Double Buffering

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Server Suite
Universal Multichannel Middleware Server for
Rich-Clients A Java Framework for
Agent-basedClient/Server Programming
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Content

• EsprIT ServerSuite Overview
• Web- or rich-clients?
• Multi-channel client sessions
• Agent concept
• Client-Commands / Async-Tasks
• MVC over net / Alive Business Objects
• Workflows
• EsprIT client framework
• EsprIT server functions
• Server Cascading
• Server Database Access
• Key advantages

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Web- or Rich-client?
Web-Browser
ServletJSPsStrutsHtmlXMLTaglibsPHPASPPEARL
CGI
WebServer
HTTP/HTML
WebClient
statelessunidirectional
What the web-server for web-clients...
Java VM
Java Object- Serialization
EsprIT-Server
RichClient
Agents
statefullbidirectional
...is the EsprIT-server for rich-clients
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Rich-clients come back
Advantages/Disadvantages Summary

• Web-client
• No software installation required
• - Browser dependent
• - Limited to browsers GUI
• - Limited complexity
• - No real session management
• - Difficult to make fail-safe
• - Software difficult to maintain
• - Tough server-polling
• - Reduced performance (HTML)
• - Heavy server side load

• Rich-client
• - Needs installation on each client
• (Automatic since Java-Webstart)
• No browser needed at all
• Full GUI power
• Unlimited complexity
• Real session management
• Robust and fail-safe
• Software easy to maintain
• Instant client updates
• Best possible performance
• Load balanced on client/server

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Client Connection

• EsprIT multi-channel client connections
• Request/Response channel for sync/async client
  requests
• Message channel for async server messages
• (optional) Transfer channel for mass data
  transfer
• (optional) Web channel for access to HTML
  documents
• Request/Response and Message channel build a
  client-session

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Request/Response Channel

• Request/Response channel (synchroneous)
• Request is sent to server and client waits until
  Response is received
• Request and Response can carry a serializable
  Object argument
• Request may run into timeout either on server or
  on client
• Request can have a low/high priority
• Request can be async (Response is sent in a
  Message)
• sync client blocks waiting for response
• async only the calling GUI action blocks waiting
  for response in message

Request
EsprIT Server
Database
Client
Response
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Message Channel

• Message Channel (asynchroneous)
• Server sends asynchroneous Messages to client
• Message can carry any serializable Object
  argument.
• Message may be caused by Server, other clients or
  client himself
• Different types of Messages cause different
  client reactions
• Client may register/deregister for particular
  types of Messages
• Client may receive an executable command in a
  Message

Client registersfor message types
EsprITServer
Message
Database
Client
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Transfer channel

• Transfer channel for mass data transfer
• Temporary TCP connection just for mass data
  transfer
• Performs mixed up/download of filesets in a
  transaction
• Can run sync/async, locked/unlocked, with
  high/low priority
• Only connected, authenticated clients can use
  transfer port
• Many file transfers may run in parallel

transactionalup/downloadof file sets
EsprIT Server Transfer channel
Database
Client
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Web channel

• Integrated Webserver
• Provides access to HTML documents, images,
  classes etc.
• PUBLIC Web root-directory for unauthorized access
• PRIVAT Web root-directory for authorized access

public area
private area
HTTP Request
EsprIT Server Web Channel
Database
Client
HtmlImages etc...
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Agent concept

• Synchroneous Agent execution
• Agent may be an argument of Request/Response or
  Message
• Agent is executed on the server and then returned
  in Response
• Agent is postprocessed on client at receive time
• Carries input params for execution as well as
  results of execution
• May run with user defineable priority
• Can have any Serializable Object argument (zipped)

Request
Sync
Database
Client
Response
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Async Agents

• Asynchroneous Agent execution
• Agent can be executed asynchroneously on server
• After execution Agent is sent back to client in a
  Message
• The calling GUI Action blocks until Agent-Message
  is received
• Async Agent can be cancelled by the client at any
  time
• Client can run many async Agents in parallel on
  the server
• When client disconnects, server terminates all
  it's running Agents

Request
Database
Client
Async
Message
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Parallel Agent Execution

• Parallel Agent execution on client and server
• Async Agent is synchroneously executed on server
  and immediately returned to client in Response
  (with partial results)
• Async execution of Agent is started on server
• Postprocessing of sync Response-Agent is started
  on client
• Server sends finished Agent to client in Message
  (with full results)
• Client postprocesses the received Message-Agent
• Thus server and client have been processing in
  parallel

Request
Sync
Database
Client
Response
Async
Message
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Sequenced Agents

• Sequenced Agents are received in multiple
  messages
• Large result data are sent in a sequence of
  multiple chunks
• Chunk size is user definable
• Client can display progress in a progress bar
• Client GUI action blocks until last chunk is
  received
• Example read large record sets from a database

Request
Client
Database
Async
Async
Async
Multiple Messages
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Client Commands

• Server can send a command to the client
• Is executed on the client when received
• Can be executed sync or async within client
• Can do ANYTHING on client side
• Server uses client-command to control
  clientsExample forced termination of client
• Users can send client-commands to other users

Client-Command
Client
EsprIT Server
Database
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Remote Tasks

• Synchronization between local and remote task
• Client thread starts remote thread (process) on
  the server
• Client thread awaits task-events of the
  server-thread
• Server-thread sends process-typical
  task-eventsSTART, PROGRESS, SUCCEEDED,
  CANCELLED, FAILED, FINISHED
• The FINISHED-event terminates wait-state of
  client in any case
• Simplifies programming of async workflows

Local Thread
Remote Thread
Local Thread
TaskEvent
EsprIT Server
Client
Progress Monitoring
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Client Communication

• Clients can directly communicate to each other
• A client can send as message to
• - a particular other client (SessionId)
• - all clients of a particular user (UserId)
• - alle connected clients
• Integrated client-chat-tool
• Integrated client-notification-tool

Message
Integrated client chat-tool
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Writing Applications

• Agents are the programming API for custom
  applications
• Agents contain code for processing on Server and
  Client
• Thus an Agent encapsulates a particular custom
  functionality
• Writing a custom application means Writing
  particular Agents for particular functions -
  thats all!
• No server code needs to be changed
• Comprehensive Agent-library available for
  standard functions

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MVC over Net

• Model-View-Controller over net

A client (Controller) modifies the Model
All clients are beeing notified and refresh
their view
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Alive Business Objects

• Alive" Business Objects, global accessible
  server-objectswith dynamic updating on all
  clients (via event notification)

EsprIT Server
One client modifiesthe business-object
All clients are beeing notified and refresh their
view
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Alive Business Objects II

• Alive Business Objects (ABOs)
• Use MVC over net
• ABOs are distinguished by PrimaryKey
• Changes are notified to all accessing clients
• ABOs can be accessed with exclusive lock
• ABOs can be database-persistent
• Extremly easy to use
• fetch(withLock, PrimaryKey) Access by PrimaryKey
  (evtl. with exclusive lock)
• find(SqlCondition) Search all ABOs matching the
  condition
• drop() Forget this ABO (no updates any more)
• create() Create new ABO on server side
• update() Update local changes on server side
• delete() Delete ABO on server side

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Alive Business Objects III

• ABO Server-cache
• Server caches ABOs for fast access
• Server knows, which client has access to which
  ABO
• Change-events are only sent to accessing clients
• Client can "drop" ABO and wont receive
  change-events any more
• Server removes ABO from cache if nobody accesses
  it any more
• Cache-resistent ABOs remain in the cache forever

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Workflows

• Workflows
• Controls execution of a set of async tasks
• Incl. remote-tasks, file-transfers,
  stream-downloads etc...
• Workflow Monitor displays planned/running/done
  tasks

• Decision-points allow for manual interaction and
  flow control
• Cancellable any time
• Clean error processing
• Many workflows can run at the same time

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Resource Locks

• Server resource locks
• Any Server-Object can be associated with a lock
• SHARED protects against deletion during access
• EXCLUSIVE protects against foreign changes
• Resource Locks are "leased"
• Client must retrigger a lock in timeIf client
  goes away all its locks are beeing released
  automatically
• Administrator can enforce release of a lock
• Examples
• Lock server file access
• Lock database access
• Lock ABO (Alive Business Object) access

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EsprIT Client

• Comprehensive customizable client framework
• Powerful GUI framework for developing clients
• Dynamic attach/detach to/from EsprIT-Server
• Direct inter client communication
• Many ready to use GUI components and support
  classes
• Powerful async task framework

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Client Activity Monitor

• Client's asynchroneous activity can consist of
• Agents Running async Agents on the server
• Transfers Running async transactional file
  transfers
• Processes Running async local OS-processes
• Commands Running async commands received from
  server
• All client activity can be visually monitored
• User may cancel any async activity at any time

Connect/disconnect button
Client activity monitor
Request/message indicator LEDs
3 async Agents currently running on server
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EsprIT Admin Client

• Administration client for controlling EsprIT
  Server
• Observe server activity by viewing server profile
• Observe server console messages and server events
• View and manage server logfiles
• Configure server runtime parameters dynamically
• Allows to monitor and control clients
• Communicate to clients (via messages)

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EsprIT Server

• Fully equipped multi-channel middleware server
• Runs as a background (Java) process on any
  platform
• Real session-management (Request/Response,
  Message)
• Optional services (Transfer-, Web-channels)
• Scalable thread pools (configurable at runtime)
• Integrated User/Group manager
• Manages resource locks (leasing)
• Comprehensive logging functionality
• Server-status notification to clients (messages)
• Observable server statistics
• Depends on nothing but Java
• Easy customizable by pluggable server components
• UserManager, TaskManager, PermissionManager
  etc...

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Server Profile

• Server activity profile snapshot

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Integrated WebServer

• Webservice access to documentation, images etc...

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Database Access

• Client access to database (full edit
  functionality)

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Server Cascading

• EsprIT servers can be connected to each other
• A server may be client of any other server
• Co-client/co-server connections are failsafe
  (monitored)
• Requests can be routed to any target server
• Agents can travel around multiple servers

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Co-Clients, Co-Server

• Co-client and co-server connections

This server has another server as a co-client
This server is co-client of 2 other co-servers
3 users logged in
One user holds an exlusive lock on a server
resource
One user is running a file transfer
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More Server Features

• Additional server features
• Support for batch-processes (time scheduled
  background jobs)
• Self-surveillance with alarm notification via
  E-Mail
• Self-healing inter-server connections
• Dynamic connection-pool to database (parallel
  transactions)
• Simultaneous connections to multiple
  databases(with direct data transfer between
  different vendors databases)

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Application Example I

• INCA Project, BGR Hannover

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Application Example II

• HiLocate Project, ISA Telematics

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Application Example III

• BDE-IS Project, Hydro Aluminium Hamburg

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Key Advantages

• Key advantages of EsprIT Client/Server Technology
• True sessions (Request/Response and Message
  channels)
• Client notification via message, no
  server-polling,true Model-View-Controller (MVC)
  over net
• Fast and easy data transfer (Java-serialization)
• No overhead like XML or data conversionHigh
  performance (stable TCP connections)
• Transactional file-transfers
• Upload/download of mass-data client?server,
  server?server
• Extremely flexible Agent concept
• Agents serve as easy to program API for custom
  functionality
• Alive Business Objecst (ABOs)
• Gives all clients a consistent view of the world.
• Server Cascading
• Allows for scalability and task sharing among
  many hosts

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Key Advantages II

• Key advantages of EsprIT Client/Server Technology
• Chaining complex sync/async operations with
  Agents, ClientCommands, Tasks, FileTransfers,
  etcExample Client starts CAD system and
  creates input-fileInput-file is automatically
  beeing uploaded to central serverCentral server
  creates database entry and forwards data to
  compute-server Compute-server starts calculation
  and transfers results to central-serverCentral-se
  rver updates database and notifies clientClient
  downloads result file(s)Client starts CAD-system
  for displaying results...All this in an
  automatic procedure, whereas each operation
  triggers the next
• Independent from database system (pure JDBC)
• Independent from hardware platform (pure Java)
• Many, many possible applications

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Best Rich-Client Support

• Where EsprIT Server is the best fit
• The ideal server for rich-client support
• Rapid development of client/server applications
• Best support for clients
• which are complex in functionality,
• need to be highly responsive,
• need to be dynamically kept up to date
• EsprIT server may perform
• auditing or monitoring of remote processes
• running time scheduled server processes
• Server-cascading allows for
• running different tasks on different hosts
• surveillance of activity on remote hosts

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Comparision
EsprIT-Server or Application-Server?

• EsprIT-Server
• Low cost
• Low maintenance effort
• Low learning effort
• Server cascading
• Easy programming API (Agent)
• No restrictions in functionality
• Client message notification
• Best possible performance (dual port TCP)
• - Cannot be clustered

• Application-Server
• - High cost
• - High maintenance effort
• - Very high learning effort
• - No Server cascading
• - Complex mixture of technologies
• - Restricted to EJBs
• - No client message notification
• - Limited performance (RMI, SOAP, XML etc...)
• Can be clustered