The NaradaBroker: A Flexible Messaging Infrastructure Rahim Lakhoo (Raz) DSG Seminar 12 th April 2004

2 Outline Introduction Underlying Technologies –Java Messaging Service (JMS) Overview of the NaradaBroker Brokers Capabilities Brokers Current Usages Live Demo (screenshots) Summary Conclusions Future Work

3 Introduction NaradaBrokering was developed by Community Grids Lab at Indiana University Distributed messaging infrastructure – Message orientated Middleware (MoM) – Notification framework Originally designed to provide uniformed multicasting for supporting real-time collaboration via the publish/subscribe architecture NaradaBrokering is defined as a network of cooperating brokers

4 JMS Unified messaging infrastructure from Sun Microsystems Support for messages containing Java objects Provides guaranteed message delivery: – Once-and-only-once delivery semantics – Client acknowledge mode or transacted sessions can be used to ensure transmission Used to provide Message Orientated Middleware JMS domains can be classified as either: – Point-to-Point – Publish/Subscribe Includes common API –

5 JMS – Point-to-Point (PTP) Point-to-Point messaging: – Concept of FIFO message queues – Messages are addressed to a specific queue – Clients extract messages from the queue

6 JMS – Publish/Subscribe A Topic is a JMS-managed object, which manages the message flow from publisher to subscriber Publish/Subscribe messaging: – Messages are addressed to a topic with a content hierarchy – Generally topics are anonymous and dynamic – Can provide the ability for software multicast via topics

7 JMS Topics Topics can be published as – Tag pair value Make=Ford, Model=Focus, Colour=* – “/” separated string /UoP/dsg/chat – Integer 10 JMS also handles topic sessions JMS does not specify how to organise topics Messages can be missed due to latencies when a subscriber subscribes to a topic

8 JMS Message Header: – Contains ID – Used for routing messages Properties: – Optional Header field – Extra Descriptions for the payload Body: – Stream message – Java primitive types – Map message – Tag value pairs – Text message – String type – Object message – Java object – Bytes message

9 What JMS does not do Load balancing Fault tolerance Error notification Administration Security Wire protocol Message repository Language for creating message definitions

10 NaradaBroker NaradaBrokering is a collection of cooperating brokers Implementation of JMS (1.0.2b compliant) Event based messaging: –Events are time stamped messages Asynchronous communications Capable of supporting: – Grid services – Web Services – P2P – Audio/Video conferencing (Java Media Framework) Publish/Subscribe architecture with XML based Topics

11 NaradaBroker continued Supports multiple protocols: – TCP/IP (blocking & non-blocking) – UDP – Multicast – SSL – HTTP – RTP – HHMS (PDA’s, mobile phones) Provides an interface to a reliable storage Compress/decompress messages (zlib) Capable of fragmenting large files (>1GB) Supports JXTA interactions

12 NaradaBroker continued Cluster based architecture: – Attempts to map the virtual network to the physical network via cluster groups – Lowers the strain on the network infrastructure – Each broker is assigned a logical address e.g. [ ] Can bypass firewalls and work across NAT’s or proxies: – Contains a transport probe that scans ports that are usable/open

13 NB Topology Brokers are arranged hierarchically in clusters: – Cluster – Super-Cluster – Super Super-Cluster Brokers each hold Broker Network Maps (BNM): – Used to calculates the cost for traversals across connections

14 NaradaBrokering

15 Broker Locators Broker Locators are used by clients to find Brokers to connect to The Broker Locator propagates the Brokers information to the client: – Hostname/IP – Listening port – Transport protocol Client uses this information to transparently connect to the Broker Clients may have connections to multiple Brokers This provides load balancing

16 Broker Locators

17 Profiles Profiles at a node signify an interest in events which match certain templates Includes a constraint that events need to satisfy before being routed Every profile has a unique ID Each profile has a matching destination This is generally considered as a subscription Subscriptions are in a hierarchy which can potentially overload a super super-cluster controller - solution is to add more controllers

18 Organisation & Routing Client subscriptions stored in a hierarchy within the system: – Broker maintains client subscriptions – Cluster controller maintains broker subscriptions Events received are matched (matching engine) against stored profiles and destinations are computed: – Cluster controller manages broker destinations – Broker manages client destinations Each broker has a set of destinations, it computes the best destination based on broker hops

19 Organisation & Routing

20 Event messaging

21 NB Matching Engines Possibility for multiple matching engines at each node, depending on what needs to be supported Different types of constraints can be used on subscriptions/profiles for matching: – String based Topics separated by “/” – Integer topics – Tag = value pairs – XPath queries – String based coupled with SQL like queries – Regular expressions

22 Types of Matching Engines String based: – Separated by “/” e.g. /UoP/dsg/chat – Subscriptions to a topic does not include all sub-topics String based coupled with SQL like queries: – First matches the string based topic – Second matches with SQL92 like query against the events properties – Reduces amount of times SQL matches are calculated Tag = value pairs: – “,” separated pairs – Also allows for * type wildcard Integer based

23 Types of Matching Engines XPath based queries: – XPath query language searches, locates and identifies parts of an XML document – Searches for XML advertisements across the Broker network Regular Expressions: – For text based content

24 Narada Transport Framework

25 NB transport framework User Channels: – Applications interface with the broker – Supports the publish/subscribe architecture Links: – Implements a data protocol – Different underlying transport protocol – Administration link negotiates best available communications protocol

26 Performance Monitoring Performance monitoring: – Monitors links originating from a node – Displays a set of metrics: Average delays Round trip latency Jitter Loss rates Throughput –The metrics are returned to a performance aggregator The metrics are available either via the built in application or through the integrated web server The performance data gathered is an XML document

27 Performance Aggregator

28 Security Framework

29 Security Framework KMC – Key Management Centre: – Includes Authorization module – Manages keys associated with entities and topics – Ensures secure communications with entities via SSL – Entities register their public key with the KMC – Multi-KMC also being investigated Comprises of two basic parts: – Authentication for all Publishers and Subscribers – Secured Publishing and Receiving ACL’s are associated to topics published Similar to X.509 certificate chaining, KMC hierarchy designed to verify signatures

30 Security Framework Supports different cryptographic algorithms with various different key sizes: – DES/3DES – AES – RSA – RC2 Designed to support: – JMS messages – JXTA messages – Audio/video conferencing KMC only a prototype and thus currently is a centralised implementation instead of distributed

31 JXTA JXTA stands for Juxtapose, meaning side-by-side JXTA is a Peer-to-Peer protocol specification which defines a standard for the behavior JXTA peers Six protocols define the JXTA platform: – Peer Resolver Protocol (PRP) allows peers to send search queries – Peer Discovery Protocol (PDP) allows peers to discover advertisements – Peer Information Protocol (PIP) allows peers to poll the status of another peer – Pipe Binding Protocol (PBP) allows peers to bind a pipe to a peer – Endpoint Router Protocol (ERP) allows peers to request routing information – Rendezvous Protocol (RVP), here peers subscribe to a propagation service

32 NB-JXTA JXTA is included with the NaradaBroker JXTA peers do not communicate with NaradaBrokers direct NaradaBroker provides a JXTA proxy This process is transparent to JXTA peers NaradaBroker adds its own header to JXTA messages

33 NB-JXTA

34 NB Web Services WS-Eventing: – Allows Web Services to subscribe to or accept subscriptions for event notification messages WS-ReliableMessaging: – Allows messages to be delivered reliably in the presence of software component, system or network failures SOAP: – Support for SOAP messages will be provided in version 1.0 of the NaradaBroker

35 NB Web Services

36 NB GridFTP Provides support for GridFTP transfers Data from client stored in a local temporary file Data in temporary file is then read and sent over the NaradaBrokering system to the endpoint Temporary stores provide support for failures Seems to be a prototype implementation

37 NB GridFTP

38 Screenshots Broker Command used to access Broker Connection made to another broker Link ID Node Address Request Distance calculation with hops Operations available New logical address

39 Screenshot JMS Chat Initial Chat application connection Link registration Publishing Topic Subscribin g Topic Conversations between 3 clients across 3 brokers

40 Screenshots Video Transmitter Receiver Subscription to topic

41 Summary JMS used for unified messaging and topics NaradaBroker supports multiple protocols Cluster based topology Only has partial capabilities for bypassing firewalls Only has a prototype security framework Capable of video conferencing Supports JXTA clients Prototype support for GridFTP Emerging Web Service support NaradaBroker is still pre version 1.0

42 Conclusions Parts of the NaradaBroker has been hard coded for the Windows OS, which hampers its portability The Broker has the potential for bridging services Firewalls still cause issues for the broker Some stability issues are caused when links are abruptly terminated Will the integration of Grid Services still be feasible considering GT4 is based on Web Services? Version 1.0 is to be released soon, hopefully this will be more refined

43 Future work Further investigation of the services provided by the NaradaBroker Investigate the feasibility of GridP2P with the NaradaBroker Collaborate with other universities to establish a UK testbed Evaluate the NaradaBroker across a Wide- Area-Network (WAN)

44 University of Portsmouth Members of the DSG Community Grids Lab Acknowledgements

45 Links JMS - JXTA - NaradaBrokering – JMF - media/jmf/index.jsphttp://java.sun.com/products/java- media/jmf/index.jsp GridFTP -