The EAServer architecture is component-oriented. Each component maintains its own state. When a single client instantiates several PowerBuilder objects on the server, EAServer maintains program variable space for the objects separately. Each PowerBuilder user object running in EAServer has its own copy of the global and shared variables. The PowerBuilder objects share no common state. They can communicate only through methods, EAServer shared components, server files, and databases.
To allow clients to share state information, EAServer provides support for shared components. Shared components allow multiple clients to share the same component instance.
Marking a component as shared in a PowerBuilder wizard is equivalent to marking it as shared on the Instances page of the Component Properties dialog box in EAServer Manager. Only a single instance of the component can be instantiated in EAServer.
Clients (and other server components) access a shared component as if it were any other kind of component.
Shared components allow you to:
Provide convenient access to common data that would otherwise need to be retrieved separately by each client connection
Reduce the number of database accesses, allowing the database server to be available for other processing
EAServer shared components offer many of the same benefits as PowerBuilder shared objects. PowerBuilder components that you deploy to EAServer can act as clients to EAServer shared components, as well as to PowerBuilder shared objects. EAServer shared components can also be accessed by components and clients that are not implemented in PowerBuilder.
However, EAServer does not treat PowerBuilder shared objects as if they were EAServer shared components. Therefore, the functions used to manipulate PowerBuilder shared objects (SharedObjectRegister, SharedObjectGet, and so forth) do not work with EAServer shared components. If you try to call one of these functions inside a PowerBuilder component running in EAServer, the request will fail.
