Scenario 1, exploiting JRE from non-Java (Re: Minor thoughts (Re: [External] : Re: JEP draft: Prepare to Restrict The Use of JNI

[Rony G. Flatscher]

Consider the following ooRexx program that exploits the JRE (the Java classes available via the Java 
runtime environment, installed by OpenJDK):

    /* purpose: demonstrate how to fetch and list all links with jsoup */
    parse arg source     -- command line argument: can be html, xml; a local file or URL
    url? = source ~startsWith("http")   -- do we need to parse a URL?
    timeout = 10000                     -- timeout: 10 sec (10000 msec)
    if url? then src=.bsf~new("java.net.URL", source)  -- create URL object
             else src=.bsf~new("java.io.File", source)  -- create File object

    clzJsoup = bsf.importClass("org.jsoup.Jsoup")      -- import Jsoup class
    if url? then rootNode = clzJsoup~parse(src, 10000) -- timeout: 10 second
             else rootNode = clzJsoup~parse(src)

    allLinks = rootNode~select("a")  -- get all a-elements
    len=length(allLinks~size)        -- get length of size for right-adjusting
    say "there are" pp(allLinks~size) "links"
    do counter c link over allLinks  -- iterate over the collection (ArrayList)
        -- say "#" c~right(len)":" pp(link~absURL('href')) "for" pp(link~text)
        say "#" c~right(len)":" pp(link~attr('href')) "for" pp(link~text)
    end

    ::requires "BSF.CLS"             -- get ooRexx-Java bridge
    /* purpose: demonstrate how to fetch and list all links with jsoup */
    parse arg source     -- command line argument: can be html, xml; a local file or URL
    url? = source ~startsWith("http")   -- do we need to parse a URL?
    timeout = 10000                     -- timeout: 10 sec (10000 msec)
    if url? then src=.bsf~new("java.net.URL", source)  -- create URL object
             else src=.bsf~new("java.io.File", source)  -- create File object

    clzJsoup = bsf.importClass("org.jsoup.Jsoup")      -- import Jsoup class
    if url? then rootNode = clzJsoup~parse(src, 10000) -- timeout: 10 second
             else rootNode = clzJsoup~parse(src)

    allLinks = rootNode~select("a")  -- get all a-elements
    len=length(allLinks~size)        -- get length of size for right-adjusting
    say "there are" pp(allLinks~size) "links"
    do counter c link over allLinks  -- iterate over the collection (ArrayList)
        -- say "#" c~right(len)":" pp(link~absURL('href')) "for" pp(link~text)
        say "#" c~right(len)":" pp(link~attr('href')) "for" pp(link~text)
    end

    ::requires "BSF.CLS"             -- get ooRexx-Java bridge

The result of running the above program against http://openjdk.net

    E:\WU\Lehrveranstaltungen\Materialien\BP2_AutoJava\254_AutoJava_jsoup_code>rexx jsoup_05.rxj
    http://openjdk.org
    there are [132] links
    #   1: [https://www.oracle.com/technetwork/java/javase/overview/index.html] for [Java Platform,
    Standard Edition]
    #   2: [projects/jdk/20] for [latest open-source JDK]
    #   3: [https://jdk.java.net/20] for [jdk.java.net/20]
    #   4: [https://www.oracle.com/technetwork/java/javase/downloads/index.html] for [here]
    #   5: [projects/amber] for [Amber]
    #   6: [https://wiki.openjdk.org/display/loom/Main] for [Loom]
    #   7: [projects/panama] for [Panama]
    #   8: [https://wiki.openjdk.org/display/valhalla/Main] for [Valhalla]
    #   9: [projects/jdk/19] for [the next version of Java and the JDK]
    #  10: [https://dev.java] for [dev.java]

    ... cut ...

    # 119: [/projects/tiered-attrib] for [Tiered Attribution]
    # 120: [/projects/tsan] for [Tsan]
    # 121: [/projects/type-annotations] for [Type Annotations]
    # 122: [/projects/valhalla] for [Valhalla]
    # 123: [/projects/verona] for [Verona]
    # 124: [/projects/visualvm] for [VisualVM]
    # 125: [/projects/wakefield] for [Wakefield]
    # 126: [/projects/zero] for [Zero]
    # 127: [/projects/zgc] for [ZGC]
    # 128: [https://oracle.com] for []
    # 129: [/legal/tou/] for [Terms of Use]
    # 130: [/legal/gplv2+ce.html] for [GPLv2]
    # 131: [https://www.oracle.com/us/legal/privacy/] for [Privacy]
    # 132: [https://openjdk.org/legal/openjdk-trademark-notice.html] for [Trademarks]

This program runs on all versions of Java/OpenJDK unchanged.

With your currently intended warning all of a sudden all users of such programs/applications get 
frightened for no good reason!

---rony

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