revenue", SUM(orders[amount])
      )
    </Statement>
  </Command>
  <Properties>
    <PropertyList>
      <Catalog>Olytix Core</Catalog>
    </PropertyList>
  </Properties>
</Execute>

Supported Discovery Types

Schema Rowset	Description
MDSCHEMA_CUBES	List available cubes
MDSCHEMA_DIMENSIONS	List dimensions in cubes
MDSCHEMA_MEASURES	List measures in cubes
MDSCHEMA_HIERARCHIES	List dimension hierarchies
MDSCHEMA_LEVELS	List hierarchy levels
DBSCHEMA_TABLES	List tables (cubes)
DBSCHEMA_COLUMNS	List columns (dimensions/measures)
DISCOVER_PROPERTIES	Server properties
DISCOVER_DATASOURCES	Data source information

Session Management

XMLA supports stateful sessions for maintaining context across multiple requests:

# Create a session
curl -X POST http://localhost:8000/api/v1/dax/sessions \
  -H "Authorization: Bearer YOUR_API_KEY"

# Response
{
  "session_id": "sess_abc123",
  "created_at": "2024-01-20T10:30:00Z",
  "timeout_seconds": 3600
}

Include the session ID in subsequent requests:

curl -X POST http://localhost:8000/api/v1/dax/execute \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "X-Session-ID: sess_abc123" \
  -H "Content-Type: application/json" \
  -d '{"query": "EVALUATE orders"}'

Security

DAX queries respect Olytix Core's security model:

Row-Level Security (RLS): Filters are automatically applied based on user context
Column-Level Security: Masked columns return obfuscated values
Authentication: API key or JWT token required

Supported DAX Functions

Olytix Core supports common DAX functions across these categories:

Category	Examples
Aggregation	SUM, COUNT, COUNTROWS, AVERAGE, MIN, MAX, DISTINCTCOUNT
Filter	FILTER, ALL, ALLEXCEPT, CALCULATE, CALCULATETABLE
Table	SUMMARIZECOLUMNS, SUMMARIZE, ADDCOLUMNS, SELECTCOLUMNS
Information	ISBLANK, ISERROR, HASONEVALUE
Logical	IF, AND, OR, NOT, SWITCH
Date/Time	YEAR, MONTH, DAY, TODAY, NOW

See DAX Queries for detailed function support.

Key Features​

Architecture​

Concept Mapping​

API Endpoints​

REST Endpoints​

XMLA Endpoint​

Quick Example​

XMLA Protocol Basics​

Discover​

Execute​

Supported Discovery Types​

Session Management​

Security​

Supported DAX Functions​

Next Steps​