GENERATION TOOL FOR DBMS FOCUSED APPLICATIONS

Transcription

1 GENERATION TOOL FOR DBMS FOCUSED APPLICATIONS Carlos del Cuvillo Universidad Politecnica de Madrid Ctra. de Valencia km. 7 E28031 Madrid Hector Garcia Universidad Politecnica de Madrid Ctra. de Valencia km. 7 E28031 Madrid Diego Perez Universidad Politecnica de Madrid Ctra. de Valencia km. 7 E28031 Madrid Eva Franco Universidad Politecnica de Madrid Ctra. de Valencia km. 7 E28031 Madrid ABSTRACT The dynamic code generators provide software developers a great help in software development process by generating code dynamically according with prerequisites specified by the designers. Benefits obtained by using this kind of applications are the save of time and effort, which implies economical benefits, guarantees of code correction and easiness of development. The database applications cover a wide spectrum in software development, we consider there is a lack concerning the dynamic generation of database applications. The application we have implemented intends to provide software developers a new dynamic code generator for database data processing. This tool will provide developers the chance to obtain correct programs by implementing the process of data in databases as well as generating an interface according to developers specifications and dealed data. Goals, scope, functionalities, generated code, development, advantages and benefits about this tool are defined in this document. KEYWORDS Computer Aided Software Engineering, Automatic Programming, Design Automation, Software Tools, Software Engineering, Software Prototyping. 1. INTRODUCTION What does programming to provide programming means? Programming to provide programming comes to summarize expert software developers latest products. Once computers limitations are overcome, once powerful programming languages have been created, once we are able to program a computer and implement a whole virtual life, next step is to provide software developers support and so programming to facilitate programming. In order to support software development, RAD tools and dynamic code generators were implemented, becoming an essential part of software development. Advantages obtained from its use are save of time and I - 279

2 IADIS International Conference Applied Computing 2004 effort, improvement in code correction, economical issues... Databases are the backbone used to keep and manage information. Referring previous paragraph and considering great part of processed information is related to databases we consider there is a gap concerning dynamic code generation for processing data on database applications development. The tool contribution to current state of the art is the generation of integral code, almost independent which allows two or three layer architecture. Known applications will dynamically generate forms which could be related to databases or will facilitate access to databases from the application. We have found some resemblances with other applications but none of them provide completely functional code. The idea of developing such application arises from our own development experience needs. Processing databases is not the most complex programming process but really tedious, repetitive and dangerous considering integrity and security needs (encryption and Internet security needs). Why not standardize the generation of shared code between applications in terms of reuse? Furthermore, What could be standardized respecting database related software development process? At this point, and based on our own experience, we can assure around 80% of most database processing code could be standardized. The main goal of the application is to support software development related to database applications. Far from being a tight-area scope product, it is an open product, able to support many different code generation functions. The fact of generating code following Java standard, and considering Java as one of the most used programming standards, makes the application available for a great amount of users, as well as easy to modify, to understand and to generate new code based on the generated code. The large number of available generated code possibilities provides support in many different application domains. Remaining part of the document describes the product. First, we would like to specify the decisions we took concerning product development as well as justify them. Next, application characteristics and different possibilities in its use are exposed. We attach examples and experiences using it. Finally, conclusions, will describe benefits and advantages of the product. 2. SETTING CHARACTERISTICS AND DEVELOPING LANGUAGE 2.1 Application Characteristics Aiming to develop a useful and robust tool, there are some essential bases, which should be considered concerning both, the tool itself and the generated applications. First, we would like to establish the characteristics we aim the product to provide: Open application: In order to get a useful and available application for anyone. Modularity: Modularity involves independence concerning modules or packages and facilitates new code development in order to add tool functionalities or modifications. Portability: In order to get an application able to be run on any platform. Usability: In order to offer an application easy to use for expert, medium and junior programmers. Second, we would like to remark main characteristics the generated applications should implement. We will make a difference between the developer and the final user. Developer: This is the real user of our tool. Relationship between developer and our tool is the application itself and the generated code. Main desirable characteristics to provide to the developer are: o Portability: In order to generate useful applications available to be run on any platform. o Standardized code: Provides understandable code to the developer as well as allows developer to import generated code. o No need of additional software o Provide Internet/Intranet features Final user: Final user could be anyone using the generated applications. Some desirable features are: o Standardized interface: In order to save training time. o Clear interface: In order to increase usability. I - 280

3 GENERATION TOOL FOR DBMS FOCUSED APPLICATIONS o o Specific functions: To allow data management (new, edit, delete). Access to data through Internet/Intranet. 2.2 Development Language Taking in mind we aim to obtain an application extended over a wide area and supposing users will apply standard rules to the physical model of data, the generated code must assure following characteristics: - Multiplatform - Object Oriented Design standards: required to provide application scalability. - Wide extended programming language: Desirable to generate understandable code for as much developers as possible. - Able to work with different DBMS: required to offer flexibility. - Provide metadata access to support code generation. We chose to generate Java code as long as Java meets all mentioned requirements: platform independence, ability to connect with any database, object oriented and widespread through development community. In addition, Java standard defines JDBC (Java Data Base Connectivity). JDBC provides connectivity and data exchange with databases. Within JDBC, objects defined provide a full database data processing and metadata access. This led us to chose Java for developing the tool and as target language for generated applications. 3. THE PRODUCT 3.1 Broad Outline of the Product The product is a dynamic program generator, which supplies the code to process data in databases. We are offering a tool, which does not need any other application or special software to work with. Users of the product should provide the database connection information as well as the characteristics and processing mode for fields. The result is a Java application to process data in databases. The figure below provides the reader a view of the product: Figure 1. Broad outline of the tool I - 281

4 IADIS International Conference Applied Computing Steps to Follow While Using the Product Connecting to the Database: The application will require the connection strings including driver name, URI, user and password. At first, the application is capable to operate with any database, even if some modifications in the code could be required when connecting with databases different from ORACLE or ODBC data sources. Mostly generated code is SQL standard 1992 and so possible to process any database Selecting Table to Process and Setting Options Once we are connected to the database, the list of tables contained on the database is shown. Developer should choose the table to process. Note that tables having relationships with the selected one will be processed if necessary for integrity. Following, an interface to set the developer desirable options, concerning the process of the table arises. The offered options for each field contained in the table are defined next: Primary key: user is able to decide which would be the group of fields composing user s primary key. Visibility: a field set as visible will be shown in the final interface. Updateable: a field set as updateable will allow final user to modify it. Combo boxes: relationships with domain tables are shown as combo boxes. Encrypted: possibility of encrypting data is offered as well as the possibility of encryption following different encryption models. Null option: This is a boolean which indicates if referred field could be null or otherwise is mandatory. Data type: field data type. Range of values: application offers the possibility of setting a limited range of values for a field Completing Code Once we have chosen a table and defined the characteristics to the process of the table, code files are dynamically generated. Functions of each code file are defined next point. Note that developers could modify code, if not, generated code, which is already complete and full functional, will fit the defined options set during generation configuration step. 3.3 Generated Code Generated code can be considered from two different points of view. In one hand we have considered the generated code itself (lines of code), in the other hand we have considered the application implemented by the generated code. Following this division, we will refer to generated code and to implemented application Feature of Generated Code Code files are generated following Java standard and using object oriented programming. Java applets and applications are generated; the fact of using Java applets involves a set of characteristics as: Modularity Independence Universal access (Internet application). No installation needed. Feasible to be imported on any development environment In order to maximize the generated code understandability and maximize the code quality the developer is provided with: High-quality code: Generated code is a good-quality code. The quality of Java code will be similar to that generated by an expert programmer but for optimum performance on the execution of SQL sentences expert revision is needed in some cases for obvious reasons. I - 282

5 GENERATION TOOL FOR DBMS FOCUSED APPLICATIONS Meaningful names: By using meaningful names, understanding of code is much easier than using trivial names. Variables, objects, classes and packages will have meaningful as names as those defined in database design. Example: If we are processing a table named Staff and there is a column referred as Age, generated package would be named as Staff as well as if there is an object referring the column Age it will be named as ObjectTypeAge. In addition, meaningful names used to name methods will also describe the function that referred method implements. Comments: Some comments clarifying the meaning of following part of the code are dynamically generated. Structured Code: Related functions are generated one after one providing a clear code structure. Some lines of generated code are shown below to let the reader confirm what related above: private void disableedits(){ modifybutton.setenabled(false); deletebutton.setenabled(false); exitbutton.setenabled(true); newbutton.setenabled(true); fieldlist.setenabled(true); closeenable=true; TEACHERNUMBERtextfield.setEditable(false); IDNUMBERtextfield.setEditable(false); CATEGORYNUMBERtextfield.setEditable(false); DEPARTMENTNUMBERtextfield.setEditable(false); CENTERNUMBERtextfield.setEditable(false); TEACHERNAMEtextfield.setEditable(false); With the purpose of providing a complete functionality, generated code implements following functions: Data processing: Generated code supports the data processing defined above. Common functionalities as add, delete, modify and create a new row are implemented following user specifications and restricting functionalities if needed. Furthermore, special searches are provided too, we will refer to them at the point about the generated application. Alignment: Appropriate alignment of different shown fields is generated. That means final interface will have, without need to add or modify code, a good look and feel and fields will fit in the final interface. To get this feature, defined lenght for each field is considered, fitting two different short fields at the same height or minimizing a big field adding scrolling functionality... Automatic window scrolling: As it is just noted, sometimes, if there is a long defined field, instead of showing the whole length of the field, application will generate needed code to show just a part of it and will allow scrolling on it. In addition scrolling for fields, which offer a list of possible values, is generated too. Encryption: A function to encrypt data, which should be encrypted to fulfill Spanish and European legality, is implemented. Depending on the country, which the application is deployed for, this function could be modified. Editing Control: The code needed to control correction and integrity concerning field types is implemented Generated Application At this point we are referring to the application from the point of view of the final user. It is our intention to define here the offered interface as well as provided functionality. Different applications from the one described here could be generated since developer could have modified generated code in order to change interface aspect or functionalities. However, basic description I - 283

6 IADIS International Conference Applied Computing 2004 would be the same. Mainly, generated interface, could be explained as an unique window composed by four different areas: Figure 2. Diagram of generated application First area is the area containing search and selection fields. Second Area includes operation button: o Insert button: Allows user to define a new element on the table (new row). When insert button is clicked, fields are clean and user is allowed to edit them. Following described functionalities offered will assure correction and integrity: Fields set as not null able shall be fulfilled; otherwise a warning message will be displayed. Fields with a defined range of possible values will show options and will not allow user to insert a different value of those set by developer. Usually, these fields will be domain fields from the database. A function to assure type correction is also implemented. It will not be allowed to user to insert different types from those defined. This means that user is not able to insert a decimal number if defined as integer, or able to insert a character if dealing with a field defined as numeric. In addition, if there is a length defined for a field (for example zip code), this function assures user will introduce correct length by displaying a warning message if length does not match with defined length for that field. When inserting a new row, the tool will automatically create the internal primary key for database, which will differ from primary key defined for users. o Delete button: Allows user to delete an element on the table. o Modify button: When modify option is selected, updateable fields allow user to edit them. o Updateable fields will be those set by the developer as updateable. Help button: This button connects user with a help page. The help page provides user general information describing through static interfaces and examples the functionality provided. These pages are not generated by the tool. Third area shows user information. Visible fields will be shown in here and, if editing, this would be the editing area. As it is already mentioned, fields fitting process is implemented and so the interface look will result similar as shown in the graphic above. Order of fields is preserved, fields are shown in the same order they were defined on the table. Forth area includes communication or operation buttons during edition: o Accept: To confirm. o Cancel: To cancel o Exit: To exit application. (This button is here in order to offer user a homogenized and standard interface) To conclude, we will like to show a real generated interface in order to let the reader note the easiness of use and understandability that the interface offers for any kind of user and: I - 284

7 GENERATION TOOL FOR DBMS FOCUSED APPLICATIONS Figure 3. Example of a generated interface. 4. CONCLUSIONS Even though there are not completely reliable studies, it is considered conclusions exposed in here could be applied to low, medium and large size projects. Following, a case of study and results obtained using the tool will be detailed. Next, general advantages and limitations will also be described. 4.1 Case of Study Case of Study The case of study is a medium size project using as Database Management System Oracle 9i. Twenty-three primitive functionalities have been implemented. The number of lines of generated code comes to Java Applet format lines and Java JSP, HTML, CSS and JavaScript lines Results The increase in productivity goes from 55% for high complexity process, 78% to medium complexity process and 89% for low complexity process. Concerning deadlines, the project deadline to be implemented was estimated in two years, it was given and implemented in eleven months. As a result of the standardized and reused generated code the number of lines was reduced in a 19%. Although there are not trustworthy studies it has been detected, during maintenance period, that effort necessary to generate a new application was lower than the required effort to modify the original code. Furthermore, a significant decrease in the number of code errors was also detected. I - 285

8 IADIS International Conference Applied Computing Advantages Save of effort: Save of effort is an obvious advantage. Instead of programming a whole application, it is just necessary to set some required options of pretended subject and it will be dynamically generated. Shorter development periods: Medium development time needed in developing an application as the one the tool dynamically generates decrease in a great percentage. We consider after one month dealing with the tool decrease on developing time is more than 95% if we are referring to a junior programmer and around 75% if we refer a senior programmer or expert. Increase in code quality: Generated code offers to the developer the guarantee of standard and correct code. In consequence test time is reduced. Easy maintenance: Considering code characteristics defined, maintenance would be possible for any programmer without extra effort. Not high qualification needs: expert developers are not required to manage the product and so a junior-medium programmer is able to use it obtaining better results than the results obtained by a expert programmer not using the tool. Economical benefits: advantages above derive in an obvious decrease of projects budget. 4.3 Limitations Limitations are referring application scope. This product will not be useful for applications not based on databases or for applications not dealing with update, delete, modify or enquiry data from databases. It is also important to note the tool has been tested with ORACLE and ODBC data sources. As it is already noted, the generated code is mainly developed following SQL standard 1992, and obviously it is possible to increase SQL execution performance of generated sentences. Workflow applications are also a target if they satisfy some requirements. ACKNOWLEDGEMENT Authors are indebted to the development team for allowing this project to become real, for their support and useful comments. REFERENCES Alves, L., von Staa, A., A construction process for artifact generators using a CASE Tool. Proceedings of Workshop on Generative Programming Austin, Texas, USA, pp Arisholm, E. et al Incorporating Rapid User Interface Prototyping in Object-Oriented Analysis and Design with Genova. The Eighth Nordic Workshop on Programming Environment Research. Batory, et al The GenVoca Model of Software-System Generators. IEEE Software, /94. Calejo, M. et al Web Application Maker - A model based approach to web database development. 6th International Conference on Enterprise Information Systems. Grønbæk, K.et al ApplBuilder - an Object-Oriented Application Generator Supporting Rapid Prototyping. The 4th International Conference on Software Engineering & Its Applications. Jongmoon, B., Boehm, B., Empirical Analysis of CASE Tool Effects on Software Development Effort. Technical Report University of South Carolina. Center for Software Engineering. I - 286