DDS and XMPP

DDS vs. XMPP

Angelo Corsaro Gerardo Pardo-Castellote
OMG DDS Co-Chair OMG DDS Co-Chair
PrismTech RTI
angelo.corsaro@prismtech.com gerardo@rti.com

1

Agenda

- XMPP Intro
- Some XMPP Extension
- XMPP vs DDS
- Concluding Remarks

OMG DDS SIG

XMPP History

XMPP = eXtensible Messaging and Presence Protocol

- 1999: Jabber starts as an Open Source project
- 2001: Jabber Software Foundation (JSF) is established
- 2002: XMPP Working Group started at IETF
- 2004: XMPP RFCs (3920-3923)
- 2006: JSF becomes the XMPP Standards Foundation

OMG DDS SIG

Core XMPP Features

- XMPP started as a standard for messaging and
presence. Today it is more than simply messaging
and presence, providing:
 Channel encryption and authentication
 Presence and Contact Lists
 One-to-one and Multi-Party Messaing
 Alerts and Notifications (XMPP Pub/Sub extension)
 Peer-to-Peer Media Sessions (Jingle)
 Data Forms and Remote Command

OMG DDS SIG

XMPP Architecture
- Client/Server
- Network of Decentralized Servers
- (Authenticated) Long Lived Connection from Client to Servers

Server Server
jabber.org mac.com

<message to=‘giorgia@jabber.org’>
<body> Have you seen my new
stratocaster?
</body>
</message>

Carmen Giorgia
carmen@jabber.org OMG DDS SIG giorgia@mac.com

Addressing

- User are addressed by Jabber ID (JID)
 es. carmen@jabber.com

- Resource can be addressed via full JID
 es. carme@jabber.com/concerts

OMG DDS SIG

Communication Primitives

- XMPP defines three different communication
primitives--called stanzas

- XMPP Stanzas are:
 <message/>
 <presence/>
 <iq/>

OMG DDS SIG

<message/>

- A <message/> stanza contains:
 From, To
 Type
 Subject + Body (Payload)

<message from=‘carmen@jabber.com
to=‘giorgia@jabber.org’>
<subject>Got a new Strato!</subject>
<body> Have you seen my new
stratocaster?
</body>
</message>

OMG DDS SIG

<presence/>

- The <presence/> stanza is used to advertise
presence and contains:
 Status
 Status Message

<presence from=‘carmen@jabber.com>
<show>xa</show>
<status>C9sus</status>
</presence>

OMG DDS SIG

<iq/>

- The <iq/> stanza is used to perform Request/
Response interactions (similar to HTTP GET, POST,
PUT)
<iq type=”get”>
<query xmlns=”jabber:iq:roster”/>
</iq>

<iq type=”result”>
<query xmlns=”jabber:iq:roster”>
<item jid=”carmen@jabber.org”/>
<item jid=”mario@jabber.org”/>
<item jid=”franco@jabber.org/>
</query>
</iq>
OMG DDS SIG

Pub/Sub Extension

- XMPP has been extended with basic Pub/Sub
capabilities

- <iq/> stanzas are used to manage subscriptions,
as well as to do pub/sub

OMG DDS SIG

Pub/Sub Extension - Subscription

<iq from=”carmen@jabber.org”
id=”cc7409”
to=”notify.jabber.org”
type=”set”>

<pubsub xmlns=”http://jabber.org/protocol/pubsub”>
<subscribe node=”musicisti-ct”
jid=”carmen@jabber.org”/>
</iq>

OMG DDS SIG

Pub/Sub in XMPP
musicisti-ct {
carmen@jabber.org
Mario
giorgia@mac.com Server
mario@xmpp.org mario@xmpp.org
} xmpp.org

Server Server
jabber.org mac.com

Carmen Giorgia
carmen@jabber.org giorgia@mac.com
OMG DDS SIG

Pub/Sub in XMPP
musicisti-ct {
carmen@jabber.org
Mario
} xmpp.org

Server Server
jabber.org mac.com

<iq
from=”carme@jabber.org”
to=notify.jabber.org”>
...
</iq>

Carmen Giorgia
OMG DDS SIG

Pub/Sub in XMPP
musicisti-ct {
carmen@jabber.org
Mario
giorgia@mac.com
<iq Server
mario@xmpp.orgfrom=”carme@jabber.org” mario@xmpp.org
to=notify.jabber.org”> xmpp.org
} ...
</iq>

Server Server
jabber.org mac.com
<iq
...
</iq>

Carmen Giorgia
OMG DDS SIG

Pub/Sub in XMPP <iq
...
</iq>
musicisti-ct {
carmen@jabber.org
Mario
} xmpp.org

Server Server
jabber.org mac.com

<iq
...
</iq>

Carmen Giorgia
OMG DDS SIG

Jingle Extension

- XMPP is not designed for distributing data with
real-time constraints

- XMPP Jingle is used to set-up direct connections
between points for streaming
 Voice
 Audio
 Video
 ...

- After negotiating a connection via XMPP,
communication goes through other protocols, e.g.,
RTP, etc.
OMG DDS SIG

What is Standardized?
- DDS - XMPP
 API Standard
 Wire Protocol Standard  Wire Protocol Standard

Application
Application
Object/Relational Mapping

Data Local Reconstruction Layer (DLRL)

DDS v1.2
Content
Ownership Durability
Subscription

Minimum Proﬁle
API (?)
Data Centric Publish/Subscribe (DCPS)
DDSI v2.1

RFC-3920/9
eXtensible Messaging and
Real-Time Publish/Subscribe Protocol Presence Protocol

DDS Interoperability Wire Protocol Wire Protocol

UDP/IP TCP

OMG DDS SIG

Architecture
- DDS - XMPP
 Fully Distributed  Store and Forward
 Topic-Based Pub/Sub  Client/Server
 QoS Enabled  Pub/Sub as a protocol extension
 Data Centric (keys, queries, etc.)  “Source Addressing”-based
discovery
 Dynamic Discovery

DDS XMPP
Subscriber
Publisher
Server Server
B

m
jabber.org mac.com
A F

Subscriber
Publisher J
D C

K
E

Publisher
Client Client
Subscriber

OMG DDS SIG

Type/Message Encoding

- DDS - XMPP
 Efficient binary encoding  XML encoding for both data
for both data-payload payload and protocol
and protocol messages messages
 Strongly Typed Topic  Just one message type, an
Types XML message
 Polymorphic Type
 Type extensibility/  Type extensibility/evolvability
evolvability supported by by leveraging XML
upcoming xTopics RFP

 Note: Multiple encoding
supported via xTopics

OMG DDS SIG

Performance

- DDS - XMPP
 Targeting high performance  Targeting interactive systems
systems  Discovery traffic often shown
 Very low latencies to introduce non-negligible
 Very high throughputs load
 Real-Time determinism

OMG DDS SIG

Concluding Remarks

- DDS and XMPP target different application domains
- DDS is able to address very sophisticated data
distribution needs, where complex QoS need to be
satisfied

- XMPP is targeting interactive web applications
- DDS provides complete transparency w.r.t changes
in the infrastructure

- Due to its “source-addressing”-based discovery
XMPP might propagate back to the application
changes into the infrastructure

OMG DDS SIG

DDS and XMPP

More Related Content

What's hot

Viewers also liked

Similar to DDS and XMPP

More from Angelo Corsaro

Recently uploaded

DDS and XMPP