T Network Application Frameworks and XML Mobile Middleware Sasu Tarkoma

Contents n Mobile Middleware u Motivation u Examples n Summary

Mobile Middleware I n Middleware is typically designed and implemented for fixed-network hosts u High bandwidth, low latency, reliable communication u Persistent storage and sufficient computing power u No mobility n Mobile environment requires new solutions u Existing middleware services do not scale u Previous lectures: mobility is challenging u Small devices / embedded systems pose totally different challenges

Mobile Middleware II n Goals for middleware: u fault-tolerance, adaptability, heterogeneity,scalability, resource sharing n Mobile middleware u dynamically changing context u decoupled F events, tuple spaces u Basic solution for wireless F Use a proxy

Reflection n In general, middleware provides transparency to the underlying conditions u Location transparency in RPC/RMI n In mobile environments this is not always desired u Sometimes we need to know about location changes, QoS changes, etc. n Requirement for reflective middleware u Should expose APIs for querying / changing important parameters u Under development

NAF XML Security Objects Middleware IPv6 mobility, HIP Mobility Wireless CORBA Secure mobile XML routing Plain IPv4 MIP J2ME Symbian.NET WAE

Examples n WAE n J2ME n Wireless CORBA n Fuego

WAE n Wireless Application Environment (WAE) u A suite of protocols and specifications for optimizing data transfer for wireless communication n WAP stack u Focus on binary transmission u Protocols F WSP (Wireless Session Protocol) HTTP replacement, “compressed” F WTP (Wireless Transaction Protocol) Request/response, more efficient than TCP F WTLS (Wireless Transport Layer Security) Based on TLS, may not be end-to-end with a gateway F WDP (Wireless Datagram Protocol) UDP replacement

Comparison TCP/IP UDP/IP TCP/IP UDP/IP TLS - SSL HTTP HTML/JS Transport Layer (WDP,UDP) Bearers: SMS,CDMA,.. Security Layer (WTSL) Transaction Layer (WTP) Session Layer (WSP) WAE Other

WAE: current status n WAP Forum now in OMA (Open Mobile Alliance) n WAP 2.0, is a re-engineering of WAP using a cut- down version of XHTML with end-to-end HTTP n Gateway and custom protocol suite is optional. n WAP used by many handsets u 1.2 version introduced WAP Push (typically using an SMS message) n Typically versatile networking stacks with also IPv6 support

Java 2 Platform Micro Edition (J2ME) n Java for consumer electronics and embedded devices n A virtual machine and a set of APIs n Configurations and profiles u Configurations F two-low level APIs and optimized VMs CDC, CLDC u Profiles F API specification on top of a configuration for complete runtime F CLDC: MIDP F CDC: Foundation, Personal Basis, Personal F Specify both APIs and Configurations F Profiles defined using Java Community Process (JCP)

Source:

J2ME optional packages n JSR 172: J2ME Web Services Specification n Content Handler API (CHAPI) JSR 211 u allows the invocation of J2ME platform applications from native applications and vice versa n Security and Trust Services JSR-177 n J2ME Client Provisioning JSR-124 u J2ME Client Provisioning Specification defines a server partitioning standard for provisioning applications. n Mobile Media API JSR-135

CLDC Technology n Connected Limited Device Configuration (CLDC); JSR 30, JSR 139 n Mobile Information Device Profile (MIDP); JSR 37, JSR 118 n Information Module Profile, (IMP); JSR 195 n Java Technology for the Wireless Industry, (JTWI); JSR 185 n Wireless Messaging API (WMA); JSR 120, JSR 205 n Mobile Media API (MMAPI); JSR 135 n Location API for J2ME; JSR 179 n SIP API for J2ME; JSR 180 n FileConnection and PIM API (JSR-75) n Security and Trust Services API for J2ME, (SATSA); JSR-177 n Mobile 3D Graphics; JSR-184 n J2ME Web Services APIs, (WSA); JSR 172 n Bluetooth API (JSR-82, Motorola, Java Partner Site) n J2ME Content Handler API, (CHAPI); JSR 211

CDC Technology n Connected Device Configuration (CDC); JSR 36, JSR 218 n Foundation Profile, (FP); JSR 46, JSR 218 n Personal Basis Profile, (PBP); JSR 129, JSR 217 n Personal Profile, (PP); JSR 62, JSR 216 n J2ME RMI Optional Package, (RMI OP); JSR 66 n JDBC Optional Package for CDC/Foundation Profile API; JSR 169 n Java TV API; JSR 927 n Java Secure Socket Extension for Connected Device Configuration (JSSE)

Wireless CORBA n CORBA does not support accessing mobile objects or wireless communication u Wireless CORBA specification n Three basic requirements u Invocations from mobile objects u Invocations to mobile objects u Wireless communication n Home bridge n Access bridges n Tunnelling over wireless n Handoff protocols

Mobile IP vs. WCORBA n MIP addresses host mobility, not object mobility n MIP does not specifically support wireless protocols n MIP hides all handoff events u location-aware services difficult to implement

Architecture Redirects requests for services on the terminal Keeps track of the current access bridge Other side end of the Access Bridge Encapsulate/decapsulates msgs Generates mobility events Encapsulates, forwards or ignores incoming GIOP messages Decapsulates and forwards messages from the GIOP tunnel Generates mobility events Lists available services Abstract transport-independent tunnel for GIOP messages Concrete tunnels for TCP/IP, UDP/IP and WAP WDP. Protocol requires reliable and ordered delivery

Handoffs n Network initiated handoff u started by an external application u optional to support make-before-break n Terminal initiated handoff u terminal discovered a new Access Bridge u make-before-break is required n Access recovery n The Home Location Agent is updated n Old Access Bridges are informed n Mobility events are generated in the visited domain and the terminal domain

Network Initiated Handoff

Fuego Core (HIIT) n Mobile and wireless environments have different requirements than desktop systems u User mobility, terminal mobility, connectivity, device characteristics, dynamic environments n Vision: A service application is distributed among various application servers, network elements and terminals n Three year Tekes project ( ) u Industrial partners: Nokia, TeliaSonera, Elisa, Ericsson, Movial u Open source software n Demonstration at WMCSA 2004

Fuego Architecture n The Fuego middleware service set for mobile computing u Data communication F Efficient wireless SOAP F Efficient content-based routing (asynchronous events) u Data synchronization F 3-way XML document merging F XML-aware distributed file system u Applications F Presence service, mobile ticker, image-album

End-to-end authentication of hosts Encryption of network traffic using IPsec Mobility and multihoming support Resilient sockets End-to-end authentication of hosts Encryption of network traffic using IPsec Mobility and multihoming support Resilient sockets Reliable messaging Multiplexing multiple connections on TCP Prioritization of connections Reliable messaging Multiplexing multiple connections on TCP Prioritization of connections Efficient sync/async messaging Efficient XML serialization Persistent connections across mobility Efficient sync/async messaging Efficient XML serialization Persistent connections across mobility Expressive async. communication Content-based routing using filters Event buffering / mobility support Support for context-aware operation Expressive async. communication Content-based routing using filters Event buffering / mobility support Support for context-aware operation Automatic reconciliation of XML documents Optimized storage of XML Ad-hoc file sharing Integrates with existing file systems (NFS) Automatic reconciliation of XML documents Optimized storage of XML Ad-hoc file sharing Integrates with existing file systems (NFS) Presence service based on events Control of presence attribute visibility Presence service based on events Control of presence attribute visibility

FUEGO DEMO

Summary n Mobile middleware u Desktop middleware not usable on small, mobile devices u Special solutions are needed u J2ME, WAE, Wireless CORBA,.. n Current trend u Flexibility, decoupled nature u Convergence / unification