GraphQL, GRPC, REST, WebFlux, OData il existe une multitude de protocoles et formats pour implementer des API au dessus d'une base de donnees comme Cassandra. Chez DataStax nous avons eu l'occasion de toutes les implementer pour tester. Je vous propose un tour d'horizon des différentes solutions avec les pros, les cons et surtout beaucoup de code !

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Cédrick Lunven
4 octobre 2018

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About ME
Cedrick Lunven
Developer Advocate @ DataStax
Twitter : @clunven
Github : https://github.com/clun

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Apache Cassandra
Cassandra - Evelyn de Morgan (1855-1919)

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Distributed
Architecture
Node
DataCenter
DC1 DC2
Cluster

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No Single Point
of Failure (SPOF)
 Masterless
 Data is replicated among
nodes
 Read/Write Everywhere with
custom consistency
80
Client

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Linear
Scalability
3000 - 5000
Tx / Second / Core
1 - 3 Terabytes
(SSD or rotational)

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Deployment
San
Francisco
On Prem
Munich
On Prem
Azure
AWS
 Any Cloud
Provider
 Hybrid-Cloud
 Multi-Cloud

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Data Model
symbol date price side
Demo Keyspace
Market_prices Table
CQL Example
CREATE TABLE market_prices (
symbol TEXT,
date TIMESTAMP,
price DECIMAL,
side INT,
PRIMARY KEY (symbol, date)
) WITH CLUSTERING ORDER BY (date DESC);
PRIMARY KEY ((symbol), date)
Partition Key Clustering Key

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Data Model
https://academy.datastax.com/resources/ds220

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Java Development
http://killrvideo.github.io
Builder clusterConfig = newBuilder();
contactPoints.stream()
.forEach(clusterConfig::addContactPoint);
clusterConfig.withPort(port);
clusterConfig.withAuthProvider(
newDsePlainTextAuthProvider(
dseUsername.get(),dsePassword.get()));
clusterConfig.withQueryOptions(
newQueryOptions()
.setConsistencyLevel(ConsistencyLevel.QUORUM));
clusterConfig.withLoadBalancingPolicy(
newTokenAwarePolicy(
DCAwareRoundRobinPolicy.builder()
.withLocalDc(localDc).build()));
DseSession dseSession = clusterConfig.build()
.connect(keyspace);

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MCD

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Application Workflow
Q2: Find comments posted for a user with a known id
(show most recent first)
comments_by_video
comments_by_user
Q1: Find comments for a video with a known id
(show most recent first)
Q3: CRUD On video details page
Q4: _RUD On user details page

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Logical Data Model
userid
creationdate
commentid
videoid
comment
comments_by_user
K
C
↑
videoid
creationdate
commentid
userid
comment
comments_by_video
C
↑
K
C
↑
↑C

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Physical Data Model
userid
commentid
videoid
comment
comments_by_user
TIMEUUID
K
TEXT
C
UUID
UUID
↑
videoid
commentid
userid
comment
comments_by_video
TIMEUUID
K
TEXT
C
UUID
UUID
↑

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DDL Schema
CREATE TABLE IF NOT EXISTS comments_by_user (
userid uuid,
commentid timeuuid,
videoid uuid,
comment text,
PRIMARY KEY ((userid), commentid)
) WITH CLUSTERING ORDER BY (commentid DESC);
CREATE TABLE IF NOT EXISTS comments_by_video (
videoid uuid,
commentid timeuuid,
userid uuid,
comment text,
PRIMARY KEY ((videoid), commentid)
) WITH CLUSTERING ORDER BY (commentid DESC);

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ECLIPSE & DAO…

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API Design
Q1: Find comments posted by a video with a known id (show most recent first)
Q2: Find comments posted for a user with a known id (show most recent first)
Q3: CRUD On video details page
Q4: _RUD On user details page

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API Design
Q1 : Find comments posted by a user (user page)
/api/v1 /users /{userid} /comments
Best practice to use major version number in URL
Retrieve list of users overviews (out of scope)
Retrieve single user details (out of scope)
Q1
?pagingState=.&pageSize=.

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API Design
Q1 : Find comments posted by a user (user page)
Attribute Value
Method GET
URL /api/v1/users/{userid}/comments?pagingState=&pageSize=
Request N/A
Response • 200 List of comments
• 204 No content
• 400 Bad parameter
• 404 User not found
• 500 internal Error

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API Design
Q3 : Create comment
/api/v1/videos/{videoid}/comments/addPOST
PUT /api/v1/videos/{videoid}/comments/{commentid}
Attribute Value
Method PUT
URL /api/v1/videos/{videoid}/comments/{commentid}
Request {"comment": "Hello World ! }
Response • 400 Invalid request (validation message)
• 404 Video not found
• 201 Created (no body)
• 202 Updated (no body)

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ECLIPSE…

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And this Time, it is true