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1. 3rd Technical MedWet Codde Meeting, MCU Athens, 9-11 February 2006 State of the art and perspectives of Web Information Systems (WIS)- Design considerations and functions Panagiotis Katsaros Dept. of Informatics Aristotle University of Thessaloniki 54124 Thessaloniki, GREECE ICN IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

2. Presentation overview State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece Web Information System (WIS) design concepts- 7 slides WIS architecture - 2 slides Dynamic Web Pages - 3 slides Security policies for Web data - 5 slides Multilanguage support - 2 slides Geographic Information Systems - 12 slides Web-based GIS ICN IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

3. WIS design concepts I State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece 1. THE CONTENT ICN - integration of one or more data sources - use of hypertext links to redirect the user in different views of the data provided by the WIS - use of search forms to request data based on specific search criteria 2. THE STRUCTURE - categorization hierarchy that will allow users to classify content into various topics. - use of the devised structure to provide different navigation aids: category tree, keyword search etc IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

4. WIS design concepts II State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece ICN 3. THE LAYOUT - each category with all information related to it is represented in its own Web page - all children and children-children categories are shown on the same page IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

5. WIS design concepts III State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece 3. THE LAYOUT (continued) ICN - each category is represented by its own ID and for this reason ID can be used to dynamically create the corresponding page requested by a user - we define separate interfaces for different user roles (reader, editor, administrator) - the editor interface just adds the functions of creating, editing or deleting data records - the administrator interface allows the user to add, change and remove users of the system and to edit their access rights IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

6. WIS design concepts IV State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece 3. THE LAYOUT (continued) ICN - When users log in with a password, they are identified by the system (authenticated). Attached to each user is his/her role of reader, editor or administrator. This information allows the system to dynamically create the corresponding user interface. - The system has to check whether the authenticated user has the necessary access rights (is authorized) to perform an action or to access a specific piece of information. If that action is not allowed it is not enabled or even not shown. IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

7. WIS design concepts V State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece 3. THE LAYOUT (continued) ICN - users should be supported by easy-to-use and consistent interfaces. The addition of new data should not be difficult, even for inexperienced users. - it is necessary to not allow addition of inconsistent data - consistency mandates that the same navigational element should always behave in a similar way - navigational elements should not be put on two different places on the page and the same navigational element should always be represented in the same way IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

8. WIS architecture I State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece ICN IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

9. WIS architecture II State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece ICN Data storage layer: - relational database scheme - mechanism for generating Web pages dynamically Application layer: - functions to store, process, present and pick up content Representation layer: - page-oriented user interface that handles user interaction IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

10. Dynamic Web Pages I State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece Two kinds of dynamic web pages: - program code executed by the web browser to control the user interface behavior - program code executed by the web server to create web pages on the fly when they are requested by a client application ICN Technologies for web browser based dynamic code: - scripting languages like JavaScript, ECMA Script, VBScript - Java applets Technologies for web server based dynamic code: - Server Side Includes (SSI) - Common Gateway Interface (CGI) - Active Server Pages (ASP) or PHP - Perl - Java Servlets - JDBC and ODBC IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

11. Dynamic Web Pages II State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece First approach to create dynamic server-side pages: to write an HTML page with placeholders for content that should be retrieved dynamically from a database HTML code is mixed with program code of another programming language (e.g. ASP, JSP) the program code is then replaced by actual data when the page is requested ICN IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

12. Dynamic Web Pages III State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece Second approach to create dynamic server-side pages: to embed the HTML code inside the execution code when the page is requested, the content is dynamically fetched Common Gateway Interface (CGI): the user interface designer has to split the HTML code into many portions and incorporate these into the complex execution code ICN Third approach to create dynamic server-side pages: use of XML instead of HTML for the definition of the structure of a page an XML file can be transformed with the help of XSLT into any other data format such as, HTML advantage: several output formats can be produced for different user interface types by using the same XML document it is possible to generate a Web version (HTML) and a printed version of the same XML data without changing the XML document IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

13. Security policies for Web data protection I State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece The simpler access control mechanism: - use a “log in” page that picks up the user name and password and checks it against the users that are known by the WIS - when the user is authenticated the “logged in” state is saved for the session - every page can check that state in its dynamic code and depending on the state, show or hide its content - role-dependent behavior of the WIS: every page and form can check the role of the user in its dynamic code and, according to that role, offer users a choice of actions they can perform e.g. a data provider should only be able to edit his own documents but not the documents of others ICN IGUT Basic principle: Complex security policies impose high administration costs. MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

14. Security policies for Web data protection II State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece Issues and requirements in defining security policies for Web data: ICN - subject qualification: the subjects are the users entitled to access data. Subjects are referred to on the basis of an “ID” based mechanism, exploiting some information for their identification in the system. Examples of identity information could be a user name, an IP address or a combination of user name and IP address. Web user population is highly dynamic in that the number and type of users is not known a priori and can change very frequently over time. We employ the notion of subject credentials. Subject credentials assert arbitrary properties of a subject such as characteristics and properties deriving from relationships the subject has with other subjects (e.g. qualifications within an organization). User roles can be specified as sets of subject credentials. IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

15. Security policies for Web data protection III State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece - protection granularity levels: the access control policies must be flexible enough to support spectrum of protection granularity levels, such as all the data regarding an item, a portion of this data, or the data regarding a set of items. Having the possibility of specifying fine-grained protection objects, different policies can be formulated. ICN - access privileges: specification of access control policies requires also the identification of the privileges that subjects can exercise on protection objects. Privileges correspond to the different modes with which data to be protected can be accessed (e.g. browsing, editing etc). - specification levels: security policies can be specified at two different levels, either instance-level or schema-level. Instance-level policies apply to a single instance (i.e. an item) only, while schema-level policies apply to a set of instances simultaneously. IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

16. Security policies for Web data protection IV State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece A policy type for access control <Who, What, How, KindOfAccess, KindOfGrant> - Who{UserID, Credential} denotes the way subjects are qualified in the policy, either identity-based or credential-based - What{Item, typeOfitem, setOfItems, setOfTypesOfItems} denotes the target protection objects to which the policy applies. In this way, it is possible to specify policies either at the instance or schema level. - How{whole, portion, content} denotes the kind of policy protection granularity for the target protection object specified in the What field. - KindOfAccess{browsing, authoring} denotes the kind of access to be allowed/denied on the protection object(s) of the policy. - KindOfGrant{Grant, Deny} denotes the kind of authorization to be granted. ICN IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

17. Security policies for Web data protection V State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece An example policy type <Credential, Item (wetland), portion, browsing, grant> corresponds to a permission grant policy for credential-based browsing of a selected portion of an item ICN The shown policy type specification is a design tool, allowing the Security Administrator to select the most appropriate type of policy for a target source. Important to remember: The level of flexibility required in specification of complex security policies determines the accompanied development (programming) and administration costs. IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

18. Multilanguage support I State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece Proper multi-language support requires a certain structure in the underlying relational database. We need to have a master table of all of the different words in all of the different languages. ICN When a new language is to be added, no new tables or columns are added (this may be done only when developing the WIS). Only new rows to existing tables and columns are added and this allows to support an unlimited number of languages. IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

19. Multilanguage support II State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece A multi-language database example ICN features table with multi-language support IGUT master list of language attributes MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

20. GIS I State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece What is a GIS? (more than one definition) GIS have been developed in recent years for the purpose of using and studying geographic information. Geographic information is information that expresses and describes the locations of objects and features (what is where on the earth) like for example: - physical features or phenomena like rivers, roads, forests etc - human features or phenomena like population, migration etc With GIS it is possible to map, model, query, and analyze large quantities of data all held together within a single database. ICN IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

21. GIS II State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece What is the value of combining geographic information? A single set of geographic information is limited in its analysis potential. It can be used to provide information about the location of the features to which it relates and this can be used as the basis for recording and investigating distributions. However, the great appeal of GIS stems from their ability to integrate different geographical information themes and to provide a powerful repertoire of analytical tools to explore them. The geography, or location, is used as the common denominator – the link. In this way, the GIS has the potential to generate new information on patterns and relationships between multiple sets of geographic information that would otherwise be missed, and to aid in answering more complex questions or decision making. ICN IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

22. GIS III State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece An example of a GIS based analysis: map overlay analysis GIS allows us to arrange information about a given region or city as a set of maps with each map displaying information about one characteristic of the region. Each of these separate thematic maps is referred to as a layer, coverage, or level. Each layer is carefully overlaid on the others so that every location is precisely matched to its corresponding locations on all the other maps. The bottom layer represents the grid of a commoncoordinate system. ICN IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

23. GIS IV State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece What are the essential elements of geographic information? - Location of the geographic information – maps use a coordinate system to allow locations to be read - The shape (geometry) of the geographic information – the shape of the features and themes are drawn onto the map - The description of the geographic information – a legend provides descriptions of the shapes drawn on the map ICN IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

24. GIS V State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece What are the essential elements of geographic information? - Metadata are also called “data about data”. They are used to determine if the data meets the user’s needs. They play a critical role in GIS system interoperability. Metadata describe different aspects of data, including: Identification – What is the name of the data set? Who developed the data set? What geographic area does it cover? What themes of information does it include? Restrictions on accessing or using the data. Data Quality – Information that allows a user to decide if the data are suitable for his or her purpose. What is the positional and attribute accuracy? Are the data complete? Entity and Attribute Information – What geographic information (roads, houses etc) is included? How is the information encoded and what do the codes mean? ICN IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

25. GIS VI State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece How do we represent shapes? Two methods: 1. Physical features and human features are reduced to points, lines and polygons which are linked to information that describes them (attributes). This method of representing the world around us is called vector. 2. Physical features and human features are divided into a regular grid with each cell in the grid holding descriptive information about its contents. This method of representing the world around us is called raster. ICN Shape representation with vector According to the vector method, all shapes, no matter how complicated, can be simplified to a number of very simple tables containing information about the shapes that are linked together. The linked tables together use a database to draw the shapes. Possible to represent: points, lines, polygons IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

26. GIS VII State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece Example of a vector representation ICN IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

27. GIS VIII State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece Shape representation with raster Physical features and human features can usually be divided into a grid and this is a much more simple way of representing the world around us than using points, lines and polygons. An example of a lake in a park Raster is limited in the reality with which it can represent geographic information and the detail that the raster data is able to provide is limited by the size of the grid that is used. ICN IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

28. GIS IX State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece Describing vector data In the same way that the information needed to draw points, lines and polygons using the vector method can be held in one or more tables, so the attribute information can also be held in tables. The following table holds information about two polygons that form boundaries of two agricultural fields. The crop planting history of the last two years is recorded in the table. ICN Describing raster data Raster data does not use tables of information linked to the grid shapes to describe the information. Instead, each grid cell contains a single code that represents the geographic information held within the cell. IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

29. GIS X State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece The components required to represent the physical features and human features in a geographic information system ICN IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

30. GIS XI State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece Spatial relationships GIS have the power to record more than location and simple attribute information. In some situations, we will want to examine spatial relationships based upon location: - Absolute and relative location - Distance between features - Proximity of features - Features in the “neighborhood” of other features - Direction and movement from place to place - Boolean relationships of “and”, “or”, “inside”, “outside”, “intersecting”, “non-intersecting” etc. ICN IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

31. GIS XII State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece Functional relationships among geographic features and their attributes Information about how features are connected and interact in real-life terms. As an example, consider the case of assessing habitats, where various environmental conditions function together to define the optimal living environments for certain species. ICN Logical relationships among geographic features and their attributes Logical relationships involve “if-then” and “and-or” conditions that must exist among features stored in the dataset. As an example, development may disallowed in the habitat of some endangered species. IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

32. Web-based GIS State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece Motivation for the development of a Web-based GIS - To provide a widely accessible on-line tool that will offer a powerful repertoire of analytical tools to explore the data - To make geographic information available for use within a large spatial data infrastructure (interoperability support) - To utilize the geographic information available in a large spatial data infrastructure (geographical information e.g. for population density, road network etc) - To support decision making for geographically distributed organizations ICN IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

33. Conclusion State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece We provided an overview of the technologies and design concerns we (would like to) take into account in the development of the MedWet WIS - WIS basic design concepts - WIS architecture - Security policies for the protection of Web data - Multilanguage support - Coverage of basic GIS functionality - Technology perspectives ICN IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

34. 3rd Technical MedWet Codde Meeting, MCU Athens, 9-11 February 2006 MedWet WIS Access Control Policy Panagiotis Katsaros Dept. of Informatics Aristotle University of Thessaloniki 54124 Thessaloniki, GREECE ICN IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE

35. Basic principles State of the art and perspectives of WIS Panagiotis Katsaros / Aristotle University of Thessaloniki, Greece The level of flexibility required in specification of complex security policies determines the accompanied development (programming) and administration costs. ICN Complex security policies impose high administration costs. We propose an access control mechanism that will balance the need for a functional and at the same time cost-effective solution (limited development and administration costs). The proposed mechanism takes into account and keeps open the prospects for the implementation of more advanced security administration functionality. IGUT MedWet information and knowledge network for the sustainable development of wetland ecosystems / MedWet CODDE