Transcript CLICK TO ADD MAIN TITLE

Developing Blackboard Building
Blocks™: Getting Started
Presented By Bob Alcorn
Blackboard Inc.
April 12, 2005
Overview
•
•
•
•
Goals
Blackboard Building Blocks Technology
Java/JSP Development Tools
Blackboard Building Block Development
– Tools and Techniques
2
Now a word from our lawyers…
Any statements in this presentation about future expectations, plans and
prospects for Blackboard and other statements containing the words
"believes," "anticipates," "plans," "expects," "will," and similar expressions,
constitute forward-looking statements within the meaning of The Private
Securities Litigation Reform Act of 1995. Actual results may differ
materially from those indicated by such forward-looking statements as a
result of various important factors, including the factors discussed in the
"Risk Factors" section of our most recent 10-K filed with the SEC. In
addition, the forward-looking statements included in this press release
represent the Company's views as of April 11, 2005. The Company
anticipates that subsequent events and developments will cause the
Company's views to change. However, while the Company may elect to
update these forward-looking statements at some point in the future, the
Company specifically disclaims any obligation to do so. These forwardlooking statements should not be relied upon as representing the
Company's views as of any date subsequent to April 11, 2005. Blackboard,
in its sole discretion, may delay or cancel the release of any product or
functionality described in this presentation.
Audience
• Basic to Intermediate Java developer
• Java/JSP/Servlet development is
assumed
• Blackboard Building Block development
is not assumed, but is helpful
• Familiarity with, but not necessarily
expertise in, current Java development
tools
Goals
• Focus on process and environment,
rather than Blackboard Building Block
technology
• Cover a selection of tools that are
available to build Blackboard Building
Blocks
• Describe techniques and practices that
will make the development process
easier
Blackboard Building Blocks
Technology
• Extensibility mechanism for Blackboard®
– Provide drop-in functionality, or...
– Provide a bridge to an external system
• Standards-based
– Blackboard Building Blocks are Java
webapps with additional metadata
– Rely on/integrate with embedded Tomcat
engine
Blackboard Building Blocks
Architecture
Business Layer
(JSP, Servlet, Struts)
View Layer
(JSP, Servlet, Tag Library)
Data Objects
Core Services
Security
Log
Config
Session
Context
Persistence
Plug-ins
I18N
VXI
Anatomy of a Blackboard Building
Block
Package (.war/.zip file)
web.xml (Servlets)
Platform Descriptor
bb-manifest.xml
Blackboard Manifest
Servlets, JSP (Java)
Web Resources
Libraries
.class, .jar files (Java)
The Process
• Feature Planning
– Defines what you’ll need in terms of entry points
• Set up the build environment
– Local Blackboard server works best
• Perform an initial build
– Get entry points defined
– Install the Blackboard Building Block
• Iterate
– Build/rebuild
– Redeploy
The Build Stages
• Compile
– Custom .java files compiled into .class files
• Stage
– Web app structure is created from other
components
• Package
– Web app structure is zipped into the .war file
• Deploy
– An alternate to “package”, depending on the cycle
The Process
Preliminary
Feature
Planning
Compile
Environment
Set-up
Stage
Initial Build/
Install
Package
Iterate
Compile
Stage
Deploy
The Process
• Initial Install vs. Re-deploy
– Initial Install reads manifest and
establishes the entry points
– Re-deploy simply makes Blackboard
Building Block inactive, then makes it
Available again
• Cycles webapp, reloads classes
• Inactive/Available cycle unnecessary for JSP
changes
Example – The Build Environment
• JDK 1.4/5.x – The core Java library
you’ll need
• Eclipse 3.x – An IDE for
editing/debugging/formatting
• Ant 1.6.2 – A tool to automate many of
the tasks (within Eclipse and via shell
automation)
• ... All Freely Available
The Tools – JDK
• Version is dependent on which
Blackboard install is targeted
– 6.0.11 and higher supports 1.4.x
– 6.3 and higher require 5.x
• New language features are extremely nice
The Tools – Ant
• An Apache Software Foundation project
• Not bound to Blackboard release
• Samples developed against 1.6.2, but
should work against earlier versions
The Tools – Eclipse
• Java IDE with substantial productivity
features
– Ant integration
– Refactoring
– JUnit integration
– Plugins (e.g., SCM integration, JSP editing)
– You’ll need 3.1 if you’re developing with
JDK 5.x
The Strategy
• Organize the workspace to separate the different
types of files you’ll work on
–
–
–
–
Web Files (JSPs)
Logic Files (.java files, servlets, etc.)
Configuration Files (.tld, .xml)
Etc.
• Use a tool that will automate the transformation of
each artifact into the next
– Build the configuration to support rapid iteration
• Use the tools to support unit development, unit
testing, and debugging
– Better encapsulated, smaller units helps make the iteration
easier
Organizing the workspace...
Example – The Directories
Compiled Classes
Config Files
Library Files
Java Source
“Prep” Directory
JSP/HTML/Image
Automating the environment...
An Ant Primer
• Build utility to manage compile/build tasks and
dependencies
• Uses XML as the syntax (compare to make, etc).
• Core data model:
project  target  task
• Targets define dependencies and contain tasks
• Tasks are the units of work...
– Many built-in tasks (javac, jar, copy, etc.)
– Easy to customize
An Ant Primer
• File typically named “build.xml”
– Ant will automatically process that file if no file
argument is provided
• Arguments can include specific targets
– Project default target is used if no target is provided.
E.g.,
• c:\projects\sample>ant
• c:\projects\sample>ant compile
• c:\projects\sample>ant -f alternate.xml compile
Example – A Simplified Build File
Init properties, files
Compile Java Files
Copy files to staging
Create .war file
Copy to install
Example – Build File
Example – Eclipse Integration
Making It Easier
• The Starting Block
• Server Blackboard Building Block to
Install, Cycle, and Uninstall
• An Ant task to invoke the Starting Block
from your build environment
Using the tools...
Test Driven Development
• Write objects that can be used
independently of the container
– Re-use
– Testability
• Get used to writing methods (and tests)
corresponding to user interface features
Example – JUnit Integration
Debugging
• A valuable and under-used technique
– Avoid System.out.println() like the plague
• Limitations actually encourage better
practices
– If you’re used to stepping through code, and hate
the lack of JSP  source correlation, you’ll build
better business objects
• Caveat: environment is slightly different,
notable the security manager is not enabled
by default
Debugging – How To
• Stop the Blackboard Tomcat instance
• Open a command line, define the JPDA
environment variables
• Execute the shell launcher that brings
Tomcat up in JPDA mode
• Connect with debugger of choice
Debugging – How To (Windows)
c:\blackboard\apps\tomcat>
net stop bb-tomcat
c:\blackboard\apps\tomcat>
set JPDA_ADDRESS=2222
c:\blackboard\apps\tomcat>
set JPDA_TRANSPORT=dt_socket
c:\blackboard\apps\tomcat>
bin\blackboard-tomcat.bat jpda start
Debugging – How To (Unix)
/usr/local/blackboard/>
./tools/admin/ServiceController.sh
services.appserver.stop
/usr/local/blackboard/>
export JPDA_ADDRESS=2222
/usr/local/blackboard/>
export JPDA_TRANSPORT=dt_socket
c:\blackboard\apps\tomcat>
./bin/blackboard-tomcat.sh jpda start
Debugging – Connecting
Debugging – Connected
Debugging – Connected
Conclusion
• Planning your build environment can
help ease some of the headache of
Blackboard Building Block development
• Use tools that help automate the
process
Resources
•
•
•
•
Ant: http://ant.apache.org/
Eclipse: http://www.eclipse.org/
Java/JDK: http://java.sun.com/
Blackboard Building Blocks:
http://buildingblocks.blackboard.com/