Striving for Versatility in Striving for Versatility in - - PowerPoint PPT Presentation
Striving for Versatility in Striving for Versatility in Publish/Subscribe Publish/Subscribe Infrastructures Infrastructures Roberto S. Silva Filho and David F. Redmiles Roberto S. Silva Filho and David F. Redmiles {rsilvafi rsilvafi, ,
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{ {rsilvafi rsilvafi, , redmiles}@ics.uci.edu redmiles}@ics.uci.edu Department of Informatics Donald Bren School of Information and Computer Sciences University of California, Irvine Presented at SEM 2005 – September 4th, 2005
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– – data, flow and timing decoupling between producers and data, flow and timing decoupling between producers and consumers of information consumers of information – – content content-
based filtering and communication
– – intermediates the communication between publishers and intermediates the communication between publishers and subscribers in a distributed setting. subscribers in a distributed setting.
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– – software monitoring, groupware, workflow management software monitoring, groupware, workflow management systems, software development and deployment, mobile systems, software development and deployment, mobile applications and so on. applications and so on.
– – Advanced event processing, guaranteed event delivery, Advanced event processing, guaranteed event delivery, transactions, event persistency, secure communication transactions, event persistency, secure communication channels, authentication, mobility support and many others channels, authentication, mobility support and many others
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Standardized one Standardized one-
size-
fits-
all solutions: CORBA-
NS or JMS Minimal content Minimal content-
based routers such as ELVIN, SIENA, HERALD HERALD
example: CASSIUS, GEM, YEAST and others. example: CASSIUS, GEM, YEAST and others.
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They are usually not designed for change and evolution, They are usually not designed for change and evolution, Nor to be expanded and contracted to address specific applicatio Nor to be expanded and contracted to address specific application n needs needs
– – The need for direct source code modification of existing solutio The need for direct source code modification of existing solutions ns (when available) (when available) – – The implementation of additional features at the application lev The implementation of additional features at the application level el – – the build of new pub/sub infrastructures the build of new pub/sub infrastructures
resulting in the proliferation of incompatible proprietary resulting in the proliferation of incompatible proprietary infrastructures that are costly to evolve and maintain infrastructures that are costly to evolve and maintain
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– – Support for Evolution Support for Evolution
Extensibility Extensibility – – add new functionality to the existing set add new functionality to the existing set Programmability Programmability – – redefine software behavior redefine software behavior Reuse Reuse
– – Support for Variability (footprint configuration) Support for Variability (footprint configuration)
Static (build or design time) Static (build or design time) Dynamic (runtime) Dynamic (runtime)
– – Usability Usability
Considerations about workplace environment Considerations about workplace environment Nielsen Nielsen’ ’s attributes: s attributes: learnability learnability, efficiency, , efficiency, memorability memorability, few errors , few errors and satisfaction. and satisfaction.
– – Preserving middleware requirements of: Preserving middleware requirements of:
Scalability, interoperability, heterogeneity and communication Scalability, interoperability, heterogeneity and communication
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– – combining language and infrastructure evolution combining language and infrastructure evolution – – with static and dynamic plug with static and dynamic plug-
in configurations
– – achieving interoperability and support for different event model achieving interoperability and support for different event models s and routing strategies and routing strategies
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Extended version (see Protocol*) of Extended version (see Protocol*) of Rosenblum Rosenblum and Wolf and Wolf’ ’s model that s model that represent the variability dimensions in our approach represent the variability dimensions in our approach
Interaction protocols Interaction protocols: authentication, : authentication, manual roaming manual roaming Infrastructure protocols Infrastructure protocols: federation, : federation, replication, fault replication, fault-
tolerance
the service the service
Protocol* Protocol*
tuple tuple-
based, record-
based, XML documents documents Specifies how events are Specifies how events are represented represented
Event Event
client client-
side, server-
side defines where in the system defines where in the system (publishers/subscribers/routers) (publishers/subscribers/routers) the extensions are placed the extensions are placed
Resource Resource
push, pull, both, others. push, pull, both, others. specifies how notifications are specifies how notifications are delivered to subscribers delivered to subscribers
Notification Notification
content content-
based, topic-
based, advanced event processing event processing specifies how subscribers specifies how subscribers express interest in subsets of express interest in subsets of events events
Subscription Subscription
Example Example Definition Definition Dimension Dimension
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"
"
$
" "
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"
"
$
" "
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"
"
"
legend
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"
"
"
legend filters
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"
"
"
legend filters protocols
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Configuration managers that interpret configuration Configuration managers that interpret configuration descriptions descriptions Dynamic parsers Dynamic parsers Resource Resource Protocol plug Protocol plug-
ins Protocol Protocol Extensible event representation Extensible event representation Filters Filters Event adapters and publish/subscribe cores Event adapters and publish/subscribe cores Event Event Extensible notification language Extensible notification language Notification plug Notification plug-
ins Notification Notification Extensible subscription language Extensible subscription language Subscription plug Subscription plug-
ins Subscription Subscription
Approach Approach Dimension Dimension
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– – Events can also be objects. Events can also be objects.
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Consider the following sequence detection subscription as an exa Consider the following sequence detection subscription as an example: mple: <subscribe> <subscribe> <sequence> <sequence> <or> <or> <filter> <filter> < <eq eq> <name> > <name> name name </name> </name> <value> <value> Roberto Roberto </name> </ </name> </eq eq> > </filter> </filter> <filter> <filter> … … </filter> </filter> </or> </or> <filter> <filter> … … </filter> </filter> </sequence> </sequence> <push> <push> </subscribe> </subscribe>
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!
!"##
filters adapters clients legend
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!
&
!"##
filters adapters clients legend
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!
&
+**
filters adapters clients legend
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&
+**
filters adapters clients legend
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#
+**
! filters adapters clients legend
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extension using extension using XML Schema XML Schema
ins and filters for that extension that extension
in in the configuration the configuration file file
with the new with the new configuration configuration
plug-ins adapters legend filters protocols
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– – It is monolithic and no additional features can not be easily It is monolithic and no additional features can not be easily added to it or removed from it. added to it or removed from it.
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Different pie slices represent peers in the network peers in the network Users can drag and drop files Users can drag and drop files to be shared to be shared Concentric circles define Concentric circles define different sharing levels different sharing levels Files placed in the center Files placed in the center are persistent and available to are persistent and available to all the members of the group all the members of the group Files outside the pie are not Files outside the pie are not shared and become invisible shared and become invisible to other peers to other peers Files blink with the peer Files blink with the peer color whenever someone reads color whenever someone reads
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(&!)$$" (&!)$$"
*
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adapters protocols legend filters
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adapters protocols legend filters
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adapters protocols legend filters $*
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$
adapters protocols legend filters $*
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*
$*
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+ ,
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&* ' )/ 12$
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+**
(
adapters protocols legend filters
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– – Event persistency Event persistency – – Event typing enforcing Event typing enforcing – – Pull notification delivery Pull notification delivery
– – Event source discovery Event source discovery – – Event type hierarchy browsing Event type hierarchy browsing – – Authentication Authentication
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*. +**
adapters protocols legend filters
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* *. " /0 '+-"
adapters protocols legend filters
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*
* (
'+-"
$
*
adapters protocols legend filters
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Configurability Configurability: The combination of : The combination of plug plug-
ins and extensible languages provide coherent composition of interdependent features; provide coherent composition of interdependent features;
– – the subset of language extensions and plug the subset of language extensions and plug-
ins also define the footprint footprint of the
server. server.
Extensibility Extensibility: new features can be provided by extending the language and : new features can be provided by extending the language and implementing new plug implementing new plug-
ins and filters Reuse Reuse: plug : plug-
ins can depend on one another, speeding up the development process process Support for multiple infrastructures Support for multiple infrastructures: the microkernel approach allows : the microkernel approach allows different publish/subscribe cores to be installed at the same ti different publish/subscribe cores to be installed at the same time me Variability Variability: plug : plug-
ins can be installed at load time (configuration file) and runtime (downloaded as needed). They are also allocated accordin runtime (downloaded as needed). They are also allocated according to the g to the application needs application needs Multiple event models Multiple event models: adapters to different pub/sub cores permit multiple : adapters to different pub/sub cores permit multiple event representations to co event representations to co-
exist.
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Performance: Performance:
– – In our experiments, the XML technology (subscription and notific In our experiments, the XML technology (subscription and notification ation parsing) adds an extra 100 ms to the subscription process (but t parsing) adds an extra 100 ms to the subscription process (but this is a his is a
– – The plug The plug-
in hierarchy adds an extra 50 ms to the notifications routing time (but the throughput is compatible with Siena and Elvin ~800 time (but the throughput is compatible with Siena and Elvin ~8000 events/second) due to our buffering strategy events/second) due to our buffering strategy
Framework costs: Framework costs:
– – Initial generalization and implementation Initial generalization and implementation – – Initial learning curve (not much worse than more advanced pub/su Initial learning curve (not much worse than more advanced pub/sub b systems as CORBA systems as CORBA-
NS)
Non Non-
functional requirements are not so easy to implement (need to extend many points in the system, AOP may help) extend many points in the system, AOP may help)
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