PTW051: Understanding and Programming for the AppServer

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PTW-051Understanding and Programming for the
AppServer

• Jamie Townsend
• Technical Architect
• Progress Switzerland

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Understanding and Programming for the AppServer
Agenda

• Architecture
• Accessing an Application Server Process
• Operating Modes
• Managing Context
• Parallel Client Requests

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Architecture
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Architecture
Any client
OpenEdge Application Server
Application Code
AppServer
Data
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Architecture
Any client
OpenEdge Application Server
WebSpeed Transaction Server
Application Code
AppServer
Data
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Components
AppServer Architecture
AppServer
Application Server Processes
Application Broker
Clients
NameServer
4GL Business Logic
Data
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Components
Application Server Process

• Executes OpenEdge 4GL procedures
• Application Server processes are reused
• Determined by AppServer operating mode

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Components
Application Broker

• Typically started at system startup-time
• Manages pools of re-usable application server
  processes
• Manages client requests for 4GL procedure
  execution

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Components
NameServer
Location transparency
Inventory (A and B)
Clients
NameServer
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Understanding and Programming for the AppServer
Agenda

• Architecture
• Accessing an Application Server Process
• Operating Modes
• Managing Context
• Parallel Client Requests

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Accessing the AppServer

• Create server handle

CREATE SERVER hdl.

• Connect to AppServer

Ret hdlCONNECT("-S 5353 -H pisces
-AppService Account").

• Run procedures

RUN AccountBL.p ON SERVER hdl (INPUT
account-number).

• Disconnect

ret hdlDISCONNECT().

• Delete server handle

DELETE OBJECT hdl.
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Connecting to the AppServer
How does it work?
ASInventory Hostzeus Port3097
hdlCONNECT("-H gemini -S 5162 -AppService
Inventory")
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Running AppServer Procedures
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Understanding and Programming for the AppServer
Agenda

• Architecture
• Accessing an Application Server Process
• Operating Modes
• Managing Context
• Parallel Client Requests

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AppServer Operating Mode

• Specified when AppServer is configured
• Determines how client requests dispatched to
  individual Application Server processes
• Design time considerations
• Design development of application
• Application context
• Performance Goals
• System resources, network response
• Request throughput and response time

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Session Models Operating Modes
Connection management

• Session managed model
• State-reset
• State-aware
• Stateless
• Session-free model
• State-free

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Operating Modes
Session Managed Model

• State-reset
• One client per Application Server process
• Session state is reset on disconnect
• State-aware
• One client per Application Server process
• Session state is maintained across connections
• Stateless
• Connection managed by AppServer Broker
• Many clients per application server process
• Context must be managed externally

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Operating Modes state-aware state-reset
Session Managed Model
AppServer
Application Server Processes
Client 1
Client 2
Application Broker
NameServer
Data
Client 3
Client 4
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Operating Modes stateless
Session Managed Model
AppServer
Application Server Processes
Client 1
Client 2
Application Broker
NameServer
Data
Client 3
Client 4
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Operating Modes
Session-free Model

• State-free
• No connection maintained between client and
  AppServer process
• Pooled connections
• 4GL requests on the server handle
• Web service requests on the WSA
• Requests dispatched similar to stateless except
• Multiple requests from one client run in parallel
• Each request runs independently
• Context must be managed externally

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Operating Modes state-free
Session-free Model
4GL Clients
AppServer
Application Server Processes
Client 1
Open Clients
Client 2
Application Broker
Web Service Client
Data
Web Services Adapter
Client 3
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CONNECT()

• Session-free connection
• Pool of re-usable socket connections
• AppServer handle points to pool
• Managed transparently by 4GL client
• Connections allocated as needed
• Tunable using CONNECT() properties

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Session-free

• Some applications not inherently connection
  oriented
• Requests executed regardless of other requests
• i.e. web page request for information
• Efficiency and Performance
• Parallel execution on any AppServer
• Efficient use of resources
• Performance gains
• Scalability

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Session-free

• Design considerations
• Procedures can execute concurrently
• Order of completion not predictable
• Persistent procedures
• Create a context
• Internal procedures execute
• On same AppServer
• Serially, losing parallel advantage
• Reduce scalability

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Resource Considerations
System Resources
Throughput
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Programming Considerations
Server Responsiveness
Development Costs/ Time
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Understanding and Programming for the AppServer
Agenda

• Architecture
• Accessing an Application Server Process
• Operating Modes
• Managing Context
• Parallel Client Requests

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Managing Context
Configuration procedures

• 4GL procedures available to you to manage context
• Startup/Shutdown (state-aware stateless)
• Connect/Disconnect (all session managed modes)
• Activate/Deactivate (stateless state-free)
• Specified when you configure an AppServer
• Called automatically at the right time

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Managing Context
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Managing Context Session level
Available to state-aware and stateless
Startup Shutdown
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Managing Context Connection level
Available to state-aware, state-reset, and
stateless
Connect Disconnect
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Managing Context Request level
Available to stateless, unbound requests
Activate Deactivate
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Managing Context
stateless - bound / unbound

• To ensure all requests are directed to the same
  AppServer process
• Two ways to bind to a stateless AppServer
• Automatically
• Run a remote persistent procedure
• Dynamically
• Set SESSIONSERVER-CONNECTION-BOUND-REQUEST to
  TRUE

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Managing Context
stateless

• Application specific context database
• Use SESSIONSERVER-CONNECTION-ID attribute
• Globally unique ID automatically set
• Recommended for an application specific context
  db
• Use Activate/Deactivate configuration procedures
  to load/unload application context
• Let the Application Broker do it
• Use SESSIONSERVER-CONNECTION-CONTEXT attribute
• Progress character string
• Set to last value assigned in context of
  corresponding connection

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CLIENT-CONNECTION-ID attribute

• Session managed
• Character attribute on a server handle
• Returns connection ID string for the AppServer
  connection
• Session-free
• Returns unknown-value
• Logical connection to AppServer represented by a
  pool of connections

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Managing Context

• Application specific context database using
  SESSIONSERVER-CONNECTION-ID
• Globally unique ID automatically set
• Recommended for application specific context db
• Use Activate/Deactivate configuration procedures
  to Load/Unload context
• Let the Application Broker do it
• SESSIONSERVER-CONNECTION-CONTEXT attribute
• Progress character string
• Set to last value assigned in context of
  corresponding connection

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Understanding and Programming for the AppServer
Agenda

• Architecture
• Accessing an Application Server Process
• Operating Modes
• Managing Context
• Parallel Client Requests

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Running Remote Procedures
Standard AppServer calls - synchronous
Blocks the client during an active call
SynchronousAppServer
Request 1
Request 2
Total Processing Time

Client
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Running Remote Procedures
AppServer calls - asynchronous
The client can make multiple calls to multiple
servers

RUN proc ON server ASYNCHRONOUS. . . .

Request 1
2
Total Processing Time

Client
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Example

• Calling procedure

RUN BL.p ON SERVER hAppSrv ASYNCHRONOUS SET
hRq2 EVENT-PROCEDURE BL-evt-proc IN
THIS-PROCEDURE (INPUT-OUTPUT TABLE
order-table, OUTPUT iCount).

• Event procedure

PROCEDURE BL-evt-proc DEFINE INPUT PARAMETER
TABLE FOR order-table. DEFINE INPUT PARAMETER
iCount as INT NO-UNDO.
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ASYNC-REQUEST-COUNT()

• Indicates outstanding requests

If hAppSrvASYNC-REQUEST-COUNT 0 THEN APPLY
CLOSE TO THIS-PROCEDURE.
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CANCEL-REQUESTS() method

• Session managed
• Raises STOP for request currently running
• Purges send request queue of pending requests
• Session-free
• Raises STOP for ALL requests currently running
• Purges queued requests

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Understanding and Programming for the AppServer
Summary Questions

• Architecture
• Accessing an Application Server Process
• Operating Modes
• Managing Context
• Parallel Client Requests

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Additional Information
Other Exchange Sessions

• SOA-03
• Open Up Access to your 4GL Applications Using Web
  Services
• DEV-12
• Bridging the Microsoft and Progress Worlds with
  the .NET Open Client
• DONE-02
• Where Did You Go Wrong? Diagnostics and
  Troubleshooting in OpenEdge
• DONE-04
• Best Practices - Designing for Performance
  These are a Few of My Favorite Tricks
• DONE-08
• Sizing and Performance Tuning N-Tier Applications

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Additional Information
Documentation

• OpenEdge Documentation
• Getting Started
  Application and Integration Services
• Application Server
• Administration
• Developing AppServer Applications
• Development
• Open Client Introduction Programming
• Expert Series
• OpenEdge Revealed Achieving Server Control
  with Fathom Management

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Additional Information
Education www.progress.com/education
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Thank you for your time!
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