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A. Caproni

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Papers by A. Caproni

ACS from development to operations

Software and Cyberinfrastructure for Astronomy III, 2016

The ALMA Common Software (ACS), provides the infrastructure of the distributed software system of... more The ALMA Common Software (ACS), provides the infrastructure of the distributed software system of ALMA and other projects. ACS, built on top of CORBA and Data Distribution Service (DDS) middleware, is based on a Component-Container paradigm and hides the complexity of the middleware allowing the developer to focus on domain specific issues. The transition of the ALMA observatory from construction to operations brings with it that ACS effort focuses primarily on scalability, stability and robustness rather than on new features. The transition came together with a shorter release cycle and a more extensive testing. For scalability, the most problematic area has been the CORBA notification service, used to implement the publisher subscriber pattern because of the asynchronous nature of the paradigm: a lot of effort has been spent to improve its stability and recovery from run time errors. The original bulk data mechanism, implemented using the CORBA Audio/Video Streaming Service, showed its limitations and has been replaced with a more performant and scalable DDS implementation. Operational needs showed soon the difference between releases cycles for Online software (i.e. used during observations) and Offline software, which requires much more frequent releases. This paper attempts to describe the impact the transition from construction to operations had on ACS, the solution adopted so far and a look into future evolution.

Integrating the CERN LASER Alarm System with the ALMA Common Software

SPIE Proceedings, 2006

An alarm system is a cornerstone service in every computer controlled environment. Its purpose is... more An alarm system is a cornerstone service in every computer controlled environment. Its purpose is the notification of exceptional conditions in the system requiring an intervention from the staff. The specifications for the alarm system in the Alma Common Software (ACS) require not only that each alarm has to be shown to operators in a short time, but also that correlated alarms must be "reduced" and presented in compact form in such a way that operators are able to easily identify the root cause for an abnormal condition. In the development of ACS we always investigate the availability of adequate implementations before writing a service from scratch. Such an implementation, the CERN Laser Alarm System, developed for the Large Hadron Collider, was fulfilling and exceeding our requirements. We have therefore started a pilot collaboration project to verify the possibility of integrating Large Hadron Collider Alarm Service (LASER) into ACS. A test suite was developed to demonstrate that the full chain of events starting from the publication of new alarms from a set of sources to their representation in a GUI happened as expected. Particular attention was given to the reduction mechanism for its importance in helping the operators in finding the real cause of each problem in a short time. The project showed that it is possible to integrate two different software systems if they are written with well defined interface and have a similar infrastructure. In this paper we describe the modifications we introduce to integrate CERN LASER into ACS.

Application development using the ALMA common software

SPIE Proceedings, 2006

The ALMA Common Software (ACS) provides the software infrastructure used by ALMA and by several o... more The ALMA Common Software (ACS) provides the software infrastructure used by ALMA and by several other telescope projects, thanks also to the choice of adopting the LGPL public license. ACS is a set of application frameworks providing the basic services needed for object oriented distributed computing. Among these are transparent remote object invocation, object deployment and location based on a container/component model, distributed error, alarm handling, logging and events. ACS is based on CORBA and built on top of free CORBA implementations. Free software is extensively used wherever possible. The general architecture of ACS was presented at SPIE 2002. ACS has been under development for 6 years and it is midway through its development life. Many applications have been written using ACS; the ALMA test facility, APEX and other telescopes are running systems based on ACS. This is therefore a good time to look back and see what have been until now the strong and the weak points of ACS in terms of architecture and implementation. In this perspective, it is very important to analyze the applications based on ACS, the feedback received by the users and the impact that this feedback has had on the development of ACS itself, by favoring the development of some features with respect to others. The purpose of this paper is to describe the results of this analysis and discuss what we would like to do in order to extend and improve ACS in the coming years, in particular to make application development easier and more efficient.

An overview of the ALMA Common Software (ACS)

The ALMA Common Software (ACS) is an application framework designed to provide a common and homog... more The ALMA Common Software (ACS) is an application framework designed to provide a common and homogeneous software architecture and infrastructure, spanning the end to end needs of an Astronomical observatory, from the Telescope Control system to high-level data flow management. ACS offers, at the lower level, several basic services needed for object-oriented distributed computing like transparent remote object invocation, object deployment and location, distributed error, alarm handling, logging and events. On top of this it provides an application architecture based on the Component/Container paradigm that fosters sharing and reusing of software components. Although developed for the ALMA project, ACS is now used by several other projects worldwide, among which the Italian Sardinia Radio Telescope (SRT). Besides, there is an active community that shares ideas, concepts and actual software components. Major drivers for this diffusion were the choice of adopting the LGPL public license and the adoption of CORBA, a free but reliable and widely used middleware software. In this paper we present an overview of the main features of ACS, emphasizing in particular the role of INAF-OAT in this project.

The pilot project for the TNG Long-Term Archive

The pilot project aiming at the definition of a long-term archive for the national Galileo telesc... more The pilot project aiming at the definition of a long-term archive for the national Galileo telescope (TNG) is described. The scope of the project, its development plan and the current status are reported, with particular reference to the requirements for interoperability with other archives, aimed at the inclusion of the TNG long-term archive in the phase-B of the European Astronomical Virtual Observatory (AVO) project.

The Alma Common Software, Acs Status and Developments

The ALMA Common Software (ACS) is a software infrastructure for the development of distributed sy... more The ALMA Common Software (ACS) is a software infrastructure for the development of distributed systems based on the Component/Container paradigm. ACS is being developed primarily for the ALMA collaboration to provide a common and unifying infrastructure used by all partners and across all layers of the system (5). The usage of ACS extends from high-level applications such as the Observation

The Integrated Alarm System of the Alma Observatory

ALMA is composed of many hardware and software systems each of which must be properly functioning... more ALMA is composed of many hardware and software systems each of which must be properly functioning to ensure the maximum efficiency. Operators in the control room, follow the operational state of the observatory by looking at a set of non-homogeneous panels. In case of problems, they have to find the reason by looking at the right panel, interpret the information and implement the counter-action that is time consuming so after an investigation, we started the development of an integrated alarm system that takes monitor point values and alarms from the monitored systems and presents alarms to operators in a coherent, efficient way. A monitored system has a hierarchical structure modeled with an acyclic graph whose nodes represent the components of the system. Each node digests monitor point values and alarms against a provided transfer function and sets its output as working or non nominal, taking into account the operational phase. The model can be mapped in a set of panels to increa...

The ALMA common software: a developer-friendly CORBA-based framework

Advanced Software, Control, and Communication Systems for Astronomy, 2004

The ALMA Common Software (ACS) is a set of application frameworks built on top of CORBA. It provi... more The ALMA Common Software (ACS) is a set of application frameworks built on top of CORBA. It provides a common software infrastructure to all partners in the ALMA collaboration. The usage of ACS extends from high-level applications such as the Observation Preparation Tool [7] that will run on the desk of astronomers, down to the Control Software [6] domain. The purpose of ACS is twofold: from a system perspective, it provides the implementation of a coherent set of design patterns and services that will make the whole ALMA software [1] uniform and maintainable; from the perspective of an ALMA developer, it provides a friendly programming environment in which the complexity of the CORBA middleware and other libraries is hidden and coding is drastically reduced. The evolution of ACS is driven by a long term development plan, however on the 6-months release cycle the plan is adjusted based on incoming requests from ALMA subsystem development teams. ACS was presented at SPIE 2002[2]. In the two years since then, the core services provided by ACS have been extended, while the coverage of the application framework has been increased to satisfy the needs of high-level and data flow applications. ACS is available under the LGPL public license. The patterns implemented and the services provided can be of use also outside the astronomical community; several projects have already shown their interest in ACS. This paper presents the status of ACS and the progress over the last two years. Emphasis is placed on showing how requests from ACS users have driven the selection of new features.

A Generic Software Interface Simulator for Alma Common Software

The generic software interface simulator framework for Atacama Large Millimeter Array (ALMA) Comm... more The generic software interface simulator framework for Atacama Large Millimeter Array (ALMA) Common Software (ACS) provides ALMA developers with an easy means to create and configure the behaviour of interfaces that have been defined using Common Object Request Broker Architecture (CORBA) Interface Definition Language (IDL). ACS consists of a set of application frameworks built on top of CORBA and provides

<title>The ALMA common software: dispatch from the trenches</title>

Advanced Software and Control for Astronomy II, 2008

The ALMA Common Software (ACS) provides both an application framework and CORBA-based middleware ... more The ALMA Common Software (ACS) provides both an application framework and CORBA-based middleware for the distributed software system of the Atacama Large Millimeter Array. Building upon open-source tools such as the JacORB, TAO and OmniORB ORBs, ACS supports the development of component-based software in any of three languages: Java, C++ and Python. Now in its seventh major release, ACS has matured, both in its feature set as well as in its reliability and performance. However, it is only recently that the ALMA observatory's hardware and application software has reached a level at which it can exploit and challenge the infrastructure that ACS provides. In particular, the availability of an Antenna Test Facility(ATF) at the site of the Very Large Array in New Mexico has enabled us to exercise and test the still evolving end-to-end ALMA software under realistic conditions. The major focus of ACS, consequently, has shifted from the development of new features to consideration of how best to use those that already exist. Configuration details which could be neglected for the purpose of running unit tests or skeletal end-to-end simulations have turned out to be sensitive levers for achieving satisfactory performance in a real-world environment. Surprising behavior in some open-source tools has required us to choose between patching code that we did not write or addressing its deficiencies by implementing workarounds in our own software. We will discuss these and other aspects of our recent experience at the ATF and in simulation.

A generic software interface simulator for ALMA common software

The generic software interface simulator framework for Atacama Large Millimeter Array (ALMA) Comm... more The generic software interface simulator framework for Atacama Large Millimeter Array (ALMA) Common Software (ACS) provides ALMA developers with an easy means to create and configure the behaviour of interfaces that have been defined using Common Object Request Broker Architecture (CORBA) Interface Definition Language (IDL). ACS consists of a set of application frameworks built on top of CORBA and provides the glue which binds other ALMA software subsystems together [7]. In short, ACS provides an implementation of the component-container design pattern via CORBA. Using the simulation framework, one can choose to predefine the behaviour of a simulated component by embedding simple Python commands within a section of the XML-based ACS configuration database (CDB). The option to configure simulated components' behaviour at run-time is also a possibility using a provided graphical user interface (GUI) or application programming interface (API) executed within the context of an interactive Python session. Additionally, if the means above have not been utilized to setup the components' behaviour the framework will dynamically provide an implementation of the entire component with a randomized behaviour. This framework is especially useful to ALMA developers for two reasons. On one side it allows developers to test their own component, which is dependent upon other types of components that have been defined via IDL interfaces, but not yet implemented. On the other side this tool has proven itself to be quite valuable because it allows developers to connect clients such as graphical user interfaces to (simulated) components encapsulating hardware devices. Not only can the physical hardware devices be absent in this type of scenario, but the software representing the hardware need not be available either. The end result here is that clients and components can be developed and tested in parallel completely independent of each other. This paper discusses the design, implementation, and current usage of the simulator framework within ALMA software as well as future improvements to be made.

The ALMA common software: dispatch from the trenches

Storage and Retrieval for Image and Video Databases, 2008

The ALMA Common Software (ACS) provides both an application framework and CORBA-based middleware ... more The ALMA Common Software (ACS) provides both an application framework and CORBA-based middleware for the distributed software system of the Atacama Large Millimeter Array. Building upon open-source tools such as the JacORB, TAO and OmniORB ORBs, ACS supports the development of component-based software in any of three languages: Java, C++ and Python. Now in its seventh major release, ACS has

<title>Application development using the ALMA common software</title>

by Klemen Zagar, Matej Sekoranja, Mark Plesko, and A. Caproni

Advanced Software and Control for Astronomy, 2006

The ALMA Common Software (ACS) provides the software infrastructure used by ALMA and by several o... more The ALMA Common Software (ACS) provides the software infrastructure used by ALMA and by several other telescope projects, thanks also to the choice of adopting the LGPL public license. ACS is a set of application frameworks providing the basic services needed for object oriented distributed computing. Among these are transparent remote object invocation, object deployment and location based on a container/component model, distributed error, alarm handling, logging and events. ACS is based on CORBA and built on top of free CORBA implementations. Free software is extensively used wherever possible. The general architecture of ACS was presented at SPIE 2002. ACS has been under development for 6 years and it is midway through its development life. Many applications have been written using ACS; the ALMA test facility, APEX and other telescopes are running systems based on ACS. This is therefore a good time to look back and see what have been until now the strong and the weak points of ACS in terms of architecture and implementation. In this perspective, it is very important to analyze the applications based on ACS, the feedback received by the users and the impact that this feedback has had on the development of ACS itself, by favoring the development of some features with respect to others. The purpose of this paper is to describe the results of this analysis and discuss what we would like to do in order to extend and improve ACS in the coming years, in particular to make application development easier and more efficient.

ACS from development to operations

Software and Cyberinfrastructure for Astronomy III, 2016

The ALMA Common Software (ACS), provides the infrastructure of the distributed software system of... more The ALMA Common Software (ACS), provides the infrastructure of the distributed software system of ALMA and other projects. ACS, built on top of CORBA and Data Distribution Service (DDS) middleware, is based on a Component-Container paradigm and hides the complexity of the middleware allowing the developer to focus on domain specific issues. The transition of the ALMA observatory from construction to operations brings with it that ACS effort focuses primarily on scalability, stability and robustness rather than on new features. The transition came together with a shorter release cycle and a more extensive testing. For scalability, the most problematic area has been the CORBA notification service, used to implement the publisher subscriber pattern because of the asynchronous nature of the paradigm: a lot of effort has been spent to improve its stability and recovery from run time errors. The original bulk data mechanism, implemented using the CORBA Audio/Video Streaming Service, showed its limitations and has been replaced with a more performant and scalable DDS implementation. Operational needs showed soon the difference between releases cycles for Online software (i.e. used during observations) and Offline software, which requires much more frequent releases. This paper attempts to describe the impact the transition from construction to operations had on ACS, the solution adopted so far and a look into future evolution.

Integrating the CERN LASER Alarm System with the ALMA Common Software

SPIE Proceedings, 2006

An alarm system is a cornerstone service in every computer controlled environment. Its purpose is... more An alarm system is a cornerstone service in every computer controlled environment. Its purpose is the notification of exceptional conditions in the system requiring an intervention from the staff. The specifications for the alarm system in the Alma Common Software (ACS) require not only that each alarm has to be shown to operators in a short time, but also that correlated alarms must be "reduced" and presented in compact form in such a way that operators are able to easily identify the root cause for an abnormal condition. In the development of ACS we always investigate the availability of adequate implementations before writing a service from scratch. Such an implementation, the CERN Laser Alarm System, developed for the Large Hadron Collider, was fulfilling and exceeding our requirements. We have therefore started a pilot collaboration project to verify the possibility of integrating Large Hadron Collider Alarm Service (LASER) into ACS. A test suite was developed to demonstrate that the full chain of events starting from the publication of new alarms from a set of sources to their representation in a GUI happened as expected. Particular attention was given to the reduction mechanism for its importance in helping the operators in finding the real cause of each problem in a short time. The project showed that it is possible to integrate two different software systems if they are written with well defined interface and have a similar infrastructure. In this paper we describe the modifications we introduce to integrate CERN LASER into ACS.

Application development using the ALMA common software

SPIE Proceedings, 2006

The ALMA Common Software (ACS) provides the software infrastructure used by ALMA and by several o... more The ALMA Common Software (ACS) provides the software infrastructure used by ALMA and by several other telescope projects, thanks also to the choice of adopting the LGPL public license. ACS is a set of application frameworks providing the basic services needed for object oriented distributed computing. Among these are transparent remote object invocation, object deployment and location based on a container/component model, distributed error, alarm handling, logging and events. ACS is based on CORBA and built on top of free CORBA implementations. Free software is extensively used wherever possible. The general architecture of ACS was presented at SPIE 2002. ACS has been under development for 6 years and it is midway through its development life. Many applications have been written using ACS; the ALMA test facility, APEX and other telescopes are running systems based on ACS. This is therefore a good time to look back and see what have been until now the strong and the weak points of ACS in terms of architecture and implementation. In this perspective, it is very important to analyze the applications based on ACS, the feedback received by the users and the impact that this feedback has had on the development of ACS itself, by favoring the development of some features with respect to others. The purpose of this paper is to describe the results of this analysis and discuss what we would like to do in order to extend and improve ACS in the coming years, in particular to make application development easier and more efficient.

An overview of the ALMA Common Software (ACS)

The ALMA Common Software (ACS) is an application framework designed to provide a common and homog... more The ALMA Common Software (ACS) is an application framework designed to provide a common and homogeneous software architecture and infrastructure, spanning the end to end needs of an Astronomical observatory, from the Telescope Control system to high-level data flow management. ACS offers, at the lower level, several basic services needed for object-oriented distributed computing like transparent remote object invocation, object deployment and location, distributed error, alarm handling, logging and events. On top of this it provides an application architecture based on the Component/Container paradigm that fosters sharing and reusing of software components. Although developed for the ALMA project, ACS is now used by several other projects worldwide, among which the Italian Sardinia Radio Telescope (SRT). Besides, there is an active community that shares ideas, concepts and actual software components. Major drivers for this diffusion were the choice of adopting the LGPL public license and the adoption of CORBA, a free but reliable and widely used middleware software. In this paper we present an overview of the main features of ACS, emphasizing in particular the role of INAF-OAT in this project.

The pilot project for the TNG Long-Term Archive

The pilot project aiming at the definition of a long-term archive for the national Galileo telesc... more The pilot project aiming at the definition of a long-term archive for the national Galileo telescope (TNG) is described. The scope of the project, its development plan and the current status are reported, with particular reference to the requirements for interoperability with other archives, aimed at the inclusion of the TNG long-term archive in the phase-B of the European Astronomical Virtual Observatory (AVO) project.

The Alma Common Software, Acs Status and Developments

The ALMA Common Software (ACS) is a software infrastructure for the development of distributed sy... more The ALMA Common Software (ACS) is a software infrastructure for the development of distributed systems based on the Component/Container paradigm. ACS is being developed primarily for the ALMA collaboration to provide a common and unifying infrastructure used by all partners and across all layers of the system (5). The usage of ACS extends from high-level applications such as the Observation

The Integrated Alarm System of the Alma Observatory

ALMA is composed of many hardware and software systems each of which must be properly functioning... more ALMA is composed of many hardware and software systems each of which must be properly functioning to ensure the maximum efficiency. Operators in the control room, follow the operational state of the observatory by looking at a set of non-homogeneous panels. In case of problems, they have to find the reason by looking at the right panel, interpret the information and implement the counter-action that is time consuming so after an investigation, we started the development of an integrated alarm system that takes monitor point values and alarms from the monitored systems and presents alarms to operators in a coherent, efficient way. A monitored system has a hierarchical structure modeled with an acyclic graph whose nodes represent the components of the system. Each node digests monitor point values and alarms against a provided transfer function and sets its output as working or non nominal, taking into account the operational phase. The model can be mapped in a set of panels to increa...

The ALMA common software: a developer-friendly CORBA-based framework

Advanced Software, Control, and Communication Systems for Astronomy, 2004

The ALMA Common Software (ACS) is a set of application frameworks built on top of CORBA. It provi... more The ALMA Common Software (ACS) is a set of application frameworks built on top of CORBA. It provides a common software infrastructure to all partners in the ALMA collaboration. The usage of ACS extends from high-level applications such as the Observation Preparation Tool [7] that will run on the desk of astronomers, down to the Control Software [6] domain. The purpose of ACS is twofold: from a system perspective, it provides the implementation of a coherent set of design patterns and services that will make the whole ALMA software [1] uniform and maintainable; from the perspective of an ALMA developer, it provides a friendly programming environment in which the complexity of the CORBA middleware and other libraries is hidden and coding is drastically reduced. The evolution of ACS is driven by a long term development plan, however on the 6-months release cycle the plan is adjusted based on incoming requests from ALMA subsystem development teams. ACS was presented at SPIE 2002[2]. In the two years since then, the core services provided by ACS have been extended, while the coverage of the application framework has been increased to satisfy the needs of high-level and data flow applications. ACS is available under the LGPL public license. The patterns implemented and the services provided can be of use also outside the astronomical community; several projects have already shown their interest in ACS. This paper presents the status of ACS and the progress over the last two years. Emphasis is placed on showing how requests from ACS users have driven the selection of new features.

A Generic Software Interface Simulator for Alma Common Software

The generic software interface simulator framework for Atacama Large Millimeter Array (ALMA) Comm... more The generic software interface simulator framework for Atacama Large Millimeter Array (ALMA) Common Software (ACS) provides ALMA developers with an easy means to create and configure the behaviour of interfaces that have been defined using Common Object Request Broker Architecture (CORBA) Interface Definition Language (IDL). ACS consists of a set of application frameworks built on top of CORBA and provides

<title>The ALMA common software: dispatch from the trenches</title>

Advanced Software and Control for Astronomy II, 2008

The ALMA Common Software (ACS) provides both an application framework and CORBA-based middleware ... more The ALMA Common Software (ACS) provides both an application framework and CORBA-based middleware for the distributed software system of the Atacama Large Millimeter Array. Building upon open-source tools such as the JacORB, TAO and OmniORB ORBs, ACS supports the development of component-based software in any of three languages: Java, C++ and Python. Now in its seventh major release, ACS has matured, both in its feature set as well as in its reliability and performance. However, it is only recently that the ALMA observatory's hardware and application software has reached a level at which it can exploit and challenge the infrastructure that ACS provides. In particular, the availability of an Antenna Test Facility(ATF) at the site of the Very Large Array in New Mexico has enabled us to exercise and test the still evolving end-to-end ALMA software under realistic conditions. The major focus of ACS, consequently, has shifted from the development of new features to consideration of how best to use those that already exist. Configuration details which could be neglected for the purpose of running unit tests or skeletal end-to-end simulations have turned out to be sensitive levers for achieving satisfactory performance in a real-world environment. Surprising behavior in some open-source tools has required us to choose between patching code that we did not write or addressing its deficiencies by implementing workarounds in our own software. We will discuss these and other aspects of our recent experience at the ATF and in simulation.

A generic software interface simulator for ALMA common software

The generic software interface simulator framework for Atacama Large Millimeter Array (ALMA) Comm... more The generic software interface simulator framework for Atacama Large Millimeter Array (ALMA) Common Software (ACS) provides ALMA developers with an easy means to create and configure the behaviour of interfaces that have been defined using Common Object Request Broker Architecture (CORBA) Interface Definition Language (IDL). ACS consists of a set of application frameworks built on top of CORBA and provides the glue which binds other ALMA software subsystems together [7]. In short, ACS provides an implementation of the component-container design pattern via CORBA. Using the simulation framework, one can choose to predefine the behaviour of a simulated component by embedding simple Python commands within a section of the XML-based ACS configuration database (CDB). The option to configure simulated components' behaviour at run-time is also a possibility using a provided graphical user interface (GUI) or application programming interface (API) executed within the context of an interactive Python session. Additionally, if the means above have not been utilized to setup the components' behaviour the framework will dynamically provide an implementation of the entire component with a randomized behaviour. This framework is especially useful to ALMA developers for two reasons. On one side it allows developers to test their own component, which is dependent upon other types of components that have been defined via IDL interfaces, but not yet implemented. On the other side this tool has proven itself to be quite valuable because it allows developers to connect clients such as graphical user interfaces to (simulated) components encapsulating hardware devices. Not only can the physical hardware devices be absent in this type of scenario, but the software representing the hardware need not be available either. The end result here is that clients and components can be developed and tested in parallel completely independent of each other. This paper discusses the design, implementation, and current usage of the simulator framework within ALMA software as well as future improvements to be made.

The ALMA common software: dispatch from the trenches

Storage and Retrieval for Image and Video Databases, 2008

The ALMA Common Software (ACS) provides both an application framework and CORBA-based middleware ... more The ALMA Common Software (ACS) provides both an application framework and CORBA-based middleware for the distributed software system of the Atacama Large Millimeter Array. Building upon open-source tools such as the JacORB, TAO and OmniORB ORBs, ACS supports the development of component-based software in any of three languages: Java, C++ and Python. Now in its seventh major release, ACS has

<title>Application development using the ALMA common software</title>

by Klemen Zagar, Matej Sekoranja, Mark Plesko, and A. Caproni

Advanced Software and Control for Astronomy, 2006

The ALMA Common Software (ACS) provides the software infrastructure used by ALMA and by several o... more The ALMA Common Software (ACS) provides the software infrastructure used by ALMA and by several other telescope projects, thanks also to the choice of adopting the LGPL public license. ACS is a set of application frameworks providing the basic services needed for object oriented distributed computing. Among these are transparent remote object invocation, object deployment and location based on a container/component model, distributed error, alarm handling, logging and events. ACS is based on CORBA and built on top of free CORBA implementations. Free software is extensively used wherever possible. The general architecture of ACS was presented at SPIE 2002. ACS has been under development for 6 years and it is midway through its development life. Many applications have been written using ACS; the ALMA test facility, APEX and other telescopes are running systems based on ACS. This is therefore a good time to look back and see what have been until now the strong and the weak points of ACS in terms of architecture and implementation. In this perspective, it is very important to analyze the applications based on ACS, the feedback received by the users and the impact that this feedback has had on the development of ACS itself, by favoring the development of some features with respect to others. The purpose of this paper is to describe the results of this analysis and discuss what we would like to do in order to extend and improve ACS in the coming years, in particular to make application development easier and more efficient.