DTO Objects Model and Objects Relationship

DTO Objects Model and Objects Relationship

For the purpose of this manual, DTO classes are arranged in the following functional categories:

In order to be able to configure and monitor the behavior of PSQL engine, users will have to connect to the engine first. This category provides functionality necessary to connect and disconnect to PSQL database engines.

The DtoSession object manages the connection to a database engine.

Monitoring and Diagnostic

This category provides functionality to monitor PSQL engines and clients and provides diagnostic information.

The DtoMonitor object and its descendents provide server monitoring and diagnostic information. You can also obtain engine information directly from DtoSession with the DtoEngineInformation object.

This category allows the user to configure the PSQL engines and clients. The DtoCategories collection and its descendents provide this functionality.

You can also add and remove product licenses using the DtoLicenseMgr object.

Catalog and Dictionary

Functionality grouped in this category allows users to create new databases, new data dictionaries and also define and drop tables, columns, and indexes.

The DtoDictionary class and its descendents provide catalog functionality.

DTO Object Tree

Many DTO objects are exposed as properties of other DTO objects. The relationship provides developers with a logical, tree-like structure that simplifies programming with automation controllers. Many objects can be referenced using the familiar dot notation used to access properties and methods.

The DTO object tree contains three main branches, logically grouping objects for Configuration, Monitor and Catalog.

The following table shows usage information regarding the two versions of DTO:


Item	DTO2		DTO1
	x86	x64	x86
DLL name	DTO2.DLL	w64DTO2.DLL	DTO.DLL
Library	DTOLib2		DTOLib
ProgID of DtoSession	DTO.DtoSession.2		DTO.DtoSession.1
ProgID of DtoDatabase	DTO.DtoDatabase.2		DTO.DtoDatabase.1
ProgID of DtoDictionary	DTO.DtoDictionary.2		DTO.DtoDictionary.1

A new DLL was released with PSQL V8 SDK that added objects and new properties to existing objects. In order to maintain backward compatibility, a new DLL was created instead of adding this to the previous DTO.DLL. Both are installed and registered with PSQL SDK and you can use either one to develop DTO applications. Using the previous DTO.DLL may be important to you if you cannot recompile your application to use the new DLL. However, if you continue to use the previous DTO.DLL, you cannot use the new objects or some new properties that were added to existing objects. DTO2.DLL supports 32-bit development environments, including the .NET framework.

The PSQL v11 SP1 SDK added 64-bit support for 64-bit environments, including the .NET framework.

In order to utilize DTO for 64-bit applications, you will need to install the 64-bit server or client with your 64-bit application. Installing the 64-bit server or client installs the 64-bit version (W64DTO2.DLL), whereas installing the 32-bit server or client installs the 32-bit version (DTO2.DLL or DTO.DLL), as described in the previous table.

Understanding How Applications and DLLs Interact

To better understand how applications and DLLs interact, we will examine the following scenarios.

Assuming we have the following three DLLs:

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And the following application executables:

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The following tables illustrate the results when you try and run the application executables and DLLs together, on 32-bit and 64-bit machines.

Table 1

32-bit Machine Process


Application Executable	Runs as	DTO.DLL	DTO2.DLL	W64DTO2.DLL
ANYCPU.EXE	32-bit process	Loads	Loads	BadImageFormat Exception
X86.EXE	32-bit process	Loads	Loads	BadImageFormat Exception
X64.EXE	BadImageFormat Exception

Table 2

64-bit Machine Process


Application Executable	Runs as	DTO.DLL	DTO2.DLL	W64DTO2.DLL
ANYCPU.EXE	64-bit process	BadImageFormat Exception	BadImageFormat Exception	Loads
X86.EXE	32-bit process	Loads	Loads	BadImageFormat Exception
X64.EXE	64-bit process	BadImageFormat Exception	BadImageFormat Exception	Loads