merge: Introduce schema for trace API (#88)

This pull request updates the OpenDC trace API to support proper specification 
of a schema of the tables exposed by the traces. This functionality makes it easier 
for the API consumer to understand the types exposed by the API.

## Implementation Notes :hammer_and_pick:

* Introduce type system for trace API
* Add benchmarks for odcvm trace format 
* Add benchmarks for Azure trace format
* Add conformance suite for OpenDC trace API 

## External Dependencies :four_leaf_clover:

* N/A

## Breaking API Changes :warning:

* Removal of typed `TableColumn`. Instead, `TableColumn` instances are now 
   used to describe the columns belonging to some table.
* `TableReader` and `TableWriter` do not support accessing arbitrary objects 
   anymore. Instead, only the types supported by the type system are exposed.

1 files changed, 2 insertions, 5 deletions

diff --git a/opendc-trace/opendc-trace-api/src/main/kotlin/org/opendc/trace/internal/TableImpl.kt b/opendc-trace/opendc-trace-api/src/main/kotlin/org/opendc/trace/internal/TableImpl.kt
index b848e19a..1e1bf676 100644
--- a/opendc-trace/opendc-trace-api/src/main/kotlin/org/opendc/trace/internal/TableImpl.kt
+++ b/opendc-trace/opendc-trace-api/src/main/kotlin/org/opendc/trace/internal/TableImpl.kt
@@ -37,13 +37,10 @@ internal class TableImpl(val trace: TraceImpl, override val name: String) : Tabl
      */
     private val details = trace.format.getDetails(trace.path, name)
 
-    override val columns: List<TableColumn<*>>
+    override val columns: List<TableColumn>
         get() = details.columns
 
-    override val partitionKeys: List<TableColumn<*>>
-        get() = details.partitionKeys
-
-    override fun newReader(projection: List<TableColumn<*>>?): TableReader {
+    override fun newReader(projection: List<String>?): TableReader {
         return trace.format.newReader(trace.path, name, projection)
     }