Culture (Language ) Analyzing activities. Community (Roles, Norms, Conventions, Rules ) Activities motivated by Objectives

Transcription

1 Analyzing activities Culture (Language ) Community (Roles, Norms, Conventions, Rules ) Activities motivated by Objectives Actions driven by Goals Operations determined by Conditions Artifacts (objects of activity or tools) 1

2 Information system design Real World Requirements Collection and Analysis Conceptual Design Data Model Mapping 2

3 Metadata schema design Requirements identification Collect and analyze data about the activities an information object is used in to identify the metadata that needs to be collected and maintained Empirical data collection Observations (observe users in the activities what are some of the resource attributes used by the user?) Interviews (ask users questions about the activities and metadata needs/uses in those activities) Expensive (we will not use this approach in this course) Analytic/Conceptual data generation and analysis Develop hypothetical stories scenarios - of the activity Inexpensive Ideally, one should use both the empirical and conceptual design methods in design requirements identification 3

4 What is metadata problem scenario? A concrete description of activity that the user engages in when performing a specific task, and which includes sufficiently detailed claims about positive or negative aspects of particular metadata presence or absence in the system s data model (adapted from Carroll 1995). 4

5 Claims Analysis (Go04) Scenario are used not only as a shared vision among analysts and designers but also as key material for analysis Claims enumerate implicit causal relations such as tradeoffs in a scenario Helps designers discuss the consequences of design moves at various levels of analysis Claim examples Adding the SomeContentDB_ID element to the metadata schema + will allow to reference and integrate metadata and content from SomeContentDB, - but requires someone to populate and maintain that element, - can increase the time needed to load and render a metadata record on an user s computer screen 5

6 Scenario Based Requirements Analysis (Go04) 6

7 Scenario Exploration (Go04) Starts from a basic scenario illustrating the root concept Participants put 5W+1H" and What-If questions to the scenario For each question, participants provide solution as scenarios The scenario and questions iteratively evolve as the analysis progress 7

8 Scenario Exploration (cont.) (Go04) Example - Basic scenario: Sending a message Scenario: Ben is working on a presentation describing the Jewish immigrant life in Colorado at the end of 19th century. He already has some relevant texts, but he would like to have some photographs from that period as well. He was thrilled to learn that SomeCity Public Library had a cultural heritage database which might include photographs of Colorado communities from the late 19th and early 20th centuries. Question: What if Ben is a genealogy researcher and looking for information about his ancestors who emigrated from Eastern Europe? Scenario: Ben is looking for information about his ancestors who emigrated to the US from Minsk and settled in Colorado at the end of 19th century. He was thrilled to learn that SomeCity Public Library had a cultural heritage database which might include photographs of Colorado communities from the late 19th and early 20th centuries. 8

9 Use of scenarios [Adapted from Go04] An inexpensive way to generate empirical data of metadata use or needs, which then can be used as an explicit rationale for designing more usable metadata models or evaluating the existing ones Scenarios are detailed descriptions of potential/hypothetical user system - metadata interaction instances, including the context of interaction Similar to iterative design, scenarios can be written iteratively making their claims increasingly specific and precise at every stage 9

10 Conceptual modeling Entity Relationship (ER) Model - high-level conceptual data model. Includes entities and links (relationships) among them Entities distinguishable objects, can be concrete or abstract Entity set a set of entities of the same type Attributes a set of properties/characteristics that define the type of an entity There is no entity without attributes Modeling objects as Entities vs Attributes Model as an attribute if only a single feature of the object is used Key a set of Attributes that uniquely identify Entities Data Model a group of concepts that specifies the element structure and content rules for an information object 10

11 Conceptual modeling (cont.) Entity Relationship Modeling Relationships associate two or more entities with each other Structural Constraints on Relationship Types Arity Relationships can be binary, tertiary, and so on Cardinality the number of relationship instances that Entity can participate in Common cardinality ratios for binary relationships - 1:1, 1:N, M:N Participation constraint - specifies whether the existence of an entity depends on its participation in this particular relationship Required (Existence Dependency), Non-Required (Partial) 11

12 Translating E-R diagrams into relational tables Collection of relations Each relation is a table where each row represents a collection of related data values Values describe an entity or a relationship instance Table name usually coincides with the name of an entity or an relationship Column names coincide with the names of the entity or relationship attributes and specify how to interpret data in the rows Table is called a relation, a row is called tuple, column name is called attribute 12

13 Relational tables Title Metadata fundamentals for all librarians System architecture with XML Author Year Publisher Caplan 2003 ALA Daum & Merten 2003 Morgan Kaufmann Organizes and stores Data Efficiently - removes redundancy and overlaps Data is stored as atomic relations Schema information and business rules are centrally defined and maintained Effective for Client Server Architecture can provide each client with a customized view without changing the database structure! 13

14 XML vs. Relational Tables XML encoded objects combine object Schema with content Inefficient for Data Storage adding metadata to each and every record creates redundancy and increases the file size Effective for Data Exchange and Preservation - data is Selfdescribing and Portable 14

15 Design process example Develop scenarios Shuheng is doing a bioinformatics course project to determine the taxonomy of the giant panda from the phylogenetic perspective. She wants to collect the ND2 gene sequence of the giant panda and six different kinds of bears from the GenBank to do phylogenetic analysis. In particular, she is trying to determine whether the giant panda belongs to Ursidae as true bears or is an independent species. To answer this question, the student wants to collect the ND2 gene sequence from multiple individuals within a species. Even though they have their own identifiers, several records retrieved from the GenBank are repetitive or redundant, representing the same sequence. As no identity information about the specimen (individual) is provided in the GenBank, the student has to examine the publication information in each record or read the publications that discuss the data to determine if the sequence was collected from the same individual or not. John wants to analyze proteins in Androgen-repressed human prostate cancer (ARCaP) cells. He has the names and International Protein Index (IPI) accession numbers (identifiers) of these proteins, and wants to identify their cellular locations, functions, and pathways by searching the NCBI databases and the Pathway Interaction Database. However, these databases do not identify proteins by the IPI accession number. 15

16 Design process example (cont.) Develop scenarios Ben is working on a presentation describing the Jewish immigrant life in Colorado at the end of 19th century. He already has some relevant texts, but he would like to have some photographs from that period as well. He was thrilled to learn that SomeCity Public Library had a cultural heritage database which might include photographs of Colorado communities from the late 19th and early 20th centuries. Alice is the newly hired digital librarian at SomeCity Public Library. She found an amazing collection of the images of manuscripts from a local historical society. She is anxious to put the collection online, but she does not know who owns the rights on the images 16

17 Design process example (cont.) Requirements suggested by the scenarios To meet Ben s and Alice s information needs, the image database schema needs to have at least the following elements: Description Date when the photo was taken Location Subject Format Copyright 17

18 Design process example (cont.) Construct a ER diagram to elaborate on, document, and communicate design ideas N User USES Resource N Subject Description Format ID Date Copyright Location 18

19 Design process example (cont.) Relational table ID Description Date Location Subject Copyright Format 1 A man in black 1889 Colorado Jewish Immigration SomeCity Jewish Society JPEG 2 A girl in white dress 1886 Colorado Some Community Some Society TIFF 19

20 Design process example (cont.) XML Schema <?xml version="1.0" encoding="utf-8"?> <xs:schema xmlns:xs=" <xs:annotation> <xs:documentation xml:lang="en">somecity Public Digital Library Schema</xs:documentation> </xs:annotation> <xs:element name="id" type="elementnumeric" /> <xs:element name="description" type="elementstring" /> <xs:element name="subject" type="elementstring" /> <xs:complextype name="elementstring"> <xs:simplecontent> <xs:extension base="xs:string"> <xs:attribute ref="xml:lang" /> </xs:extension> </xs:simplecontent> </xs:complextype> <xs:complextype name= record"> <xs:sequence> <xs:element name= id" type= elementnumeric"/> <xs:element name= description" type= elementstring"/> </xs:sequence> </xs:complextype> </xs:schema> 20

21 Design process example (cont.) Object/record instance in XML <?xml version="1.0" encoding="utf-8"?> <record xmlns=" <id>1</id> <description>a man in black </description> <date>1889</date> <location>colorado</location> <subject>jewish Immigration Society</subject> <format>jpeg</format> </record> 21