Difference between revisions of "RPC HELP TRPCBroker CreateContext Method"

Latest revision as of 13:50, 5 July 2015

CreateContext Method

Example

Applies to

   TRPCBroker component

Declaration

   function CreateContext(strContext: string): boolean;

Description

You can use the CreateContext method of the TRPCBroker component to create a context for your application. To create context, pass an option name in the strContext parameter. If the function returns True, a context was created, and your application can use all RPC entered in the option's RPC multiple. If the TRPCBroker component is not connected at the time context is created, a connection will be established. If for some reason a context could not be created, the CreateContext method will return False.

Since context is nothing more than a client/server "B"-type option in the OPTION file (#19), standard MenuMan security is applied in establishing a context. Therefore, a context option can be granted to user(s) exactly the same way as regular options are done using MenuMan. Before any RPC can run, it must have a context established for it to on the VistA M Server. Thus, all RPCs must be registered to one or more "B"-type option(s). This plays a major role in Broker security.

A context cannot be established for the following reasons:

• The user has no access to that option.
• The option is temporarily out of order.

An application can switch from one context to another as often as it needs to. Each time a context is created the previous context is overwritten.

NOTE: See the CurrentContext property for information about saving off the current context in order to temporarily create a different context and then restore the previous context.

NOTE: See RPC Limits for information about the size of parameters and results that can be passed to and returned from the TRPCBroker component.

NOTE: Whenever the Broker makes a call to the VistA M Server, if the cursor is crDefault, the cursor is automatically changed to the hourglass symbol as seen in other Microsoft-compliant software. If the application has already modified the cursor from crDefault to something else, the Broker will not change the cursor.

NOTE: For a demonstration that creates an application context, please run the BrokerExampleEXE located in the ..\BDK32\Samples\BrokerEx directory.