An Introduction To Web Service
tangliu@kingsoft.com
Agenda
- Introduction
- An Example
- Some Solution
Introduction
What's web service?
A web service is a software function provided at a network address over the web or the cloud (from wiki)
Some Example?
How to do?
- HTTP
- API
- Data Protocol
HTTP
No HTTP, No web.
All are based on HTTP!
- HTTP Request
- HTTP Response
API
- RPC
http://host/bucket/addFile?name=abc
http://host/bucket/getFile?name=abc - Restful
post http://host/bucket/abc
get http://host/bucket/abc
Data Protocol
- XML
- JSON
- etc......
Basic for HA Service
- Availability
- Scalability
- Reliability
- Manageability
- etc......
CAP
- Consistency
- Availability
- Partition Tolerance
Example
File Storage Web Service
Two Method:
- upload
- download
Initial Architecture
FS Service: store file
Client: upload or download file from FS Service directly
I think it's like a FTP.
But when files are too many?
Partition
File: Meta + Data
Data are stored in difference Data Service
Meta Service can find where
How to find?
How to find?
Generality: Hash
- Simple Hash: id(file name) % number(Data Service)
- Consistent Hash
Consistent Hash
Consistent Hash
Control and Data Flow
Many Clients download file data through meta service?
- Client request Meta Service to download
- Meta Service return Data Service location
- Client download from Data Service directly
Redundancy
Data Storage may corrupted!!!
Backup, when master failed, use backup service!
Cache
Can download more quickly?
- Cache Expired?
- Cache Consistent?
Load Balancer
Meta Service may also have bottleneck!
Proxy
Use proxy for safer download!!!
GFS
Some Solution
Service HA
Heartbeat
Keepalived
MYSQL HA
- Master/Slave
- Master/Master
- Semi-Sync Replication
- etc...
OceanBase
