物件導向軟體之架構(Object-Oriented Software Construction)探討

It is shown that, particularly for terrestrial cellular telephony, the interference-suppression feature of CDMA (code division multiple access) can result in a many-fold increase in capacity over analog and even over competing digital techniques. A single-cell system, such as a hubbed satellite network, is addressed, and the basic expression for capacity is developed. The corresponding expressions for a multiple-cell system are derived. and the distribution on the number of users supportable per cell is determined. It is concluded that properly augmented and power-controlled multiple-cell CDMA promises a quantum increase in current cellular capacity. >

On the capacity of a cellular CDMA system

The objective of this paper is to give a comprehensive introduction to applied cryptography with an engineer or computer scientist in mind. The emphasis is on the knowledge needed to create practical systems which supports integrity, confidentiality, or authenticity. Topics covered includes an introduction to the concepts in cryptography, attacks against cryptographic systems, key use and handling, random bit generation, encryption modes, and message authentication codes. Recommendations on algorithms and further reading is given in the end of the paper. This paper should make the reader able to build, understand and evaluate system descriptions and designs based on the cryptographic components described in the paper.

[서평]「Applied Cryptography」

/pdf/a-break-in-the-clouds-towards-a-cloud-definition-svovsw1r5a.pdf

A Break in the Clouds: Towards a Cloud Definition

From the Book:
“Clean code that works” is Ron Jeffries’ pithy phrase. The goal is clean code that works, and for a whole bunch of reasons:
Clean code that works is a predictable way to develop. You know when you are finished, without having to worry about a long bug trail.Clean code that works gives you a chance to learn all the lessons that the code has to teach you. If you only ever slap together the first thing you think of, you never have time to think of a second, better, thing. Clean code that works improves the lives of users of our software.Clean code that works lets your teammates count on you, and you on them.Writing clean code that works feels good.But how do you get to clean code that works? Many forces drive you away from clean code, and even code that works. Without taking too much counsel of our fears, here’s what we do—drive development with automated tests, a style of development called “Test-Driven Development” (TDD for short). 
In Test-Driven Development, you:
Write new code only if you first have a failing automated test.Eliminate duplication.

Two simple rules, but they generate complex individual and group behavior. Some of the technical implications are:You must design organically, with running code providing feedback between decisionsYou must write your own tests, since you can’t wait twenty times a day for someone else to write a testYour development environment must provide rapid response to small changesYour designs must consist of many highly cohesive, loosely coupled components, just to make testing easy

The two rules imply an order to the tasks ofprogramming:
1. Red—write a little test that doesn’t work, perhaps doesn’t even compile at first
2. Green—make the test work quickly, committing whatever sins necessary in the process
3. Refactor—eliminate all the duplication created in just getting the test to work


Red/green/refactor. The TDD’s mantra.

Assuming for the moment that such a style is possible, it might be possible to dramatically reduce the defect density of code and make the subject of work crystal clear to all involved. If so, writing only code demanded by failing tests also has social implications:
If the defect density can be reduced enough, QA can shift from reactive to pro-active workIf the number of nasty surprises can be reduced enough, project managers can estimate accurately enough to involve real customers in daily developmentIf the topics of technical conversations can be made clear enough, programmers can work in minute-by-minute collaboration instead of daily or weekly collaborationAgain, if the defect density can be reduced enough, we can have shippable software with new functionality every day, leading to new business relationships with customers


So, the concept is simple, but what’s my motivation? Why would a programmer take on the additional work of writing automated tests? Why would a programmer work in tiny little steps when their mind is capable of great soaring swoops of design? Courage.
Courage
Test-driven development is a way of managing fear during programming. I don’t mean fear in a bad way, pow widdle prwogwammew needs a pacifiew, but fear in the legitimate, this-is-a-hard-problem-and-I-can’t-see-the-end-from-the-beginning sense. If pain is nature’s way of saying “Stop!”, fear is nature’s way of saying “Be careful.” Being careful is good, but fear has a host of other effects:
Makes you tentativeMakes you want to communicate lessMakes you shy from feedbackMakes you grumpy

None of these effects are helpful when programming, especially when programming something hard. So, how can you face a difficult situation and:
Instead of being tentative, begin learning concretely as quickly as possible.Instead of clamming up, communicate more clearly.Instead of avoiding feedback, search out helpful, concrete feedback.(You’ll have to work on grumpiness on your own.) 

Imagine programming as turning a crank to pull a bucket of water from a well. When the bucket is small, a free-spinning crank is fine. When the bucket is big and full of water, you’re going to get tired before the bucket is all the way up. You need a ratchet mechanism to enable you to rest between bouts of cranking. The heavier the bucket, the closer the teeth need to be on the ratchet.

The tests in test-driven development are the teeth of the ratchet. Once you get one test working, you know it is working, now and forever. You are one step closer to having everything working than you were when the test was broken. Now get the next one working, and the next, and the next. By analogy, the tougher the programming problem, the less ground should be covered by each test.

Readers of Extreme Programming Explained will notice a difference in tone between XP and TDD. TDD isn’t an absolute like Extreme Programming. XP says, “Here are things you must be able to do to be prepared to evolve further.” TDD is a little fuzzier. TDD is an awareness of the gap between decision and feedback during programming, and techniques to control that gap. “What if I do a paper design for a week, then test-drive the code? Is that TDD?” Sure, it’s TDD. You were aware of the gap between decision and feedback and you controlled the gap deliberately.

That said, most people who learn TDD find their programming practice changed for good. “Test Infected” is the phrase Erich Gamma coined to describe this shift. You might find yourself writing more tests earlier, and working in smaller steps than you ever dreamed would be sensible. On the other hand, some programmers learn TDD and go back to their earlier practices, reserving TDD for special occasions when ordinary programming isn’t making progress.

There are certainly programming tasks that can’t be driven solely by tests (or at least, not yet). Security software and concurrency, for example, are two topics where TDD is not sufficient to mechanically demonstrate that the goals of the software have been met. Security relies on essentially defect-free code, true, but also on human judgement about the methods used to secure the software. Subtle concurrency problems can’t be reliably duplicated by running the code.

Once you are finished reading this book, you should be ready to:
Start simplyWrite automated testsRefactor to add design decisions one at a time

This book is organized into three sections.
An example of writing typical model code using TDD. The example is one I got from Ward Cunningham years ago, and have used many times since, multi-currency arithmetic. In it you will learn to write tests before code and grow a design organically.An example of testing more complicated logic, including reflection and exceptions, by developing a framework for automated testing. This example also serves to introduce you to the xUnit architecture that is at the heart of many programmer-oriented testing tools. In the second example you will learn to work in even smaller steps than in the first example, including the kind of self-referential hooha beloved of computer scientists.Patterns for TDD. Included are patterns for the deciding what tests to write, how to write tests using xUnit, and a greatest hits selection of the design patterns and refactorings used in the examples.

I wrote the examples imagining a pair programming session. If you like looking at the map before wandering around, you may want to go straight to the patterns in Section 3 and use the examples as illustrations. If you prefer just wandering around and then looking at the map to see where you’ve been, try reading the examples through and refering to the patterns when you want more detail about a technique, then using the patterns as a reference.

Several reviewers have commented they got the most out of the examples when they started up a programming environment and entered the code and ran the tests as they read.

A note about the examples. Both examples, multi-currency calculation and a testing framework, appear simple. There are (and I have seen) complicated, ugly, messy ways of solving the same problems. I could have chosen one of those complicated, ugly, messy solutions to give the book an air of “reality.” However, my goal, and I hope your goal, is to write clean code that works. Before teeing off on the examples as being too simple, spend 15 seconds imagining a programming world in which all code was this clear and direct, where there were no complicated solutions, only apparently complicated problems begging for careful thought. TDD is a practice that can help you lead yourself to exactly that careful thought.

Test Driven Development: By Example

Quality of service, QoS, has a great impact on wider adoption of cloud computing. Maintaining the QoS at an acceptable level for cloud users requires an accurate and well adapted performance analysis approach. In this paper, we describe a new approximate analytical model for performance evaluation of cloud server farms under burst arrivals and solve it to obtain important performance indicators such as mean request response time, blocking probability, probability of immediate service and probability distribution of number of tasks in the system. This model allows cloud operators to tune the parameters such as the number of servers and/or burst size, on one side, and the values of blocking probability and probability that a task request will obtain immediate service, on the other.

/pdf/performance-analysis-of-cloud-centers-under-burst-arrivals-3vq83g13fd.pdf

Performance Analysis of Cloud Centers under Burst Arrivals and Total Rejection Policy

Advances in Conceptual Modeling - Theory and Practice

ER 2006 Tutorials.- Conceptual Modeling for Emerging Web Application Technologies.- State-of-the-Art in Modeling and Deployment of Electronic Contracts.- ER 2006 Workshops.- Preface to BP-UML 2006.- Extending the UML 2 Activity Diagram with Business Process Goals and Performance Measures and the Mapping to BPEL.- UN/CEFACT'S Modeling Methodology (UMM): A UML Profile for B2B e-Commerce.- Capturing Security Requirements in Business Processes Through a UML 2.0 Activity Diagrams Profile.- Finite State History Modeling and Its Precise UML-Based Semantics.- A UML Profile for Modeling Schema Mappings.- Model to Text Transformation in Practice: Generating Code from Rich Associations Specifications.- CoMoGIS 2006 - 3rd International Workshop on Conceptual Modeling for Geographic Information Systems.- Preface for CoMoGIS 2006.- Keynote.- Large-Scale Earth Science Services: A Case for Databases.- Spatial and Spatio-temporal Data Representation.- Time-Aggregated Graphs for Modeling Spatio-temporal Networks.- An ISO TC 211 Conformant Approach to Model Spatial Integrity Constraints in the Conceptual Design of Geographical Databases.- Access Control in Geographic Databases.- Optimizing Representation and Access to Spatial Data.- VTPR-Tree: An Efficient Indexing Method for Moving Objects with Frequent Updates.- New Query Processing Algorithms for Range and k-NN Search in Spatial Network Databases.- A ONCE-Updating Approach on Moving Objects.- Spatio-temporal Data on the Web.- A Progressive Transmission Scheme for Vector Maps in Low-Bandwidth Environments Based on Device Rendering.- Map2Share - A System Exploiting Metadata to Share Geographical Information.- CoSS 2006 - International Workshop on Conceptual Modeling of Service-Oriented Software Systems.- Preface for CoSS 2006.- Building Semantic Web Services Based on a Model Driven Web Engineering Method.- Choreographies as Federations of Choreographies and Orchestrations.- Designing Web Services for Supporting User Tasks: A Model Driven Approach.- Designing Service-Based Applications: Teaching the Old Dogs New Tricks ...or Is It the Other Way Around?.- ECDM 2006 - 4th International Workshop on Evolution and Change in Data Management.- Preface for ECDM 2006.- Keynote.- Reduce, Reuse, Recycle : Practical Approaches to Schema Integration, Evolution and Versioning.- Accepted Papers.- A DAG Comparison Algorithm and Its Application to Temporal Data Warehousing.- Handling Changes of Database Schemas and Corresponding Ontologies.- Evolving the Implementation of ISA Relationships in EER Schemas.- Schema Change Operations for Versioning Complex Objects Hierarchy in OODBs.- Representing Versions in XML Documents Using Versionstamp.- OIS 2006 - 1st International Workshop on Ontologizing Industrial Standards.- Preface for OIS 2006.- Accepted Papers.- XBRL Taxonomies and OWL Ontologies for Investment Funds.- A Semantic Transformation Approach for ISO 15926.- Modeling Considerations for Product Ontology.- Ontologizing EDI Semantics.- WSDL RDF Mapping: Developing Ontologies from Standardized XML Languages.- QoIS 2006 - 2nd International Workshop on Quality of Information Systems.- Preface for QoIS 2006.- to QoIS06.- Information Quality, System Quality and Information System Effectiveness: Introduction to QoIS'06.- Information System Quality.- Quality-Driven Automatic Transformation of Object-Oriented Navigational Models.- HIQM: A Methodology for Information Quality Monitoring, Measurement, and Improvement.- Evaluating the Productivity and Reproducibility of a Measurement Procedure.- Data Quality.- Quality of Material Master Data and Its Effect on the Usefulness of Distributed ERP Systems.- Towards Automatic Evaluation of Learning Object Metadata Quality.- Expressing and Processing Timeliness Quality Aware Queries: The DQ2L Approach.- SemWAT 2006 - 1st International Workshop on Semantic Web Applications: Theory and Practice.- Preface for SemWAT 2006.- Semantic Web Applications (I).- Combining Declarative and Procedural Knowledge to Automate and Represent Ontology Mapping.- Visual Ontology Alignment for Semantic Web Applications.- Automatic Creation of Web Services from Extraction Ontologies.- Semantic Web Applications (II).- An Architecture for Emergent Semantics.- Semantic Web Techniques for Personalization of eGovernment Services.- Query Graph Model for SPARQL.

Advances in conceptual modeling - theory and practice : ER 2006 Workshops BP-UML, CoMoGIS, COSS, ECDM, OIS, QoIS, SemWAT, Tucson, AZ, USA, November 6-9, 2006 : proceedings

When a large number of machine-to-machine (M2M) terminals attempt to access the Long-Term Evolution (LTE)/LTE Advanced (LTE-A) cellular network using the physical random access channel (PRACH), congestion and overload may result, which can lead to serious degradation of performance for both M2M and human-to-human (H2H) terminals. The main cause for this is the inherent complexity of the four-way handshake used for random access, which is well suited for H2H terminal access but unsuitable for massive M2M access. In this paper, we describe an efficient scheme for concurrent M2M and H2H access on the PRACH, which separates the resources for M2M and H2H access at the level of preamble codes and avoids the use of the four-step handshake for M2M terminals by implementing a carrier sense multiple access with collision avoidance (CSMA/CA) overlay network using the designated preamble codes. We analyze the performance of the scheme for both H2H and M2M traffic and show the values of the most important design parameters that enable this scheme to support concurrent access by H2H and M2M terminals with little performance degradation.

Sharing It My Way: Efficient M2M Access in LTE/LTE-A Networks

The success of architecture-centric development of software product lines is critically dependent upon the availability of suitable architecture assessment methods. While a number of architecture assessment methods are available and some of them have been widely used in the process of evaluating single product architectures, none of them is equipped to deal with the main challenges of product line development. In this paper we present an adaptation of the Architecture Tradeoff Analysis Method (ATAM) for the task of assessing product line architectures. The new method, labeled Holistic Product Line Architecture Assessment (HoPLAA), uses a holistic approach that focuses on risks and quality attribute tradeoffs - not only for the common product line architecture, but for the individual product architectures as well. In addition, it prescribes a qualitative analytical treatment of variation points using scenarios. The use of the new method is illustrated through a case study.

Vojislav B. Misic

Papers

Performance Analysis of Cloud Centers under Burst Arrivals and Total Rejection Policy

Advances in Conceptual Modeling - Theory and Practice

Advances in conceptual modeling - theory and practice : ER 2006 Workshops BP-UML, CoMoGIS, COSS, ECDM, OIS, QoIS, SemWAT, Tucson, AZ, USA, November 6-9, 2006 : proceedings

Sharing It My Way: Efficient M2M Access in LTE/LTE-A Networks

A holistic architecture assessment method for software product lines