EMF - The off beat path

Chetan Kumar K, RBEI jointly with Annamalai C, ANCiT

In-memory dbase content D-Base UI display What is a model ??? That is a model!

What is model ???

Placeholder of data

Can “get” and “set” data

Get data Set data Get data Data In memory representation of data

Can be derived from a design

… and so on Will you spend time writing each class ?? Map design and code (model) PIM PSM Or be smart and generate them ?? UML Java

Typical code-generation flow PIM Generator Model Code Generation Engine Code generation templates PSM PSM

EMF a code generator.

EMF is one such code-generator

Let’s you generate concrete classes based on a design (UML)

Let’s look at an example…

Code generation flow – EMF way PIM (ecore) Generator Model genmodel EMF Code Generation Engine Code generation Templates (JET) PSM (Java)

First look of EMF as a code-generator… Tap along guys…

The complete Example UML

Properties of (E)Attribute Data type of attribute EType Default value assigned when containing class is instantiated Default value Literal Find out if an attribute was touched Unsettable Value can be changed or not Changeable Attribute isn’t persisted Transient No associated storage (value can be calculated) Volatile Meaning Property

M-V-C architecture thru EMF

… EMF first impressions.

EMF generates code – will it steal my job!

EMF generates UI stuff – why pay a UI developer ?

Oh god! Something new – too much learning curve

Should I learn “Modeling” or write code now ?

Points 3, 4 courtesy Ed Merks It will be great if these points are myths … wat say ?

EMF.Edit Control how model elements are displayed, edited.

EMF.Edit – bird’s eye view. Contains UI Providers for each Model Element. Content Provider Label Provider Property Source Item Provider Generated implementation for different providers

EMF.Edit control flow – Content Providers “ +” clicked Item provider code eGet api calls Generated api getter(s)

EMF.Edit control flow – Label Providers Item provider code eGet api calls Generated api getter(s)

EMF.Edit control flow – Property Source Tree item selected Item provider code Individual feature’s property descriptor built Property descriptors

EMF.Edit providers – one for all, all for one

Content, Label, Image, and Property source providers all through one provider instance!!

Now that’s called … convenience.

EMF.Edit commands Command based model editing support

EMF.Edit Commands Command based editing of model instances Editing domain UI display “ Set” event as Command Command stack setXXX() undoable Model object

EMF.Edit – How do I create/use Commands ? Model object EMF Editing Domain

Contains command stack

Factories to create commands

EMF.Edit – commands, a deeper look Command interface Existing Command implementations Do you need to implement this interface ??

EMF.Edit – “Change… is here!” Should I have one command per operation ? Can I “record” changes done to a model ? Oooo yess!! Works on change notofications given on each operation ChangeRecorder recoreds these notifications from individual setters. Hence, bulk undo is possible  Can I perform many operations in one command ?

Should I always generate EMF.xxx code ?

Nope … can work with “Dynamic EMF”

Ecore – instantiate model (load) – edit – persist … is possible

Responsible code: EMF Reflective API, EMF Reflective Item Providers

Model xml / xmi load save UI display What after you edit ?? – can ya persist ?

EMF serialization Model object EMF Resource EMF Resource Set xml / xmi

Load and save flows Model object xml / xmi load save EMF Reosource Typical code snippet:

EMF Serialization – behind the scenes

EAnnotations stores mapping b/w XML and Ecore

Any model element can have EAnnotations

Can I directly persist EMF Objects into dbase ? Yes, u can – using EMF Teneo ( http:// www.eclipse.org/modeling/emf/?project = teneo ) Create HbDataStore Create Hibernate Session, Transaction Begin Transaction Create EMF Model root object, make it persistent Create sub-tree under persistent root Commit Tx

Get all students aged > 5

Model Navigation and search Isn’t there a better way than loops ? Can’t I “Query” an EMF model ?? The cool “Query way”

In the end… what is EMF ?

Code generator based on a design (UML)

Means of Java XML binding with Inbuilt persistence mechanism

Command based model editing support, with generated item providers

All in all, a base for applications based on MDA

EMF Transaction Thread-safe editing of a single Model Instance Transaction style editing of model instances

Model editing through multiple threads Thread 1 Change name : “ Jimmy Bend” Thread 2 Change name “ James Bond” name: Harry Potter name: ??? Model object Model object

“ A mind once stretched by a thought never regains its original dimensions”

References