DLCSPM - Canadian Software Support Seminar - April 1998 - DAPSCT1 A means to ensure software...

DLCSPM - Canadian Software Support Seminar - April 1998 - DAPSCT

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A means to ensure software supportability

Support Analysis for Software

R. [email protected]


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Presentation Overview

The Support Analysis for Software (SAS) Process Overview

Software Identification and Breakdown Categorisation of Software Supportability Analysis The Support Concept Interfaces to other disciplines The SAS database Reference Documentation


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Supportability Plan and Case

Software Supportability Plan: As part of the System Supportability Plan, it describes the activities to be undertaken in order to achieve the software supportability objectives. It also describes activities to be undertaken to demostrate achievement of those objectives

Software Supportability Case: A written documenation about how product supportability was verified/developed at each stage of software development as per the SW Supportability Plan

It is convenient, in order to ensure software supportability, to frame the management of software supportability around two key components:


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A Process for Software Supportability

determined satisfied demonstrated

Any process (based on the Software Supportability Plan) must achieve that the customer requirements for software supportability shall be:

Such a process has therefore to determine those requirements influence design so that supportability is built into the product establish the Support Concept and ensure it is implemented be itself validated


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The response:

A methodological process that derives supportability requirements on the basis of the support functions to be carried out:

Support Analysis for Software


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What is SAS?

It’s obvious:

A trick of the contractors to ask for more money

Both Some stupid elucubration from an academic that

has never done such an analysis, has never supported software, has never talked to the victims of bad support (the poor users), would not even recognize software if it were put on his dinner plate.

A combination of all above (remember Murphy’s Law...)

A new “geniality” of the government to waste even more money (after all, it’s just the taxpayers who pay...)


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What is SAS?

It is a consistent methodology that seeks the achievement of system and software supportability throughout requirements, specification and design, in order to define the most cost effective support concept that meets the operational requirements,

and to ensure that the necessary support infrastructure is in place before the system enters

into service.


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Goals for a SAS Process

Establish supportability requirements in the early programme phases so that they can be properly addressed

Influence design during development in order to ensure software supportability, both for operation and modification

Ensure that supportability problems do not affect negatively the operation and/or the availability of the fielded system

Ensure all required support processes and infrastructure are properly implemented prior to entry into service

Reduce as far as feasible the cost of ownership Be itself cost-effective (i.e, the savings and/or achieved

improvements must outweigh the cost of the SAS process)


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Structure for a SAS ProcessProject Life Cycle

Pre-Concept

Concept

Development

Post-Development

PROGRAM PLANNING AND CONTROL– Development of an early SAS Strategy – SAS Plan– Program and Design Reviews

MISSION, DEVELOPMENT & SUPPORT SYSTEMS DEFINITION– Use Study – Technological Opportunities– Standarization – Design Factors– Comparative Analysis – Integration of ADP Systems

PREPARATION AND EVALUATION OF ALTERNATIVES– Functional and Non-Functional Requirements– Support System Alternatives – Evaluation of Alternatives & Trade-Offs

DETERMINATION OF SASR REQUIREMENTS– Operational Task Analysis– Software Exception/Problem Support Analysis (FRACAS)– Software Modification Analysis– Software Transition Analysis– Post-Deployment Software Support (PDSS)/Logistics Management Analysis

SOFTWARE SUPPORTABILITY ASSESSMENT (CASE)– Operation – Modification – Problem Reaction – Logistics Management– Lessons Learnd

But: It is convenient to continue during the service phase!


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Outline of a SAS Analysis

Software Identification & Breakdown

Categorisation

Evaluation of Support

Alternatives

Identification of Support Resources

Trade-OffsSelection of

Support Option

Documentation of

Support Concept, CRLCMP

VendorSupport

Other SupportOptions

Use Study


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Identification of SW within a Project

The identification/structuring of software within a project has always been a major problem.

One approach that has worked well (e.g., in the EF-2000 project) is the association of software to the hardware where it executes because:

– That is the target machine– It is where hardware/software integration testing will be carried out– It is where the software will reside

This strategy can be made consistent with the LSA breakdown This strategy, however, might not work in networks or modular avionics BUT: It should be kept in mind that there are TWO different breakdowns

of software, depending on the support function to be assessed:– Functional breakdown (i.e, how software is designed) for modification– Physical breakdown (i.e, the “loadable” elements) for the operation


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Functional Breakdown Principles

The “Functional” Software are all those elements that depict the functional/design aspects of interest to the software engineers

This is the Software that has to be considered for Modification Support It is important that this breakdowns follows as closely as possible the

actual software design– Because otherwise it will falsify your support considerations– Because an Audit Trail to the existing design is required– Because that is the starting point for support– Because the software documentation is structured that way

BUT: You can include "Dummy" Software Items to group sets of functionality that are documented as a whole or which have a separate Design, provided that:

– Dummy Items are used to provide an additional level of abstraction– Dummy Items do not change the overall structure and functionality of

the Design


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Functional Breakdown of Software

Notes: Shaded areas indicate complete designs (CSCIs) CSCI Candidates are framed, Candidates for Integration in double frames, Dummy Candidate Numbers in brackets. S1AA also includes the interfaces to the other CSCIs & acts as if it were the Top-Level Design;

S1

S1A

S1AA

S1AB

S1B

S1

S1A S1B

(S1AA) S1AB

S1AAA

S1AAB

S1AAG

S1AAC S1AAD S1AAE S1AAF S1ABA

S1ABB S1ABC S1ABD

S1ABE

Candidates forSeparate Software

Support are Framed

S1ABE included in design of S1ABA


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Functional Breakdown Perspectives

The Software Breakdown is ONLY one of the possible views of the Software.

Support Decisions CANNOT be basedONLY on this perspective.

The Software Breakdown is ONLY one of the possible views of the Software.

Support Decisions CANNOT be basedONLY on this perspective.

StructureHierarchical perspective(Functional dependencies)

S1A S1B

S1SoftwareDependencies between the different software items exist both horizontally and vertically.

S1AS1B

S1

Design perspective(Module coupling & cohesion)

S1A

S1B


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Physical Breakdown Principles

The “Physical” Software is all those elements that can be manipulated separately by the operator/user

This is the Software that has to be considered for Operational Support

Two approaches can be used here:– It is part of the hardware element where it is loaded– It is part of the hardware element where it resides

Similarly, several levels of breakdown can be identified:– System– Line-Replaceable Item (Computer)– Shop-Replaceable Item (Computer Card)– Component (Chip)


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Physical Breakdown of Software

L1Comms System Load

L11 TransceiverLRI Load

L12 Audio Mgr.LRI Load

L11-LApplication

SW Load

L11-F Firmware

Load

L121-F Audio Firmware

Load

L12-LApplication

SW Load

L121-SAudio Module

SW Load

L122-SDVI Module

SW Load

L122-F DVI Firmware

Load

LRI

SRI

Chip

Loading level

Green indicates “groups” of loadable elements

Other colors indicate individual loadable elements


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Software Categorisation A minimum set of information should be collected for Categorisation. This information should indicate the main parameters that would affect software

Support (e.g., Operational Importance, Property Rights, Frequency of Change, etc) The result of the Categorisation should be a decision to:

Not continue with the Analysis Collect a minimum Data Set Explore all possible Support Alternatives

Categorisation criteria are important!

Too much analysis

(expensive)

Too little analysis

(lousy support)

Note that Categorisationcan be made on:- Functional Units- Physical Units- Both


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Selection of SAS Candidates

SAS Candidates are elements which are going to be subject to some kind of supportability analysis

SAS Candidates should be selected on the basis of their operational or supportability significance

Three types of distinct SAS Candidates should be selected: Functional Software Elements Physical Software Elements Data

Each of these has its own characteristics and different supportability problems


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Selection of Functional Candidates Inherent Candidates:

– The Item that includes all Software in the System and/or LRI– All Items (CSCIs) that have a separate Design – All intermediate Items between the CSCIs and the Top-Level CSCI at which

Integration is performed Potential Candidates: All Support Anomalies such as

– Software Items requiring special hardware or software tools– Software Items of different risk classes than the software where they are

embedded– Proprietary software, such as Run-Time Libraries or COTS Software– Software Items that have different versions for use of the parent software on

different platforms (e.g., different I/O handlers, so that the Software can run both on an A/C and on the Flight Simulator)

– Different programming languages (specially weird ones)– Deviations to the Design Environment– Reused Software


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Selection of Physical Candidates

For Software:– All software executables that can be loaded and/or installed

separately or that require different loading/installation tasks– All groups of the above that are loaded/installed together in one

single operation For Data:

– All databases– All data blocks (e.g., mission data) that:

Are manipulated as a single entity Require specific software for creation, manipulation or

evaluation (e.g., post-flight analysis) Are installed, loaded or unloaded by means of a specific task


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Function-oriented Supportability Analysis

It is convenient to carry out the Supportability Analysis from the point of view of the support functions that have to be carried out, and not from the point view of the product

When considering the functions (e.g., modify software, operate software), it is much easier to determine the necessary tasks, as well as those aspects that will simplify those tasks (e.g., software modularity helps modification, installation requires a loading device)

A first assessment of those tasks early in the development cycle will be useful to determine the software supportability requirements and objectives

But: software supportability in only one of the system supportability parameters, and should be always assessed in this context


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Analysis for Modification Support

The Analysis for Modification Support should be based both on the software to be modified and the tasks to be carried out to make that modification.

The first step should use a set of standard tasks (say, from IEEE 1219, ISO 12207, MIL-STD-498 or equivalent).

The standard tasks can be usually related to a specific hierarchical level within the software.

A cost or effort estimation tool (e.g., COCOMO) can provide the effort for the modification task. On the basis of existing metrics or software engineering studies, this effort can be statistically distributed over the different tasks.

The next step consists of identifying the support elements required to carry out those tasks. The use of those elements usually can be derived from the effort and duration of the tasks.


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Determination of Effort

A cost-estimation tool is used to determine the effort, manpower and duration for each phase of a typical modification

This is adjusted to the number of annual changes The resulting value, with minor adjustment, can be

considered to be the “use” of the necessary support resources.

Image courtesy of Price Systems


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Determination of Support Resources

Each Support Task might require specific Support Resources to be carried out

These Resources might require, on their turn, other Resources

Program Design

Program Source Code

Ada Programm

er

Training in Ada

Ada LRM

User Manuals

Operating

System

Host Comput

er

CodingAda

Program

Ada Compiler


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Trade-offs

Effort Cost of Ownership Response Times

Trade-Offs are simulated bycreating a Support Environment with all its parameters and then comparing:

There are tools that permit to consider different support alternatives and assess the most adequate one:

Operational Impact Required Investment Technological interests


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Analysis for Operational Support

Unfortunately, there are no standards for Operational Support from which a set of standard tasks could be derived

One practical approach is to derive a set of Support Initiators, that is, a set of events that might affect software

These Support Initiators result in a process to be modeled, from which resources can then be identified

It is convenient that this is harmonised with the LSA Process, as many of the Support Initiators can be identified through FMECA. Tools used for LORA can often be also used for this purpose

Typical Support Initiators include:– New software release / new firmware– Repair of computing hardware– Corruption of data or executable code (including virus infection)– System/Software failure – New system mission (with change of software and/or mission data)


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Operational Support Issues

Supportability decisions might have severe operational impact. Some examples:

– Where is software loaded? (increases spares or response time)– Are computers stored with or without software? (configuration

control, response times)– How many software versions/variants are at each site? (config.)– How do you ship computers containing classified software for

repair? (security problem)– Is the bootstrap loader loadable? (might be fun if power goes away

while loading it!)– Do you need to test after loading? (safety issues)– Can you actually shut down the system to install new software?– What do you do if the safety-critical software has a problem?


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Analysis for Logistics Management There are no standards either for Logistics Management Support from

which a set of standard tasks could be derived Tasks can be identified by modelling the Logistics Management functions

or by using a set of Support Initiators as triggers for the process to be carried out

Typical Logistics Management Support functions include:– Problem reporting and corrective actions– System/software configuration control– Packaging– Distribution– Installation and checkout– User Support (including help desk, technical representatives)

Process modelling tools can be used to determine support effectivity The classic Integrated Logistic Support (ILS) aspects such as Training,

Technical Publications, etc, should be also covered here.


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Data Support

Data Support is often neglected despite the fact that it often is critical to mission achievement

It is, by its mainly electronic nature, often handled in a similar way as software, with which it has a strong dependency

In this context, it is convenient to analyze its support together with that of the software (though not in the same way)

Support aspects to be considered include:– Data preparation software and hardware– Need for validation– Media, transmission networks, security aspects– Usage (e.g. by other programs, or other computers)– Loading/unloading process and/or tools– Compatibility aspects (e.g., with software, or certain system configurations)– Size, data formats


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Establishment of the Support Concept, CRLCMP The Support Concept provides

the global view about how the Software Support will addressed

It is coherent - Activities related to different support functions are grouped into processes, which themselves are grouped in accordance with the location (level) and the people (agents) involved, for each software product and all resources and facilities that are available for support purposes.

This overall concept is then described in the Computer Resources Life-Cycle Management Plan (CRLCMP)

Support Classes

Support Profile

Support Function

s

Opera

tion

Log

isti

cs

Man

ag

men

tM

odifi

cati

on

Proc

esse

s

Prod

uct

Enviro

nmen

t

Levels

Agents

Activities


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Supportability CASE The Supportability CASE is demonstrated by:

– Quantitative Evidence– Qualitative Evidence– Historical or Comparative Evidence

This demonstration can be also achieved by means of:

– The reports generated from the SASR– The CRLCMP


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Interfaces to other disciplines

SAS has also a link to the classic ILS disciplines, to which it issues requirements for Training, Support Equipment and Support Software, Technical Publications, Facilities, etc., in a similar way as LSA

The Link to LSA is established through the “Physical Software” breakdown and its relationship with the hardware

It is convenient that LSA (if carried out) documents the SAS results for the Operational Support, so that all operational matters are stored together

The link to RM&T is also only for operational purposes - RM&T for Software Modification is carried out as part of the SAS Analysis

The link to Engineering is through the software design. It is convenient that SAS participates as part of an Integrated Project Team (IPT), or at least as a reviewer during the whole software design.


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Interface to LSA

The LSAR and SASR should be linked, in order to obtain overall system consistency and ensure system supportability

The link are the loadable elements and their associated hardware

LSA and SAS have to collaborate in this context, so as to ensure that no incompatible support decisions are taken:

(e.g., incompatible loading levels after HW repair and after SW update)


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The SAS Database (SASR)

It provides a single master data repository for all software related information (everybody works on the basis of the same data)

It integrates such information from multiples sources, for all software in one single system or across multiple related systems

It provides an overview of all required support resources, thus making it easier to identify commonalities or consider combined support

It can be queried to seek out specific information, such as software metrics, system load, deviations....

It can be linked to software engineering tools or information, as well as to logistics-related information (the LSAR)

Though often disconsidered in the Supportability Analysis, the use of a database for all software supportability information is of great importance since:

However: There is no standard for such a database and the LSAR cannot be used for this purpose


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Simplified Relational Graph of SASR

Support Tasks

TrainingEquipment

Software

Facilities

Publications

Staff

Media

Host Hardware

Software-Specific

Information

<SW, Tasks>

Support Resources

<SW, Tasks,

Resources>

<SW,Tasks,Resource

s, Training>


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Conclusions

A Supportability Analysis can be carried out in a similar way as the LSA Process (but don’t try to use MIL-STD-1388!)

It is not specially difficult, but it is convenient that it is done by a mix of software engineers and logisticians

Critical to this is the establishment of a software Supportability Plan in the early programme phases

Not only support can benefit from this approach, even the design process might be optimized because of it

The Supportability Case prevents that supportability is killed due to schedule or cost constraints - it is a contractual requirement!

But it should be always kept in mind: Supportability for its own sake is a waste of money!


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Some Reference Documentation

DEF STAN 00-60, “Integrated Logistic Support”, Issue 2, October 1996, Part 3: “Logistic Support Analysis Application to Software Aspects of Systems”

SAE Standard JA1004 (Draft), “Software Supportability Program Standard”, in SAE Ballot MIL-HDBK-347, “Mission-Critical Computer Resources Support”, May 1990 SAE Aerospace Information Report AIR5121, “Software Supportability - An Overview”,

January 1997 SAE Report JA1006 (Draft), “Software Support Concept”, in SAE Ballot SAE Recommended Practice JA1005, “Software Supportability Implementation Guide” (Draft) Software Logistics Planning Handbook, US Army, CECOM, October 1995 ISO Standard 12207, “Information Technology - Software Life Cycle Processes”,

August 1995 IEEE Standard 1219, “IEEE Standard for Software Maintenance”, June 1993 MIL-STD-498, “Software Development and Documentation”, December 1994

SAE G-11 Software Committtee Homepage (http://www.sae.org/TECHCMTE/g11soft.htm) DEF STAN 00-60 Homepage (http://www.demon.co.uk/ilsuk.html)

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