What is HP aPaaS?

HP aPaaS means High-Productivity Application Platform as a Service--a jargon coined by Gartner.  This class of application development platforms are also called Low-Code Development Platform (e.g., by Forrester Reserach).  Gartner suggested the following feature set to be pursued by HP aPaaS (Gartner, Market Guide for High-Productivity Rapid Application Development Tools, May 24, 2016).  The following can be regarded desirable patterns of HP aPaaS functionalities and architecture.


Model over Code:  Best-in-class HP aPaaS's are agile, visual model-driven, low-code development platforms.  A best-in-class HP aPaaS allows developers to design UI that directly enables CRUD, to integrate SOA services and applications using SOAP/REST APIs, to create, access and update RDBMS/NoSQL based on a domain model (UML class disgram) through APIs without coding, and to specify and automate business processes and logic using BPMN.

Mobile Responsive Web: It allows developers to design server-side and client-side control logic for single page and responsive web UI that automatically adjust to various devices such as smart phones, tablets, PCs, etc.

Low Code Support:  It allows developers to extend models with scripting languages, 4GL or 3GL.

One-Button Application Deployment:  It allows developers to perform CI, CD, DevOps automatically with one-button click, even with their existing toolsets (e.g., Jenkins, GitLab) integrated.

One-Button Revision Control:  It allows developers to enjoy a single, managed view with point-in-time revision control for all software assets in the development project.

Live Prototyping: It allows developers to integrate prototyping directly into UI design.

Runtime Platform Support:  It allows developers to deploy applications on multiple public cloud services, a private cloud or an on-premise server.  It supports containers as well including Docker and Kunernetes.

Service-Oriented Architecture:  It allows developers to expose and consume REST and SOAP APIs for service composition and app integration.

Smart Application Connectors: It provides drag-and-drop adapters to well-known apps such as CRM, ERP, etc.

Collaborative & Social Development: It provides agile project management and team collaboration tools, private & public developer portals, communities and app stores.

App Management and Analytics:  It provides app management, traceability and built-in real-time analytics for reporting on application usage and potential performance issues.


One can see that the patterns of HP aPaaS listed above satisfy all the principles of VOLF (Value-Obsessed Lean Framework) explained in the VOLF page in this blog site.  The VOLF adoption strategy explained in that page can be applied when adopting a HP aPaaS.  Most of the VOLF patterns coincide with the patterns of HP aPaaS, including Design Model Prototyping, Agile Development, Business Requirements to Software Requirements Transformation, Just-In-Time Analysis, XP-Based DevOps, Metamodel-Based Inter-Model Consistency, and Service-Oriented Architecture patterns.  

Figure 1 shows HP aPaaS vendors in 2017 (Forrester Wave™: Low-Code Development Platforms For AD&D Pros, Q4 2017).  Outsystems, Mendix and Appian are leading vendors.  Gartner predicts that by 2020, at least 50% of all new IT line-of-business applications will be created with HP aPaaS toolsets (Refer to Gartner, Market Guide for High-Productivity Rapid Application Development Tools, May 24, 2016).  MarketsandMarkets predicts that HP aPaaS market size is expected to grow from USD 3.20 Billion in 2016 to USD 27.23 Billion by 2022, at a Compound Annual Growth Rate (CAGR) of 44.49% during the forecast period.  Figure 2 shows that HP aPaaS is now a very mature technology that companies can adopt without hesitation.

Figure 1. Low-Code Development Platforms (Adopted from The Forrester Wave™: Low-Code Development Platforms For AD&D Pros, Q4 2017)

Figure 1. Low-Code Development Platforms (Adopted from The Forrester Wave™: Low-Code Development Platforms For AD&D Pros, Q4 2017)

Figure 2.  PaaS Hype Cycle (Adopted from Gartner, Hype Cycle for Platform as a Service, 2018)

Figure 2. PaaS Hype Cycle (Adopted from Gartner, Hype Cycle for Platform as a Service, 2018)

Who should and Why they should consider HP aPaaS?

As is true of all profound IT changes, the apparent revolution of computing that we see today (including mobile, social, cloud, big data, IoT, AI, blockchain, etc.) is, in fact, a synergetic aggregation of evolutions in multiple, well-established technology directions.  For enterprises to be successful with the adoption of new technologies, they need to well synthesize their existing technologies and new technologies.  Companies, which have not updated their technology and skill portfolios to absorb advances in IT along all different avenues, will find them failing in capturing values from new technology adoptions, because their current inventory of technologies, skills and practices conflict with the assumptions underlying and ingredients comprising the new technologies.  To summarize, they fail in the synthesis of existing and new technologies, skills and practices.

We recall that many companies bought and implemented SAP ERP (then called R/3) instead of building their custom solution when the computing paradigm shifted from mainframe to client/server in 1990s. Client/server computing brought in a whole new collection of technologies such as desktops, servers, Unix, RDBMS, LAN, distributed computing, middleware, RPC, Windows GUI, object-oriented programming, component-based development, RAD, IDE, etc.  Companies which used to use mainframe computers for centralized, batch and online transaction processing had to master a great number of new tools, skills and practices to be able to migrate their mainframe legacy apps to client/server environments or build new innovative apps using client/server technologies.  Because there were too much values from shifting their mainframe-based IT to client/server, they had to go after client/server, but few of them were ready to do that from scratch.  This is why many of them chose an already synthesized, client/server apps such as SAP R/3.

How many companies today are technologically mature enough and ready for synthesizing a creative digital business through fast release and adaptation cycles?  To be ready, they should have built a solid foundation in object-oriented design and programming, model-driven design, BPM, SOA, responsive UI development, XP, agile development, etc.  Successful digital businesses are well capable of microservice architecture, cloud-native app development, DevOps, containers and their orchestration, IoT, analytics, AI, etc.--all based on the solid foundation mentioned above that has been diligently  built up over the past 20 years.

There are more companies technologically not ready than those that are ready.  For those which are not ready, it is risky to now strengthen various technical ingredients that were established in 1990s or 2000s, and at the same time catch up with new technologies that emerged in 2010s, and try to synthesize them all to create a new digital business model.  This is why many companies turn to HP aPaaS--an already synthesized, digital business platform that even a non-technical business person can use to build a digital business app in her imagination after some intensive training in modeling.  Even a technologically mature company with its IT professionals well trained in new technologies may utilize a HP aPaaS for developing apps of Mode 2, because it can dramatically reduce the time to market compared with HC (High-Control) aPaaS or more conventional app development platforms.

As mentioned in the previous section, HP aPaaS well incorporates the principles and patterns of VOLF.  A HP aPaaS thus would often be a choice of app development platform when you want to apply the VOLF framework.  In the next section, I introduce one of the best HP aPaaS's in the market, named Mendix.


Mendix is one of the best HP aPaaS as shown in Figure 1.  It implemented pretty much all of the desirable patterns of HP aPaaS listed in the previous section.  It is currently used by 60,000+ developers.  In August 2018, Siemens acquired Mendix for €0.6 Billion to accelerate adoption of MindSphere (Siemens' IoT platform) and 10x faster application development.

I am not a Mendix expert.  I just started exploring it, and developed a simple app based on a Mendix-provided learning path called "Become a Rapid Developer 2018".  I will share my experience of developing that simple app using Mendix, because doing so, I believe, can give you an easy introduction to the HP aPaaS and how it  realized the principles, patterns and practices of VOLF.

Both Mendix and OutSystems offer free community editions of their platforms.  I used the free edition of Mendix platform to build a sample app.  The free edition includes everything you need to design, build, and deploy demos, prototypes, or small applications. It includes a deployment environment for each application that provides access to up to 10 internal users. You just sign up, get started right away, and build as many applications as you want.

Mendix App Development Exercise (I)

Mobile App to Develop

The app I am developing is for managing a public training business, and contains a subset of functionalities of the Public Software Training app that is analyzed in the Business Analysis page in this blog site.  Figure 3 shows the home page of the LearnNow Training Management app.

Figure 3. Home Page of LearnNow Training Management App

Figure 3. Home Page of LearnNow Training Management App

Domain Model

I started with designing the domain model using the Mendix Web Modeler--a no-code, web-based application development environment.  Figure 4 shows the domain model which includes Course, TrainingClass, Teacher, Location, Trainee and Registration classes, and associations among those classes.

The domain model in Mendix uses only simple associations (i.e., 1:1, 1:N, M:N) and generalization (i.e., super class-subclass association).  Other types of associations in UML (e.g., qualified association, association class, aggregation, composition, categorization) should be transformed to simple associations, sometimes using a system-generated identifier.

As I confessed earlier, I have not studied Mendix enough, so there may be errors in my statements about Mendix.  I hope Mendix experts out there will correct any error in this page.

Figure 4.  Domain Model of LearnNow Training Management App

Figure 4. Domain Model of LearnNow Training Management App

User Stories

Next, user stories are ideated for the domain, which are to be validated by users.  High-priority stories are selected into the sprint backlog and scheduled on the task board as shown in Figure 5.  User stories can be identified through customer-obsessed, adaptive requirement analysis approaches such as design thinking, lean UX, etc.

When developing a complex, large-scale business application, the developers often need to design the overall business architecture (e.g., using TOGAF ArchiMate) and design a hierarchy of relatively high-level business processes using BPMN 2.0.  In this case, the leaf-level tasks are transformed to user stories, as explained earlier in the Business Analysis page in this blog site.

Figure 5.  User Stories and Scrum Task Board

Figure 5. User Stories and Scrum Task Board

Class Responsibility Assignment

Let's consider a user story that goes:  "As an administrator, I want to be able to schedule a training event more efficiently, so that I spend as little time as possible on this."  The classes to be responsible for realizing this user story must be identified as in Figure 6.  Course, TrainingClass, Teacher and Location classes are required to realize the user story.

Figure 6.  Class Responsibility Assignment for the User Story

Figure 6. Class Responsibility Assignment for the User Story

UX Design

The user experience for scheduling a training class is designed next.  We will have the course administrator to pick a course in the course list page and schedule a class for the chosen course.  Therefore, the UI for class scheduling is designed as shown in Figure 7.

Mendix provides a UX design framework called Atlas UI that makes building elegant user experiences a rapid process.  The UI design process is simplified with ready-made page templates, building blocks, and widgets that can be arranged and customized to suit your app.  Atlas UI is built to be fully responsive.  Mendix Atlas UI is completely open source and accessible on GitHub.  The framework leverages Bootstrap & Sass.

Figure 7.  UX Design for Class Scheduling

Figure 7. UX Design for Class Scheduling

Logic Design

Application logic is created in Mendix in the form of microflows which employ a subset of BPMN 2.0 notation.  You can drag microflows and pages into a microflow, extract and use sub- microflows, extend a microflow with the Java Action Call, etc.  The Java action call activity can be used to call a Java action. Arguments can be passed to the action and the result can be stored in a variable.

Figure 8 shows how the logic is designed for the action to be triggered by pushing the Add button in Figure 7.  The logic is designed as what Mendix calls a Microflow (i.e., a discrete business process) that is expressed in BPMN 2.0.  The process first creates a Course object, and then displays an empty page where the user can input values of the member variables of the Course class.  Figure 9 shows the logic design for the Detail button that shows detailed information about the selected Course.  The button simply opens a page that displays attribute values of the selected Course object.

Figure 10 shows the logic design for the Schedule button that allows the administrator to create a new TrainingClass for the selected Course.  The Schedule button triggers a microflow.  The microflow, when triggered, receives a parameter, i.e., an input data, of type object--in this case a Course object.  The microflow first creates a TrainingClass object whose Course variable represents the Course linked via the TrainingClass_Course association in the domain model in Figure 6.  It then displays an empty page where the administrator can input values of the member variables of the TrainingClass class.  The Course variable is prefilled, however, in that page with the input parameter value. 

Figure 8. Logic Design for the Add Button in the Course List Page

Figure 8. Logic Design for the Add Button in the Course List Page

Figure 9.  Logic Design for the Detail Button in the Course List Page

Figure 9. Logic Design for the Detail Button in the Course List Page

Figure 10.  Logic Design for the Schedule Button in the Course List Page

Figure 10. Logic Design for the Schedule Button in the Course List Page

One-Click Deployment

Once you have completed implementing a user story, you can click the Publish button in the Web Modeler menu to build and deploy the incremented app on the public Mendix Cloud for free.   Yes, the one-click is all it takes to do continuous integration (CI), continuous deployment (CD), and DevOps.  You don't need to worry about Cloud Foundry, Docker, Kubernetes, etc., even if those technologies are in fact employed by the Mendix platform.  If you use the Enterprise edition of Mendix platform, you may deploy your app on your subscribed cloud services such as IBM, SAP, Azure, AWS, Pivotal, or your private cloud, or on-premise servers.

App Services and App Store

You can publish app data (i.e., classes) and functionality (i.e., microflows) as SOA services (Mendix App Services, REST Services or Web Services) within your enterprise or to the entire Mendix community.  Users of your app service can directly drag and drop actions that you designed into their microflows and use your classes (a.k.a. entities) in their project.  All that without worrying about web services, xml mappings or schemas!

The Mendix App Store contains many useful and reusable widgets and modules created by Mendix as well as by its partners and customers.  Mendix community downloaded more than 3500 items from the App Store in the past year, and is uploading 50 new or updated items every month.  The App Store is completely integrated with the Community Profile, so you can find out information about who developed the item you are downloading.  Mendix offers a private App Store limited to your company, and a public App Store open to all Mendix Community developers.  You may license your app services, allowing downloading the app services into consumers' Desktop Modeler,  or just advertise them without allowing downloading.

Microservice Architecture in Mendix

Microservices offer a software architecture that is best aligned with small Agile DevOps teams. This architecture is best capable of benefitting from the qualities of containers. Containers enable you to deploy your application in any cloud, in an automated fashion, and to ensure quality, repeatability, and speed. Deployment standardization enables a small DevOps team to handle anything related to operations.


Within the Mendix Cloud, the logical term “app container” is used to describe the application isolation. Each application is fully separated from other apps for computing, memory, and storage. A Mendix app runs in one or more containers, wherein a container can only support a single application. Also, for each application, a dedicated database and S3 bucket is provisioned, in order to have full isolation on the data level as well.

Designing microservices that have a full stack (from UI to DB) in the same deployable will minimize the impact of change.  The business process is usually the best basis for dividing a functional scope into good microservices.  So you should involve business owners and process architects to define the microservice architecture.

The teams and the architecture can be aligned with the business functions they support, achieving maximum autonomy to evolve easily and generate value.  So a microservice and a DevOps team size can be small or large depending on the size of the business function, but not too big. (Forget about the word “micro”, but keep the team size ≤ 10.)

Mendix App Development Exercise (II)

Let's develop another user story in the LearnNow Training Management app.  Consider a user story that goes:  "As an administrator, I want to be able to add registrations from my mobile phone, so that I can add registrations while traveling."  The classes to be responsible for realizing this user story must be identified as in Figure 11.  All the classes in the domain model in Figure 4 are required to realize the user story.

Figure 11.  Classes Responsible for the User Story

Figure 11. Classes Responsible for the User Story

The user experience for registering a trainee to a training class is designed as Figure 12.  We want to allow the course administrator to pick a training class in the training class list page, register a trainee in that training class, and display the list of all trainees registered in that training class.

Logic design for the Add button is similar to Figure 8; that for the Class Detail button is similar to Figure 9; and that for the Register a Trainee button is similar to Figure 10.  The logic design for the List Registered Trainees button is given in Figure 13.  The button triggers a microflow, which contains a single activity that shows the list of trainees registered in the training class.  The training class under consideration is input as a parameter to the microflow.  The microflow then opens a page called Training_Class_Registration_List.  This page contains a text describing the training class under consideration, and a list view that lists all current registrations in the training class.  The list view retrieves, from the database, all the objects of the Registration class defined in the domain model in Figure 11.

Figure 12.  UX Design for Trainee Registration in a Training Class

Figure 12. UX Design for Trainee Registration in a Training Class

Figure 13.  Logic Design for the

Figure 13. Logic Design for the "List Registered Trainees" Button in the "TrainingClass List" Page

You may view and test the LearnNow Training Management app on a mobile device.  Download the Mendix Mobile App for iOS or Android from:  https://docs.mendix.com/refguide/getting-the-mendix-app.  Select the "Scan QR code" from the menu of the Mendix Mobile App, and scan the QR code given here.  Then the Mendix app is instantly started in your mobile device.

Mendix ORM and Database

Mendix ORM generates DDL upon deployment of your app, which automatically create the correct database schema based on your domain model.  It stores persistable classes in your domain model in the database of your choice.  You can define security rules and validation rules for each class.  Whenever you change your domain model, Mendix automatically update the database schema and automatically migrate your data into the changed schema.  Mendix supports many database servers including MySQL, MariaDB, PostgreSQL, Microsoft SQL Server, Microsoft Azure SQL Database, Oracle Database, IBM DB2.

Mendix offers a number of ways to specify queries:  (1) Both the Desktop Modeler and Web Modeler offer visual ways to specify your query needs;  (2) To retrieve specific objects or a set of related objects, you can use XPath expressions;  (3) For reporting needs (where aggregation and the joining of multiple entities into a single result set is important), Mendix offers OQL queries.  Under the hood, all queries are first translated into XPath, then into OQL, and finally into database-specific SQL statements.  You may use a stored procedure in the database of your Mendix application via the Mendix Java API.  You may also use JDBC to execute SQL statements on your Mendix app database.  If you are using an external database like the legacy database in your company, you can use the Database Connector (e.g., Oracle Connector) add-on available in the Mendix App Store, to handle DBMS-specific features such as table APIs, stored procedures, packages, ref cursors, user-defined types, etc.

Mendix handles transaction management as well.  Every request to the Mendix Runtime automatically starts a new transaction. Upon successful completion of the request, the transaction is committed with all related data. In case of an error, all the data changes are rolled back by default. You have the option to provide custom error handling logic to change this default behavior.

Mendix Architecture

Figure 14 shows an overview of Mendix architecture.  I will try to elaborate on internal architecture and mechanism of Mendix as I learn more about the platform.  So far Mendix looks to me an impressive product trying to balance prefabricated, pattern-based automation to make software development easier and faster with openness to harmonize the platform with the fast-changing global software ecosystem.  Conventional RAD tools were more closed and opaque.  Mendix should be complimented for its openness.

Figure 14.  Mendix Architecture (Adopted from David Ramel, Mendix App Platform Integrates with PhoneGap for Cross-Platform Mobile Development, 10/21/2014)

Figure 14. Mendix Architecture (Adopted from David Ramel, Mendix App Platform Integrates with PhoneGap for Cross-Platform Mobile Development, 10/21/2014)

Figure 15 shows key components of the Mendix platform (https://www.mendix.com/evaluation-guide/enterprise-capabilities/platform-architecture).  The Mendix Platform is a completely integrated aPaaS offering for designing, building, deploying, and managing enterprise apps. Go to the following link to see how Mendix apps satisfy the Twelve-Factor App requirements for SaaS:  https://www.mendix.com/evaluation-guide/enterprise-capabilities/twelve-factor-architecture.

The platform is accessible for developers and administrators through the Developer Portal, which provides access to apps as well as services for requirements and development, and a Cloud Portal for operations and administration of apps and app services. The platform includes both the Desktop and Web Modeler. The Desktop Modeler and Web Modeler are the multi-user modeling studios of the Mendix Platform. The general purpose of the Modelers is to provide an integrated, unified modeling space, where business analysts, and IT engineers can work closely together to model the various application elements. The Desktop Modeler runs locally on the developer’s computer and has an integrated build service for working fully offline, while the Web Modeler is hosted on the Mendix Cloud. Mendix Cloud is a PaaS-based cloud offering based on Cloud Foundry technology that runs on the IaaS layer of Amazon Web Services.  A Mendix application will run in a container provided by Cloud Foundry.  For the database, the Mendix Cloud makes use of RDS PostgreSQL, and for the file storage, it makes use of S3.  Mendix App Store features hundreds of publicly available building blocks to speed up development. The Mendix App Store can be configured for private use as well, so that apps and building blocks can be shared across your organization. The platform features online collaboration amongst users through the Dev Portal, Mendix app, and both modelers.

Figure 15.  Key Components of Mendix Platform

Figure 15. Key Components of Mendix Platform

Mendix reminds me of Cool:Plex that I used to develop a web application in 1999.  Samsung funded me to develop a Partner Relationship Management app.  I was a professor in the University of Iowa at the time.  I set up a lab with 5 software engineers, and collaborated with the HON Company (the second largest office furniture manufacturer in North America, headquartered in Muscatine, Iowa) to develop the PRM using COOL:Plex. (See Figure 16 for COOL:plex' pattern-based design.)

COOL: Plex was originally called Obsydian and was developed by Synon.  Sterling Software acquired Synon in 1998 and changed the product name to COOL:Plex. CA (previously Computer Associate) acquired Sterling Software in 2000 and changed the product name again to CA Plex.  CA is the current distributor of the product.

Obsydian is regarded the pioneer of so-called Architected Rapid Application Development (ARAD) tools.  ARAD is based on object-oriented analysis and design, and incorporates analysis and design patterns, frameworks and models, typically reducing coding efforts by 50-70%.  Mendix seems a descendent of ARAD tools, but made significant improvements by incorporating new advanced technologies and practices such as business process management (BPM), responsive Web design patterns, service-oriented architecture/microservice architecture patterns, ORM patterns and frameworks, extreme programming (XP), agile development, social development, app store, PaaS/IaaS, container, continuous delivery (CD), DevOps and real-time monitoring/analytics.

Figure 16.  COOL:Plex' Pattern-Based Design

Figure 16. COOL:Plex' Pattern-Based Design

Figure 17 shows IT Market Clock for Application Development published by Gartner in 2013.  AMD SODA (Architected Model-Driven Service-Oriented Design of Applications) pursues 100% code generation based on shared business and IT modeling standards.  I would place the current Mendix in this category.  CASE/Code Generator (such as IEF, Composer) in 1980-90s also pursued model-based 100% code generation, but was based on structured analysis and design or information engineering.  ARAD based on object-oriented analysis and design and pursuing pattern-based development such as Obsydian appeared in mid 1990s.  ARAD SODA (Architected Rapid Application Development Service-Oriented Design of Applications) came out in mid 2000s by vendors like IBM, Microsoft, CA, Artisan, Interactive Objects, Mendix, MID, Wyde, etc. trying to reduce the learning curve and increase productivity of Web developers making transition from traditional client/server to service-oriented development of applications.  HP aPaaS like Mendix now supports model-based, pattern-based, service-oriented development of applications, with minimal to zero coding, for deployment in PaaS+IaaS DevOps environments.

Figure 17.  IT Market Clock for Application Development 2013 (Gartner)

Figure 17. IT Market Clock for Application Development 2013 (Gartner)

Mendix Challenges

In this section I would like to discuss the challenges that arise when we use Mendix to develop a digital business.

Multitenancy Support

As I am only a beginner user of Mendix, I have not faced any serious challenge so far.  However, one of the challenging questions I heard is about how Mendix supports multitenancy.  Is it easy to build a multitenant SaaS using Mendix compared to other platforms such as Force.com and Apprenda?  (Refer to: https://developer.salesforce.com/page/Multi_Tenant_Architecture and https://apprenda.com/platform/features/multi-tenancy-enablement/)

Mendix Platform Evaluation Guide (https://www.mendix.com/evaluation-guide/enterprise-capabilities/runtime-security#5-how-does-my-mendix-app-support-multi-tenancy) explains the following about multitenancy support:  Multi-tenant apps in Mendix share the same database, application logic, and user interface.  However, application logic can be extended with tenant-specific logic, and the UI can be styled per tenant.  Multi-tenancy can be implemented as follows:

  • Define a tenant-aware object model for the application.  Tenant-level access to domain objects is configured using XPath definitions, which restricts access to those application object instances for the company to which the end-user belongs.
  • Define tenant-specific microflows and configure access rights to implement tenant-level application and process logic.
  • Apply tenant-specific styling of the UI by making the CSS dependent on the companies defined in the MxID.

Tenants can be custom defined in the application as well by using identifiers like division, country, and site.

I posed a question to the Mendix community regarding the multitenancy support. I got answers from a couple of Mendix experts.  Here's a summary of what they said:  Mendix does not have an out-of-the-box multitenant model--i.e., it's not a simple on/off, but you have to define multitenancy on every entity of your application. The term, multitenancy, is quite generic but often used for very specific requirements.  It all comes down to how you design your application. However, generally, you can implement multitenancy with Mendix by correctly applying security models.There are helpful things in the app store that help with building a multitenant app: e.g., an administration module that supports multitennants (https://appstore.home.mendix.com/link/app/80498/); a nice widget that allows you to have multiple themes in your project, allowing you to switch between themes based on which user a company is from (https://appstore.home.mendix.com/link/app/106033/), etc.

Process Orchestration & Choreography

Mendix uses BPMN models called Microflows to specify application logic inside a microservice.  BPM/SOA platforms (shown in Figure 18 adopted from Gartner, Magic Quadrant for Intelligent Business Process Management Suites, 2017) support BPMN-based orchestration of SOAP, REST and micro services.  The microservice architecture prefers choreography over orchestration typically using publish-and-subscribe, event-driven messaging.

A challenging question regarding Mendix is what Mendix does or will likely do in the near future to help developers implement business process orchestration and choreography involving many micro, REST and SOAP services internal and external to the Mendix platform?  I posed this question to the Mendix Community, and a Mendix expert answered, "You really shouldn't think of Mendix as a BPM tool. Instead, think of it as an abstraction of Java: Mendix is a general purpose programming language with a pretty user interface. Microflows have much more in common with a Java method than with a BPMN model - even if they look more like the latter."  I tend to agree with him.  I would rather use the free edition of BizAgi Studio to prototype a complex workflow or orchestration-driven business applocations.  If we compare Figures 1 and 18, we can find quite a few overlaps of products in both categories--viz., Appian, BizAgi, K2, AgilePoint, PNMSoft are both iBPMS and HP aPaaS.  This means that many HP aPaaS use BPMN as a basic modeling notation (for business process orchestration modeling or for application logic design), and many BPM suites have become a agile, model-driven low-code development platforms.

Capgemini seems to have done process orchestration pulling together Mendix apps and SAP SOA services.  And it seems contributing to CORA (Common Reference Architecture) to further advance BPM/SOA directions in the face of new types of SOA services such as the microservices generated from HP aPaaS like Mendix.  Can we use BizAgi to orchestrate microservices developed in Mendix?  I will have to test this.

Figure 18.  Intelligent Business Process Management Suites (Gartner 2017)

Figure 18. Intelligent Business Process Management Suites (Gartner 2017)


We will now look at how it is like to build an application using a HP-aPaaS which is also a BPM Suite.  We will use the free edition of BizAgi Studio here. A quick overview of app developmnent using BizAgi can be seen in this video:  https://www.youtube.com/watch?v=HgBw_Eu98uA.

Process Model:  BizAgi starts app development with process modeling.  Figure 19 is the process model of Equipment Loan process drawn using BizAgi Modeler.

Domain Model:  The next step is to design the domain model containing all classes needed to run the process, which is shown in Figure 20. 

Figure 20. Domain Model for Equipment Loan Process

Figure 20. Domain Model for Equipment Loan Process

Figure 19.  Equipment Loan Process Modeled by BizAgi Modeler

Figure 19. Equipment Loan Process Modeled by BizAgi Modeler

UI Model:  Once the process model and the domain model are designed, we can design the UI for each user task in the process model by mapping class attributes in the domain model to UI controls.  Figure 21 shows that domain model-to-UI mapping for each user task.

Business Rules:  Next, decision rules at each gateway is specified.  Each outgoing sequence flow from an exclusive or inclusive OR gateway is described by a Boolean condition.

Process Automation Actions can be defined to be automatically triggered On Enter, On Save or On Exit of a process task so as to automate the process as much as possible.  Figure 22 shows business rules specified for the two gateways, and an action specified for the task of Request Equipment Loan that set the Request Date to Today.

Figure 21.  Domain Model-UI Mapping for User Tasks

Figure 21. Domain Model-UI Mapping for User Tasks

Figure 22.  Business Rules and Automated Actions

Figure 22. Business Rules and Automated Actions

Workflow Automation:  A user task is automatically assigned to an actor corresponding to the lane containing the task.    When more than one users qualify the actor profile of the given task, a pre-selected allocation method such as load balancing is applied.  The work portal shows which user is responsible for performing a specific case (instance) of a task.  Users have login credentials. The BizAgi platform can be integrated with any existing IAM directory or can create its own user directory and profiles.

SOA Service Orchestration:  A service task such as the Check Equipment Availability task calls a SOAP web service API of an external system such as an ERP system.  Figure 23 shows a specification of a SOAP web service, and its input and out parameters that are mapped from the domain model.

External System Integration:  Another service task of Notify Equipment Delivery in the process model is implemented by defining an automated action like in Figure 22.  In this case, an On Exit action is specified to send out an email to the Requester's Email address defined in the domain model.  The subject line and main body of the email may include any attribute from the domain model.  Figure 23 shows a specification of the email send action.

Figure 23.  Service Orchestration and External Systems Integration

Figure 23. Service Orchestration and External Systems Integration

Comparison between Mendix and BizAgi

Both Mendix and BizAgi apply fundamentally the same software modeling principles explained in other pages in this blog site--the Business Analysis page, the Microservice page, and the VOLF page.  But the recommended process of modeling and applied patterns of models are slightly different.

Mendix starts with (1) a domain model, (2) identifies user stories desirable in the domain, (3) designs the UI for each user story, and then (4) specifies logic to be executed for each UI control.  The logic often involves microflows expressed in BPMN, and can call SOA APIs.

BizAgi, on the other hand, starts with (1) a business process model,  and (2) defines the domain model to completely support the process model.  Then it designs different kinds of flow objects in the BPMN model (not in a particular order): (A) it designs the UI for each human-workflow task (called User Task in BPMN terminology); (B) it specifies the SOAP web services for each straight-through processing task (called Service Task in BPMN terminology); (C) it defines business rules for each exclusive or inclusive gateway; (D) it specifies automated actions for some tasks.

Figure 24 compares the software modeling approaches of Mendix (on the LHS) and BizAgi (on the RHS) based on Figure 14: Metamodel of Software Requirement Models in the Business Analysis page in this blog site.  It is notable that both Mendix and BizAgi apps are founded on the domain model.  Relatively speaking, Mendix' app development is UX-driven, while BizAgi's app development is process-driven.  In Mendix, the semantic architecture of a domain model is reflected on the UI architecture of user stories developed on that domain.  In BizAgi, on the other hand, the architecture of the process model is reflected on the semantic architecture of the domain model supporting the process.  Again relatively speaking, Mendix emphasizes user stories and UX design for those stories, whereas BizAgi emphasizes automation of both human workflows and service orchestrations.

An important thing to remember is that no platform is universally effective, so you may need to use different platforms for different apps.  However, established principles, patterns and practices of software modeling explained in the previous pages on Business Analysis, Microservice and VOLF are foundational knowledge, with which you can quickly digest any new platform or tool for app development as they come and go.

Figure 24.  Software Modeling Approaches: Mendix vs. BizAgi

Figure 24. Software Modeling Approaches: Mendix vs. BizAgi

Digital Process Automation (DPA) and BizDevOps

Gartner classifies application platform as a service (aPaaS) into HC (High Control) and HP (High Productivity) aPaaS. HP aPaaS are also called Low Code Development Platforms (LCDP). I would further classify LCDP into the LCDP based on business process management (BPM) and those that are not and more UX centric. Let me call the former BPM-Centric LCDP and the latter UX-Centric LCDP. Comparing Figures 1 and 18, you can find platforms that are appearing in both vendor landscapes, and they are BPM-Centric LCDPs (which include Appian, BizAgi, K2, AgilePoint, PNMSoft, etc.)

Forrester calls the BPM-centric LCDP the Digital Process Automation (DPA) software (Refer to: Forrester, The Forrester Wave™: Digital Process Automation Software, Q3 2017).  Figure 25 shows DPA software vendors.  Pegasystems, IBM, SoftwareAG, Oracle, etc. are added to the group of BPM-Centric LCDPs we identified hereinbefore.  Forrester's criteria for DPA software include the following specific functionalities: (1) create digital front-end process experiences and consumer-grade UX for web and mobile; (2) support process analysis, modeling, automation and integration; (3) allow low-code or no-code development; (4) commit to innovation of the DPA product with AI (such as business decisions based on machine learning) and IoT support; (5) support dynamic case management and robotic process automation (RPA).

RPA is an emerging form of business process automation technology based on the notion of software robots or AI workers.  In traditional workflow automation tools, a software developer produces a list of actions to automate a task and interface to the back-end system using internal APIs or dedicated scripting language. In contrast, RPA systems develop the action list by watching the user perform that task in the application's GUI, and then perform the automation by repeating those tasks directly in the GUI. This can lower the barrier to use of automation in products that might not otherwise feature APIs for this purpose.  RPA tools have strong technical similarities to GUI testing tools. (





What drives the BPMS vendors to change their products to DPA software is to support Digital Transformation of customers.  As organizations undertake digital transformation efforts, an important realization emerges: process matters. Investments in beautifully designed web and mobile experiences won’t move the needle unless app development and delivery professionals ensure that the processes on the back end align to support a true end-to-end customer experience (CX). (Refer to: Ibid.)

Digital business is the next generation of businesses.  Application development platforms including HC aPaaS, UX-Centric HP aPaaS, BPM-Centric HP aPaaS (a.k.a. DPA software) all will try to evolve into a platform most helpful for building and running digital businesses.  Let's recall the pattrens of digital business (in the Digital Business Patterns and Antipatterns section in the Software Business page of this blog site) because they are the functionalities future app development platforms will aim to support:  single code baseservice-oriented architecturemass customizationtalent management, layered cloud architectureself-servicemetered serviceelastic serviceprocess automationmultitenancy, single instancecontinuous deploymentmultitenant software architecturemetadata-based customizationweb 2.0 marketing, partner ecosystembusiness analysis expertisestandard processstrategic training programasset-based servicetime managementopportunity managementiterative projectprofessional service automation, IoT reference architecture, OT/IT integration, asymmetric competition, business model innovation, IoT-enabled operations, IoT-enabled product design, IoT-enabled CRM, digital value chain, product servitization, API business, pace-layered application architecture, system of systemsIt will be interesting to think about which digital business patterns are served by different functionalities pursued by DPA software.  Thinking through those goals-means relationships will help you understand deeper why and how to utilize DPA software capabilities for your digital business initiatives.

DPA software coupled with DevOps have made business process-driven app development, upgrade and maintenance easier and faster.  Non-IT business people can develop enterprise applications, especially new digital business applications.  Business domain and process experts' roles are critically important in DevOps teams especially for emerging digital business projects.  We need software-savvy business process users who will co-create apps with developers.  DPA software are evolving into BizDevOps tools that maximally automates design, build, deployment and operation.

Figure 25.  Digital Process Automation Software Vendors, 2017 (Adopted from The Forrester Wave™: Digital Process Automation Software, Q3 2017)

Figure 25. Digital Process Automation Software Vendors, 2017 (Adopted from The Forrester Wave™: Digital Process Automation Software, Q3 2017)


Nick Ford

10.09.2018 15:53

Thank you for covering Mendix in your blog so comprehensively. The Mendix community would welcome your participation should you wish to join?

Latest comments

21.03 | 17:18

Took me time to read all the comments, but I really enjoyed the article. It proved to be Very helpful to me and I am sure to all the commenters here! It’s always nice when you can not only be informed

05.02 | 01:55

Very good job of discussing both MSA as well as SOA and providing adoption considerations etc.

10.09 | 15:53

Thank you for covering Mendix in your blog so comprehensively. The Mendix community would welcome your participation should you wish to join?

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