Evaluation of Application Requirements
When evaluating an application, you need to consider several questions. Even though you may not have every answer at the preliminary design stage, you should be able to at least narrow the field a bit for the possible technologies. The questions generally revolve around the interface that the application will have with SAP. The application may be as simple as getting an SAP report to work through a Web browser, or as complicated as having bidirectional communications between SAP and the new application.
What Is the Server/Client Relationship between the Application and SAP?
Will the application always initiate the request to SAP, or will SAP initiate the requests from the application? Sometimes it is both ways. If the new application will at any time act like a server, then you probably should develop the interface with RFCs (Remote Function Calls), IDocs (Intermediate Documents), or something similar (for example, SAP's new Business Connector technology). If the application will act only as the client, then you can use almost any interface method.
| Note | In a two-system environment that includes bidirectional communication, either system can be the client or the server, depending on the initiation of the call. |
Does the Application Need to Be Executed Outside the Firewall?
Though most of these technologies can be set up to work outside the corporate firewall, some are easier than others to set up. ITS (Internet Transaction Server), for example, is very easy to set up and provides many layers of security; in contrast, the Orbix Java server does not have a robust security set. You must also consider how the user will be allowed to connect through the firewall. One possibility is to use a secure connection, established by the user manually, and connect to a corporate system through modems and servers that are not connected to the Internet. Another way to connect through the firewall is to use the Internet (that is, through ITS).
Does the Application Need to Be Synchronous with SAP?
If the application will be waiting for responses from SAP, you might consider using BAPIs, ITS, or the GUI (Graphical User Interface) method. An example of a synchronous connection is one that has an entry screen, written in Java, with several input fields. After the user finishes entering data on a screen, the program will perform an RFC call to SAP to validate the values. The same example, however, is asynchronous if you simply take the values from the screen and send them to SAP without requiring a return validation/confirmation message. If you do not need an immediate response, you can also consider using the full range of protocols, such as RFCs and IDocs, or the transaction method.
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Relating to the Internet/intranet, a firewall is a combination of hardware and software that enables you to communicate with an outside network, while limiting outside access to your network. The most important part of a firewall is the proxy server. Proxy servers make a firewall safely permeable to users behind the secured entrance, while closing entryways in the private network to potential attacks from the outside. The proxy server must act as both a server and client. It acts as a proxy client when it accepts approved requests for external servers, and as a proxy server when it requests services from those servers on behalf of its clients. Other types of firewalls include packet filtering, as well as commercial software that monitors for open ports and other potential illegal entry vehicles.
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What Is the Knowledge Level of the Programming and Support Staff?
The knowledge level of the programming and support staff is a key point that is often overlooked in the application development stage. You must consider the types of technologies with which both the development and the support staff are familiar. If one of your potential technologies is not going to be used elsewhere in the organization and there is another way to set up the application, use the alternate method. For example, if you develop a solution that uses Business Connector and no other solution is using this technology, then you are forcing the support staff to learn about Business Connector just to support your application. A possible alternative in this case is to use RFCs.
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