Solutions Global Design Patterns

Overview

This article summarizes the set of design patterns. All design patterns discussed in this article are included in the SolutionGlobal Open Source project.

Solution Global is hosted at Source Forge

https://sourceforge.net/projects/solutionsglobal/

1 Application Patterns/Package

1.1 Utility

The util package contains global classes used as common shared global services.

Class Summary
BeanComparator	Comparator implementation that uses JavaBean properties to compare two objects.
Config	This class provides read access to key/value pairs loaded from file properties (static implementation).
Cryption	Cryption provides a set of functions to encrypting and decrypting binary and ASCII text.
Debugger	Debugger provides a set of functions to handle application logger.
JavaBean	JavaBean provides a set of functions to manage JavaBeans.
Organizer	Organizer provides a set of functions to sort, filter and find elements in container objects such as collections, arrays and maps.
Presenter	Presenter message view helper.
PROXY	PROXY provides a set of functions to execute an operation on an object
Setting	This class provides read access to key/value pairs loaded from the properties file properties (non-static implementation).
Text	Text contains common functions for text strings.
TextTest	JUNIT test case
Util	Util contains common functions and constants used by the application

1.2 IO

The IO package contains object to manage file system input and output.

Interface Summary
Fileable	Represents the retrieval of a file

Class Summary
AbsolutePathFileableText	Wrapper to return the absolute path of a Fileable object's file representation
BackupDirectoryExecutable	Backup the content of given file/folder
CopyDirectoryExecutable	Copy the content of the directory
DeleteExecutable	Deletes a given file/folders
FileTokenizer	Parses tokenizer from a given file name
FolderFileTokenizer	List the folders in a given folder.
FolderFileTokenizerTest	JUNIT test case
FolderFilter	IO file filter to list folders
IO	IO provides a set function related to system IO reads/writes.
SynchronizedIO	SynchronizedIO provides a thread safe way to write files.
WildCardFilter	WildCardFilter filter used when monitor files.

1.3 Decorator

The decorator pattern is used to format output text/information.

Decoration of a certain object is done at runtime. The Textable interface is typically used within the decoration pattern. The Textable interface has a method (getText) that returns a string. The TextDecorator is a Textable. It wraps the target Textable object and adds additional text as needed.

This pattern allows multiple decorators to be stacked on top of each other, each time adding new formatting options.

Interface Summary
TextDecorator	TextDecorator interface to wrap a target object with additional text
TimeIntervalDecorator	Decorate date/time

Class Summary
MacroTextDecorator	Macro implement for text objects
MappedTextFormatDecorator	This object using a Free Marker template API (http:// http://freemarker.org/) to format mapped. Each value in the map is Textable object. The keys are replaced in the placeholders of a given text template.
ParseTextDecorator	Decorate the Textable by parsing out a given string token.
ParseTextDecoratorTest	JUNIT test case
ReplaceRegExpTextDecorator	Replaced a given Regular Expressions in the target Textable with a given output.
StringText	Simple Textable implementation to wrap a String variable.
ToStringWrapperText	Textable implementation interface to return the toString method of a target object.
XmlReflection	Converts any object to an XML string.
XmlXslDecorator	Transforms a given XML document using XSL and returns the text output.

1.4 Service Factory

ServiceFactory defines an interface for creating service components.

The service factory is a framework that supports pluggable services.

The ServiceFactory default implementation uses the Spring Core dependency injection framework to construct objects (see Spring Framework details at http://www.springsource.org/).

1.5 XML Patterns

This package contains a set of functions to perform XML based operations.

Interface Summary
XMLInterpreter	XMLInterpreter supports object to XML conversions
XMLizable	Interface that indicates that an object has a method to convert its data into an XML text.

Class Summary
XML	XML utility class.
XmlObjectTextable	Textable implementation to converts objects to XML.
XSL	The objects is used to perform a transformation in the simplest manner possible (3 statements).

1.5.1 XStream

Class Summary
XStreamInterpreter	XStreamInterpreter is an XMLInterface implementation. It is wrapper for the xstream XML API(s) (see http://xstream.codehaus.org/)

1.6 Worker Thread Pattern

This design pattern allows multiple threads to service any number of tasks. Each task is an instance of the Runner interface. A worker thread takes a task from a queue and executes it. All threads take tasks from the queue until all tasks are completed.

Interface Summary
Supervisor	Supervisor manages a list of workers
Worker	Worker interface for an object managed by the supervisor thread.
WorkQueue	Contains a list of tasks (each task is a Runner implementation).
WorkState	Represents a supervisor and work threads state.

Class Summary
Boss	Boss worker thread supervisor implementation
MemorizedQueue	MemorizedQueue is an implementation of a WorkerQueue where all tasks are held in memory.
StartState	StartState starts a worker thread if it is not alive
StopState	StopState stops a worker thread
WorkerThread	WorkerThread is a thread based implementation of a worker.

1.7 Command

1.7.1 Executable command

The Executable command is used to represent an operation. These objects create instances of Executable objects using the ServiceFactory implementation object. The client of the Executable is the object MainExecutable (usually for running standalone) or WebExecutableRESTfulService (used to running via web based service) objects. These clients objects are wired with an instance of the Executable object at runtime.

1.7.2 FileCommand command

FileCommand is an implementation of a command for processing files and folders.

Class Summary
BackupFileCommand	Backup the content of given file/folder
ConditionFileCommand	Execute a given file command if the boolean expression is true
ConditionFileCommandTest	JUNIT test case
FileCommandRunner	Runner implementation of a file command.
FileExecutable	File executable implementation for modifying file content
FileExecutableTest	JUNIT test case
FileFormatCommand	Read the file content and applied text formatting
MacroFileCommand	The Macro file command
ParseReplaceCommand	Parse and replace content in a given file.
PdfFileCommandTest	JUNIT Test case for PdfFileCommand.
ReLookupCommand	Uses complex regular expressions to the determine nested FileCommand to execute
ReplaceIncludeRelatedFileCommand	This class includes the text content of a related file into the given file.
ReplaceWithFormattedRelatedFileCommand	This class includes the text content of a related file into the given file (also supports text formatting).
ReplaceWithFormattedRelatedFileCommandTest	Test case for ReplaceWithFormattedRelatedFileCommand
ReplaceWithTextCommand	Overwrite the file with textable.getText().
ReReplaceCommand	This class using regular expressions to replace content in a file.
WorkerThreadFileExecutable	Implementation of the file executable based on the worker thread design pattern

1.8 RESTFul web service

The system uses a RESTful web service implementation of the command design pattern. The RESTful service parameters are distributed to implementations of the RESTful commands. The command to execute is specified is in an input argument (default parameter name is "cmd"). The RESTful service uses the ServiceFactory to lookup the implementation of the indicated command.

The following are the list of core RESTful service commands.

Class Summary
AbstractRESTfulCommand	Abstract implement contain useful shared functions
MacroRESTfulService	Macro command implementation to run one or more RESTful services.
RESTfulServlet	Front controller for RESTFul web based services
ScriptingRESTfulService	Scripting based RESTful web service
SendMailRESTFulCommand	Service to send email messages
SendMailRESTFulCommandTest	JUNIT test cases
WebExecutableRESTfulService	execute executable for post operations
WebLockSessionRESTfulCommand	Wrap a call to the WebLock object to synchronize access to the web application.
WebReleaseLockSessionRESTfulCommand	Wrap a call to the WebLock object to synchronize access to the web application.

1.9 Scripting

This package encapsulates the execution of embedded scripting languages. Examples of scripting languages are JRUBY, Groovy, Apache Bean Scripting Framework and Spring Framework's SPEL.

Interface Summary
Scripting	Interface for using bean scripting frameworks (such as GROOVY, SpEL, JRuby, etc)

Class Summary
SpringExecutable	Execute a spring expression (see Spring SPEL language at http://www.springsource.org/)
SpringExecutableTest	JUNIT test
SpringFramework	Script implement to execute a spring expression (see Spring SPEL language at http://www.springsource.org/)

1.10 Caching

This package supports application caching for performance improvements.

Interface Summary
Cache	Interface to Cache of a collection of objects

Class Summary
CacheFarm	Implementation of a Cache that maintains objects in a map

1.11 Security

1.11.1 Authentication/Authorization Pattern

The LoginAction is a JSF managed bean use to authenticate users.

The LoginAction uses an implementation of an Authentication interface to validate a username/password. The Authentication implementation is instantiated by the ServiceFactory object.

An implementation of the SecurityGuard object is used to determine if an authenticated user can access a web application resource. ConfigSecurityGuard is a SecurityGuard where the list of allowed users is configured through the config.properties file. The SessionIdAppSecurityGuard is a SecurityGuard where the request's session ID must exist in the web container's application scope (note this is often useful for securing web services, such as RESTful services).

SecurityFilter is an implementation of a J2EE web Filter. It uses Security Guard to protect a given request. The implementation of the SecurityGuard is obtained from the ServiceFactory.

1.12 Sample Usage Collaborations

A application needs to update process map content from a web Admin application. The process is performed in a series of steps. Each step in the process is displayed to the users in the web browser. This gives the users an idea of the progression of the content generation.

The following collaborations diagram explains the objects that are involved in each of the content generation steps.

Figure 8 Update Content Collaboration Diagram

The following table provides additional details for each process step.

Step

Description

Step 1

The processing begins when the WebLockSessionRESTfulCommand is initiated. This will assert that no two people can update content at the same time. The request is then initiated to the WebExecutableRESTfulService.

Step 2

WebExecutableRESTfulService initiates the SpringExecutable object. This encapsulates a Spring SPEL script that calls DisprocUtil.cacheProcessDocSummary's method.

Step 3

WebExecutableRESTfulService is called as the first process in step 3 to initialize any needed directories.

Step 3

The WebExecutableRESTfulService calls the SpringExecutable. This includes a Spring SPEL expression to create a directory specified by the configuration property for the rotated image output path.

Step 4

WebExecutableRESTfulService is called as the first process in step 4 to copy content from the share drive to a configured output directory.

Step 4

MacroExecutable is called to execute a delete and copy operation on the output directory.

Step 4

DeleteExecutable deletes the last generated output. The CopyDirectoryExecutable copies the share directory content to the configured output directory

Step 5

WebExecutableRESTfulService is called as the first process in step 5 to process content in the output directory.

Step 5

WorkThreadFileExecutable is used to process the process map, RACI, guidance documents content via the worker thread design pattern.

10.

Step 5

ReLookupCommand is used to execute one ore more File Commands. The command execution is determined if the file names matches a given regular expression in the map key. The reference FileCommand object in the value of the map is executed for each regular expression in the key of the map that matches a file name (see Spring Dependency Framework for an explanation of the XML structure).

Sample Definitions

<bean id="reLookup" singleton="false"

class="org.solutions.global.patterns.command.file.ReLookupCommand">

<map>

<entry>

<key>

<value>(000)|.*\.htmvalue>

key>

entry>

<entry>

<key>

<value>(001)|.*\.htmvalue>

key>

entry>

<entry>

<key>

<value>(002)|.*\.htmvalue>

key>

entry>

<entry>

<key>

<value>(003)|.*\.htmvalue>

key>

entry>

<entry>

<key>

<value>(004)|.*\.htmvalue>

key>

entry>

<entry>

<key>

<value>(005)|*map_1.htmvalue>

key>

entry>

…

11.

Step 6

WebExecutableRESTfulService is called as the first process in step 6 to process print content such as the process maps.

12.

Step 6

WorkThreadFileExecutable is used to process the process map images via the worker thread design pattern.

13.

Step 6

MacroFileCommand is used to execute the rotation of image file commands.

14.

Step 6

RotateImageFileCommand is called to copy of each process map image and turn it 90 degrees. This is used for landscape printing of the process maps.

15.

Step 7

WebExecutableRESTfulService is called as the first process in step 7 to process Q/A page.

16.

Step 7

FileExecutable is called to process the qa.html file.

17.

Step 7

The ReplaceWithTextCommand is used to add the standard Discovery Process web header, menus and footer HTML.

18.

Step 8

WebExecutableRESTfulService is called as the first process in step 8 to clean the application cache that was locked in step one.

19.

Step 8

The SpringExecutable object is called with a configured Spring SPEL expression

20.

Step

The SPEL expression calls the DiscProUtil.clearCacheProcessDocSummary method.

The user is presented with the following view when all processing is complete.