youngoli commented on a change in pull request #12445: URL: https://github.com/apache/beam/pull/12445#discussion_r466758649
########## File path: sdks/go/examples/xlang/wordcount/xlang_wordcount.go ########## @@ -0,0 +1,107 @@ +// 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. + +// xlang_wordcount exemplifies using a cross language transform from Python to count words +package main + +import ( + "context" + "flag" + "fmt" + "log" + "regexp" + "strings" + + "github.com/apache/beam/sdks/go/pkg/beam/core/typex" + "github.com/apache/beam/sdks/go/pkg/beam/core/util/reflectx" + + "github.com/apache/beam/sdks/go/pkg/beam" + "github.com/apache/beam/sdks/go/pkg/beam/io/textio" + "github.com/apache/beam/sdks/go/pkg/beam/x/beamx" + + // Imports to enable correct filesystem access and runner setup in LOOPBACK mode + _ "github.com/apache/beam/sdks/go/pkg/beam/io/filesystem/gcs" + _ "github.com/apache/beam/sdks/go/pkg/beam/io/filesystem/local" + _ "github.com/apache/beam/sdks/go/pkg/beam/runners/universal" +) + +var ( + // Set this option to choose a different input file or glob. + input = flag.String("input", "./input", "File(s) to read.") + + // Set this required option to specify where to write the output. + output = flag.String("output", "./output", "Output file (required).") +) + +var ( + wordRE = regexp.MustCompile(`[a-zA-Z]+('[a-z])?`) + empty = beam.NewCounter("extract", "emptyLines") + lineLen = beam.NewDistribution("extract", "lineLenDistro") +) + +// extractFn is a DoFn that emits the words in a given line. +func extractFn(ctx context.Context, line string, emit func(string)) { + lineLen.Update(ctx, int64(len(line))) + if len(strings.TrimSpace(line)) == 0 { + empty.Inc(ctx, 1) + } + for _, word := range wordRE.FindAllString(line, -1) { + emit(word) + } +} + +// formatFn is a DoFn that formats a word and its count as a string. +func formatFn(w string, c int64) string { + return fmt.Sprintf("%s: %v", w, c) +} + +func init() { + beam.RegisterFunction(extractFn) + beam.RegisterFunction(formatFn) +} + +func main() { + flag.Parse() + beam.Init() + + if *output == "" { + log.Fatal("No output provided") + } + + p := beam.NewPipeline() + s := p.Root() + + lines := textio.Read(s, *input) + col := beam.ParDo(s, extractFn, lines) + + // Using Cross-language Count from Python's test expansion service + // TODO(pskevin): Cleaner using-face API + outputType := typex.NewKV(typex.New(reflectx.String), typex.New(reflectx.Int64)) + external := &beam.ExternalTransform{ + In: []beam.PCollection{col}, + Urn: "beam:transforms:xlang:count", + ExpansionAddr: "localhost:8118", Review comment: Gotcha, but it might still be a good idea in this example if the expansion servers' addresses can change. I'd expect that if you were a user writing and running cross language pipelines, you wouldn't want to change the address in your code each time, you'd want some flag you can change instead. Same if you have multiple different expansion servers. Of course, if expansion servers are expected to have a consistent address then this seems good as-is. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
