pskevin commented on a change in pull request #12445:
URL: https://github.com/apache/beam/pull/12445#discussion_r465373680
##########
File path: sdks/go/pkg/beam/external.go
##########
@@ -16,10 +16,151 @@
package beam
import (
+ "context"
+ "fmt"
+
"github.com/apache/beam/sdks/go/pkg/beam/core/graph"
+ "github.com/apache/beam/sdks/go/pkg/beam/core/runtime/graphx"
"github.com/apache/beam/sdks/go/pkg/beam/internal/errors"
+ jobpb "github.com/apache/beam/sdks/go/pkg/beam/model/jobmanagement_v1"
+ pipepb "github.com/apache/beam/sdks/go/pkg/beam/model/pipeline_v1"
+ "google.golang.org/grpc"
)
+// ExternalTransform represents the cross-language transform in and out of the
Pipeline as a MultiEdge and Expanded proto respectively
+type ExternalTransform struct {
+ id int
+ Urn string
+ Payload []byte
+ In []PCollection
+ Out []FullType
+ Bounded bool
+ ExpansionAddr string
+ Components *pipepb.Components
+ ExpandedTransform *pipepb.PTransform
+ Requirements []string
+}
+
+// CrossLanguage is the temporary API to execute external transforms
+// TODO(pskevin): Handle errors using the TryN and Must strategies instead one
function handling multiple points of failure
+func CrossLanguage(s Scope, p *Pipeline, e *ExternalTransform) []PCollection {
+ if e.ExpansionAddr == "" { // TODO(pskevin): Better way to check if the
value was ever set
+ // return Legacy External API
+ }
+
+ /*
+ Add ExternalTranform to the Graph
+ */
+ // Validating scope and inputs
+ if !s.IsValid() {
+ // return nil, errors.New("invalid scope")
+ fmt.Println("invalid scope")
+ }
+ for i, col := range e.In {
+ if !col.IsValid() {
+ // return nil, errors.Errorf("invalid pcollection to
external: index %v", i)
+ fmt.Printf("\ninvalid pcollection to external: index
%v", i)
+
+ }
+ }
+
+ // Using exisiting MultiEdge format to represent ExternalTransform
(already backwards compatible)
+ payload := &graph.Payload{
+ URN: e.Urn,
+ Data: e.Payload,
+ }
+ var ins []*graph.Node
+ for _, col := range e.In {
+ ins = append(ins, col.n)
+ }
+ edge := graph.NewCrossLanguage(s.real, s.scope, ins, payload)
+
+ // TODO(pskevin): There needs to be a better way of associating this
ExternalTransform to the pipeline
+ // Adding ExternalTransform to pipeline referenced by MultiEdge ID
+ if p.ExpandedTransforms == nil {
+ p.ExpandedTransforms = make(map[string]*ExternalTransform)
+ }
+ p.ExpandedTransforms[fmt.Sprintf("e%v", edge.ID())] = e
+
+ /*
+ Build the ExpansionRequest
+ */
+ // Obtaining the components and transform proto representing this
transform
+ pipeline, err := graphx.Marshal([]*graph.MultiEdge{edge},
&graphx.Options{})
+ if err != nil {
+ panic(err)
+ }
+
+ // Adding fake impulses to each input as required for correct expansion
+ // TODO(pskevin): Remove these fake impulses from final Pipeline since
multiple producers of the same PCollections is logically wrong
+ transforms := pipeline.Components.Transforms
+ rootTransformID := pipeline.RootTransformIds[0]
+ for tag, id := range transforms[rootTransformID].Inputs {
+ key := fmt.Sprintf("%s_%s", "impulse", tag)
+
+ output := map[string]string{"out": id}
+ impulse := &pipepb.PTransform{
+ UniqueName: key,
+ Spec: &pipepb.FunctionSpec{
+ Urn: graphx.URNImpulse,
+ },
+ Outputs: output,
+ }
+
+ transforms[key] = impulse
+ }
+
+ // Assembling ExpansionRequest proto
+ req := &jobpb.ExpansionRequest{
+ Components: pipeline.Components,
+ Transform: transforms[rootTransformID],
+ Namespace: s.String(),
+ }
+
+ /*
+ Querying Expansion Service
+ */
+ // Setting grpc client
+ conn, err := grpc.Dial(e.ExpansionAddr, grpc.WithInsecure())
+ if err != nil {
+ panic(err)
+ }
+ defer conn.Close()
+ client := jobpb.NewExpansionServiceClient(conn)
+
+ // Handling ExpansionResponse
+ res, err := client.Expand(context.Background(), req)
+ if err != nil {
+ panic(err)
+ }
+ e.Components = res.GetComponents()
+ e.ExpandedTransform = res.GetTransform()
+ e.Requirements = res.GetRequirements()
+
+ /*
+ Associating output PCollections of the expanded transform with
correct internal outbound links and nodes
+ */
+ // No information about the output types and bounded nature has been
explicitly passed by the user
+ if len(e.Out) == 0 || cap(e.Out) == 0 {
+ // Infer output types from ExpansionResponse and update e.Out
+ if e.Out == nil {
+ // Use reverse schema encoding
+ } else {
+ // Use the coders list and map from coder id to
internal FullType?
+ }
+ }
Review comment:
Makes sense. Will do!
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