NetBeans Architecture Answers for Database Explorer module

General Information

Question (arch-what): What is this project good for?
Answer:

This project provides access to objects defined in the Database Explorer. Documentation is available in the Javadoc.

Question (arch-overall): Describe the overall architecture.
Answer: DatabaseExplorerAPI -

The Database Explorer API provides access to the database connections defined in the Database Explorer. It allows a client to retrieve the connection list and their properties and to create new connections.

The Database Explorer also manages a list of JDBC drivers used to connect to databases. The API provides access to these drivers and allows to specify the JDBC driver when creating a new connection. New JDBC drivers can be registered using the Services API (by adding a file to the module layer).

The API allows the registration of database runtimes. Runtimes are pluggable parts allowing a database server to be started when a connection is made. Runtimes are registered using the Services API.

Question (arch-usecases): Describe the main use cases of the new API. Who will use it under what circumstances? What kind of code would typically need to be written to use the module?
Answer:

Registering JDBC drivers

An external module can register JDBC drivers. A typical example is a J2EE application server which bundles a database server. When the server is registered in the IDE the JDBC drivers for the database servers are added. The drivers are registered using the Services API by adding their XML descriptions to the module layer.

Retrieving the list of JDBC drivers

When creating a new connection the JDBC driver for it can be specified. A list of all the registered JDBC drivers can be retrieved using JDBCDriverManager.getDrivers().

Registering database runtimes

An external module can register new database runtimes. A database runtime is an abstraction of a database server instance (typically bundled with a J2EE server). It allows a database server instance to be started and stopped when a connection to this instance is made in the IDE. Database runtimes are represented by the DatabaseRuntime SPI interface and are registered using the Services API.

Creating database connections

An external module can create new database connections. Again, this is typical for a J2EE server bundling a database server. The new connections are added by calling ConnectionManager.create() to create a new DatabaseConnection instance and then ConnectionManager.addConnection() to add the connection.

Retrieving and displaying the list of database connections

Sometimes the list of connections needs to be displayed somewhere else in the IDE than the Runtime tab. A typical example is the SQL Editor, which allows the user to select the database connection the SQL statement will be executed against in a combo box in the editor toolbar. The list of connections can be obtained by calling ConnectionManager.getConnections(), which returns an array of DatabaseConnection instances.

The client usually needs to show the display name of the connection. The display name can be retrieved using the DatabaseConnection.getDisplayName() method.

Retrieving the properties of database connections

Sometimes a client needs to retrieve the connection properties, such as the driver class. An example could be a J2EE server creating a connection pool. The properties can be retrieved using the getDriverClass(), getConnectionUrl(), getSchema(), getUser() and getPassword() methods of the DatabaseConnection class.

Showing the Add Connection dialog

Usually when displaying a list of connections (usually in a combo box), the last item is "Add Connection", which displays the standard Add Connection dialog of the JDBC manager. This can be achieved by calling ConnectionManager.showAddConnectionDialog().

Connecting to a database

A component which provides database functionality (such as the SQL Editor) will need to connect to a database. This can be achieved using the showConnectionDialog() DatabaseConnection method and the java.sql.Connection can be retrieved using the getJDBCConnection() method.
Question (arch-time): What are the time estimates of the work?
Answer:

Most code is already written. About a week of implementation work still needed and about two weeks shall be spent writing tests. The milestone by which this API should be stable is promo-G.

Question (arch-quality): How will the quality of your code be tested and how are future regressions going to be prevented?
Answer:

All Javadoc-specified functionality should be covered by unit tests.

Question (arch-where): Where one can find sources for your module?
Answer:

Project and platform dependencies

Question (dep-nb): What other NetBeans projects and modules does this one depend on?
Answer:

Lookup - JDBC drivers and database runtimes are registered in the default lookup.

org.openide.actions - Needed in the Database Explorer UI.

org.openide.filesystems - Neded for writing JDBC driver registration files.

org.openide.util - Multiple usages (bundles, request processor).

org.openide.modules - For installing a ModuleInstall.close() method which disconnects the connected connections upon IDE shutdown.

org.openide.nodes - Needed in the Database Explorer UI.

org.openide.dialogs - Needed in the Database Explorer UI.

org.openide.options - Various settings of the Database Explorer, including the list of connections, are saved using a SystemOption.

org.openide.windows - Needed in the Database Explorer UI (the Execute Command top component).

org.openide.loaders - Neded for writing JDBC driver registration files.

org.netbeans.api.progress - Needed in the Database Explorer UI.

Question (dep-non-nb): What other projects outside NetBeans does this one depend on?
Answer:

None.

Question (dep-platform): On which platforms does your module run? Does it run in the same way on each?
Answer:

No known platform dependencies.

Question (dep-jre): Which version of JRE do you need (1.2, 1.3, 1.4, etc.)?
Answer:

XXX no answer for dep-jre

Question (dep-jrejdk): Do you require the JDK or is the JRE enough?
Answer:

XXX no answer for dep-jrejdk

Deployment

Question (deploy-jar): Do you deploy just module JAR file(s) or other files as well?
Answer:

XXX no answer for deploy-jar

Question (deploy-nbm): Can you deploy an NBM via the Update Center?
Answer:

XXX no answer for deploy-nbm

Question (deploy-shared): Do you need to be installed in the shared location only, or in the user directory only, or can your module be installed anywhere?
Answer:

XXX no answer for deploy-shared

Question (deploy-packages): Are packages of your module made inaccessible by not declaring them public?
Answer:

Only official API and SPI packages are exported.

Question (deploy-dependencies): What do other modules need to do to declare a dependency on this one?
Answer:

XXX no answer for deploy-dependencies

Compatibility with environment

Question (compat-i18n): Is your module correctly internationalized?
Answer:

XXX no answer for compat-i18n

Question (compat-standards): Does the module implement or define any standards? Is the implementation exact or does it deviate somehow?
Answer:

No.

Question (compat-version): Can your module coexist with earlier and future versions of itself? Can you correctly read all old settings? Will future versions be able to read your current settings? Can you read or politely ignore settings stored by a future version?
Answer:

XXX no answer for compat-version

Access to resources

Question (resources-file): Does your module use java.io.File directly?
Answer:

XXX no answer for resources-file

Question (resources-layer): Does your module provide own layer? Does it create any files or folders in it? What it is trying to communicate by that and with which components?
Answer:

XXX no answer for resources-layer

Question (resources-read): Does your module read any resources from layers? For what purpose?
Answer:

XXX no answer for resources-read

Question (resources-mask): Does your module mask/hide/override any resources provided by other modules in their layers?
Answer:

XXX no answer for resources-mask

Lookup of components

Question (lookup-lookup): Does your module use org.openide.util.Lookup or any similar technology to find any components to communicate with? Which ones?
Answer:

JDBC drivers and database runtimes are searched for in the global lookup.

Question (lookup-register): Do you register anything into lookup for other code to find?
Answer:

XXX no answer for lookup-register

Question (lookup-remove): Do you remove entries of other modules from lookup?
Answer:

XXX no answer for lookup-remove

Execution Environment

Question (exec-property): Is execution of your code influenced by any environment or Java system (System.getProperty) property?
Answer:

XXX no answer for exec-property

Question (exec-component): Is execution of your code influenced by any (string) property of any of your components?
Answer:

XXX no answer for exec-component

Question (exec-ant-tasks): Do you define or register any ant tasks that other can use?
Answer:

XXX no answer for exec-ant-tasks

Question (exec-classloader): Does your code create its own class loader(s)?
Answer:

XXX no answer for exec-classloader

Question (exec-reflection): Does your code use Java Reflection to execute other code?
Answer:

XXX no answer for exec-reflection

Question (exec-privateaccess): Are you aware of any other parts of the system calling some of your methods by reflection?
Answer:

XXX no answer for exec-privateaccess

Question (exec-process): Do you execute an external process from your module? How do you ensure that the result is the same on different platforms? Do you parse output? Do you depend on result code?
Answer:

XXX no answer for exec-process

Question (exec-introspection): Does your module use any kind of runtime type information (instanceof, work with java.lang.Class, etc.)?
Answer:

XXX no answer for exec-introspection

Question (exec-threading): What threading models, if any, does your module adhere to?
Answer:

XXX no answer for exec-threading

Question (security-policy): Does your functionality require modifications to the standard policy file?
Answer:

XXX no answer for security-policy

Question (security-grant): Does your code grant additional rights to some other code?
Answer:

XXX no answer for security-grant

Format of files and protocols

Question (format-types): Which protocols and file formats (if any) does your module read or write on disk, or transmit or receive over the network? Do you generate an ant build script? Can it be edited and modified?
Answer:

XXX no answer for format-types

Question (format-dnd): Which protocols (if any) does your code understand during Drag & Drop?
Answer:

XXX no answer for format-dnd

Question (format-clipboard): Which data flavors (if any) does your code read from or insert to the clipboard (by access to clipboard on means calling methods on java.awt.datatransfer.Transferable?
Answer:

XXX no answer for format-clipboard

Performance and Scalability

Question (perf-startup): Does your module run any code on startup?
Answer:

XXX no answer for perf-startup

Question (perf-exit): Does your module run any code on exit?
Answer:

XXX no answer for perf-exit

Question (perf-scale): Which external criteria influence the performance of your program (size of file in editor, number of files in menu, in source directory, etc.) and how well your code scales?
Answer:

Performance scales linearly with the number of connections and drivers, but usually the numbers are small.

Question (perf-limit): Are there any hard-coded or practical limits in the number or size of elements your code can handle?
Answer:

None known.

Question (perf-mem): How much memory does your component consume? Estimate with a relation to the number of windows, etc.
Answer:

XXX no answer for perf-mem

Question (perf-wakeup): Does any piece of your code wake up periodically and do something even when the system is otherwise idle (no user interaction)?
Answer:

XXX no answer for perf-wakeup

Question (perf-progress): Does your module execute any long-running tasks?
Answer:

XXX no answer for perf-progress

Question (perf-huge_dialogs): Does your module contain any dialogs or wizards with a large number of GUI controls such as combo boxes, lists, trees, or text areas?
Answer:

XXX no answer for perf-huge_dialogs

Question (perf-menus): Does your module use dynamically updated context menus, or context-sensitive actions with complicated and slow enablement logic?
Answer:

XXX no answer for perf-menus

Question (perf-spi): How the performance of the plugged in code will be enforced?
Answer:

Some methods of the database runtimes may take a long time (especially the start method). These methods are never called in the event thread and a progress dialog is displayed.