Nikitas N. Karanikolas, Maria Nitsiou, Emmanuel J. Yannakoudakis and Christos Skourlas

1. CUDL Language Semantics, Liven Up the FDB Data Model Nikitas N. Karanikolas, Maria Nitsiou, Emmanuel J. Yannakoudakis and Christos Skourlas

2. FDB framework We have a new database framework that supports dynamically evolving database environments and corresponding schemata, allowing storage and manipulation of • variable length data, • a variable number of fields per record, • variable length records, • manipulation of authority records, • links between records and fields, and • dynamically defined objects (relations in the traditional sense) • multi-value fields • multi-attribute fields • a combination of the last two above Eliminates completely the need for reorganisation at both logical and internal levels The structure of the FDB model allows easy schema evolution

3. FDB MODEL SCHEMA The improvedbasic schema of the proposed framework has the following form (note that primary keys are underlined): • Languages (language_id, lang_name) • Datatypes (datatype_id, datatype_name) • Messages (message_id, language, message) • Entities (frame_entity_id, title) • Tag_attributes (entity, tag, title, occurrence, repetition, authority, language, datatype, length) • Subfield_attributes (entity, tag, subfield, title, occurrence, repetition, language, datatype, length)

4. FDB MODEL SCHEMA (CONT.) • Catalogue (Entity, Frame_object_number, Frame_object_label, Temp_stamp) • Tag_data (Entity, Frame_object, Tag, Repetition, Chunk, Tdata) • Authority_links (From_entity, Auth_tag1, To_entity, Auth_tag2, mn_data_loc) • Subfield_data (Entity, Frame_object, Tag, Tag_repetion, Subfield, Subfld_Repetition, Chunk,sdata) ONE database schema for any application There are no new tables for each new entity

5. Metadata of an FDB database defining the project entity Messages Tag_attributes Subfield_attributes Entities

6. Metadata explained of an FDB database defining the project entity Datatypes Tag_attributes Subfield_attributes Entities We have inserted the value NULL in the length attribute because in certain datatypes (such as int, date, etc) we can not define a specific length

7. Complicated in use The framework is complicated and the management and operation of it is difficult, laborious and time-consuming It requires from the user a very good acquaintance of the • proposed framework, • the structures and organisation of it (metadata anddata) • the processes of the management of the elements that compose it.

8. CUDL Language(Conceptual Universal Database Language) The CUDL language uses simple statements to manipulate the applications that have been created based on the proposed FDB framework With CUDL the user will not be compelled to know in-depth all the details of the structure of information that are supported by this model The user conceives the data as a extension of the relational model with fields of variable length, multiple values, subfields, table in the place of a field value, etc

9. CUDL language The CUDL language undertakes the management of the complicated structures of the FDB model By the use of CUDL, access in the information of an FDB application becomes very simple with the use of particularly simple statements.

10. How the user conceives the structure of a project frame (tuple) Projects Actions

11. The language deals with • Schema definition, to declare the structures, integrity constraints, and access privileges of a database • Schema manipulation, to alter a schema definition • Data manipulation, to populate a database and access FDB data • Transaction management, to define and manage FDB transactions • Connection management, to establish and manage FDB connections • Session management, to set the attributes of an FDB session

12. Schema and Data Manipulation Language We will focus on the Schema andData Manipulation Language Both aspects of the language use variations of the statements: • FIND • ALTER • DELETE • ADD to manipulate values from the meta-data and data sets of the model

13. Find The most frequently used operation in data sources is the data retrieval operation which retrieves instances from a set The FIND statement specifies which instances to include in the result set and it is used to retrieve zero or more instances from one or more sets in a data source In specifying a FIND query, the user specifies a description of the desired result set, but he does not specify what physical operations must be executed to produce that result set. The result from the implementation of a FIND statement is a new virtual set that contains the elements that were asked by the user or the value NULL, if no values meet the requirements of the Find statement.

14. Find • Find values in the meta-data sets (example 1) # Find tag_attributes when title = ‘DVD_code’

15. Find • Find values in the meta-data sets (example 2) # Find tag_attributes when entity = ‘customer’ and repetition=‘r’ and datatype=‘char’

16. Find • Find values in the data sets (example 1) # Find data when entity = ‘customer’ and tag =‘cust_code’ Informally this statement takes the sequence of all customers and creates a sequence of their ‘cust_code’. The result of typing in this query is that a sequence of ‘cust_CODE’ is printed out.

17. Find • Find values in the data sets (examples 2, 3, 4) # Find data when entity = ‘videos’ and tag = ‘title’ This statement retrieves the titles of the videos (the projected field is ‘title’). # Find data when entity = ‘videos’ and tag = ‘title’ frame Notice that by adding the keyword frame we take all the data of all the tags for every frame that meets the user requirements. The condition and tag=‘title’ is unnecessary and can be excluded from the statement. # Find data when entity = ‘videos’ and tag = ‘title’ restr data like ‘M%’ and tag = ‘year’ restr data = ‘2003’ We have to mention that the conditions can be composed by a where part and a restriction part. For example the condition and tag = ‘title’ restr data like ‘M%’ has a where part tag = ‘title’ and a restriction part restr data like ‘M%’. The fields that take place in the where part of the conditions also participate in the results (projected fields).

18. Add The ADD statement specifies which values to include in a database set In specifying an ADD query, the user specifies the desired values to be inserted in a specific desired set, but he does not specify what physical operations must be executed for the insertion The result from the implementation of an ADD statement is a new augmented set that contains also the new elements that were asked by the user or merely the old set if the new values can not de added

19. Add • Addition of meta-data Let us for example assume that there is no tag ‘language’ for the entity ‘videos’. The statement in the CUDL language: # Add tag_attributes entity = ‘videos’ title = ‘language’ will result in the tuple shown in Table 5 stored in the tag attributes set.

20. Add • Addition of data (example of the creation and population of a whole frame) # Add data set 'title' = ' A Movie ' when entity = ‘videos’ new frame # Add data set 'year' = '2007' when entity = ‘videos’ and tag = ‘title’ restr data = ‘A Movie’ … # Add data set ‘actor1’ = ‘Al Patsino’ when entity = ‘videos’ and tag = ‘title’ restr data = ‘A Movie’ # Add data set ‘actor2’ = ‘Robert DeNiro’ when entity = ‘videos’ and subfield = ‘actor1’ restr data = ‘Al Patsino’ Note that by adding the key-phrase ‘new frame’ the data are inserted in a new frame. Otherwise if those keywords are omitted the data are inserted in an already existing frame that the user must specify by adding the keywords when tdata = ‘<some value>’. If the user does not use the specification referred above then a suitable message is presented to him and the statement is not executed.

21. Delete The DELETE statement specifies which values to exclude from a database set In specifying a DELETE query, the user specifies the desired values to be removed from a specific set, but he does not specify what physical operations must be executed for the removal The result from the implementation of a DELETE statement is a new set that does not contain the elements that the user asked to be removed or the old set if the values can not de removed

22. Delete • Deletion from a metadata set: # Delete tag_attributes when entity = ‘videos’ and title = ‘actors’ This will result in the deletion from the set tag_attributes of all the values that correspond to the combination of the entity ‘videos’ and the tag (title) ‘actors’. In the simplified relational view that the user conceives these statements remove the field actors from the table videos. The deletion will only occur under the condition that there do not exist data for the ‘actors’ tag and also the specified tag does not participate in any authority link (set authority_links).

23. Delete • Deletion from a data set: # Delete data ‘category’ when entity = ‘videos’ and tag = ‘DVD_code’ restr tdata = ‘Vid01’ # Delete data whole_frame when entity = 'videos' and tag = 'DVD code' restr data = 'Vid01‘ We have to mention that the set ‘catalogue’ is affected as well, by this delete statement. As the set catalogue is used to keep the values of the entity and each frame for this entity that the set tag_data contains, since a whole frame from the set tag_data was erased the corresponding entity and frame from the set catalogue should be erased too.

24. Alter The ALTER statement specifies which values to alter in a database set In specifying a ALTER query, the user specifies the desired values to be modified from a specific set, but he does not specify what physical operations must be executed for the modification The result from the implementation of an ALTER statement is a new set that does not contain the altered elements that the user asked for or the old set if the values can not de modified

25. Alter • Alter values in a metadata set # Alter tag_attributes set occurrence = ‘M' when entity = ‘customer’ and title = ‘address’

26. Alter • Alter values in a data set # Alter data set ‘title’ = ‘Movie1’ when entity = ‘videos’ and tag= ‘DVD_code’ restr data = ‘Vid01’ and tag = ‘title’ restr data = ‘A Movie’ This statement modifies the data value of the tag title ‘A Movie’ to the data value ‘Movie1’ . This will only occur under the condition that the specified tag (in the specified frame) has no tag repetitions under the tag title

27. Conclusions The FDB model can form the basis for the creation and maintenance of dynamically evolving database environments TheCUDL language undertakes the management of the complicated structures of the FDB model and the user experiencesa simple extension of the relational model with the usage of very simple statements

28. Thank you for your attention !!! nnk@teiath.gr mbnit@aueb.gr