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Static JSF EL Expression Validator

Perform analysis of JSF 2.x, 1.2, or 1.1 JSP or Facelets pages and validate that all EL expressions reference only existing managed beans and their properties or action methods.

USAGE

See the main class net.jakubholy.jeeutils.jsfelcheck.[Abstract]JsfStaticAnalyzer (To actually instantiate it you need one of the JSF version specific subclasses, see e.g. static-jsfexpression-validator-jsf20 (JSF 2.0+)). You can try to run it from the command line (it prints the usage info).

DOWNLOADS

You can get the binaries via Maven or manually from the Maven Central Repository. Select version compatible with your JSF:

  1. JSF 1.1: static-jsfexpression-validator-jsf11
  2. JSF 1.2: static-jsfexpression-validator-jsf12
  3. JSF 2.x: static-jsfexpression-validator-jsf20

INTRODUCTION AND EXAMPLES OF USAGE

See the detailed description of how to use the tool at the (outdated by still valuable) introductory [blog post "Validating JSF EL Expressions in JSF Pages with static-jsfexpression-validator"]. (http://theholyjava.wordpress.com/2011/06/22/validating-jsf-el-expressions-in-jsf-pages-with-static-jsfexpression-validator/)

You can also check the test webapps to see how the validator is used, especially test-webapp-jsf12 and test-webapp-jsf20-facelets_owb, i.e. JSF 2.0 Facelets test class and JSF 1.2 JSP test class. (It's best to download the complete sources of the test web application from GitHub or Maven.)

CURRENT LIMITATIONS

  • JSF 1.1 implementation distinguishes between value and method bindings only based on the attribute name (methods: action, actionListener, validator, valueChangeListener) and thus won't recognize other method bindings
  • The signature of methods used in a MethodBinding isn't checked (i.e. whether it has the correct return type and arguments, the only thing checked is that a public method with the name exists)
  • Functions are not checked for existence and correct signature
  • Facelets support could be better, namely included content (layout, custom components, custom tags) isn't checked
  • Local variable declaring tags such as h:dataTable and ui:repeat are only allowed to declare one variable, i.e. e.g. varStatus is not recognized

To see some of the things that should ideally work but do not, execute

mvn -Djsfelcheck.runFailingTests=true test

PROJECT STATUS

Further development of this project is driven exclusively by user demand. If you have a feature request then it's most welcomed if you can also collaborate on implementing it.

Requests and bug reports may be submitted via the project's GitHub issue tracker.

TODO - FURTHER DEVELOPMENT

Top Limitations:

  • Facelets: Add support for declaring custom taglibs?
  • Facelets: When parsing, descend into referenced resources, handling over locally defined variables and tag attribute bindings (templates, custom tags, composites)
  • Facelets: Make it possible to extract local variables from/for ui:param, tag attributes, custom runtime tags etc.

Note: Problems testing directly in -jsfXX: Faces init fails for it searches for libs under WEB-INF/lib or st. like that.

Facelets parsing:

  • Check non-detected ELs in net.jakubholy.jeeutils.jsfelcheck.expressionfinder.impl.facelets.ValidateAllExpressionsInFaceletsTest
    1. Currently we do not process referenced pages such as templates, custom tags and composites; we likely should do it for we want to check that we're supplying valid parameters (or do we trust the developer that she is sending an object of the right type?)
    2. Also we do not process tags that produce local variables, namely ui:param, c:set, composite attributes (expected via composite:attribute) + tag attributes (undeclared) and any custom tags (ex: my:set) by the user or a library (same problem as with JSP; the user should have the possibility to register custom TagJsfVariableResolver for such tags). (I'd actually wouldn't mind ignoring c:set as mixing build-time and runtime components is generally a bad practice)
  • Current limitation in Facelets: No way to detect what is value or Method expression => we try value first and method next, should autodetect somehow, min. for the standard tags and let users delcare it => teach the EL validator at least about the standard tags' method and value expressions
  • enable filtering of views to process at least as done for JSPs now
  • add support for declaring custom taglibs (File/InputStream? - what with taglibs in framework jars?)
  • see TODOs in NotifyingCompilationManager

  • finishing touches:

    • add addFunctionReturnTypeOverride -> MethodFakingFunctionMapper - useful? wait til the bus-based architecture?
  • better support for view file filtering (includes/excludes)

  • JsfElFilter should take something more reasonable than ParsedElExpression - remove setters, ref.to Iterator, incl.file name, tag, line

    • how does it work with "#{b[nestedBean.itsProp].property + anotherBean}"?
    • likely wait for the bus-based architecture

  • test with various JSF projects ?
  • better error msgs - see below => make it clear the solution is st. like propertyTypeOverrides.put("bean.listProperty.*", TheElementType.class);

  • TagJsfVariableResolvers:
    1. Pass declared local vars to all resolvers, not only dataTable
    2. Allow a tag to declare multiple local vars and add them to dataTable/ui:repeat
  • full JSF 1.2+ support: support EL functions (not just 'function tolerance' as implemented now)
  • FIX: MethodFakingFunctionMapper currently allows only 1 arity for a function, i.e. not having the same fun name with different number of arguments
  • don't mock implementations of Map/Collection, instantiate them instead (eg ArrayList)
  • consider using more modern jasper for JSF2.x than 6.0.29 used in 1.2
  • consider parallelization (take ~30s for our 200 pages on my PC)
  • better handling of includes:
    1. possibility to exclude pages from processing (the non-standalone ones)
    2. whenever dynamic jsp include encountered, switch to processing of that page, passing local variables in
  • consider extending the Facelets compiler to be able to actually render the views into html (see stackoverflow.com/questions/6625258/how-do-i-build-a-facelets-site-at-build-time/7928541)

  • Consider enabling in-container testing (- slower, + complete & correct env. setup, no need to search for m.beans). Not too difficult to implement - just run with an embedded Jetty either reading the default config & injecting our resolvers if possible after the initialization or with custom config defining our resolvers, trigger the tests form a app. state listener when everything loaded. Perhaps also support other containers such as Tomcat.

IDEA: Architecture refactoring: Stateless objects and message passing through a central delegator with support for plugging-in filters. Key components:

  • Message: Contains Context, input, output (may be of the same type as the input). Context holds the static global state (e.g. user-registered local vars), public state from upstream workers (e.g. current EL), and private state of each worker that needs it (e.g. per-page cache of functions), and indicator whether processing of the current resource (page/tag/EL) should continue or not (for filtering, ...)
  • WorkHub:
    • has delegateWork (exp. sb. to transform the input into output) and notifyOf (no recipient required)
    • creates instances of work processors un demand, initializes them with itself/other stuff
  • Worker: Has an instance of WorkHub => advantages:1) Easy to do multithreaded processing; 2) Powerful & flexible arch. for users: the can plug in filters that reject resources or modify messages (inputs/outputs) or just collect info for reporting/stats
  • Global shared state objects: E.g. cache shared across all threads (or force them into the ctx?)
  • Issues
    • complicates interfaces and thus reuse outside of JsfElV, e,g, Result validate(String EL) => Event val.(Event)
    • storing private state in the ctx makes it more expensive to access (logN, negligible?), sb. else can possibly modify it
    • how to pass state needed in collbacks? (easy with instance var., not so with ctx as method param.)
    • system initialization (Compiler is created by Jasper via new C.() => can't get objects from outside)
    • how to handle exceptions in listeners/workers?
    • ...

Use it:

  • let the user decide whether an attribute is method or value binding
  • powerful file/tag/attribute filtering

TODO - improve error messages

Ex.1.: PropertyNotFoundException on class Error_YouMustDelcareTypeForThisVariable

  • include advice how to solve it

Ex.2.: Forgotten .* in property override

Invalid EL expression 'List item value: #{myCollectionBean.list[0].value}': PropertyNotFoundException - Property '0' not found on type net.jakubholy.jeeutils.jsfelcheck.webtest.jsf12.testbean.MyCollectionBean$ValueHolder$$EnhancerByMockitoWithCGLIB$$ec64146]; expression=List item value: #{myCollectionBean.list[0].value}, file=/testLocalVariables.jsp, tagLine=32]

  • add tip that the user might have forgotten the .* if we can guess that it would help

Ex.3.: Missing property override

Invalid EL expression 'List item value: #{myCollectionBean.list[0].value}': PropertyNotFoundException - Property 'value' not found on type net.jakubholy.jeeutils.jsfelcheck.validator.MockObjectOfUnknownType$$EnhancerByMockitoWithCGLIB$$f3296ef8]; expression=List item value: #{myCollectionBean.list[0].value}, file=/testLocalVariables.jsp, tagLine=32]

  • property not found & collection => advice to use withPropertyOverride

Ex.4.:

Invalid EL expression 'Unknown managed bean - extra variable: #{iAmExtraVariable}': VariableNotFoundException - No variable 'iAmExtraVariable' among the predefined ones.]; expression=Unknown managed bean - extra variable: #{iAmExtraVariable}, file=/testLocalVariables.jsp, tagLine=35]

  • advice to declare it either as a local variable or with withExtraVariable

DEVELOPEMET INTRO

Key classes

  • AbstractJsfStaticAnalyzer - the main method, wires all together
  • JsfElValidatingPageNodeListener - drives the validation based on JSP tags being processed and composes the failures/successes report
  • ValidatingJsfElResolver - actual checks of JSF EL expressions

Other:

  • net.jakubholy.jeeutils.jsfelcheck.expressionfinder.impl.jasper.PageNodeExpressionValidator.isMethodBinding(String) - distinguish value and method binding

Note on JSF 1.2 and 2.0

http://www.roseindia.net/jsf/jsf-versions.shtml

Expression Language, referred to as EL, was first introduced in JSTL 1.0, and later included in JSP 2.0. A variant of the EL was used in JSF 1.0. In JSP 2.1, JSF 1.2 and JSTL 1.2, an unified EL was defined.

JSF 1.1 (27 may 2004)

  • Bug fix release. No specification changes.

JSF 1.2(11 may 2006)

  • Unified EL for JSP and JSF, introduced ELResolver => support for setters, calling methods

JSF 2.0

  • The Java EE 6 EL: "The expression language has changed in minor ways. Perhaps the most useful enhancement for JSF programmers is the use of arguments in action methods."

IMPLEMENTATIONS

  • JSF 1.2: org.apache.tomcat:el-api:6.0.29 and org.apache.tomcat:jasper-el:6.0.29
  • JSF 2.0: likely org.apache.tomcat:tomcat-jasper-el:7.0.16 and org.apache.tomcat:tomcat-el-api:7.0.16

Note:

  • JSF 2.0 <=> JavaEE 6 => Servlet 3.0 and JSP/EL 2.2 => Tomcat 7.0.x
  • JSF 1.2 <=> JavaEE 5 => Servlet 2.5 and JSP 2.1 =>Tomcat 6.0.x

Sources:

Interesting Links


NOTES

Version 1.0.0

Reviewed and corrected documentation.

Version 0.9.9

  • added support for ui:repeat

Version 0.9.8

  • Support for detecting managed beans based on annotations (analyzer.withManagedBeansAndVariablesConfiguration(fromClassesInPackages(..)..))
  • The directory passed to analyzer.validateElExpressions must the root of your web application; alternatively you can pass in two directories - the webapp root and the directory containing the pages to analyze

Version 0.9.7

  • Fix: Do actually check EL for a method binding (before the check succeeded even if the method didn't exist) (however we check only the name of the method, not the type and number of parameters)
  • New: Support for Facelets (stil somehow limited)
  • Autodetection of method binding in JSP-based JSF 1.2+ (based on the tag attribute's type being javax.el.MethodExpression; before we decided what it is just based on the attribute name)
  • Report all functions found (for they are not really validated); see net.jakubholy.jeeutils.jsfelcheck.ResultsReporter.printWarningAboutUncheckedFunctions

Version 0.9.6

Quick bugfix release:

  • support imported Spring subconfigx and multiple/... faces configs
  • static-jsfexpression-validator-jsf11.jar: Add missing dependencies on jasper-el to avoid ClassNotFound ex. when parsing
  • fixed EL expression recognizer to ignore immediate evaluation expr. (${..}) and only accept ordinary JSF (deffered eval.) ones
  • added File... version of from* methods also for the non-static ones in Man.BeansAndVarConfig
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