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2015, Sunday May 3

SOLID Design Principles

I've just updated the documentation part about the SOLID Design Principles.
The former blog article (almost 4 years old!) sounds like a bit deprecated now...
This is why I would extract here an updated version of this material.

Ensure you checked the corresponding part of the mORMot documentation, which is the updated reference, and probably the easiest to read - including links to all the other documentation.

The acronym SOLID is derived from the following OOP principles (quoted from the corresponding Wikipedia article):

  • Single responsibility principle: the notion that an object should have only a single responsibility;
  • Open/closed principle: the notion that "software entities ... should be open for extension, but closed for modification";
  • Liskov substitution principle: the notion that "objects in a program should be replaceable with instances of their subtypes without altering the correctness of that program” - also named as "design by contract";
  • Interface segregation principle: the notion that "many client specific interfaces are better than one general purpose interface.";
  • Dependency inversion principle: the notion that one should "Depend upon Abstractions. Do not depend upon concretions.". Dependency injection is one method of following this principle, which is also called Inversion Of Control (aka IoC).

If you have some programming skills, those principles are general statements you may already found out by yourself. If you start doing serious object-oriented coding, those principles are best-practice guidelines you would gain following.

They certainly help to fight the three main code weaknesses:

  • Rigidity: Hard to change something because every change affects too many other parts of the system;
  • Fragility: When you make a change, unexpected parts of the system break;
  • Immobility: Hard to reuse in another application because it cannot be disentangled from the current application.

Continue reading...

2014, Friday April 18

Introducing mORMot's architecture and design principles

We have just released a set of slides introducing 

  • ORM, SOA, REST, JSON, MVC, MVVM, SOLID, Mocks/Stubs, Domain-Driven Design concepts with Delphi, 
  • and showing some sample code using our Open Source mORMot framework.

You can follow the public link on Google Drive!

This is a great opportunity to discovers some patterns you may not be familiar with, and find out how mORMot try to implement them.
This set of slides may be less intimidating than our huge documentation - do not be terrified by our Online Documentation!
The first set of pages (presenting architecture and design principles) is worth reading.

Feedback is welcome on our forum, as usual.

2013, Thursday March 7

64 bit compatibility of mORMot units

I'm happy to announce that mORMot units are now compiling and working great in 64 bit mode, under Windows.
Need a Delphi XE2/XE3 compiler, of course!

ORM and services are now available in Win64, on both client and server sides.
Low-level x64 assembler stubs have been created, tested and optimized.
UI part is also available... that is grid display, reporting (with pdf export and display anti-aliasing), ribbon auto-generation, SynTaskDialog, i18n... the main SynFile demo just works great!

Overall impression is very positive, and speed is comparable to 32 bit version (only 10-15% slower).

Speed decrease seems to be mostly due to doubled pointer size, and some less optimized part of the official Delphi RTL.
But since mORMot core uses its own set of functions (e.g. for JSON serialization, RTTI support or interface calls or stubbing), we were able to release the whole 64 bit power of your hardware.

Delphi 64 bit compiler sounds stable and efficient. Even when working at low level, with assembler stubs.
Generated code sounds more optimized than the one emitted by FreePascalCompiler - and RTL is very close to 32 bit mode.
Overall, VCL conversion worked as easily than a simple re-build.
Embarcadero's people did a great job for VCL Win64 support, here!

Continue reading...

2013, Saturday January 5

Domain-Driven-Design and mORMot

Implementing Domain-Driven-Design (DDD) is one goal of our mORMot framework.

We already presented this particular n-Tier architecture.

It is now time to enter deeper into the material, provide some definition and reference.
You can also search the web for reference, or look at the official web site.
A general presentation of the corresponding concepts, in the .NET world, was used as reference of this blog entry.

Stay tuned, and ride the mORMot!

Continue reading...