Compatibility between external components and deployed applications

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Compatibility between external components and deployed applications

Overview

Updating a component in a deployed application

Compatibility modes

See also

Compatibility between external components and deployed applications

Overview

A component can evolve in many ways:

new or edited features,
bug fixes, etc.

This help page presents:

How to update a component in a deployed application.
The different compatibility modes of a component: backward and forward compatibility.

Updating a component in a deployed application

There are two methods to update an external component in an application that has already been deployed to end-user computers:

Recompiling the project that uses the external component (recommended).
Directly distributing the ".WDK" file.

1. Recompiling the project that uses the external component (recommended)

Recompile the project that uses the component and redistribute the application (with the component).

In this case, no version problem or compatibility problem will occur.

The recompilation is required in the following cases:

New functions have been added to the component and they must be taken into account by the application.
The parameters of some procedures have been modified.
Incompatibility between new and earlier versions of the component.
...

2. Directly distributing the ".WDK" file

Make a component update (".WDK" file) available to end users without recompiling the project.

This method can be used in the following cases:

The new version is used to correct problems of an earlier version.
New features have been added to the component but are not required to run the application.

Compatibility modes

Definition

Compatibility is linked to the versions of the component. If changes are made to the component, the applications that use the component may encounter runtime problems if they are not synchronized with it.

Compatibility is an important aspect when distributing a component.

There are two types of compatibility:

backward compatibility: the version of the component (.WDK file) used to compile the applications must always be greater than or equal to the version currently used. WINDEV manges compatibility automatically. Applications will not run if the component version is earlier than the version they currently use.
forward compatibility: you can prevent the use of a new version of a component with a project compiled using a previous version. You need to recompile the projects to use the new version of the component.

Backward compatibility

WINDEV always checks the version number of the components to make sure that the deployed version is greater than or equal to the one used in the development project.

For example:

A project is compiled with a component in version 1.00C.
1.00C is the reference version. This means that the applications that use the component will only run if the component version is greater than or equal to the reference version.
- First case: The applications deployed on the end-user computers use a component version (.WDK file) earlier than 1.00C. An error will occur when loading these applications.
- Second case: The applications deployed on the end-user computers will run if they use the reference component version.
- Third case: The applications deployed on the end-user computers will run if the component version is greater than the reference version (only if the new version is used to fix bugs).

Forward compatibility

WINDEV automatically detects incompatibilities between two versions of the same component when the component is generated. If there are any differences, WINDEV prompts you to change the "number of the last compatible version". This number sets the reference version from which the applications that use the component will run.

For example:

A project that uses a component in version 1.00C has not been recompiled with the new component version (1.00E).
A component is distributed in version 1.00E.
- First case: the component has been modified only to fix bugs. When generating the component, the "number of the last compatible version" is not modified.
  Applications can run without recompiling the project with the new component version. The component (.WDK file) can be distributed to the end users directly.
- Second case: the component has been modified to add a parameter to a procedure. When generating the component, the "number of the last compatible version" is modified.
  In order for the applications to run properly, the project must be recompiled with the new component version. Otherwise, applications will not run to avoid compatibility errors with the new component version.