| // Licensed to the Apache Software Foundation (ASF) under one or more |
| // contributor license agreements. See the NOTICE file distributed with |
| // this work for additional information regarding copyright ownership. |
| // The ASF licenses this file to You under the Apache License, Version 2.0 |
| // (the "License"); you may not use this file except in compliance with |
| // the License. You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package beam |
| |
| import ( |
| "github.com/apache/beam/sdks/go/pkg/beam/core/graph" |
| "github.com/apache/beam/sdks/go/pkg/beam/internal/errors" |
| ) |
| |
| // External defines a Beam external transform. The interpretation of this primitive is runner |
| // specific. The runner is responsible for parsing the payload based on the |
| // spec provided to implement the behavior of the operation. Transform |
| // libraries should expose an API that captures the user's intent and serialize |
| // the payload as a byte slice that the runner will deserialize. |
| func External(s Scope, spec string, payload []byte, in []PCollection, out []FullType, bounded bool) []PCollection { |
| return MustN(TryExternal(s, spec, payload, in, out, bounded)) |
| } |
| |
| // TryExternal attempts to perform the work of External, returning an error indicating why the operation |
| // failed. |
| func TryExternal(s Scope, spec string, payload []byte, in []PCollection, out []FullType, bounded bool) ([]PCollection, error) { |
| if !s.IsValid() { |
| return nil, errors.New("invalid scope") |
| } |
| for i, col := range in { |
| if !col.IsValid() { |
| return nil, errors.Errorf("invalid pcollection to external: index %v", i) |
| } |
| } |
| |
| var ins []*graph.Node |
| for _, col := range in { |
| ins = append(ins, col.n) |
| } |
| edge := graph.NewExternal(s.real, s.scope, &graph.Payload{URN: spec, Data: payload}, ins, out, bounded) |
| |
| var ret []PCollection |
| for _, out := range edge.Output { |
| c := PCollection{out.To} |
| c.SetCoder(NewCoder(c.Type())) |
| ret = append(ret, c) |
| } |
| return ret, nil |
| } |