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EE may provide additional -mechanism, such as injection, but the SE mechanisms should work as well, so any code written in SE is fully -portable to EE as well. -This can only be achieved by providing a static accessor, e.g.</p> -</div> -<div class="listingblock"> -<div class="content"> -<pre class="prettyprint highlight"><code class="language-java" data-lang="java">Configuration config = Configuration.current();</code></pre> -</div> -</div> -<div class="paragraph"> -<p>The call above should work exactly the same in EE. To enable this the static call must be delegated in the -internals of the singleton, depending on the runtime. In EE the executing component can behave contextually, -or even be loaded within the CDI environment (at least for post loading, application runtime aspects, but not earlier).</p> -</div> -<div class="paragraph"> -<p>Additionally in EE it should also be possible to inject Configuration, which gives you the same results as the call -above:</p> -</div> -<div class="listingblock"> -<div class="content"> -<pre class="prettyprint highlight"><code class="language-java" data-lang="java">@Inject -private Configuration cfg;</code></pre> -</div> -</div> -</div> -<div class="sect2"> -<h3 id="_simple_lookup_of_properties">Simple Lookup of Properties</h3> -<div class="paragraph"> -<p>Users just want to create a configuration ad hoc, from given property files. The -files could be locally in the file system, on the classpath.</p> -</div> -<div class="paragraph"> -<p>Tamaya should provide a simple Java API for accessing key/value based configuration. Hereby users want to access -properties as simple String values.</p> -</div> -<div class="paragraph"> -<p>Hereby returning Java 8 Optional values must be considered as well, instead of returning null.</p> -</div> -</div> -<div class="sect2"> -<h3 id="_value_placeholders">Value Placeholders</h3> -<div class="paragraph"> -<p>Users just want to to be able to add placeholders to the values of configuration (not the keys). The mechanisms for -resolving the placeholders hereby should be not constraint to one single lanmguage like EL. Instead of different -replacement strategies should be selectable, e.g. by prefixing an expression with the name of the resolver that -should do the work (eg "blabla ${env:HOME} using Java version ${sys:java.version}.". -This allows resolution mechanism to be isolated easily and also allows to use simpler mechanisms, if no more complex -ones like EL are required. This is especially useful to deal with low resource environment like ME.</p> -</div> -</div> -<div class="sect2"> -<h3 id="_type_safe_properties">Type Safe Properties</h3> -<div class="paragraph"> -<p>Users just want to access properties not only as Strings, but let Tamaya do the conversion to the required -or the configred target type. By defauklt all java.ui.lang wrapper and primitive types should be supported, but also -other common types like date/time types, math numeric types and more.</p> -</div> -<div class="paragraph"> -<p>It must be possible that users can register their own custom types.</p> -</div> -<div class="paragraph"> -<p>Finally users also want to be able to dynamically provide or override type adaption (conversion), when reading a value, -for a certain key/value pair.</p> -</div> -</div> -<div class="sect2"> -<h3 id="_configuration_templates">Configuration Templates</h3> -<div class="paragraph"> -<p>Users want to be able to let Tamaya implement an interface template based on configuration. -This use case is pretty similar to the injection use case. Basically the values are not injected, -but cached within the template proxy returned, e.g. as DynamicValue. -Similarly it could even be possible to define callback methods (default methods) -or register listeners to DynamicValue instances returned.</p> -</div> -<div class="paragraph"> -<p>Templates hereby can easily be managed, but provide a excellent mechanism to provide type-safe configuration -to clients in a very transparent way. Details can be controlled by using the same annotations as for -normal configuration injection.</p> -</div> -</div> -<div class="sect2"> -<h3 id="_java_8_functional_support">Java 8 Functional Support</h3> -<div class="paragraph"> -<p>Users want to be able to benefit from the new programming styles introduced with Java 8. Configuration -should provide extension points for different aspects, where additional code can be hooked in easily. -In short: were possible functional interfaces should be modelled.</p> -</div> -<div class="paragraph"> -<p>Examples:</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>code that converts a configuration to another kind of configuration: UnaryOperator<Configuration></p> -</li> -<li> -<p>code that creates any kind of result based on a configuration: Function<Configuration,T></p> -</li> -<li> -<p>Adapters for type conversion are defined as Function<String,T></p> -</li> -<li> -<p>Key, value filters ccan be modelled as BiFunction<String,String,String></p> -</li> -<li> -<p>etc.</p> -</li> -</ul> -</div> -</div> -<div class="sect2"> -<h3 id="_configuration_locations">Configuration Locations</h3> -<div class="paragraph"> -<p>Users want to be able to</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>read configuration from different locations.</p> -</li> -<li> -<p>By default classpath and file resources are -supported. But similarly remote access using a JSON ReST call should be possible.</p> -</li> -<li> -<p>Tamaya should define a JSON and XML format for configuration.</p> -</li> -<li> -<p>Configuration locations should be scannable using ant-styled resource patterns, if possible.</p> -</li> -<li> -<p>Scanning and reading logic can be modularized by using a ConfigReader interface.</p> -</li> -</ul> -</div> -</div> -<div class="sect2"> -<h3 id="_configuration_formats">Configuration Formats</h3> -<div class="paragraph"> -<p>Users want to be able to use the format they prefer.</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>properties, xml-properties and ini-format should be supported by default</p> -</li> -<li> -<p>Other/custom formats should be easily addable by registering or providing the format on configuration evaluation (read).</p> -</li> -<li> -<p>When possible Tamaya should figure out which format to be used and how the InputStream should be correctly -interpreted.</p> -</li> -</ul> -</div> -</div> -<div class="sect2"> -<h3 id="_multiple_configurations">Multiple Configurations</h3> -<div class="paragraph"> -<p>When systems grow they must be modularized to keep control. Whereas that sounds not really fancy, it leads to additional -aspects to be considered by a configuration system.</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>Different code modules, libraries, plugins or products want to have their "own" separated configuration.</p> -</li> -<li> -<p>Similar it should be possible to add fully specific additional configurations.</p> -</li> -</ul> -</div> -<div class="paragraph"> -<p>The default configuration hereby should always be present, whereas additional configurations are optional. -Users want to be able to check the availability of such an additional configuration.</p> -</div> -<div class="paragraph"> -<p>Of course, additional configuration must be identifiable. The best way to do is to be discussed, nevertheless the -mechanism must not depend on Java EE and the identifying keys must be serializable easily. -Basically simple names are sufficient and woukld provide exact this required functionality.</p> -</div> -</div> -<div class="sect2"> -<h3 id="_external_configuration">External Configuration</h3> -<div class="paragraph"> -<p>Users want to be able to replace, override, extend or adapt any parts or all of an existing configuration from -external sources. -This also must be the case for multi-context environments, where the context identifiers are -the only way to link to the correct remote configuration.</p> -</div> -</div> -<div class="sect2"> -<h3 id="_context_dependent_configuration">Context Dependent Configuration</h3> -<div class="paragraph"> -<p>In multi tenancy setups or complex systems a hierarchical/graph model of contexts for configurations is required, or different runtime contexts are executed in parallel -within the same VN. What sounds normal for EE also may be the case for pure SE environments:</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>Users want to be able to model different layers of runtime context</p> -</li> -<li> -<p>Users want to identify the current layer, so configuration used may be adapted.</p> -</li> -</ul> -</div> -</div> -<div class="sect2"> -<h3 id="_dynamic_provisioning_uc8">Dynamic Provisioning (UC8)</h3> -<div class="paragraph"> -<p>In Cloud Computing, especially the PaaS and SaaS areas a typical use case would be that an application (or server) -is deployed, configured and started dynamically. Typically things are controlled by some "active controller components", -which are capable of</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>creating new nodes (using IaaS services)</p> -</li> -<li> -<p>deploying and starting the required runtime platform , e.g. as part of a PaaS solution.</p> -</li> -<li> -<p>deploying and starting the application modules.</p> -</li> -</ul> -</div> -<div class="paragraph"> -<p>All these steps require some kind of configuration. As of today required files are often created on the target node -before the systems are started, using proprietary formats and mechanism. Similarly accessing the configuration in place -may require examining the file system or using again proprietary management functions. Of course, a configuration -solution should not try to solve that, but it can provide a significant bunch of functionality useful in such scenarios:</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>provide remote capabilities for configuration</p> -</li> -<li> -<p>allow configuration to be updated remotely.</p> -</li> -<li> -<p>allow client code to listen for configuration changes and react as needed.</p> -</li> -</ul> -</div> -</div> -<div class="sect2"> -<h3 id="_minimal_property_source_spi">Minimal Property Source SPI</h3> -<div class="paragraph"> -<p>Users expect that implementing an additional configuration property source is as easy as possible. -So there should be an SPI defined that allows any kind of data source to be used for providing configuration data. -The interface to be implemented is expected to be minimal to reduce the implementation burden. Default -methods should be used where possible, so only a few methods are expected to be required to implement.</p> -</div> -</div> -<div class="sect2"> -<h3 id="_scannable_properties">Scannable Properties</h3> -<div class="paragraph"> -<p>If possible configuration should be scannable, meaning it should be possible to evaluate the keys available. -The corresponding capabilities should be accessible by a isScannable() method.</p> -</div> -</div> -<div class="sect2"> -<h3 id="_combine_configurations">Combine Configurations</h3> -<div class="paragraph"> -<p>Users want to be able to combine different configurations to a new configuration instance. -Hereby the resulting configuration can be</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>a union of both, ignoring duplicates (and optionally log them)</p> -</li> -<li> -<p>a union of both, duplicates are ignored</p> -</li> -<li> -<p>a union of both, conflicts are thrown as ConfigException</p> -</li> -<li> -<p>an intersection of both, containing only keys present and equal in both configurations</p> -</li> -<li> -<p>an arbitrary mapping or filter, modelled by an CombinationPolicy, which basically can be modelled -as BiFunction<String, String, String>, hereby</p> -<div class="ulist"> -<ul> -<li> -<p>a result of null will remove the key</p> -</li> -<li> -<p>any other result will use the value returned as final value of the combination.</p> -</li> -</ul> -</div> -</li> -</ul> -</div> -</div> -<div class="sect2"> -<h3 id="_mx_rest_management">MX/ReST Management</h3> -<div class="paragraph"> -<p>Users want to be have comprehensive management support, which should allow</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>to change configuration</p> -</li> -<li> -<p>to remove configuration</p> -</li> -<li> -<p>to view configuration and its provider details</p> -</li> -</ul> -</div> -</div> -<div class="sect2"> -<h3 id="_adaptable_service_context">Adaptable Service Context</h3> -<div class="paragraph"> -<p>Tamaya should support an adaptable ServiceContext to resolve any kind of implememntation services, both API services as core -framework services. The ServiceContext should be dynamically replecable by configuring an alternate instance of -using the Java *ServiceContet+.</p> -</div> -<div class="paragraph"> -<p>This decouples component usage from its load and management part and als greatly simplifies integration with -new/alternate runtime environments. -The service context is exptected to provide</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>single singleton instances: these service can be cached.</p> -</li> -<li> -<p>access to multiple instances which implement some commons SPI interface.</p> -</li> -<li> -<p>as useful priorization of components is done by the model itself.</p> -</li> -</ul> -</div> -</div> -<div class="sect2"> -<h3 id="_configuration_injection">Configuration Injection</h3> -<div class="paragraph"> -<p>Users want to be able to polulate configured items by injecting configured values. Hereby</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>the lifecycle of the instances is not managed by Tamaya</p> -</li> -<li> -<p>all references to items configured are managed as weak references, to prevent memoryleaks.</p> -</li> -<li> -<p>Injection should if possible evaluate the properties by defaults. Even properties without -any annotations are possible.</p> -</li> -<li> -<p>Users expect to exclude certain properties from calculation</p> -</li> -<li> -<p>Beside injection of properties it is also possible to call setter methods with one parameter similarly.</p> -</li> -<li> -<p>Basically injection is performed, when the instance is passed to the Tamaya configuration system. It should also -be possible to inject/provide final values, especially Strings. Changes on configured values should be -reflected in the current value. Setters methods similarly can be called again, with the new values, on changes.</p> -</li> -<li> -<p>Users expect to control dynamic values and recall of setter methods, basically the following strategies should be -supported:</p> -<div class="ulist"> -<ul> -<li> -<p>inject only once and ignore further changes.</p> -</li> -<li> -<p>reinject/reinitialize on each change</p> -</li> -</ul> -</div> -</li> -<li> -<p>Dynamic Values can easily be modeled as ConfiguredValue instances, which should have the following functionality:</p> -<div class="ulist"> -<ul> -<li> -<p>access the current value</p> -</li> -<li> -<p>access the new value</p> -</li> -<li> -<p>access the latest value access time in ms</p> -</li> -<li> -<p>access the latest value update time in ms</p> -</li> -<li> -<p>evaluate easily if the value has changed since the last access</p> -</li> -<li> -<p>accept the change</p> -<div class="ulist"> -<ul> -<li> -<p>as a shortcut it should be possible to accept the change on access of the value implicitly, hereby always accessing -the latest valid value.</p> -</li> -</ul> -</div> -</li> -<li> -<p>ignore the change</p> -</li> -<li> -<p>register Consumer<DynamicValue> liasteners to listen on the changes (ans also removing them later again).</p> -</li> -</ul> -</div> -</li> -</ul> -</div> -<div class="paragraph"> -<p>All observing functionality can be done completely asynchronously and in parallel.</p> -</div> -</div> -</div> -</div> -<div class="sect1"> -<h2 id="Requirements">Requirements</h2> -<div class="sectionbody"> -<div class="sect2"> -<h3 id="_core_configuration_requirements">Core Configuration Requirements</h3> -<div class="sect3"> -<h4 id="_general">General</h4> -<div class="paragraph"> -<p>Tamaya must provide a Java SE API for accessing key/value based configuration. Hereby</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>Configuration is modelled by an interface</p> -</li> -<li> -<p>Configuration is organized as key/value pairs, using a subset of functionality present on Map<String,String> as -follows:</p> -<div class="ulist"> -<ul> -<li> -<p>access a value by key (get)</p> -</li> -<li> -<p>check if a value is present (containsKey)</p> -</li> -<li> -<p>get a set of all defined keys (keySet)</p> -</li> -<li> -<p>a configuration must be convertible to a Map, by calling toMap()</p> -</li> -<li> -<p>a configuration must provide access to its meta information.</p> -</li> -</ul> -</div> -</li> -<li> -<p>Configuration value access methods must never return null.</p> -</li> -<li> -<p>The API must support undefined values.</p> -</li> -<li> -<p>The API must support passing default values, to be returned if a value is undefined.</p> -</li> -<li> -<p>The API must allow to throw exceptions, when a value is undefined. Customized exceptions hereby should be supported.</p> -</li> -<li> -<p>Properties can be stored in the classpath, on a file or accessible by URL.</p> -</li> -<li> -<p>Properties can be stored minimally in properties, xml-properties or ini-format.</p> -</li> -</ul> -</div> -</div> -<div class="sect3"> -<h4 id="_minimalistic_property_source">Minimalistic Property Source</h4> -<div class="paragraph"> -<p>For enabling easy integration of custom built configuration sources a minimalistic API/SPI must be defined, that</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>is modelled by an interface</p> -</li> -<li> -<p>is a minimal subset of Configuration necessary to implement a configuration.</p> -</li> -<li> -<p>must be convertible to a "Configuration+.</p> -</li> -</ul> -</div> -</div> -<div class="sect3"> -<h4 id="_extension_points">Extension Points</h4> -<div class="paragraph"> -<p>For supporting more complex scenarios, Configuration</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>must implement the composite pattern, meaning new Configuration instances can be created by combining existing -configurations.</p> -</li> -<li> -<p>must be adaptable, by creating a new configuration by applying a UnaryOperator<COnfiguration> to it.</p> -</li> -<li> -<p>must be queryable, by passing a ConfigQuery to an Configuration instance.</p> -</li> -</ul> -</div> -</div> -<div class="sect3"> -<h4 id="_type_safety">Type Safety</h4> -<div class="paragraph"> -<p>Besides Strings Configuration should also support the following types:</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>Primitive types</p> -</li> -<li> -<p>Wrapper types</p> -</li> -<li> -<p>All other types (by using a PropertyAdapter</p> -</li> -</ul> -</div> -<div class="paragraph"> -<p>Hereby type conversion should be done as follows:</p> -</div> -<div class="olist arabic"> -<ol class="arabic"> -<li> -<p>Check if for the given target type an explicit adapter is registered, if so, use the registered adapter.</p> -</li> -<li> -<p>If no adapter is present, check if the target type T has static methods called T of(String), T getInstance(String), T valueOf(String), T from(String). If so -use this method to create the non value of T.</p> -</li> -<li> -<p>Check if the target type has a constructor T(String). If so, try to instantiate an instance using the constructor.</p> -</li> -<li> -<p>Give up, throw a IllegalArgument exception.</p> -</li> -</ol> -</div> -</div> -</div> -<div class="sect2"> -<h3 id="_configuration_fomats">Configuration Fomats</h3> -<div class="paragraph"> -<p>By default Tamaya support the following configuration formats:</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>.properties</p> -</li> -<li> -<p>.xml properties</p> -</li> -<li> -<p>.ini files</p> -</li> -</ul> -</div> -<div class="paragraph"> -<p>It must be possible to add additional formats by registering them with the current ServiceContext.</p> -</div> -</div> -<div class="sect2"> -<h3 id="_mutability">Mutability</h3> -<div class="ulist"> -<ul> -<li> -<p>Configurations can be mutable, mutability can be accessed as a property.</p> -</li> -<li> -<p>Configuration can be changed by collecting the changes into a ConfigCHangeSet and apply this set to the -given Configuration instance.</p> -</li> -<li> -<p>Besides the points above, Configuration is immutable.</p> -</li> -</ul> -</div> -</div> -<div class="sect2"> -<h3 id="_serializability_and_immutability_of_configuration">Serializability and Immutability of Configuration</h3> -<div class="ulist"> -<ul> -<li> -<p>Configuration is modelled as a service. Therefore serialization may not work. This can be mitigated by adding -a freeze feature, where the know key/value pairs are extracted into an immutable and serializable form.</p> -</li> -</ul> -</div> -</div> -<div class="sect2"> -<h3 id="_configuration_combination_requirements">Configuration Combination Requirements</h3> -<div class="paragraph"> -<p>At least the following composition policies must be supported:</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>override: subsequent entries override existing ones.</p> -</li> -<li> -<p>aggregate-exception: key/values were added, in case of conflicts a ConfigException must be thrown.</p> -</li> -<li> -<p>aggregate-ignore-duplicates: similar to union, whereas duplicates are ignored (leaving the initial value loaded).</p> -</li> -<li> -<p>aggregate-combine: conflicting entries were resolved by adding them both to the target configuration by -redefining partial keys.</p> -</li> -<li> -<p>custom: any function determining the key/values to be kept must be possible</p> -</li> -</ul> -</div> -<div class="paragraph"> -<p>When combining configuration it must also be possible to override (file/classpath) configuration by</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>system properties.</p> -</li> -<li> -<p>command line arguments.</p> -</li> -</ul> -</div> -</div> -<div class="sect2"> -<h3 id="_configuration_injection_2">Configuration Injection</h3> -<div class="paragraph"> -<p>As metnioned configuration can be injected by passing a unconfigured instance of an annotated class to the -Configuration.configure static method:</p> -</div> -<div class="listingblock"> -<div class="title">Configuring a POJO</div> -<div class="content"> -<pre class="prettyprint highlight"><code class="language-java" data-lang="java">MyPojo instance = new MyPojo(); -Configuration.configure(instance);</code></pre> -</div> -</div> -<div class="paragraph"> -<p>Hereby -* It must be possible to define default values to be used, if no valid value is present. -* It must be possible to define dynamic expressions, at least for default values. -* The values configured can be reinjected, if the underlying configuration changes. This should also be the case - for final classes, such as Strings. -* Reinjection should be controllable by an loading policy. -* It must be possible to evaluate multiple keys, e.g. current keys, and as a backup deprecated keys - from former application releases. -* It must be possible to evaluate multiple configurations. -* The type conversion of the properties injected must be configurable, by defining a PropertyAdapter. -* The value evaluated for a property (before type conversion) must be adaptable as well. -* It must be possible to observe configuration changes.</p> -</div> -<div class="paragraph"> -<p>The following annotations must be present at least:</p> -</div> -<div class="ulist"> -<ul> -<li> -<p><strong>@ConfiguredProperty</strong> defining the key of the property to be evaluated. It takes an optional value, defining the -property name. It must be possible to add multiple annotations of this kind to define an order of evaluation -of possible keys.</p> -</li> -<li> -<p><strong>@DefaultValue</strong> (optional) defines a default String value, to be used, when no other key is present.</p> -</li> -<li> -<p><strong>@WithConfig</strong> (optional) defines the name of the configuration to be used. Similar to @ConfiguredProperty multiple -configuration can be defined for lookup.</p> -</li> -<li> -<p><strong>@WithConfigOperator</strong> allows to adapt the String value evaluated, <strong>before</strong> it is passed as input to injection or -type conversion.</p> -</li> -<li> -<p><strong>@WithPropertyAdapter</strong> allows to adapt the conversion to the required target type, hereby overriding any default -conversion in place.</p> -</li> -<li> -<p><strong>@WithLoadPolicy</strong> allows to define the policy for (re)injection of configured values.</p> -</li> -<li> -<p><strong>@ObservesConfigChange</strong> allows to annotate methods that should be called on configuration changes.</p> -</li> -<li> -<p>*@DefaultAreas" allows to define a key prefix key to be used for the configured key, if no absolute key -is defined.</p> -</li> -</ul> -</div> -</div> -<div class="sect2"> -<h3 id="_configuration_templates_2">Configuration Templates</h3> -<div class="paragraph"> -<p>For type safe configuration clients should be able to define an interface and let it implement by the -configuration system based on Configuration available:</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>Clients define an interface and annotate it as required (similar to above)</p> -</li> -<li> -<p>The interface methods must not take any arguments</p> -</li> -<li> -<p>The configuration system can be called to return such an interface implementation.</p> -</li> -<li> -<p>The configuration system returns a proxy hereby providing type-safe access the values required.</p> -</li> -<li> -<p>Similar to configured types also templates support multiple values and custom adapters.</p> -</li> -<li> -<p>It is possible to listen on configuration changes for templates, so users of the templates -may react on configuration changes.</p> -</li> -</ul> -</div> -<div class="paragraph"> -<p>The following snippet illustrates the requirements:</p> -</div> -<div class="listingblock"> -<div class="title">Type Safe Configuration Template Example</div> -<div class="content"> -<pre class="prettyprint highlight"><code class="language-java" data-lang="java">public interface MyConfig { - - @ConfiguredProperty("myCurrency") - @DefaultValue("CHF") - String getCurrency(); - - @ConfiguredProperty("myCurrencyRate") - Long getCurrencyRate(); - - @ConfigChange - default configChanged(ConfigChange event){ - ... - } - -}</code></pre> -</div> -</div> -<div class="paragraph"> -<p>Templates can be accessed by calling the Configuration.current(Class) method:</p> -</div> -<div class="listingblock"> -<div class="title">Accessing a type safe Configuration Template</div> -<div class="content"> -<pre class="prettyprint highlight"><code class="language-java" data-lang="java">MyConfig config = Configuration.current(MyConfig.class);</code></pre> -</div> -</div> -</div> -<div class="sect2"> -<h3 id="RequirementsServer">Server Configuration Requirements</h3> -<div class="ulist"> -<ul> -<li> -<p>Ensure Configuration can be transferred over the network easily.</p> -</li> -<li> -<p>Beside serializability text based formats for serialization in XML and JSON must be defined.</p> -</li> -<li> -<p>A management API must be defined, which allows to inspect the configuration in place, e.g. using -JMX or REST services.</p> -</li> -</ul> -</div> -<div id="RequirementsJavaEE" class="paragraph"> -<p>Java EE leads to the following requirements:</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>Configuration must be contextual, depending on the current runtime context (e.g. boot level, ear, war, …​).</p> -</li> -<li> -<p>Hereby contextual aspects can even exceed the levels described above, e.g. for SaaS scenarios.</p> -</li> -<li> -<p>Resources can be unloaded, e.g. wars, ears can be restarted.</p> -</li> -<li> -<p>The different contextual levels can also be used for overriding, e.g. application specific configuration -may override ear or system configuration.</p> -</li> -<li> -<p>Configuration may be read from different sources (different classloaders, files, databases, remote locations).</p> -</li> -<li> -<p>Configuration may be read in different formats (deployment descriptors, ServiceLoader configuration, alt-DD feature, …​)</p> -</li> -<li> -<p>JSF also knows the concept of stages.</p> -</li> -<li> -<p>Many SPI’s of Java EE require the implementation of some well defined Java interface, so it would be useful if the -configuration solution supports easy implementation of such instances.</p> -</li> -<li> -<p>In general it would be useful to model the Environment explicitly.</p> -</li> -<li> -<p>Configuration used as preferences is writable as well. This requires mutability to be modelled in way, without the -need of synchronization.</p> -</li> -<li> -<p>JNDI can be used for configuration as well.</p> -</li> -</ul> -</div> -<div id="RequirementsMultitenancy" class="paragraph"> -<p>Configurations made in the tenant or user layer override the default app configuration etc., so</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>It must be possible to structure Configuration in layers that can override/extend each other.</p> -</li> -<li> -<p>The current environment must be capable of mapping tenant, user and other aspects, so a corresponding configuration -(or layer) can be derived.</p> -</li> -</ul> -</div> -</div> -<div class="sect2"> -<h3 id="RequirementsExtensions">Extensions Requirements</h3> -<div class="paragraph"> -<p>It must be possible to easily add additional functionality by implementing external functional interfaces operating -on Configuration.</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>UnaryOperator<Configuration> for converting into other version of Configuration.</p> -</li> -<li> -<p>ConfigQuery<T> extending Function<T, Configuration>.</p> -</li> -</ul> -</div> -</div> -<div class="sect2"> -<h3 id="RequirementsNonFunctional">Non Functional Requirements</h3> -<div class="paragraph"> -<p>THe following non-functional requirements must be met:</p> -</div> -<div class="ulist"> -<ul> -<li> -<p>tbd</p> -</li> -</ul> -</div> -</div> -</div> -</div></p> - - <hr /> - </div> - </div> - <div> - <div id="push"></div> - - <div id="footer"> - <div class="container"> - <p class="muted credit">© 2014-2016 Apache Software Foundation | Mixed with <a href="http://getbootstrap.com/";>Bootstrap v3.1.1</a> - | Baked with <a href="http://jbake.org";>JBake <span>v2.5.0</span></a> - at <span>2016-12-12</span> - </p> - <p> - <b>Disclaimer</b> - Apache Tamaya (incubating) is an effort undergoing - incubation at - The Apache Software Foundation (ASF), sponsored by - the name of Apache Incubator. Incubation is required of - all newly accepted projects until a further review indicates - that the infrastructure, communications, and decision making - process have stabilized in a manner consistent with other - successful ASF projects. While incubation status is not - necessarily a reflection of the completeness or stability of - the code, it does indicate that the project has yet to - be fully endorsed by the ASF.<br /> - <a href="http://incubator.apache.org/guides/website.html"; style="border:0px;" target="_target"><img class="incubator-logo" src="logos/egg-logo2.png"/></a> - </p> - </div> - </div> - - <!-- Le javascript - ================================================== --> - <!-- Placed at the end of the document so the pages load faster --> - <script src="js/jquery-1.11.1.min.js"></script> - <script src="js/bootstrap.min.js"></script> - <script src="js/prettify.js"></script> - - </div> - </body> -</html>
