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Java One Report 2002

Technical Overview

• 1.4.0 "Merlin" now: emphasize quality, scalability, real world performance, large # processes (~72) big heap (2-4 GB ok). important new features: new io, XML, IPv6, 64 bit SPARC
• 1.4.1 "Hopper" fall 2002: 64bit Itanium, bug fixes
• 1.4.2 "Mantis" 2Q 2003
• 1.5 3/4Q 2003: quality, monitor and measure performance and scaleability, client for XML/Web Services, generics.

• 1.3 Sept 2001: connectors, JMS, message-driven beans, JAXP 1.1
• 1.4 1Q 2003: Web Services, JAX-RPC, Enterprise Web Services (JSR 109)

Client deployment options:

• Java Plug-in: for applets
• Java WebStart
• "consumer plug-in" for Windows XP, supports <applet> IE tag, supposed to be easy enough for end-users to install. early access now, FCS for hopper.

J2SE 1.4

• scaleability
• tested on 72 CPUs, big heaps
• improved GC can handle several GB heaps
• new I/O: single thread can handle multiple I/O channels via select
• new I/O
• preferences, assert, logging, exception chaining
• Unicode 3.0
• IPv6, URI class
• security fearues in the core
• JSSE : SSL and HTTPS "secure sockets"
• JAAS: authentication and authorization API
• JCE: cryptographic API
• GSS API: implements Kerberos (through OS or directly)
• JDBC 3.0 in core
• Java 2D improved performance
• optimized for common Swing operations: 2x improvement over 1.2
• allow access to hardware acceleration
• 5-10x  improvement for remote XWindows
• Swing
• pluggable image I/O : gif, jpg, png built in
• printing: controls and performance
• headless GUI for servers
• focus managemaent rewrite
• mouse wheel support
• FileChooser on Windows
• mo better: JSpinner, JProgressBar, JTabbedPanel, scrollable tabs, DnD
• java Webstart bundled
• java plug-in bundled

1.4.1 Hopper (fall 02) features

• Itanium support
• bug fixes
• shared libraries bewteen multiple JVMs
• concurrent mark and sweep GC (avoid those long pauses)

1.5 Tiger (second half 03) tentative list

• generics
• autoboxing of primitive types
• import constants :eg import java.awt.Color.RED
• generic iterate over Collections
• "metadata"
• syntactic pattern, eg get/set
• explicit language declaration, modify execution semantics (becomes part of language spec)
• implement with keyword declaration OR javadoc spec
• JMX: network management API
• JVM monitoring/manageent API (local and JMX access)
• JVM profiling : replace "experimental" JVM-PI (deemed inadequate)
• more New I/O:
• OS File system interface, eg disk usage, file attributes
• simple formatted I/O (printf)
• maybe asynch I/O
• XML
• JAXP update with Schema support
• JAXB, JAX-RPC, XML digital signitures
• better GC
• faster startup, smaller footprint
• Unicode 3.1 (cant fit in 16 bits anymore!)
• IPv6 QOS, security
• concurrency utility support (Doug Lea)
• java Isolation API
• API to invoke javac compiler from inside app
• disconnected JDBC rowset

XML:

• JAX-RPC: uses SOAP 1.1 as transport, esiest way to get started with XML. summer 2002
• JAXM: lower level than JAX-RPC, gives access to "raw" XML transfer
• JAXB: map XML types to Java types, target final release 4Q02
• JAXP: core XML services, access to SAX/DOM/XSLT, standard in J2SE 1.4 and j2EE 1.3. JAXP 2.0 will support schemas.
• JAXR: access to XML Registries (UDDI, ebXML) early access, final in a few months

Java WebStart

• enhanced sanbox: security advisory dialog: asks user permission
• lazy download (eg for help system, enhanced maps) (but getResource() currently ruins this)
• javax.jnlpDownloadService: servlet can help with absolute URLs, incremental update, version updates
• specify JRE version
• platform: : 1.2, 1.3 etc
• product: 1.1.1_02 href = "where to get it"   (the href makes it a product)
• future:
• "seamless WebStart upgrade": upgrade Webstart
• enterprise deployment
• HTTPS

Web Services

• "loosely coupled" applications
• web services developer pack currently includes JAXP, JAXM, JAXR, Tomcat 4.1, 500 p tutorial
• claim apache SOAP may be immature
• communication paradigm: 1) document vs 2) remote method
• maintaining state: cookies or URL rewriting, or pass all info in each request
• servlet containers can keep state (J2EE?)
• WSDL: describes service, enables registries (UDDI, JAXR)
• SOAP: adds headers to messages, like email headers
• JAXM: full access to SOAP headers
• JAX-RPC: simpler way yo use SOAP
• JAXR: access to XML Registries (UDDI, ebXML) early access, final in a few months
• register Web Services; JAXR is itself a web service
• "electronic yellow pages", service categorization; search and discovery
• JAXR is a common abstraction for UDDI and ebXML
• JAXR is a client API, with default implementation
• is at proposed final draft, and reference implementation (now), early access release Q1'03, final release Q2'03
• reference implementation uses JAXP, JAXB, JAXM, JAX-RPC

Swing Performance

• default models are simple and general; for large amounts of data usually want a custom class
• JTable: might use sparse matrix with hash
• protytype cells, eg JList.setPrototypeCellValue(), when you know max size
• repainting
• minimize area to repaint, check clip area
• sometimes subclass RepaintManager is very uselfull (eg if you dont want to union dirty areas)
• lots of anonymous little classes can take room on the heap, use java.lang.reflect.Proxy instead.
• use multiThreading for responsiveness, but anything toucing GUI must be on AWT event handler thread
• VolatileImage (jdk 1.4) allows access to hardware acceleration,
• apparenly meaning video memory which I think is very fast to read (but not so good to modify?)
• can not do translucence (alpha) or anti-aliasing efficiently
• jdk 1.4 VM  will try to optimize use of video memory for you
• image use
• use GC.createCompatableImage() to get the right kind of image to write to.
• use BufferedImage only when you need image in specific form.
• use VolatileImage when you want to use video memory (Swing uses for back buffer)
• can try using hardware image scaling with -DDscale
• JDK 1.4 improvements
• lower overhead on draw and graphics state changes, eg setColor()
• improvements from 1.3.1:
• menus 132%
• JTable with text: 125%
• JTree 180%
• see http://java.sun.com/docs/performance

New I/O

• Buffer Classes
• has position, limit, and capacity (invariant)
• reletive get/put: advance position, respect limits
• bulk get/put (optimizations in 1.4.1 now "operate at speed of memcpy")
• absolute get/put, ignore position, respect limit
• Channel Classes
• read = bulk put
• write = bulk get
• clear set pos = 0, limit = capacity, use before read
• flip: set pos = 0, limit = pos, use after read before write
• rewind: use before write
• compact: move to beginning
• Where to get Buffers
• ByteBuffer.allocate( size)
• ByteBuffer.wrap( byte[]), ByteBuffer.duplicate()   same backing store
• ByteBuffer.slice()   bytes remaining
• ByteBuffer.asReadOnlyBuffer()  no puts
• DirectBuffer : content in native memory, outside of GC's heap
• allows VM to avoid copy during I/O
• allocateDirect()
• memory mapped files
• JNI : NewDirectByteBuffer( JNI env)
• ByteBuffer allows mixed types, can use chaining: buf.putInt().putChar()
• uniform binary data eg CharBuffer, can be got from ByteBuffer.asCharBuffer()
• index is in sizeof(type)
• bulk get/set by type
• potentially more efficient
• File Channels
• size, position, truncate;
• reletve and absolute read/write
• where to get: FileInputStream, FileOuputStream, RandomAccessFile: getChannel()
• allocateDirect is fast
• FileChannel.transferFrom() may be able to use OS optimizations
• timing:
• old I/O                           70 MB/sec    improve
• new I/O (direct buffer)    103               1.47
• memMapped copy         132                1.90
• transferFrom()                137                1.96
• native                             150                2.16
• FileChannel locks
• acquire lock: block until available, or return immed
• entire file or part of file
• some OS dont supprt mandatory, so dont count on it
• can examine  FileLock object to seewhat actually happens
• Future Work (Tiger)
• format and scanning: leverage RegExp
• improve file system interface (File) : failure mode, file attributes, allow non-native filesystems
• asynch I/O
• Notes
• transfer() faster than memmap()
• use NIO for all new code
• selector class: keysets not thread safe
• asynch IO makes sense on files, less so on network sockets
• Regexp
• looks like perl 5
• not extensible like ORO
• see Freidl's book
• Pattern = compiled representation of reg.exp.
• Matcher = state machine that matches patterns in a string
• java.lang.CharSequence new abstraction for String, StringBuffer, CharBuffer

Java Plug-In

• targeted to IE 6.0, XP which has no Java built into it
• use <applet> tag for Internet, <embed>, <object> for inranet
• does applet caching
• adjustable max cache, compression, cleanup
• can specify "preload" for eager loading, default is lazy
• cache updating: uses expiration date, check modify date, use "jar versioning" to avoid checking for modfy date
• Security: https (1.4), jar signing, certificate management with centralized Control Panel
• DOM access to HTML
• Java Console:
• log, trace, assert for debugging;
• available from tools menu in IE, task/tools in NN
• threaded stack dump
• can be dynamically configured
• also use appletviewer for debugging
• applet signing: get security warning allowing the user to 1) grant permission for this session only 2) grant permanently (add CA), 3) view certificate chain
• For Hopper relase:
• focus on the end-user "auto-install experience"
• resumable download
• integriry check
• minimal user interaction
• single download progress bar
• option for silent install with no popup
• unify with Java Webstart

Servlets and JSP: whats next

• Servlet 2.3 was a major release, importantfeatures: global listeners, filter model
• lots of frameworks built on top of servlets
• Servlet 2.4 will focus on extensibility; portability between containers
• may move to Schema for deployment descriptors
• listeners: request/response lifecycle (start/stop/change) events; filter chain processing
• session state and login state: define clear relationship, make logout portable; session invalidation / timeout
• servlet.com good source of info
• JSP: "custom actions" most important feature.
• JSP new: expression language, like JavaScript but much smaller

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