This document discusses building an IDE for Apache Cassandra using Eclipse RCP, e4 and XText. It provides an overview of Cassandra's peer-to-peer architecture and linear scalability. It also describes Cassandra Query Language (CQL), including basic queries and table definitions. The document then discusses the DataStax DevCenter IDE, which is built using these technologies. It demonstrates features like validation, content assist and embedded editing support using XText. Finally, it discusses benefits and challenges of using the e4 framework within an Eclipse 3.x plugin.

1. Building an IDE for Apache Cassandra
With Eclipse RCP, e4 and XText
Michaël Figuière
Software Architect

2. © 2014 DataStax, All Rights Reserved.
Cassandra Peer to Peer Architecture
2
Node
Node Node
Node
Node
Node
Clients can reach any of the
Cassandra nodes
Every node have the same role,
there’s no Master or Slave

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Cassandra Peer to Peer Architecture
3
Node
Node Replica
Replica
Replica
Node
Each partition is stored in
several Replicas to ensure
durability and high availability

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Linear Scalability
4
Client Writes/s by Node Count - Replication Factor = 3

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Cassandra Query Language (CQL)
• Similar to SQL, mostly a subset
• Without joins, sub-queries, and aggregations
• Primary Key contains:
• A Partition Key used to select the partition that will store the Row
• Some Clustering Columns, used to define how Rows should be grouped
and sorted on the disk
• Supports Collections
• Supports User Defined Types (UDT)
5

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CQL: Create Table
CREATE TABLE users (
login text,
name text,
age int,
...
PRIMARY KEY (login));
login is the partition key, it will
be hashed and rows will be
spread over the cluster on
different partitions
Just like in SQL!

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CQL: Clustered Table
CREATE TABLE mailbox (
login text,
message_id timeuuid,
interlocutor text,
message text,
PRIMARY KEY(login, message_id)
);
message_id is a clustering column,
it means that all the rows with a
same login will be grouped and
sorted by message_id on the disk
A TimeUUID is a UUID that
can be sorted chronologically

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CQL: Queries
SELECT * FROM mailbox
WHERE login = jdoe
AND message_id = '2014-09-25 16:00:00';
Get message by user and message_id (date)
SELECT * FROM mailbox WHERE login = jdoe
AND message_id <= '2014-09-25 16:00:00'
AND message_id >= '2014-09-20 16:00:00';
Get message by user and date interval
WHERE clauses can only be constraints
on the primary key and range queries are
not possible on the partition key

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DataStax DevCenter
• Eclipse RCP standalone application
• Eclipse 3.x + e4
• CQL editor based on Xtext
• 1.0.0 in October 2013 - 1.3.0 March 2015
• Supports Cassandra 1.2 - 2.1
• Tens of thousands of downloads / month
9

10. DataStax DevCenter
Demo

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Xtext with CQL
11
ValidationCQL Grammar
Content Assist Quick Fixes
Syntax HighlightingFormatting
Can be extracted as a standalone library

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Validation and Quick Fix
Validation
@Fix(CqlConstants.KEYSPACE_EXIST)
public void addIfNotExistst(final Issue issue, IssueResolutionAcceptor acceptor)
{
...
createKeyspaceStmt.setIfNotExists(true);
...
}
Quick Fix
@Check
public void checkKeyspaceNotExist(CreateKeyspaceStatement stmt)
{
if (context.isKeyspaceExistInDatabase(stmt.getKeyspaceEntity()))
error(KEYSPACE_ALREADY_EXISTS, stmt, CqlConstants.KEYSPACE_EXIST);
}

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Cassandra + Script Context
13

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Current Schema for Each Statement
14

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Xtext Embedded Editor
@Inject
private EmbeddedEditorFactory factory;
editor = factory
.newEditor(resourceProvider)
.readOnly()
.withResourceValidator(resourceValidator)
.processIssuesBy(issueProcessor)
.withParent(container);
partialEditor = editor.createPartialEditor();
Injected through
Xtext’s Guice context
The SWT Container
the editor should be
inserted in

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Benefits of e4
Dependency Injection
@Inject
IEventBroker broker;
public void doSomething() {
broker.send(TOPIC, "some data");
}
Events Handling
@Inject
public void create(Composite parent, IWorkbenchHelpSystem help) {
Button button = ...;
help.setHelp(button, "com.example.button.help.id");
}
@Inject
public void receive(@EventTopic(TOPIC) Object data) {
fullRefresh();
}

17. © 2014 DataStax, All Rights Reserved.
DevCenter and e4
• DevCenter cannot be a pure e4 application…
• Relies on Xtext and Eclipse Editor
• Eclipse IDE doesn’t rely on the e4 Application Model yet
• …but can still use e4 through adapters on top of Eclipse 3.x
17

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E4 in a Eclipse 3.x Plugin
18
DIViewPart Adapter
E4View
Eclipse 3.x Plugin
Eclipse technical
code goes here
Application
logic sits here

19. Questions?
@mfiguiere
blog.datastax.com
github.com/datastax