MIDAS technology

1.Understanding MIDAS technology
MIDAS requires MIDAS.DLL, which is used by both client and server applications to manage datasets stored as data packets. Building MIDAS applications may also require the SQL explorer to help in database administration and to import server constraints into the Data Dictionary so that they can be checked at any level of the multi-tiered application.
NB:You must purchase server licenses for deploying your MIDAS applications.

Component and there Description
remote data modules-Specialized data modules that work with a COM Automation server to give client applications access to any providers they contain. Used on the application server.

provider component -A data broker that provides data by creating data packets and resolves client updates. Used on the application server.

client dataset component-A specialized dataset that uses MIDAS.DLL to manage data stored in data packets.
connection components-A family of components that locate the server, form connections, and make the IAppServer interface available to client datasets. Each connection component is specialized to use a particular communications protocol.

2.Building a multi-tiered application
The general steps for creating a multi-tiered database application are

i)Create the application server.

ii)Register or install the application server.
If the application server uses DCOM, HTTP, or sockets as a communication protocol, it acts as an Automation server and must be registered like any other r COM server. For information about registering an application, see Registering a COM object.
If you are using a transactional data module, you do not register the application server. Instead, you install it with MTS or COM+. For information about installing transactional objects, see Installing transactional objects.

iii)Create a client application.
The order of creation is important. You should create and run the application server before you create a client. At design time, you can then connect to the application server to test your client. You can, of course, create a client without specifying the application server at design time, and only supply the server name at runtime. However, doing so prevents you from seeing if your application works as expected when you code at design time, and you will not be able to choose servers and providers using the Object Inspector.

NB If you are not creating the client application on the same system as the server, and you are not using a Web connection or socket connection, you may want to register or install the application server on the client system. This makes the connection component aware of the application server at design time so that you can choose server names and provider names from a drop-down list in the Object Inspector. (If you are using a Web connection or socket connection, the connection component fetches the names of registered servers from the server machine.)


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