TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS

Transcription

1 Mestrado em Engenharia de Redes de Comunicações TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS Metodologias de Software - Software Methodologies 1

2 Outline TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 2

3 Software Emphasis and Methodology Domain Operating Context Focus of Software Process Main Notations Used Telecom Network, service and management architectures Moving from architectures, to functional entities to protocols SDL MSC ASN.1 GDMO Internet Suite of Internet protocols to support transport and applications Add new protocols as the need arises RFC822 text based protocols (SNMP, HTTP.) ASN.1 Information technology Varied computing and database applications Moving from use case definition to executable code UML XML TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 3

4 Issues in Large-Scale, Critical Software Software Architectures Communications Protocols High-level Analysis, Design and Specification Detailed Modelling Methods and Tools Distribution Software Reuse Implementation Role of Scripting and XML TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 4

5 Managing Complexity Analysing, specifying, designing and implementing ICT software systems relies on precise expression of: Requirements Behaviour Interfaces Testing.. Hence, several methods are used for precise expression TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 5

6 Comparing Telecom and IT Applications Aspect Telecommunications Application Enterprise Application Components Lean, fine-grained objects collected in components Rapid creation, short lifetime Data access objects Persistent Invocations Asynchronous, related to events, messages and triggers Synchronous Transactions Short completion deadlines Many transactions concurrently Cause state transitions in client and server Processes use linked transactions Database transactions Slower completion Data Sources Static provisioned data: user profiles, service profiles Dynamic: location, history, usage,.. Database Servers Back-end Systems Intensity Communication Computing Database TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 6

7 Modeling & Description Methods There is no one method but leaders are: Use-case descriptions: UML Static class descriptions: UML Interfaces: IDL (single), Java Class relationships: inheritance, association, : (OMT, UML) Dynamic object interactions: UML, MSC Messages (operations): (ASN.1, IDL...) Internal state and process descriptions: SDL Managed objects: ASN.1, GDMO, x-xml Analysis & Design: RM-ODP, MDA Good conversion rules and tools are required TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 7

8 Modeling & Description Methods UML Unified Modeling Language IDL Interface Description Language MSC Message Sequence Charts ASN.1 Abstract Syntax Notation One SDL Specification and Description Language XML Extensible Markup Language GDMO Generic Description of Managed Objects RM-ODP - Reference Model for Open Distributed Processing MDA Model Driven Architecture TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 8

9 From Model to Implementation MDA Protocol Specification System Specification Managed Object Definition Modelling Layer UML SDL MSC ASN.1 GDMO Architecture Layer TINA Parlay/ OSA/JAIN INCM Meta Protocol TMN Reuse Layer SC EJB Corba Beans SIB XML MIB Distribution Layer CORBA RMI SOAP SIP INAP CMISE Implementation Layer IIOP SCTP TCP/IP TCAP TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 9

10 Service-oriented or Network-oriented Plethora of Architectures INCM (IN Conceptual Model) IP Telephony: H.323, SIP Parlay/OSA/JAIN 3GPP /3GPP2 OMA TISPAN 4G TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 10

11 Plethora of Protocols Classical PSTN/IN ISUP Q.931 INAP Mobile Networks MAP CAMEL Call Control RAS Q.931 SIP TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 11

12 Plethora of Protocols Routing Protocols PNNI OSPF RIP BGP, Internet Applications HTTP FTP SMTP TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 12

13 Essentials of Protocol SPECIFICATION Message Vocabulary in Human-readable form (E.g. High-level Language) MESSAGE INSTANCE Compulsory and optional data field values Message Services: (Semantics) what the messages mean Procedures: allowed and meaningful sequences of messages, error handling Encoding Rules: Message format for efficient transmission ENCODING Efficient format for transmission ENVIRONMENT TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 13

14 Classification of Methods for: Description of Protocols, Processes and Objects TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 14

15 High-Level Analysis & Design: RM-ODP and MDA RM-ODP: formal basis for fundamental concepts and architectures MDA: portability, interoperability and reusability of components Step 1: What are the system requirements? RM-ODP Enterprise Viewpoint MDA Computation Independent Model MDA-CIM Enterprise Viewpoint Step 2: What info and processing is required? Step 3: How are computing objects packaged? Information Viewpoint Computational Viewpoint Platform Independent Model MDA-PIM Information Viewpoint Computational Viewpoint Step 4: What supporting platform is required? Step 5: What technology is to be used? Engineering Viewpoint Technology Viewpoint Platform Specific Model Generalisation TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 15

16 High-Level Analysis & Design: SDL and MSC SDL: internal behaviour of a communicating, finite state machine MSC: observable behaviour via messages passing between entities SDL Standard Defines the structure and semantics of SDL MSC Standard SDL Object- Oriented Definition Supports definition Of System, Blocks, Signals, Routes, Processes, Concrete System Specification Implementation-independent definition of the target system As instances of standard types Concrete System MSC Graphical Textual Simulator MSC ( Actual ) TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 16

17 High-Level Analysis & Design: SDL and MSC TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 17

18 High-Level Analysis & Design: SDL and MSC TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 18

19 Generic and Implementation-Specific models Meta-object Facility MOF Defines the structure and semantics of UML Computationally Independent Model Platform Independent ( PIM ) Model Unified Modelling Language - UML Supports class definition Platform Specific ( PSM ) Model Class Definition in UML Profile Language Specific Class Implementation-independent definition of classes making up the model Profile for each target language: IDL, Java, C++, XML, ASN.1, GDMO, Instance of Class Defines concrete working objects TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 19

20 Object and Data definition languages UML: notation for expressing object definitions Unified Modelling Language ( UML ) n1 link n2 Use Case Diagram Activity Diagram Sequence Diagram Class Diagram Statetransition Diagram Component Diagram Deployment Diagram Use Case Diagram: proposed functionality of system: a single unit of meaningful work Activity Diagram: a dynamic view of interactions Sequence Diagram: shows objects lifelines down the page and their interactions (Messages) Class Diagram: static view of the object s attributes and behaviour State Diagram: sequence of states an object goes through in response to events. Component Diagram: pieces of software, that make up a system Deployment Diagram: models the runtime architecture of a system TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 20

21 Object and Data definition languages Telecom Definition Languages UML RM-ODP Informational Viewpoint Distributed Communicating Process Structure & Behaviour Description Specification & Description Language -SDL Message Sequence Charts - MSC * Information Structure Definition GDMO ASN.1 *Note: SDL and MSC are more detailed than UML State and Sequence Diagrams n1 link n2 TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 21

22 Object and Data definition languages Telecom Definition Languages example of State Modeling IN Basic Call State Model DPa Point-in-Call 1 DPb Point-in-Call 2 SDL States &Transitions Start State Input A Task Output UML State Model DP = Detection Point: Report occurrence and test trigger Resume at Specified DP PIC = Point in Call: Wrapper around processing Logic End State UML Convention: At each transition On-event[if-condition-is-true] /action ^emit-message TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 22

23 ASN.1- Abstract Syntax Notation One ASN.1: formal definition of objects for communications protocols and managed objects Example for protocols Example for managed object TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 23

24 HTML - HyperText Markup Language HTML is the lingua franca for publishing hypertext on the Web. It is a non-proprietary format, based upon SGML, for describing the structure of hypermedia documents. It uses embedded codes for logical markup, using tags like <B> and </B> to make bold text, or structure text into tables, and make hypertext links, interactive forms, headings, paragraphs, lists and more. TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 24

25 HTML-HyperText Markup Language <?xml version="1.0" encoding="utf-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" " <html xmlns=" xml:lang="en-us" lang="en-us"> <head profile=" <meta http-equiv="content-type" content="text/html; charset=utf-8" /> <body> <h1 id="logo"> <img alt="the World Wide Web Consortium (W3C)" height="48" width="315" src="/icons/w3c_main" /></h1> <h2 id="slogan">leading the Web to Its Full Potential...</h2> <div id="item241" class="item"> <h3><img alt="" width="17" height="11" src="/icons/right" />Best Practices for XML Internationalization</h3> </div> </body> </html> Extract of an actual XHTML web page XHTML - Extensible HyperText Markup Language TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 25

26 extensible Markup Language Uses HTML-like Tags Always come in pairs e.g. <tag>.. </tag> May be nested Indicate the type of content Uses Document Type Definition (DTD) to create allowed tags for specific application Uses Stylesheets to output on different devices Allows alternative actions for hyperlink Does not need whole document transfer Uses Unicode encoding TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 26

27 extensible Markup Language TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 27

28 extensible Markup Language XML is essentially a method of exchanging information between applications in documents that simultaneously identifies the data fields and contains the data. Typical application of XML in specific contexts: Internet Protocol Data Record (IPDR): definition of document formats for accounting and billing information Web Services Definition Language (WSDL): a way of describing Web services VoiceXML: definition of data and scripts for control of interactive voice response units (IVR) TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 28

29 extensible Markup Language Use of XML documents to transfer data requires several supporting protocols and operations: Objective: Application uses DTD to extract data and insert into the XML instance document exchanged with another application Solution: Encapsulate the XML document in a Simple Object Access Protocol (SOAP) message Result: The encoded SOAP message is then transferred as the message body in an HTTP request with a POST method TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 29

30 extensible Markup Language Relationship between XML, SOAP and HTTP SOAP - Simple Object Access Protocol TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 30

31 Examples of other Markup Languages Communities: MathML: allows mathematics to be inserted in Web pages VML: renders vector graphics in a web page CML: used by Chemists to render molecular structure graphically Telecom oriented: CPL: allows a user to specify how incoming Internet telephony calls are to be handled WML: allows internet content to be delivered to terminals such as cellphones, pagers, PDAs TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 31

32 After HTML and XML. HTML is essentially about formatting on-screen documents XML makes data self-describing: tags identify the defined type of data uses stylesheet for formatting data Next step is capturing meaning: relationships among data objects (defined in XML) Resource Description Framework (RDF) is a technology for expressing meaning of concepts and terms, that is the relationships between entities described in XML The Semantic Web is the goal of this initiative TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 32

33 Distributed Systems The distributed nature of software processes to support services and applications is a pervading consideration in Emerging Networks With convergence and high dependence on logic and data, we are concerned with truly distributed systems To deal with the distributed nature of computing the approach is through the Open Systems Interconnection (OSI) model with a strong emphasis on openness TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 33

34 Distributed Systems The standard way of invoking services is defined as software interfaces with defined method calls, relying on accompanying data definitions The API (Application Program Interface) may be defined in an implementation language independent form, for example UML, IDL or XML, or in a standardised programming language such as Java or C++ In a fully distributed system, the interacting components may be distributed over several computing nodes, unaware of the location of components that they invoke TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 34

35 Distributed Systems The most common methods used are: RMI Remote Method Invocation Uses Java for invoking a method on a remote computer The Java Virtual Machine (JVM) provides platform independence, hiding heterogeneity in operating systems and networks Web Services Model Interfaces are defined and described using XML service identified by Uniform Resource Identifier (URI) service is invoked by passing XML-formatted messages conveyed by Internet protocols, such as SOAP and HTTP service is described in WSDL. CORBA Common Object Request Broker TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 35

36 Distributed Systems Web Services CORBA Elements TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 36

37 TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 37

38 References and Readings WWW TÓPICOS AVANÇADOS EM REDES ADVANCED TOPICS IN NETWORKS 38