Compare the yaml file you created with the default one, something is different.
Cheers ----------------- Aaron Morton Freelance Cassandra Consultant New Zealand @aaronmorton http://www.thelastpickle.com On 3/04/2013, at 12:17 AM, Heinrich Götzger <goetz...@web.de> wrote: > Hello, > > I try to read, edit, write and re-read a cassandra-yaml-config file > programmatically, but this unfortunately does not work as expected: > > Here is my example: > > /* start */ > package com.fue; > > import java.io.*; > > import org.apache.cassandra.config.*; > import org.apache.cassandra.utils.SkipNullRepresenter; > import org.yaml.snakeyaml.*; > import org.yaml.snakeyaml.DumperOptions.*; > import org.yaml.snakeyaml.constructor.*; > import org.yaml.snakeyaml.nodes.*; > > public class YamlConfigTest { > > public static void main(String[] args) throws IOException { > > // 1. reading an existing config-file, > InputStream input = new FileInputStream("/tmp/cassandra-1.2.3.yaml"); > > Constructor constructor = new Constructor(Config.class); > TypeDescription seedDesc = new TypeDescription(SeedProviderDef.class); > seedDesc.putMapPropertyType("parameters", String.class, String.class); > constructor.addTypeDescription(seedDesc); > Yaml cassandraConfYaml = new Yaml(new Loader(constructor)); > > Config conf = (Config) cassandraConfYaml.load(input); > > // 2. change the setting in the Config-object > SeedProviderDef spd = conf.seed_provider; > spd.parameters.put("seeds", "192.168.1.2"); > > DumperOptions options = new DumperOptions(); > options.setDefaultFlowStyle(DumperOptions.FlowStyle.BLOCK); > options.setDefaultScalarStyle(ScalarStyle.PLAIN); > > SkipNullRepresenter representer = new SkipNullRepresenter(); > representer.addClassTag(Config.class, Tag.MAP); > > Dumper dumper = new Dumper(representer, options); > > Yaml yamlWriter = new Yaml(new Loader(constructor), dumper); > > // 3. and writing it back to another file. > String fileName = "/tmp/myCassandra.yaml"; > Writer output = new FileWriter(fileName); > yamlWriter.dump(conf, output); > > Reader reader = new FileReader(fileName); > > Yaml myCassandraConfYaml = new Yaml(new Loader(constructor)); > > // This procedure looses these two dashes and makes the configuration not > // usable for further processing in other tasks. > Config myConf = (Config) myCassandraConfYaml.load(reader); > > } > } > /* end */ > > And this is the output: > > Exception in thread "main" Can't construct a java object for > tag:yaml.org,2002:org.apache.cassandra.config.Config; exception=Cannot create > property=seed_provider for > JavaBean=org.apache.cassandra.config.Config@3c3ac93e; > java.lang.NoSuchMethodException: > org.apache.cassandra.config.SeedProviderDef.<init>() > in 'reader', line 1, column 1: > authenticator: org.apache.cassan ... > ^ > > at > org.yaml.snakeyaml.constructor.Constructor$ConstructYamlObject.construct(Constructor.java:333) > at > org.yaml.snakeyaml.constructor.BaseConstructor.constructObject(BaseConstructor.java:182) > at > org.yaml.snakeyaml.constructor.BaseConstructor.constructDocument(BaseConstructor.java:141) > at > org.yaml.snakeyaml.constructor.BaseConstructor.getSingleData(BaseConstructor.java:127) > at org.yaml.snakeyaml.Yaml.loadFromReader(Yaml.java:481) > at org.yaml.snakeyaml.Yaml.load(Yaml.java:424) > at com.fue.YamlConfigTest.main(YamlConfigTest.java:53) > Caused by: org.yaml.snakeyaml.error.YAMLException: Cannot create > property=seed_provider for > JavaBean=org.apache.cassandra.config.Config@3c3ac93e; > java.lang.NoSuchMethodException: > org.apache.cassandra.config.SeedProviderDef.<init>() > at > org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.constructJavaBean2ndStep(Constructor.java:299) > at > org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.construct(Constructor.java:189) > at > org.yaml.snakeyaml.constructor.Constructor$ConstructYamlObject.construct(Constructor.java:331) > ... 6 more > Caused by: org.yaml.snakeyaml.error.YAMLException: > java.lang.NoSuchMethodException: > org.apache.cassandra.config.SeedProviderDef.<init>() > at > org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.createEmptyJavaBean(Constructor.java:219) > at > org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.construct(Constructor.java:189) > at > org.yaml.snakeyaml.constructor.BaseConstructor.constructObject(BaseConstructor.java:182) > at > org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.constructJavaBean2ndStep(Constructor.java:296) > ... 8 more > Caused by: java.lang.NoSuchMethodException: > org.apache.cassandra.config.SeedProviderDef.<init>() > at java.lang.Class.getConstructor0(Class.java:2715) > at java.lang.Class.getDeclaredConstructor(Class.java:1987) > at > org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.createEmptyJavaBean(Constructor.java:215) > ... 11 more > > I'm using: > - snakeyaml-1.12 > - cassandra-1.2.3 > > What am I doing wrong? > Is it a theme for cassandra or for yaml, is it in between or do I expect > impossible things. > > > There is a thread about this in th SnakeYAML-group already: > https://groups.google.com/forum/?fromgroups=#!topic/snakeyaml-core/D4M0Ciy023E > > Thanks for helping with some ideas. > > > Cheers > > Heinrich
