1. CSE Senior Design II Overview: System/Product Design Mike O’Dell Based on an earlier presentation by Bill Farrior, UTA, modified by Mike O’Dell

2. 1 CSE 4317 2 What is System Design?  A progressive definition of how a system will be constructed:  Guiding principles/rules for design (Meta- architecture) Per Portfolio (Release structure)  Top-level structure, design abstraction (Architecture Design)… Per Release (Product Backlog in its entirety)  Details of all lowest-level design elements (Detailed Design)… Per Sprint (lowest-level PBIs)

3. 1 CSE 4317 3 What is System Architecture? bridgewhat how  A critical bridge between what a product will do/look like, and how it will be constructed how  A blueprint for a system and how it will be built abstraction  An abstraction: a conceptual model of what must be done to construct the software system  It is NOT a specification of the details of the construction

4. 1 CSE 4317 4 What is System Architecture?  The top-level breakdown of how a system will be constructed:  design principles/rules  high-level structural components Layers: top-level components Subsystems: intermediate-level components  high-level data elements (external/internal)  high-level data flows, interfaces, and interactions between components (external/internal)

5. 1 CSE 4317 5 What is Detailed Design?  Expands/enhances the system architecture (more detail) refines the architecture to its lowest-level components  Can be used as an “implementation guide” for the product exactly how it should be built key relationships/dependencies between lowest- level components details of interactions between hardware and software. acceptance criteria (testing) for each module

6. 1 6 Layer Example: The Internet Protocol Stack Architecture Layers/Services:  application: supporting network applications  ftp, smtp, http  transport: host-host data transfer  tcp, udp  network: routing of datagrams from source to destination  ip, routing protocols  link: data transfer between neighboring network elements  E.g., Ethernet, 802.11 WLAN  physical: bits “on the wire” application transport network link physical

7. 1 7 Subsystem Example: Voice-Over-IP Speech RTP Compression GatewayLocationProtocol RTCP Physical Layer Protocol TCP/UDP Data Link Protocol IP Control Application UDP SDP Session Initiation Protocol

8. 1 4: Network Layer 4b- 8 Subsystem Example: The Internet Network Layer routing table Routing protocols path selection RIP, OSPF, BGP IP protocol addressing conventions datagram format packet handling conventions ICMP protocol error reporting router “signaling” Transport layer: TCP, UDP Link layer Physical layer Network layer

9. 1 9 Subsystem Example: IEEE 802.11 Architecture (Link Layer) (PCF) (DCF) 1-2 Mbps Infrared, or 2.4-2.5 GHz Freq. hopping or DSSS (1997) 54 Mbps 5-6 GHz OFDM 802.11a (1999) 11 Mbps 2.4-2.5 GHz DSSS 802.11b (2000) 54/108 Mbps 2.4-2.5 GHz OFDM 802.11g/g+ (2003) 248 Mbps (2x2) 2.4/5 GHz MIMO w/ spacial mpx 802.11n (2008) Polling mode CSMA/CA mode

10. 1 10 IEEE 802.11 MAC (Detailed Design) Timing in Basic Access Reference: W. Stallings: Data and Computer Communications, 7th ed PCF: Point Coordination Function (asynchronous, connectionless access) DCF: Distributed Coordination Function (connection oriented access) DIFS: DCF Inter Frame Space (minimum delay for asynchronous frame access) PIFS: PCF Inter Frame Space (minimum poll timing interval) SIFS: Short IFS (minimum timing for high priority frame access as ACK, CTS, MSDU…) MSDU: MAC Service Data Unit MAC frame: Control, management, data + headers (size depends on frame load and type) duration depends on MAC load type duration depends on network condition

11. 1 CSE 4317 11 Example: Team Chronos Architecture

12. 1 CSE 4317 12 Example: Team Chronos Detailed Design

13. 1 CSE 4317 13 Criteria for a Good Design (The Four I’s)  Independence – the modules are independent of each other and each module’s functions are internally-specific and have little reliance on other modules. Changes in the implementation of one module should minimally impact others.  Interfaces/Interactions – the interfaces and interactions between modules are complete and well-defined, with explicit data flows.  Integrity – the whole thing “hangs together”. It’s complete, consistent, accurate… it works.  Implementability – the approach is feasible, and the specified system can actually be designed and built using this design.

14. 1 Design Sequencing in Scrum  Architecture Design:  Done as part of the release planning  Reviewed/updated/refined during Sprint Planning for each Sprint  Modified as necessary based on changes in overall aproach  Detailed Design:  Done during each Sprint, as a task on the Sprint Backlog, for each PBI that is to be implemented in that Sprint CSE 4317 14

15. 1 CSE 4317 15 Final Thoughts – Verification Product Backlog Architecture Detailed Design Implementation Integration Testing Component Testing (a.k.a. Function Testing) Unit (SW & HW) Testing System Validation & Acceptance Testing System Verification System Definition MAP: All PBIs (per Sprint) MAP: All Low-Level Module Interfaces & Interactions MAP: All Modules MAP: All Top-Level Interfaces & Interactions 100% Done Release Planning Sprint Planning Sprint Execution