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Monday, 15 July 2019 05:12

How does a code generator enable large-team parallel development?

One of our biggest challenges at Parallel Agile is explaining how two apparently unrelated aspects of our business are actually very closely related. Specifically, how our domain driven database and API generator (aka Parallel Agile CodeBot) enables the Parallel Agile Process, which allows large teams of developers to collaborate more efficiently and breaks the “two pizza rule” on team size.

To understand how the CodeBot enables large-scale parallel development we need to go back to Brooks’ Law, the widely believed postulate that you can’t accelerate a software project by throwing more developers at it. Fred Brooks identified some key reasons why this has been (for the most part) a truism for the last 50 years. Two of the most important reasons are:

1) Communication. When you add new developers to a software project, somebody has to explain to them how the existing code is structured, and the new developers each have to experience a learning curve before they can be productive. Generally it’s the experienced developers (who are already productive) that have to take time away from their own work to train the new folks. So adding developers can actually slow you down.

2) Integration. If you have a large team of developers working (relatively) independently, it’s going to be difficult to make all of the pieces plug together and play well as an integrated whole piece of software.

It’s important to remember that Fred Brooks developed his postulate while managing a large mainframe operating project (OS/360), which was introduced in 1964. That’s a long time ago. There were no UML modeling tools, no REST APIs, no NoSQL databases. So it’s not unreasonable to ask the question 55 years later whether any modern technical innovations might mitigate some of the underlying factors that have made Brooks’ Law seem to be inviolable for such a long time. That answer turns out to be Yes – making a domain model executable mitigates both the communication and integration problems and enables large-team development to work a lot better.

While I’ve never been a big fan of Brooks’ Law, when we started the research that led to Parallel Agile, there was no particular intent of trying to disprove it. It started back in 2014 when Barry Boehm and Supannika Mobasser invited me to give a guest lecture on ICONIX Process in their CS577 Software Engineering class at the University of Southern California. Around this time I had developed an interest in geofencing, and had in mind to develop a geofenced mobile app that delivered coupons to your phone when you got physically close to the business that was offering the coupons.

LBA use cases

When I accepted the invitation to guest lecture I decided to ask if they would like me to grade a couple of UML homework assignments in addition to guest lecturing. They agreed so I split my Location Based Advertising project into 47 low level use cases and assigned one use case per student as homework (writing prototype code for the use case was optional extra credit).

To make a long story short, we were all surprised that the 47 independently developed use cases actually integrated into a cohesive system. I can clearly recall sitting in Barry’s office saying “you know, that’s not supposed to be possible” and Barry agreeing “yes, I know”. When we started investigating how the successful integration happened it seemed that we had made some fortunate choices of using a NoSQL database (Cassandra) and a REST API (Node JS), and giving all the students a code template that implemented the database access functions (aka CRUD functions) for a Cassandra collection that they could clone for their part of the database.

LBA Domain Model 2

It turned out that having the domain model in place made communication across the large (47 student) team go pretty well, and having all of the database access functions available through a REST API allowed different pieces of the system (iOS app, Android app, web app) to integrate together with ease. And when we studied the effort numbers it turned out that each of the 47 use cases took about 4 days to develop – a day on requirements analysis, a day on design, and two days of coding.

One of the student from that project joined the PhD program and implemented a code generator that turned domain models into Mongo DB and Node JS, and after using this successfully on several other projects we decided to start Parallel Agile.

So, to sum it up…having a visual model of the problem domain makes it easy for everybody to get on the same page about what’s being built. Generating your database from this domain model, and having a uniform set of functions to Create, Read, Update and Delete items in the database makes it easy for everybody’s code to integrate together. And that’s how a code generator enables large-scale parallel development.

Published in Tutorials

Tagged under

Automatically trace elements to domain model in Enterprise Architect

This script will search the text in the comments, scenario’s and linked document of the selected elements for terms in the domain model. If it finds a match it will create a trace from your selected element to the element in the domain model.

The idea is that when we write descriptions and scenario’s we often use terms already defined in the domain model, so it would be good if we had a real trace from the element in the domain model and the element using it in its description.

Link to domain model example

But it is hard to keep the descriptions and scenario’s in sync with the traces to the domain model. This script does the hard part for us and keeps those traces in sync. All you need to do is type your description and run the script. The script will find the referenced elements in the domain model and create a trace link to it. It will also remove any automatic traces that are not valid anymore.

Next to the Name, Notes, and the Linked Document, this script will also search the scenarios, both theScenario Description, as the structured Scenario Steps. In case of a Scenario Step the script will insert to the name of the domain model element in the Uses column. Link to domain model scenario

Note that the script is case sensitive. That is the reason why RoomType does not appear in the uses column. Enterprise Architect itself isn’t that picky, and it underlines Roomtype anyway because it finds a relationship to RoomType.

In order to execute the script you have to select either one or more elements in the project browser, or select a package in the project browser.

Then select Script|Link To Domain Model

Free download

The script

In the first part we ask the user to select the domain model package.
If you want to use this script on a particular model you may want to replace that by a hard coding the Domain models GUID into the script.
Since this script may run for a while on a large model, we also create an output tab so we can inform the user of our progress.

sub main
    'let the user select the domain model package
    dim response
    response = Msgbox ("Please select the domain model package", vbOKCancel+vbQuestion, "Selecte domain model")
    if response = vbOK then
         
        dim domainModelPackage as EA.Package
        set domainModelPackage = selectPackage()
        if not domainModelPackage is nothing then
            Repository.CreateOutputTab "Link to Domain Model"
            Repository.ClearOutput "Link to Domain Model"
            Repository.EnsureOutputVisible "Link to Domain Model"
            'link selected elements to the domain model elements
            linkSelectionToDomainModel(domainModelPackage)
            'tell the user we are done
            Repository.WriteOutput "Link to Domain Model", "Finished!", 0
        end if
    end if
end sub

Next we create a dictionary of all classes in domain model package and all of the sub-packages recursively.

'first get the pattern from all the classes in the domain model
dim dictionary
Set dictionary = CreateObject("Scripting.Dictionary")
 
'create domain model dictionary
'tell the user what we are doing
Repository.WriteOutput "Link to Domain Model", "Creating domain model dictionary", 0
addToClassDictionary domainModelPackage.PackageGUID, dictionary

Based on this dictionary we can create one large Regular Expression that will tell us which of the terms in the dictionary are used in a certain text.

' and prepare the regex object
dim pattern
'create the pattern based on the names in the dictionary
pattern = createRegexPattern(dictionary)
Dim regExp  
Set regExp = CreateObject("VBScript.RegExp")
regExp.Global = True  
regExp.IgnoreCase = False
regExp.Pattern = pattern

Then we check what is selected in the project browser. If the user has selected one or more elements we start process those elements. If a package is selected then we process the elements in the selected package.

' Get the type of element selected in the Project Browser
dim treeSelectedType
treeSelectedType = Repository.GetTreeSelectedItemType()
' Either process the selected Element, or process all elements in the selected package
select case treeSelectedType
    case otElement
        ' Code for when an element is selected
        dim selectedElements as EA.Collection
        set selectedElements = Repository.GetTreeSelectedElements()
        'link the selected elements with the 
        linkDomainClassesWithElements dictionary,regExp,selectedElements 
    case otPackage
        ' Code for when a package is selected
        dim selectedPackage as EA.Package
        set selectedpackage = Repository.GetTreeSelectedObject()
        'link use domain classes with the elements in the selected package
        linkDomainClassesWithElementsInPackage dictionary, regExp,selectedPackage
    case else
        ' Error message
        Session.Prompt "You have to select Elements or a Package", promptOK
end select

Here’s the complete code for the script.

option explicit
 
!INC Local Scripts.EAConstants-VBScript
 
'
' Script Name: Link to Domain Model
' Author: Geert Bellekens
' Purpose: Link elements with classes in the domain model based on their name.
' Date: 15/11/2015
'
 
 
sub main
    'let the user select the domain model package
    dim response
    response = Msgbox ("Please select the domain model package", vbOKCancel+vbQuestion, "Selecte domain model")
    if response = vbOK then
         
        dim domainModelPackage as EA.Package
        set domainModelPackage = selectPackage()
        if not domainModelPackage is nothing then
            Repository.CreateOutputTab "Link to Domain Model"
            Repository.ClearOutput "Link to Domain Model"
            Repository.EnsureOutputVisible "Link to Domain Model"
            'link selected elements to the domain model elements
            linkSelectionToDomainModel(domainModelPackage)
            'tell the user we are done
            Repository.WriteOutput "Link to Domain Model", "Finished!", 0
        end if
    end if
end sub
 
'this is the actual call to the main function
main
 
function linkSelectionToDomainModel(domainModelPackage)
    'first get the pattern from all the classes in the domain model
    dim dictionary
    Set dictionary = CreateObject("Scripting.Dictionary")
     
    'create domain model dictionary
    'tell the user what we are doing
    Repository.WriteOutput "Link to Domain Model", "Creating domain model dictionary", 0
    addToClassDictionary domainModelPackage.PackageGUID, dictionary
     
    'tell the user what we are doing
    Repository.WriteOutput "Link to Domain Model", "Interpreting dictionary", 0
    ' and prepare the regex object
    dim pattern
    'create the pattern based on the names in the dictionary
    pattern = createRegexPattern(dictionary)
    Dim regExp  
    Set regExp = CreateObject("VBScript.RegExp")
    regExp.Global = True  
    regExp.IgnoreCase = False
    regExp.Pattern = pattern
     
    ' Get the type of element selected in the Project Browser
    dim treeSelectedType
    treeSelectedType = Repository.GetTreeSelectedItemType()
    ' Either process the selected Element, or process all elements in the selected package
    select case treeSelectedType
        case otElement
            ' Code for when an element is selected
            dim selectedElements as EA.Collection
            set selectedElements = Repository.GetTreeSelectedElements()
            'link the selected elements with the 
            linkDomainClassesWithElements dictionary,regExp,selectedElements 
        case otPackage
            ' Code for when a package is selected
            dim selectedPackage as EA.Package
            set selectedpackage = Repository.GetTreeSelectedObject()
            'link use domain classes with the elements in the selected package
            linkDomainClassesWithElementsInPackage dictionary, regExp,selectedPackage
        case else
            ' Error message
            Session.Prompt "You have to select Elements or a Package", promptOK
    end select
end function
 
'this function will get all elements in the given package and subpackages recursively and link them to the domain classes
function linkDomainClassesWithElementsInPackage(dictionary,regExp,selectedPackage)
    dim packageList 
    set packageList = getPackageTree(selectedPackage)
    dim packageIDString
    packageIDString = makePackageIDString(packageList)
    dim getElementsSQL
    getElementsSQL = "select o.Object_ID from t_object o where o.Package_ID in (" &amp; packageIDString &amp; ")"
    dim usecases
    set usecases = getElementsFromQuery(getElementsSQL)
    linkDomainClassesWithElements dictionary,regExp,usecases
end function
 
 
function linkDomainClassesWithElements(dictionary,regExp,elements)
    dim element as EA.Element
    'loop de elements
    for each element in elements
        'tell the user what we are doing
        Repository.WriteOutput "Link to Domain Model", "Linking element: " &amp; element.Name, 0
        'first remove all automatic traces
        removeAllAutomaticTraces element
        'match based on notes and linked document
        dim elementText
        'get full text (name +notes + linked document + scenario names + scenario notes)
        elementText = element.Name
        elementText = elementText &amp; vbNewLine &amp; Repository.GetFormatFromField("TXT",element.Notes)
        elementText = elementText &amp; vbNewLine &amp; getLinkedDocumentContent(element, "TXT")
        elementText = elementText &amp; vbNewLine &amp; getTextFromScenarios(element)
        dim matches
        set matches = regExp.Execute(elementText)
        'for each match create a «trace» link with the element
        linkMatchesWithelement matches, element, dictionary
        'link based on text in scenariosteps
        dim scenario as EA.Scenario
        'get all dependencies left
        dim dependencies
        set dependencies = getDependencies(element)
        'loop scenarios
        for each scenario in element.Scenarios
            dim scenarioStep as EA.ScenarioStep
            for each scenarioStep in scenario.Steps
                'first remove any additional terms in the uses field
                scenarioStep.Uses = removeAddionalUses(dependencies, scenarioStep.Uses)
                set matches = regExp.Execute(scenarioStep.Name)
                dim classesToMatch 
                set classesToMatch = getClassesToMatchDictionary(matches, dictionary)
                dim classToMatch as EA.Element
                for each classToMatch in classesToMatch.Items
                    if not instr(scenarioStep.Uses,classToMatch.Name) &gt; 0 then
                        scenarioStep.Uses = scenarioStep.Uses &amp; " " &amp; classToMatch.Name
                    end if
                    'create the dependency between the use case and the domain model class
                    linkElementsWithAutomaticTrace element, classToMatch
                next
                'save scenario step
                scenarioStep.Update
                scenario.Update
            next
        next
    next
end function
 
function linkMatchesWithelement(matches, element, dictionary)
    dim classesToMatch
    'get the classes to match
    Set classesToMatch = getClassesToMatchDictionary(matches,dictionary)
    dim classToMatch as EA.Element
    'actually link the classes
    for each classToMatch in classesToMatch.Items
        linkElementsWithAutomaticTrace element, classToMatch
    next
end function
 
 
'get the text from the scenarios name and notes
function getTextFromScenarios(element)
    dim scenario as EA.Scenario
    dim scenarioText
    scenarioText = ""
    for each scenario in element.Scenarios
        scenarioText = scenarioText &amp; vbNewLine &amp; scenario.Name
        scenarioText = scenarioText &amp; vbNewLine &amp; Repository.GetFormatFromField("TXT",scenario.Notes)
    next
    getTextFromScenarios = scenarioText
end function
 
function removeAddionalUses(dependencies, uses)
    dim dependency
    dim filteredUses
    filteredUses = ""
    if len(uses) &gt; 0 then
        for each dependency in dependencies.Keys
            if Instr(uses,dependency) &gt; 0 then
                if len(filteredUses) &gt; 0 then
                    filteredUses = filteredUses &amp; " " &amp; dependency
                else
                    filteredUses = dependency
                end if
            end if
        next
    end if
    removeAddionalUses = filteredUses
end function
 
'returns a dictionary of elements with the name as key and the element as value.
function getDependencies(element)
    dim getDependencySQL
    getDependencySQL =  "select dep.Object_ID from ( t_object dep " &amp; _
                        " inner join t_connector con on con.End_Object_ID = dep.Object_ID)   " &amp; _
                        " where con.Connector_Type = 'Dependency'  " &amp; _
                        " and con.Start_Object_ID = " &amp; element.ElementID   
    set getDependencies = getElementDictionaryFromQuery(getDependencySQL)
end function
 
function removeAllAutomaticTraces(element)
        dim i
        dim connector as EA.Connector
        'remove all the traces to domain model classes
        for i = element.Connectors.Count -1 to 0 step -1
            set connector = element.Connectors.GetAt(i)
            if connector.Alias = "automatic" and connector.Stereotype = "trace" then
                element.Connectors.DeleteAt i,false 
            end if
        next
end function
 
function getClassesToMatchDictionary(matches, allClassesDictionary)
    dim match
    dim classesToMatch
    dim className
    Set classesToMatch = CreateObject("Scripting.Dictionary")
    'create list of elements to link
    For each match in matches
        if not allClassesDictionary.Exists(match.Value) then
            'strip the last 's'
            className = left(match.Value, len(match.Value) -1)
        else
            className = match.Value
        end if
        if not classesToMatch.Exists(className) then
            classesToMatch.Add className, allClassesDictionary(className)
        end if
    next
    set getClassesToMatchDictionary = classesToMatch
end function
 
'Create a «trace» relation between source and target with "automatic" as alias
function linkElementsWithAutomaticTrace(sourceElement, targetElement)
    dim linkExists 
    linkExists = false
    'first make sure there isn't already a trace relation between the two
    dim existingConnector as EA.Connector
    'make sure we are using the up-to-date connectors collection
    sourceElement.Connectors.Refresh
    for each existingConnector in sourceElement.Connectors
        if existingConnector.SupplierID = targetElement.ElementID _
           and existingConnector.Stereotype = "trace" then
           linkExists = true
           exit for
        end if
    next
    if not linkExists then
        'tell the user what we are doing
        Repository.WriteOutput "Link to Domain Model", "Adding trace between " &amp;sourceElement.Name &amp; " and " &amp; targetElement.Name, 0
        dim trace as EA.Connector
        set trace = sourceElement.Connectors.AddNew("","trace")
        trace.Alias = "automatic"
        trace.SupplierID = targetElement.ElementID
        trace.Update
    end if
end function
 
function addToClassDictionary(PackageGUID, dictionary)
    dim package as EA.Package
    set package = Repository.GetPackageByGuid(PackageGUID)
     
    'get the classes in the dictionary (recursively
    addClassesToDictionary package, dictionary
end function
 
function addClassesToDictionary(package, dictionary)
    dim classElement as EA.Element
    dim subpackage as EA.Package
    'process owned elements
    for each classElement in package.Elements
        if classElement.Type = "Class" AND len(classElement.Name) &gt; 0 AND not dictionary.Exists(classElement.Name) then
            dictionary.Add classElement.Name,  classElement
        end if
    next
    'process subpackages
    for each subpackage in package.Packages
        addClassesToDictionary subpackage, dictionary
    next
end function
 
 
'Create a reges pattern like this "\b(name1|name2|name3)\b" based on the 
function createRegexPattern(dictionary)
    Dim patternString
    dim className
    'add begin
    patternString = "\b("
    dim addPipe
    addPipe = FALSE
    for each className in dictionary.Keys
            if addPipe then
                patternString = patternString &amp; "|"
            else
                addPipe = True
            end if
            patternString = patternString &amp; className
    next
    'add end
    patternString = patternString &amp; ")s?\b"
    'return pattern
    createRegexPattern = patternString
end function
 
'returns an ArrayList of the given package and all its subpackages recursively
function getPackageTree(package)
    dim packageList
    set packageList = CreateObject("System.Collections.ArrayList")
    addPackagesToList package, packageList
    set getPackageTree = packageList
end function
 
'make an id string out of the package ID of the given packages
function makePackageIDString(packages)
    dim package as EA.Package
    dim idString
    idString = ""
    dim addComma 
    addComma = false
    for each package in packages
        if addComma then
            idString = idString &amp; ","
        else
            addComma = true
        end if
        idString = idString &amp; package.PackageID
    next 
    'if there are no packages then we return "0"
    if packages.Count = 0 then
        idString = "0"
    end if
    'return idString
    makePackageIDString = idString
end function
 
'returns an ArrayList with the elements accordin tot he ObjectID's in the given query
function getElementsFromQuery(sqlQuery)
    dim elements 
    set elements = Repository.GetElementSet(sqlQuery,2)
    dim result
    set result = CreateObject("System.Collections.ArrayList")
    dim element
    for each element in elements
        result.Add Element
    next
    set getElementsFromQuery = result
end function
 
'returns a dictionary of all elements in the query with their name as key, and the element as value.
'for elements with the same name only one will be returned
function getElementDictionaryFromQuery(sqlQuery)
    dim elements 
    set elements = Repository.GetElementSet(sqlQuery,2)
    dim result
    set result = CreateObject("Scripting.Dictionary")
    dim element
    for each element in elements
        if not result.Exists(element.Name) then
        result.Add element.Name, element
        end if
    next
    set getElementDictionaryFromQuery = result
end function
 
'gets the content of the linked document in the given format (TXT, RTF or EA)
function getLinkedDocumentContent(element, format)
    dim linkedDocumentRTF
    dim linkedDocumentEA
    dim linkedDocumentPlainText
    linkedDocumentRTF = element.GetLinkedDocument()
    if format = "RTF" then
        getLinkedDocumentContent = linkedDocumentRTF
    else
        linkedDocumentEA = Repository.GetFieldFromFormat("RTF",linkedDocumentRTF)
        if format = "EA" then
            getLinkedDocumentContent = linkedDocumentEA
        else
            linkedDocumentPlainText = Repository.GetFormatFromField("TXT",linkedDocumentEA)
            getLinkedDocumentContent = linkedDocumentPlainText
        end if
    end if
end function
 
'let the user select a package
function selectPackage()
    dim documentPackageElementID        
    documentPackageElementID = Repository.InvokeConstructPicker("IncludedTypes=Package") 
    if documentPackageElementID &gt; 0 then
        dim packageElement as EA.Element
        set packageElement = Repository.GetElementByID(documentPackageElementID)
        dim package as EA.Package
        set package = Repository.GetPackageByGuid(packageElement.ElementGUID)
    else
        set package = nothing
    end if 
    set selectPackage = package
end function
 
'add the given package and all subPackges to the list (recursively
function addPackagesToList(package, packageList)
    dim subPackage as EA.Package
    'add the package itself
    packageList.Add package
    'add subpackages
    for each subPackage in package.Packages
        addPackagesToList subPackage, packageList
    next
end function

This article was originally published on Bellekens.com

Published in Community Resources

Tagged under

APG Sparx Enterprise Architect Systems Engineering Course

APG is offering their Sparx Systems Engineering Course via web-based delivery on January 29th. Course will have live instructor with maximum of 8 students. Email This email address is being protected from spambots. You need JavaScript enabled to view it. for details and pricing.

Topics Covered:

· Build Domain Model	· Model System Design
· EA workspace configuration	· Parts and values
· Domains and blocks	· Value types, units, and dimensions
· Diagrams and elements	· SysML block definition diagrams
· Relationships and properties	· Model Constraints
· Capture System Requirements	· Constraint blocks and binding connectors
· Importing requirements from documents	· Parametric simulation
· SysML requirements diagrams	· SysML parametric diagrams
· Traceability matrices	· Model System Interaction
· Searching and navigating model	· Ports, interfaces, and signals
· Build Use Case Model	· Flow properties and flow items
· Use cases, actors, and packages	· SysML internal block diagrams
· Use case interactions and fragments	· Model System Behavior
· SysML use case and sequence diagrams	· Activities, flows, synchronization bars
· Model System State	· Partitions, pins, decisions, guards
· States, transitions, events	· SysML activity diagrams
· Guards, actions, activities	· Allocations
· SysML state machine diagrams

Published in News

Tagged under