Synopse Open Source

2012-10-06

Delphi XE3 is preparing (weak) reference counting for class instances

By AB4327-GANDI, 2012-10-06. Pascal Programming

In Delphi, you have several ways of handling data life time, therefore several ways of handling memory:

For simple value objects (e.g. byte integer double shortstring and fixed size arrays or record containing only such types), the value is copied in fixed-size buffers;
For more complex value objets (e.g. string and dynamic arrays or record containing such types), there is a reference counter handled by each instance, with copy-on-write feature and compiler-generated reference counting at code scope level (with hidden try..finally blocks);
For most class instances (e.g. deriving from TObject), you have to Create then Free each instance, and manage its life time by hand - with explicit try..finally blocks;
For class deriving from TInterfacedObject, you have a RefCount property, with _AddRef _Release methods (this is the reference-counted COM model), and you can use Delphi interface to work with such instances - see this blog article.

With Delphi XE3, we were told that some automatic memory handling at class level are about to be introduced at the compiler and RTL level.
Even if this feature is not finished, and disabled, there are a lot of changes in the Delphi XE3 Run Time Library which sounds like a preparation of such a new feature.

2012-10-03

Today's sugar: "stored AS_UNIQUE" syntax

By AB4327-GANDI, 2012-10-03. Open Source › mORMot Framework

The limited RTTI available in earlier versions of Delphi we want to support (starting with Delphi 6/7) lacks of attributes.
Even the attribute feature of newer Delphi version is not compatible with the one exposed by the FreePascalCompiler, we also want to support.

Therefore, our ORM expects unique columns in a TSQLRecord published property to be defined as stored false.
It could be misleading at first, as reported by several users.
In order to avoid any confusion, we just added a new constant named AS_UNIQUE.

2012-09-14

Updated mORMot benchmarks on another HW configuration

By AB4327-GANDI, 2012-09-14. Open Source › mORMot Framework

With a refreshed hardware, and the latest code modifications of the framework code, I run again the benchmark sample.

The new PC has an Intel Core i7-2600 CPU, running on Windows Seven 64-bit, with anti-virus (Norton) fully enabled.
Oracle 11g database is remotely accessed over a corporate network, so latency and bandwidth is not optimal.
Still no SSD, but a standard 7200 rpm hard drive of 500 GB.

The results are impressive, when compared to the previous run using a Core 2 Duo CPU - mORMot's optimized code achieves amazing speed on this platform.
And I guess the 8MB of L3 cache of the Core i7 does wonders with our code.

2012-09-10

Don't be confused by our little mORMot !

By AB4327-GANDI, 2012-09-10. Open Source › mORMot Framework

We got some interesting feedback in reddit.

I looked at your website and it is a bit confusing to be honest. After browsing for five minutes I still can't figure out what it is that this framework is supposed to do. It seems like a strange mish mash of different unrelated libraries. You've got some client-server stuff. Some SQLite stuff, which doesn't really fit with client server stuff as it is not a server database. Then there is some PDF stuff.
What is the big picture? What does this actually do?

Such confusion does make sense. Our web site is split into forum, blog, source-code repository and tickets, some wiki pages.

Here are some points of orientation.

2012-09-09

Synopse mORMot framework 1.17

By AB4327-GANDI, 2012-09-09. Open Source › mORMot Framework

Our Open Source mORMot framework is now available in revision 1.17.

The main new features are the following:

Direct ODBC support, with any edition of Delphi - even the Starter edition;
Array DML support for very fast insertion with Oracle;
SQLite3 engine updated to latest revision 3.7.14, including Delphi 5 compiler support;
Performance enhancements, especially for external databases and our very fast in-memory engine (e.g. for unique properties, or with SQlite3 writing speed), with a new included benchmark tool;
Breaking use change for *FillPrepare() methods;
Better Unicode support in report and pdf generation (e.g. font-fallback is now implemented);
TDataSet available for SynDB units;
A lot of fixes and improvements.

We have some very exciting features on the road-map for the next 1.18 release, like direct Event/CallBacks handling.
Stay tuned!

2012-09-06

Roadmap: interface-based callbacks for Event Collaboration

By AB4327-GANDI, 2012-09-06. Open Source › mORMot Framework

On the mORMot roadmap, we added a new upcoming feature, to implement one-way callbacks from the server.
That is, add transparent "push" mode to our Service Oriented Architecture framework.

Aim is to implement notification events triggered from the server side, very easily from Delphi code, even over a single HTTP connection - for instance, WCF does not allow this: it will need a dual binding, so will need to open a firewall port and such.

It will be the ground of an Event Collaboration stack included within mORMot, in a KISS way.
Event Collaboration is really a very interesting pattern, and even if not all your application domain should be written using it, some part may definitively benefit from it.
The publish / subscribe pattern provides greater network scalability and a more dynamic SOA implementation: for instance, you can add listeners to your main system events (even third-party developed), without touching your main server.
Or it could be the root of the Event Sourcing part of your business domain: since callbacks can also be executed on the server side (without communication), they can be used to easily add nice features like: complete rebuild, data consolidation (and CQRS), temporal query, event replay, logging, audit, backup, replication.

2012-09-03

Client-Server allowed back to XE3 pro

By AB4327-GANDI, 2012-09-03. Open Source › mORMot Framework

The attempt to restrict the XE3 professional license did evolve into an amazing discussion in Embarcadero forums, and Delphi-related blogs. David I announced the (reverted) EULA for Delphi Pro. Remote database access is again possible, with terms similar to Delphi Xe2. You can check the Software […]

2012-08-31

Breaking change of *FillPrepare() method parameters

By AB4327-GANDI, 2012-08-31. Open Source › mORMot Framework

I like very much user participation (SCRUM / Agile is my moto) - I never believe to be always right nor write perfect code, and I'm convinced Open Source projects are also about sharing ideas among people of good will.

So when an active member of the forum reported his confusion / concern about some of the ORM methods of our framework, it appeared that some re-factoring was necessary.

There was a breaking change about the TSQLRecord.Create / FillPrepare / CreateAndFillPrepare and TSQLRest.OneFieldValue / MultiFieldValues methods: for historical reasons, they expected parameters to be marked as % in the SQL WHERE clause, and inlined via :(...):.
Since revision 1.17 of the framework, those methods expect parameters marked as ? and with no :(...):.

For instance, instead of writing:

 aRec.CreateAndFillPrepare(Client,'Datum=?',[],[DateToSQL(EncodeDate(2012,5,4))]);

you should write now:

 aRec.CreateAndFillPrepare(Client,'Datum=?',[DateToSQL(EncodeDate(2012,5,4))]);

The void [], array (used for replacing % characters) is not to be written any more, since the default is to use bound parameters via ? and not textual replacement via %.

Due to this breaking change, user code review is necessary if you want to upgrade the engine from 1.16 or previous.

In all cases, using ? is less confusing for new users, and more close to the usual way of preparing database queries - e.g. as used in SynDB.pas units.

Both TSQLRestClient.EngineExecuteFmt / ListFmt methods are not affected by this change, since they are just wrappers to the FormatUTF8() function.