applied software architecture christine hofmeister pdf free download

applied software architecture christine hofmeister pdf free download

We found that it works well for communicating the static structure of the architecture: the elements of the architecture, their relations, and the variability of a structure.

These static properties are much more readily described with it than the dynamic properties. We could easily describe a particular sequence of activities, but not a general sequence. In addition, the ability to show peer-to- peer communication is missing from UML. Although its original purpose was for detailed design, its ability to describe elements and the relations between them makes it potentially applicable much more broadly. This paper describes our experience using UML to describe the software architecture of a system.

For these architecture descriptions, we wanted a consistent, clear notation that was readily accessible to architects, developers, and managers. It was not our goal to define a formal architecture description language. The notation could be incomplete, but had to nevertheless capture the most important aspects of the architecture.

In this paper we start by giving an overview of the kinds of information we want to capture in a software architecture description. Then we give an example of a software architecture P. Donohoe ed. Nord, and D. Soni description for part of particular system: the image processing portion of a real-time image acquisition system. The final section discusses the strengths and weaknesses of UML for describing architecture.

We separate software architecture into four views: conceptual, module, execution, and code. This separation is based on our study of the software architectures of large systems, and on our experience designing and reviewing architectures Soni, The different views address different engineering concerns, and separation of such concerns helps the architect make sound decisions about design trade-offs. The notion of this kind of separation is not unique: most of the work in software architecture to date either recognizes different architecture views or focuses on one particular view in order to explore its distinct characteristics and distinguish it from the others Bass, The Garlen and Shaw work focuses on the conceptual view Shaw, Over the years there has been a great deal of work on the module view Prieto-Diaz, There is other work that focuses on the execution view, and in particular explores the dynamic aspects of a system Kramer, ; Purtilo, The code view has been explored in the context of configuration management and system building.

The conceptual view describes the architecture in terms of domain elements. Here the architect designs the functional features of the system.

For example, one common goal is to organize the architecture so that functional features can be added, removed, or modified. This is important for evolution, for supporting a product line, and for reuse across generations of a product.

The module view describes the decomposition of the software and its organization into layers. An important consideration here is limiting the impact of a change in external software or hardware. Another consideration is the focusing of software engineers' expertise, in order to increase implementation efficiency. The execution view is the run-time view of the system: it is the mapping of modules to run-time images, defining the communication among them, and assigning them to physical resources.

Resource usage and performance are key concerns in the execution view. Decisions such as whether to use a link library or a shared library, or whether to use threads or processes are made here, although these decisions may feed back to the module view and require changes there. The code view captures how modules and interfaces in the module view are mapped to source files, and run-time images in the execution view are mapped to executable files.

Each of the four views has particular elements that need to be described. The elements must be named, and their interface, attributes, behavior, and relations to each other must be described.

Some of the views also have a configuration, which constrains the elements by defining what roles they can play in a particular system.

In the configuration, the architect may want to describe additional attributes or behavior associated with the elements, or to describe the behavior of the configuration as a whole. In the next four sections, we show how we used UML to describe each of these four views, starting with the conceptual view and ending with the code view. To make the explanation clearer, we use an example from an image acquisition system. Advice 5.

When you document the results of decisions, record the alternatives you rejected and say why. Recording rationale will save you enormous time in the long run, although it requires discipline to record in the heat of the moment. Advice 6. Documentation that is incomplete, out of date, does not reflect truth, and does not obey its own rules for form and internal consistency is not used.

Documentation that is kept current and accurate is used. Because, questions about the software can be most easily and most efficiently answered by referring to the appropriate document. If the documentation is somehow inadequate to answer the question, then it needs to be fixed.

Updating it and then referring the questioner to it will deliver a strong message that the documentation is the final authoritative source for information. During the design process, on the other hand, decisions are made and reconsidered with great frequency. Revising documentation to reflect decisions that will not persist is an unnecessary expense. Your development plan should specify particular points at which the documentation is brought up to date or the process for keeping the documentation current.

Every design decision should not be recorded the instant it is made but rather that the document is subject to version control and has a release strategy just as every other artifact being produced during a development.

Advice 7. Review documentation for fitness of purpose. Only the intended users of a document will be able to tell you if it contains the right information presented in the right way. Enlist their aid. Before a document is released, have it reviewed by representatives of the community or communities for whom it was written.

Chapter 12 "Reviewing Software Architecture Documentation" will show how to review software architecture documentation to make sure it is of high quality and utility and that it conforms to these rules, among other things.

Copyright Addison Wesley, all rights reserved 30 Draft for review: Do not circulate without permission Views Perhaps the most important concept associated with software architecture documentation is that of the view.

A software architecture is a complex entity that cannot be described in a simple one-dimensional fashion. The analogy with building architecture, if not taken too far, proves illuminating. There is no single rendition of a building architecture. Instead, there are many: The room layouts, the elevation drawings, the electrical diagrams, the plumbing diagrams, the ventilation diagrams, the traffic patterns, the sunlight and passive solar views, the security system plans, and many others.

Which of these views is the architecture? None of them. Which views convey the architecture? All of them. This definition largely survives in architecture papers today.

Parnas identified several structures prevalent in software. A few were fairly specific to operating systems such as the structure that defines what process owns what memory segment but others are more generic and broadly applicable.

Designers decompose the system into a set of key abstractions, taken mainly from the problem domain. These abstractions are objects or object classes that exploit the principles of abstraction, encapsulation, and inheritance.

In addition to aiding functional analysis, decomposition identifies mechanisms and design elements that are common across the system. The process view also specifies which thread of control executes each operation of each class identified in the logical view. The units of this view are small chunks of software—program libraries or subsystems—that can be developed by one or more developers. The development view supports the allocation of requirements and work to teams, and supports cost evaluation, planning, monitoring of project progress, and reasoning about software reuse, portability, and security.

This view maps the various elements identified in the logical, process, and development views—networks, processes, tasks, and objects—onto the processing nodes. Finally, Kruchten prescribes using a small subset of important scenarios—instances of use cases—to show that the elements of the four views work together seamlessly.

To see how the Siemens Four View model corresponds to the views described in this book, see "Siemens Four Views" on page It includes the concepts, guidelines, principles, and management tools needed to carry out industrial-scale development. Like electrical and plumbing diagrams, each view of a software architecture is used for a different purpose, and often by different stakeholders. As such, they form the basic unit for documenting a software architecture.

Figure 3: A documentation package for a software architecture is composed of several parts. The main part of the package consists of one or more view documents. The remainder consists of documentation that explains how the views relate to each other, introduces the package to its readers, and guides them through it. What are the relevant views? It depends on your goals. As we saw previously, architecture documentation can serve many purposes: a mission statement for implementors, a basis for analysis, the specification for automatic code generation, the starting point for system understanding and asset recovery, or the blueprint for project planning.

Different views also expose different quality attributes to different degrees. And so forth. Layered views are covered in Chapter 2 "Styles of the Module Viewtype". Chapter 6 "Styles of the Allocation Viewtype" covers the deployment view. Chapter 9 "Choosing the Views" prescribes how to select the set of relevant architectural views for a particular system. Different views support different goals and uses. This is fundamentally why we do not advocate a particular view or collection of views.

The views you should document depend on the uses you expect to make of the documentation. Such an approach never succeeds fully, and adjustments eventually must be made, but the damage of the initial intent is often hard to repair. This invariably leads to problems in development and occasionally in final products. We have collected several real-life reports of such developments. Addison Wesley Longman It may be disconcerting that no single view can fully represent an architecture.

Additionally, it feels somehow inadequate to see the system only through discrete, multiple views that may or may not relate to each other in any straightforward way. It makes us feel like the blind men groping the elephant. The essence of architecture is the suppression of information not necessary to the task at hand, and so it is somehow fitting that the very nature of architecture is such that it never presents its whole self to us, but only a facet or two at a time. The is its strength: each view emphasize certain aspects of the system while de-emphasizing or ignoring other aspects, all in the interest of making the problem at hand tractable.

Nevertheless, no one of these individual views adequately documents the software architecture for the system. That is accomplished by the complete set of views along with information that transcends them. The code structure is frozen at compile-time; it consists of classes in fixed inheritance relationships. In fact, the two structures are largely independent. Trying to understand one from the other is like trying to understand the dynamism of living ecosystems from the static taxonomy of plants and animals, and vice versa.

Section Chapters following in Part I introduce specific views and the uses for each. Copyright Addison Wesley, all rights reserved 34 Draft for review: Do not circulate without permission What is the documentation that applies across views?

Viewtypes and Styles Viewtypes While there is not a fixed set of views appropriate for every system, there are broad guidelines that help us gain a footing. In general, architects need to think about their software three different ways at once: 1. How it is structured as a set of implementation units 2. How it is structured as a set of elements that have run-time behavior and interactions 3. How it relates to non-software structures in its environment Each view we present in Part I falls into one of these three categories, which we call viewtypes.

The three viewtypes are 1. A viewtype constrains the set of elements and relations that exist in its views. Definition A viewtype defines the element types and relation types used to describe the architecture of a software system from a particular perspective. Copyright Addison Wesley, all rights reserved 35 Draft for review: Do not circulate without permission Documenting Software Architectures Clements, Bachmann, Bass, Garlan, Ivers, LIttle, Nord, Stafford Styles Within the confines of a viewtype, recurring forms have been widely observed, even if written for completely different systems.

These forms occur often enough that they are worth writing and learning about in their own right. Perhaps they have interesting properties not shared by others. Perhaps they represent a significant and oft-used variation of the viewtype. Our description of each viewtype includes a section on commonly-occurring forms and variations. We call these architectural styles, or styles for short.

Styles have implications for architectural documentation and they deserve definition and discussion in their own right. Definition An architectural style is a specialization of elements and relationships, together with a set of constraints on how they can be used. A style defines a family of architectures that satisfy the constraints. A style is typically described as a set of element and relation types, together with a set of constraints on how they can be used.

Styles allow one to apply specialized design knowledge to a particular class of systems and to support that class of system design with style-specific tools, analysis, and implementations. The literature is replete with a number of styles, and most architects have a wide selection in their repertoire. The result is a layered style a member of the module viewtype that imparts to systems that employ it qualities of modifiability, portability, and the ability to quickly extract a useful subset.

Different systems will have a different number of layers, different contents in each layer, and different rules for what each layer is allowed to use. However, the layered style is abstract with respect to these options, and can be studied and analyzed without binding them.

The elements in this style are clients, servers, and the protocol connectors that depict their interaction. When employed in a system, the client-server style imparts desirable properties to the system, such as the ability to add new clients with very little effort. Different systems will have a different protocols, different numbers of servers, and different numbers of clients each can support.

However, the client-server style is abstract with respect to these options, and can be studied and analyzed without binding them. Some styles occur in every software system. Decomposition, uses, deployment, and work assignment styles are examples of these. Other styles occur only in systems where they were explicitly chosen and designed in by the architect. Choosing a style for your system, whether covered in this book or somewhere else, imparts a documentation obligation to record the specializations and constraints that the style imposes and the properties that the style imparts to the system.

We call this piece of documentation a style guide. The obligation to document a style can usually be discharged by citing a description of the style in the literature this book, for example. If you invent your own style, however, you will need to write a style guide for it. Copyright Addison Wesley, all rights reserved 36 Draft for review: Do not circulate without permission For more information Each of those sections serves as an example of a style guide.

Books that catalog architectural styles include On the contrary, every system can be seen to be an amalgamation of many different styles. For example, a system might employ a pipe-and-filter style to process input data, but the result is then routed to a database that is accessed by many elements.

This system would be a blend of a pipe-and-filter and shared-data styles. Documentation for this system would include a pipe-and-filter view that showed one part of the system, and a shared-data view that showed the other part. In a case like this, one or more elements must occur in both views and have properties of both kinds of elements. Otherwise, the two parts of the system could not communicate with each other. They likely have multiple interfaces, each providing the mechanisms for letting the element work with other elements in each of the views to which it belongs.

For example, a server in a client-server system might unknown to the other servers or its own clients be implemented using a pipe-and-filter style. Documentation for this system would include a clientserver view showing the overall system, as well as a pipe-and-filter view documenting that server.

A system featuring a database repository may be seen as embodying either a shareddata style or a client-server style. If the clients are independent processes, then the system may be seen embodying a communicating process style. For instance, if the shared-data style gives you all the analysis tools you need, you might choose it in lieu of the other two options. If you need the perspective afforded by more than one style, however, then you have a choice.

You can document the corresponding views separately, or you can combine them into a single view that is roughly speaking the union of what the separate views would be. Combining views is an important concept which is covered in Section 7.

Copyright Addison Wesley, all rights reserved 37 Draft for review: Do not circulate without permission Documenting Software Architectures Clements, Bachmann, Bass, Garlan, Ivers, LIttle, Nord, Stafford All three cases make it clear for the need to be able to document different parts of a system using different views.

That is, a view need not show the entire system. A viewtype restricts the element types modules in the module viewtype, for instance and the corresponding relationship types.

But even within the confines of a viewtype, there are still choices to be made: How the elements are restricted, how they relate to each other, and constraints on their use or configuration. A style is a specialization of a viewtype that reflects recurring patterns of interaction, independent of any particular system. And even within the confines of a style, there are still choices to be made: How the elements and relations in a style are bound to actual elements and relations in a system. In the context of viewtypes and styles, then, a view can now be seen as a style that is bound to a particular system.

For example, Section 4. If you choose the publish-subscribe as a design strategy for your system, then you will produce a publish-subscribe view by naming the actual components, and the events they report and to which they subscribe. Background Style Guides Chapter 1 through Chapter 6 introduce the three viewtypes, and several prominent styles of each.

All of the viewtype and style descriptions in those chapters follow the same outline, which constitutes the standard organization of a style guide: 1. Elements, Relations, and Properties. The description of elements tells what role they play in an architecture and furnishes guidelines for effective documentation of the elements in views.

Relations determine the how the elements work together to accomplish the work of the system. The discussion names the relations among elements, and provides rules on how elements can and cannot be related.

Properties are additional information about the elements and their associated relations. When an architect documents a view, the properties will be given values. A layers view will, for each layer, specify its name, the unit of software it contains, and the virtual machine it provides. This describes what kind of reasoning is supported and, just as important, what kind of reasoning is not supported by views in the viewtype or style.

It describes typical users and their utilization of the resulting views. Its purpose is to help the architect understand to what purpose s a view in this viewtype or style may be put.

Different notations will also support the conveyance of different kinds of information in the primary presentation. Relations to other views. For example, views in two different styles might convey slightly different but related information about a system, and the architect will need a way to choose which one to employ. This section might also include warnings about other views with which a particular view is often confused, to the detriment of the system and its stakeholders. Finally, this section might include a suggestion about useful mappings that can be built by combining a view in this viewtype with another.

But for this to succeed, the distinctions have to be meaningful. Two of the categories rely on words that, it must be admitted, are not historically welldifferentiated: component and module. Like many words in computing, these two have meanings outside our field. Think stereo or home entertainment system components. Well, same here. To complicate matters, both terms have come to be associated with movements in software engineering that share a great deal of overlap in their goals.

Modules led the way. Encapsulation, information hiding, and abstract data types became the dominant design paradigms of the day, and they used module as the carrier of their meaning. Components are currently in the limelight with component-based software engineering and the component-and-connector perspective in the software architecture field. These movements both aspire to achieve rapid system construction and evolution through the selection, assembly, and wholesale replacement of independent sub-pieces.

What Eli Whitney and interchangeable parts did for rifles around , modules and components aim to do for software. Information that was likely to change over the lifetime of a system, such as the choice of data structures or algorithms, was assigned to a module, which had an interface through which its facilities were accessed.

We imply a clear run-time and deployment connotation; that is, the component has interfaces that are accessible at run-time, and at some point in its development life cycle, the component can be independently delivered and installed. Indeed, the operative model is that a component is delivered in the form of an executable binary only -- nothing upstream from that is available to the system-builder at all.

So a module suggests encapsulation properties, with less emphasis on the delivery medium and what goes on at run-time. No so with components. A component suggests independently deployed units of software with no visibility into the development process.

How can something be independently deployable and replaceable without involving encapsulation? That is, how can components not be modular? The usage of the terms in this book reflects their pedigree.

Of course, all of these run-time effects are the result of careful design-time activities. Copyright Addison Wesley, all rights reserved 40 Draft for review: Do not circulate without permission This conceptual overlap is one thing, but a given architecture will usually exhibit a very concrete overlap as well: An element that you document in a module view may well show up in a component-and-connector view as the run-time manifestation of its design-time self.

As a component, the element might be replicated many times across different processors, for example. As a module, however, it would be very unlikely to be duplicated: Why would you ask someone to produce the same piece of code twice?

As a rule, an element shows up once in a module view; a corresponding component might occur many times in a component-and-connector view. Components and modules represent the current bedrock of the software engineering approach to rapidlyconstructed, easily-changeable software systems. As such, they serve as fundamental building blocks for creating -- and documenting -- software architectures.

Some architectures for highly reliable systems replicate the same software across processors and then use a voting scheme; the idea is that a faulty component is overruled by its peers. Does it? How many voter modules would you show in a module view of this system?

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To browse Academia. Skip to main content. By using our site, you agree to our collection of information through the use of cookies. To learn more, view our Privacy Policy. Log In Sign Up. Christine Hofmeister. Dilip Soni. Hofmeister, R. Nord, D. We found that it works well for communicating the static structure the sandlot 3 full movie online free the architecture: the elements of the architecture, their relations, and the variability of a structure. These static properties are much more readily described with it than the dynamic properties. We could applied software architecture christine hofmeister pdf free download describe a particular sequence of vree, but not applied software architecture christine hofmeister pdf free download general sequence. In addition, the ability to show peer-to- peer communication downoad missing from UML. Applied software architecture christine hofmeister pdf free download its original purpose was for detailed design, its ability to describe elements and the relations between them makes it potentially applicable much more broadly. This paper describes our experience using UML to describe the software architecture of a system. applied software architecture christine hofmeister pdf free download Request PDF | On Jan 1, , Christine Hofmeister and others published Applied Software Architecture | Find, read and Join for free The second phase is the software architecture design that is adapted from [24][25][26] [27] [28​][29][30]. What do you want to download? Citation only. Citation and abstract. Download. Through four real-life case studies, this book reveals the insights and best practices of the most skilled software architects in designing software architecture​. These. Applied Software Architecture (paperback) [Hofmeister, Christine, Nord, Robert, Soni, Dilip] Get your Kindle here, or download a FREE Kindle Reading App. Describing Software Architecture with UML C. Hofmeister, R. L. Nord, D. Soni Siemens Corporate Research, Princeton, New Jersey, USA {chofmeister, mord. DownloadApplied software architecture christine hofmeister pdf. Free Download e-books You can run this portable version from any computer and keep your. Ebook Applied Software Architecture pdf by Christine Hofmeister, Dilip Soni, Download book Applied Software Architecture pdf, download almost free pdf. DRAFT COPY FOR REVIEW: DO NOT COPY WITHOUT PERMISSION COPYRIGHT , ADDISON WESLEY ALL RIGHTS RESERVEDDocumenti. Applied Software Architecture. Christine Hofmeister. Robert Nord, Software Engineering Institute. Dilip Soni. © | Addison-Wesley. Share this page. Software Architecture: System Design, Development and Maintenance. Edited by Jan Bosch, Morven Gentleman, Christine Hofmeister, and Juha Kuusela. ISBN purchaser of the work. Printed on acid-free paper. composed in a dynamic tree like structure, the Composite pattern is applied. Builders and. Skip to content. Out of these cookies, the cookies that are categorized as necessary are stored on your browser as they are as essential for the working of basic functionalities of the website. They supplement the standard notations with a few text-based extensions. Necessary cookies are absolutely essential for the website to function properly. Nord, currently the Siemens industrial resident affiliate at the Software Engineering Institute SEI hof,eister Pittsburgh, is working hofmeidter methods for architecture trade-off analysis and product-line practices. Progressive Management. Dilip Soni holds the position of Distinguished Member arcyitecture Technical Staff at SCR where he designs and evaluates software architectures for industrial systems. The file will be sent to your email address. You also have the option to opt-out of these cookies. It could work well as a textbook, or one of several texts for a term course. Click on a series title to see the full list of products in the series. Nord, Daniel J. Click on a series title to see the full list of products in the series. There's a lot of good here, and you can pick out out easily. Necessary Always Enabled. applied software architecture christine hofmeister pdf free download