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JBase Interview Questions

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jBASE is an Application Development and Database Independent Management System that enhances and extends the UNIX, Windows NT and Windows '95 Operating Systems. jBASE also allows easy migration to these Operating Systems, from other DBMS's, including Pick, Reality and anything called Uni{somthing}.

jBASE consists of run-time, development and administrative components and is designed with Open Systems and Open Software in mind. jBASE allows the most flexible overall computing environment possible by allowing multiple Operating Systems and multiple Databases to interact together in one overall heterogeneous solution.

jBASE is the most logical way to port your applications to Unix or Windows -- by compiling them to the machine code of the target system. There is no emulation layer in the way. As an end user, you can show your management that you are migrating away from Pick without abandoning applications and skillsets. As a software developer there is no longer any need to convince new customers to buy another database before buying your application.

Your development account(s) is(are) ported to a UNIX directory using an ACCOUNT-RESTORE program. Do you know how to do this?...

$ T-ATT SCT0

$ ACCOUNT-RESTORE

...we thought you would, except now you are doing it directly from a Unix shell!

The source code is "cleaned" once using our supplied code scanner. You can then call it jBC code, (the jBASE version of BASIC). The jBC code is backwards compatible with your old system, but now it is free of a few anomalies tht the old compliers let by, such as using keywords as variable names. To port it back you can use ACCOUNT-SAVE or T-DUMP.

You can now compile to machine code using the jBASE compiler. The compiler does this by converting the code to C or C++ transparently. You have two choices at this point:

Use BASIC and CATALOG;
    jBASE has a BASIC and CATALOG command so that you can maintain a familiar way of building your application. These commands call the jBASE compiler and the Unix linker to build your application, but you can remain blissfully unaware of this, if you want to.
Use the jbc command;
If you have ever compiled a c program under Unix or Windows, you will be aware that the C compiler is usually called with a comand line such as cc prog.c -o prog. The jBASE compiler follows this same convention: jbc prog.b -o prog. The advantage of moving to this type of environment is that you can use source code control systems and makefiles to control the build of your application. (Not everyone sees this as an advantage! )  

The jBASE debugger was written by developers for developers. It is by far the most useful and powerful 'BASIC' debugger yet produced.

Other development tools include a full screen editor (ED is also present), and a Unix command shell called jSHELL. These are provided to make the migration as familiar as possible. The developer is now a Unix developer and has access to all Unix tools, shells and source code control mechanisms, just like any other C developer would. You also have all the familiar tools available directly from the Unix shell you choose to use.

There are two main forms of database technology in use today, the First Normal Form databases, such as Oracle, Sybase, Informix On-line and many others and the Non First Normal Form (NF2) databases such as Pick, Reality, UniVerse, Unidata and others. jBASE supports both. The NF2 model is retained in the j-file systems supplied with jBASE, namely j1 and j2. These databases are accessed via the jBASE languages jBC, jCL and the jQL Query language. The same databases can be accessed by third-party languages such as C, PASCAL and others via the formal jEDI (API) interface.

The jBASE External Device Interface (jEDI) is significantly different to the methodology used by traditional single database development environments. It is the jEDI interface that manages and controls database access to any database. For an application to access a different database other than the jBASE databases a different jEDI is used. This is achieved without re-compiling or changing the actual application in any way. The analogous concept to jEDI is Microsoft's ODBC interface, which cam after jEDI and isn't as fast ;-).

There are two ways in which to access third-party databases such as Oracle. Firstly the application program can include normal SQL statements, which will handle updates and enquiries on SQL databases. Secondly there is a more direct access route via a third-parties own API. A jEDI is provided for each different database. Work is currently in progress on the Oracle API, the Informix API and the Sybase API. Each new API can in fact be added by any developer as long as they have the relevant database expertise. jEDIs can also be added to access NF2 databases and so jBASE becomes the master development system for a myriad of databases while the developer maintains just one source code set.

The Unix accounts can be configured to look exactly as they do under Reality/PICK environments using jSHELL and other tools. Alternatively the developer can move to a normal Unix look or use a mixture of both. jBASE Software have endeavoured to provide Reality/PICK developers migrating to Unix with everything they require to feel at home but in no way restrict the developers from using any of the many sophisticated Unix tools.

BASIC code resides in the jBASE system unchanged. The jbc compiler will in fact help cleanse the code during compilation as it is stricter than other compilers. For example, if a piece of code will never be executed, the compiler knows and will inform you with a warning message. Maintenance of the (now) jBC code is easier with the help of jBASE and Unix tools. The source code remains portable across other NF2 systems too.

jQL inquries and jCL procs run unchanged and can be executed exactly as they were in your old system if you are running the jSHELL as your login shell.

It is assumed jCL programs (procs) will eventually be replaced by the more modern Unix script languages or jBC programs. However, they are fully supported to ridiculous levels of compatibility.

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