Modes of accessing HDFS: You can access Hadoop Distributed File System in 2 different ways.
- Direct Access
- Proxy based Access
Direct Access can be through ..
- Interactive Unix Shell commands
- Through Java and C++ APIs, clients retrieve metadata such as blocks locations from Namenode. Client directly access datanodes. HDFS accessing through API is used in Map Reduce jobs.
Proxy Based Access through…
Clients communicated through a Proxy and it is strives to be language independent.
Several Proxy servers are packaged with Hadoop are
- Thrift – Interface definition language.
- WebHDFS REST – You can access HDFS through web, and the response is formatted in JSON, XML or Protocol Buffers.
- Avro – Data serialization mechanism.