1. Distributed Cache Technology in Cloud Computing and its Application in the GIS Software
Wang Qi
Zhu Yitong
Peng Cheng  

2. distributed cache technology
Introduction
Basic Concepts
Relationships .
Cloud computing
distributed cache technology
Characteristics

3. definition relationship.
Cloud computing describes a new Internet-based IT service, with value add, use and delivery function. lt is a combination of data sharing and service-sharing computing model.
Distributed cache make The distance between applications and objectives closer. It is an important way for cloud applications to improve application performance

4. two main features
"distributed" and ”cache”
the distribution of data is distributed storage, size and capacity can be great.
Cache allow concurrency control: a single node can reach hundreds of thousands of concurrency

5. Characteristics of distribute caching
Connected through a mesh connection
Reliability
High Scalability
Effective transmission of data
Latest data
Consistency

6. Characteristics
Distributed cache technology can achieve high scalability of data
Connected through a mesh connection, so that data are transmitted through multiple copies of the mechanism.
distributed cache system ensure the high performance of the effective transmission of data.
The reliability of its data to ensure distributed cache system’s high degree of reliability.
distributed cache system achieve the consistency of the data.

7. General tech of distribution cache

8. Deployment of Distributed Cache
Deployment Diagram
Operating and maintaining based on Telnet or Browser/Server
Data storage and synchronization protocol
App server
Server cluster
Cache server cluster
No-master structure, all server are equal, and meshed connected.
Data storage and synchronization protocol
Data
Access through API, don’t need to consider the distributed situation of data.
Persistent storage units
Operating consoles
Can access every Nodes, and deploy the data distribution and relationship of clusters.
Operations and maintenance by telnet or web
Control station

9. Functional Architecture program library of client
70%
Functional Architecture
Distribution Cache provided application programs with client libraries and service cluster.
Clients produce a service list and map the access request of application programs on a specific data service nodes.
Communication supporting module
55%
45%
Access control
Link management
Routing management
Data migration
40%
Data access
20%
Node 1
Node 2
Node 3
15%
Memory Management
Interfaces for accessing
SSD management
Hash management
Virtual node
management
program library of client
Server list
Database Socket
LRU
Stale data
Node 1
Node 2
server
algorithm
Node 3
LRU: least recently used
Apps

10. Layers of Data Serving Nodes
Communication supporting layer
In charge of adaptation the communication protocol, transmit & receiving communication packets of bottom layer
Data process layer
Contain Route-link Management Modules, Access-Control Modules, Data Migration and Control Modules
Communication supporting
layer
Data storage layer
Providing internal memory/SSD/hard disk management. Automatically deleting the stale data
Data process layer
Data storage layer
Hardware

11. Main Techniques Consistent Hash & virtual node NRW Intelligent routing
Distribution cache realizes the uniformity of data-access by adding data serving nodes
Consistent Hash
&
virtual node
NRW
Intelligent routing
Relationship of nodes

12. Consistent Hash & virtual node
Realizing the uniform distribution of data in cluster, and erasing hot node in server
Key-Value
𝟐 𝟑𝟐 /0
Mapping to this situation and store in the corresponding nodes
Consistency hash
Every slice map a service node which store the data

13. NRW Key value Normally, (N,R,W)=(3,2,2) N: Number of Copies of data
R: minimum need of nodes in a read operation
W: minimum need of nodes in a write operation
When R+W>N
The reliability and uniformity of data can
be ensure, that means several failure of nodes would not affect the whole module

14. Downtime in B, store and update data in A,C,D
Intelligent routing
Downtime
Store
Recover
70%
38%
Downtime in B, store and update data in A,C,D
After B recover, B access A,C’s data and timestamps, A,C notice B that B was overdue, then B update through Intelligent routing
Virtual nodes X have 3 copies stored in A,B,C
Finishing the routing exchange and data access at the same time, increasing the efficiency of routing lookup and reducing the time delay of data access

15. Relationship of nodes
Maintaining the relationship between nodes, ensuring the failure detection and recovery
seed node1
seed node2
15%
Normal node 0
Normal node 3
40%
20%
Normal node 5
Seed command to build chain
5 to 4
Seed command to build chain
4 to 0
4 to 3
Normal node 4
35%
The new seeds

16. Cloud GIS: The Distributed Cache System
PART 3
Cloud GIS: The Distributed Cache System

17. Traditional GIS Geographic information system
Geographic Information System is a kind of technology that incorporates geographic features with spatial data in order to map, analyze, and assess real-world situations.
Traditional GIS
In Traditional GIS Architecture, GIS hardware, software and data reside in-house and are owned, accessed and maintained via a local intranet connection.

18. Cloud GIS
Cloud computing furnishes GIS software and makes it maintained off premises and delivered on demand as services via the Internet.
Cloud Computing offers GIS three base service models
Software-as-a-Service(SaaS)
Platform-as-a-Service(PaaS)
Infrastructure-as-a-Service (IaaS)
The Cloud SaaS supports
GIS-as-a-Service(GaaS): incidence reporting,disaster and transport management.
Applications-as-a-Service (AaaS): General GIS Application.
Imagery-as-a-Service (IaaS): it helps GIS customers to find, acquire and subscribe to ready-to-use GIS datasets which are available.

19. The implementation method of GIS software distributed cache system
User request
Retrieve data from its local database
Resort to cache servers and cloud database.
Sent requested spatial data back and at the same time, the caching system proactively makes multiple copies of that data.
Data partition and Data routing
The spatial data in a distributed cache system is spread out over all the servers
The cache system allocates sub-sets of the spatial data to different servers
Subsequently route the spatial data requests from each corresponding server.
New Display
Work flow of GIS software distributed cache systems

20. Benefits brought by distributed cache system to Cloud GIS
Distributed cache system has greater capability in dealing with the data processing
It has the ability to fit the resources needed to cope with loads.
Distributed cache system in GIS software can detect unnecessary cache data automatically.
High Data Availability

21. PART 3
Thank you!