This presentation is dedicated to the architectural design of BExIS, which describes the overall architecture, layering, molecularity, important components, and the data access techniques using an ORM. The video of the talk is available at: https://www.youtube.com/watch?v=txLIDgEn59M

1. BEXIS Tech Talk Series
#3: The System Architecture
Javad Chamanara
March 2016

2. Recall from the first talk
• Requirements
– Data Lifecycle Management
– Generic
– Extensible
– Portable
– Scalable
BEXIS Tech Talk #3: The System Architecture 2

3. Requirements -> DLM
• Flexible Data Structures
• Data Submission
• Validation
• Preserving
• Metadata Management
• Versioning
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4. Recall from the second talk
BEXIS Tech Talk #3: The System Architecture 4
DataMetadata
Data StructureMetadata Structure Semantics Geo
Administration Security
«use»
«use»
«use» «use»
«use»

5. Core Conceptual Model
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SearchPublishing
CMLand Use
Reservation
Data
Submission

6. DLM APIs
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Core Functions
Data Structure Mgmt.
Data Mgmt.
Metadata Mgmt.
Sem. Data Mgmt.

7. Multi DBMS data access
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DB2 PgS
Data Access
Core Functions
...
Relational
XML
GIS
Multi DBMS support
Vendor unlocking
ORM support
Customization support
Data Structure Mgmt.
Data Mgmt.
Metadata Mgmt.
Sem. Data Mgmt.

8. Access to the Core Functions
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DB2 PgS
Data Access
Core Functions
UI Framework
...
Modularity
Integration

9. Access to Core Functions
BEXIS Tech Talk #3: The System Architecture 9
DB2 PgS
Data Access
Core Functions
UI
UI Framework
...
Modularity
Integration
Synthesis Work
Semantic Search
Analytics
User Defined
Spatial Querying
External Tools
Web Services
Archiving
Import/ Export
Publishing

10. Security
BEXIS Tech Talk #3: The System Architecture 10
DB2 PgS
Data Access
Security
Core Functions
UI
UI Framework
...
Modularity
Integration
Synthesis Work
Semantic Search
Analytics
User Defined
Spatial Querying
External Tools
Web Services
Archiving
Import/ Export
Publishing

11. Architectural Patterns
• Generic User Interaction
• MVC
• APIs, Web APIs
• Data Access
• Services
BEXIS Tech Talk #3: The System Architecture 12

12. Generic User Interaction
BEXIS Tech Talk #3: The System Architecture 13
Presentation
User
Services Core Services Security Data Access

13. Presentation: MVC
BEXIS Tech Talk #3: The System Architecture 14
class mvc
Controller
ModelView
«observe»
«observe»

14. Simplified MVC
BEXIS Tech Talk #3: The System Architecture 15
class mvc
View ViewModel
Controller
«observe»
Dependency

15. Classes Engaged in an Interaction
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Controller
View
Service Framework API
Data
GIS Data
ViewModel
«Observe»
«use»
«use»

16. BExIS MVC Sequence Diagram
BEXIS Tech Talk #3: The System Architecture 17
User
Controller Model ServiceViewRouting Engine
Request()
action()
GetData()
Populate()
Bind()
Render()

17. MVC Constraints
• Passive Models
• Request more data
• Manipulate entities
• Models are POCOs
• Models have no access to services
• Models may have builder/ transformers
• Views can interact with controllers’ actions only
– Interchanging data
– Calling controllers’ actions either sync or async
• No lazy loading in the Views (populated models+ajax)
BEXIS Tech Talk #3: The System Architecture 18

18. Controller
View
Service Framework API
Data
GIS Data
ViewModel
«Observe»
«use»
«use»
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Presentation
Data
Business

19. Integration
• Service Based
– Modules provide a set of services
• HTTP/S + Auth
– Internal authentication
– Remote LDAP/ Active Directory integration
• Authorization
– Restricts access to controllers’ actions
– Public actions
– Public data
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20. Public APIs
• Web API
– API namespace
• Module/Controller/Action
• Verb
• Data
• www.example.com/dcm/datasets/1
• www.example.com/dcm/datasets/1/versions
• www.example.com/dcm/versions/10
• Querystrings are allowed
• No versioning on APIs! Always the latest!!
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21. Modularity
• Modules
– A set of related user facing functions
– To extend the application’s functionality
• Layering
– Presentation
• MVC
– Service
• Access to Core services, DLM, external services, etc.
– Data Access
• Own Database/data
• Direct access to the DB/data (not recommended)
BEXIS Tech Talk #3: The System Architecture 22

22. Modularity
• Integration
– Shell integration: menus, themes, scripts, etc.
– Authorization
• Introducing actions, to be secured, to the system
• Automatic security trimming/ action authorization
• Notes
– Deployment
– Hot plug-abilities
– Upgrading/versioning
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23. Data
• Relational data
– Schema evolution
– Schema generation
– Data versioning
– Vendor/tool independence
• XML data
– File based XML
– RDBMS based XML
• GIS data
– External systems
– Integrated querying
– Security
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24. Data Access
• ORM
– NHibernate
– Vaiona
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25. Data Access Patterns
• Repository pattern
– CRUD on entities
– Querying using
• LINQ to objects
• HQL
• Native SQL (queries, views, stored-procedures)
• Vendor specific customization
– Relationship traversal
• Laziness/Eagerness
• object graph traversal
– Automatic entity state/context management
– Based on:
http://martinfowler.com/eaaCatalog/repository.html
BEXIS Tech Talk #3: The System Architecture 26

26. Data Access Patterns
• Unit of Work pattern
– Business Transaction Management
– Concurrency Control
– Operating on multiple repositories
– Transactions
• Distributed Transaction Coordination
• Transparent transaction management
• Ambient transaction detection/reuse
– Web request/session/user aware transaction mgmt.
– Automatic commit on request/session termination
– Based on:
http://martinfowler.com/eaaCatalog/unitOfWork.html
BEXIS Tech Talk #3: The System Architecture 27

27. Data Access Patterns
• Aggregates
– Cluster of entities and their dependents
• Datasets and their Versions
• Units of measurement and their conversion formula
– Simplify the service layer
– Packaged as units of work
– Better business level operation/transaction mgmt.
– Look at:
http://martinfowler.com/bliki/DDD_Aggregate.ht
ml
BEXIS Tech Talk #3: The System Architecture 28

28. Data Access Patterns
• Materialization
– Complex entity serialized as XML
– Stored in field of a table row
– Materialize on read
• Reads the XML and loads the entity
– Dematerialize on write
• Serializes the object as an XML document
– Used in Data Tuples of dataset versions
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29. ORM example
• Dataset as an Aggregate area
• DataTuple
• DataCell
• Versions
• Associations
BEXIS Tech Talk #3: The System Architecture 30

30. Dataset aggregate: conceptual
diagram
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Dataset
Dataset VersionDataset Stage
Tuple
DataValue
Data Cell
Data Structure
1
+Current Stage
1
10..1
1
1
+Variable Values
{Delta Association,
Only Structured Data}

31. Dataset aggregate: class diagram
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32. General Record Structure
Identification
Payload
Associations
Versioning
Audit
State
Technical
Extra
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33. General Record Structure
Identification
Payload
Associations
Versioning
Audit
State
Technical
Extra
BEXIS Tech Talk #3: The System Architecture 34
Identification:
it holds information about primary
keys, key generation, etc.

34. General Record Structure
Identification
Payload
Associations
Versioning
Audit
State
Technical
Extra
BEXIS Tech Talk #3: The System Architecture 35
Payload:
is the business data that the
table holds

35. General Record Structure
Identification
Payload
Associations
Versioning
Audit
State
Technical
Extra
BEXIS Tech Talk #3: The System Architecture 36
Associations:
relationships between this table
and others (also itself). Connected
and not connected foreign keys fall
into this category, too.

36. General Record Structure
Identification
Payload
Associations
Versioning
Audit
State
Technical
Extra
BEXIS Tech Talk #3: The System Architecture 37
Versioning:
information about version number
and timestamp. This is the technical
data level versioning to be used in
concurrency control. It is not the
business level data versioning.

37. General Record Structure
Identification
Payload
Associations
Versioning
Audit
State
Technical
Extra
BEXIS Tech Talk #3: The System Architecture 38
Audit:
the information about the person or
the system who has changed the data
in addition to the time, action, and
other information

38. General Record Structure
Identification
Payload
Associations
Versioning
Audit
State
Technical
Extra
BEXIS Tech Talk #3: The System Architecture 39
State:
shows the current status of the data record.
It can be set by business workflows or
quality control, e.g., “Approved”, “Rejected”,
“Published”, “Locked”, etc.

39. General Record Structure
Identification
Payload
Associations
Versioning
Audit
State
Technical
Extra
BEXIS Tech Talk #3: The System Architecture 40
Technical:
this part is used for development purposes
and is not intended to be used by data
owners or data consumers

40. General Record Structure
Identification
Payload
Associations
Versioning
Audit
State
Technical
Extra
BEXIS Tech Talk #3: The System Architecture 41
Extra:
It is an XML field to provide a place for minor extensions and
reduce the amount and frequency of changes in the
database schema (and sometimes data). Also, it can be
considered as an exertion point for customization in
different scenarios.

41. ORM mapping: The entity
<hibernate-mapping xmlns="urn:nhibernate-
mapping-2.2" assembly="BExIS.Dlm.Entities"
namespace="BExIS.Dlm.Entities.Data">
<class xmlns="urn:nhibernate-mapping-2.2"
name="Dataset" table="Datasets">
</class>
</hibernate-mapping>
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42. ORM mapping: Non payload
attributes
<id name="Id" type="Int64">
<column name="Id" />
<generator class="native" />
</id>
<version name="VersionNo" type="Int32">
<column name="VersionNo" />
</version>
<property name="Extra" type="System.Xml.XmlDocument,
System.Xml, Version=4.0.0.0, Culture=neutral,
PublicKeyToken=b77a5c561934e089">
<column name="Extra" not-null="false" sql-
type="xml" />
</property>
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43. ORM mapping: State attributes
<component name="StateInfo">
<property name="State" type="string">
<column name="State" />
</property>
<property name="Timestamp" type="DateTime">
<column name="StateTimestamp" not-null="false"/>
</property>
<property name="Comment" type="string">
<column name="StateComment" />
</property>
</component>
Same for Creation Info and Modification Info
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44. ORM mapping: Payload
attributes
<property name="LastCheckIOTimestamp" type="DateTime">
<column name="LastCheckIOTimestamp" />
</property>
<property name="CheckOutUser" type="string">
<column name="CheckOutUser" />
</property>
BEXIS Tech Talk #3: The System Architecture 45

45. ORM mapping: Associations
<set name="Versions" inverse="true" lazy="true" order-
by="Timestamp desc" cascade="all-delete-orphan">
<key>
<column name="DatasetRef" />
</key>
<one-to-many class="DatasetVersion" />
</set>
BEXIS Tech Talk #3: The System Architecture 46

46. Dataset aggregate: Database
Schema
BEXIS Tech Talk #3: The System Architecture 47

47. How to work with the model
DatasetManagerService dms = new DatasetManagerService();
Dataset ds = dms.CreateEmptyDataset(sds, rp, ms);
DatasetVersion workingCopy =
dms.GetDatasetWorkingCopy(ds);
// edit the version
dms.CheckInDataset(ds, “new version is created.", user);
BEXIS Tech Talk #3: The System Architecture 48

48. Inside the “Check In” service
method
public void CheckInDataset
(Int64 datasetId, string comment, string userName)
{
using(IUnitOfWork uow = this.GetUnitOfWork())
{
IRepository<Dataset> repo =
uow.GetRepository<Dataset>();
Dataset ds = repo.Get(…).FirstOrDefault();
// Check-in logic here…
repo.Put(ds);
uow.Commit();
}
}
}
BEXIS Tech Talk #3: The System Architecture 49

49. Outlook
Whats next in the talk series?
• General purpose components
• Third party components
• Cross-cut functionalities
BEXIS Tech Talk #3: The System Architecture 51

50. 5252
Thanks!
Questions?
Contact:
javad.chamanara@uni-jena.de
http://fusion.cs.uni-jena.de/bexis
BEXIS Tech Talk #3: The System Architecture
Acknowledgment