#co-webhdfs-plus A webhdfs client in co style.

##NOTE:

• Node verion should >= 0.11.0
• For more information about co, take a look at document for co
• For more information about webhdfs, take a look at document for webhdfs

##WHY

其实就是hdfs restful client读写文件时，webHDFS会307重定向一次，但是此时返回的是datanode域名，由于业务需要 我把域名转换成了事先对应的ip地址。

e.g.

http://node1:50075/webhdfs/v1/test/test.txt?op=CREATE&namenoderpcaddress=ns&overwrite=false&replication=3

转换成

http://192.168.1.10:50075/webhdfs/v1/test/test.txt?op=CREATE&namenoderpcaddress=ns&overwrite=false&replication=3

##Install:

npm install co-webhdfs-plus

##Usage:

var _ = require('codash'),
    co = require('co'),
    LineReader = require('co-stream').LineReader,
    Writer = require('co-stream').Writer,
    WebHdfsClient = require('co-webhdfs');

co(function *() {
    var client = new WebHdfsClient({ namenode_hosts: ['10.10.0.141', '10.10.0.140'] });
    // Or, if you don't want to enable failover:
    // var client = new WebHdfsClient({ namenode_host: '10.10.0.140' });

    var home = yield* client.getHomeDirectory();
    var files = yield* client.listStatus(home);
    console.log(_.map(files, function (f) { return f.pathSuffix }));

    yield* client.mkdirs(home + '/tmp');

    var filename = home + '/tmp/foo.txt';

    // Data style.
    yield* client.del(filename);
    yield* client.create(filename, 'foooooo\n', { overwrite: true });
    yield* client.append(filename, 'barr\n');
    console.log(yield* client.open(filename));

    // Stream style.
    var stream = new Writer(yield* client.createWriteStream(filename, { overwrite: true }));
    yield stream.writeline('xxxxxxx');
    yield _.sleep(100);
    yield stream.writeline('gggggg');
    yield stream.end();
    yield _.sleep(1000);

    var reader = new LineReader(yield* client.createReadStream(filename));
    for (var line; line = yield* reader.read();) {
        console.log('line: ', line);
    }
}).then(function () {
    console.log('finished...');
}, function (err) {
    console.log(err);
    console.log(err.stack);
});

##kerberos SPNEGO

Authentication using Hadoop delegation token when security is on:

// e.g. http://<HOST>:<PORT>/webhdfs/v1/<PATH>?delegation=<TOKEN>&op=...
var client = new WebHdfsClient({ token: 'kerberos_token', ... });

or

var client = new WebHdfsClient({ ... });
client.addAuth("cookies");
...
// cookies访问是有时效性的，所以client后续操作返回401响应，则让用户重新登录获取cookies

##API

Constructor

WebHdfsClient(options)
  options:
    user: user name, default 'hadoop'
    namenode_host: ip/hotname of namenode, default 'localhost'
    namenode_port: port of webhdfa, default 50070

Create and Write to a File

create: function *(path, data, hdfsoptions)
createWriteStream: function *(path, hdfsoptions)
  path: path of file
  data: data to write
  hdfsoptions:
    overwrite: <true|false>
    replication: <SHORT>]
    blocksize: <LONG>
    permission: <OCTAL>
    buffersize: <INT>

Append to a File

append: function *(path, data, hdfsoptions)
createAppendStream: function *(path, hdfsoptions)
  path: path of file
  data: data to write
  hdfsoptions:
    buffersize: <INT>

Open and Read a File

open: function *(path, hdfsoptions)
createReadStream: function *(path, hdfsoptions)
  path: path of file
  hdfsoptions:
    buffersize: <INT>
    offset:<LONG>
    length:<LONG>

Make a Directory

mkdirs: function *(path, hdfsoptions)
  path: path of file
  hdfsoptions:
    permission: <OCTAL>

Rename a File/Directory

rename: function *(from, to)

Delete a File/Directory

del: function *(path)

Status of a File/Directory

getFileStatus: function *(path)

List a Directory

listStatus: function *(path)

Get Content Summary of a Directory

getContentSummary: function *(path)

Get File Checksum

getFileChecksum: function *(path)

Get Home Directory

getHomeDirectory: function *()