Clojure for Windchill Development, Part 1

I always wanted to know more about functional programming and lisp – so I thought why not use Clojure. It runs on the JVM and I can try out some real-world problems with it.

Normally I use Jython – a implementation of the Python programming language which runs on the JVM – to develop for Windchill.

This is the first part of a series of post’s I’m going to make to log my progress.

In this part I’ll show how to authenticate and search in Windchill using Clojure.

Installing

I use a mac, so installing Clojure is quite easy for me – YMMV::

    $ brew install clojure

Running the Clojure REPL

That’s easy, too:

    $ clj
    Clojure 1.4.0
    user=> (+ 1 2)
    3

Installing Clojure in Windchill

This is quite easy, too. Just drop the Clojure jar file to $WT\_HOME/codebase/WEB-INF/lib. Then, when starting the REPL, be sure to have the CLASSPATH set up correctly.

First Steps using Windchill

The first Task I wanted to solve is:

• authenticate against Windchill using the RemoteMethodServer
• search for a named EPMDocument using a custom-built QuerySpec

This is what I came up with:

(import '(wt.method RemoteMethodServer)
        '(wt.epm EPMDocument)
        '(wt.fc PersistenceHelper)
        '(wt.query QuerySpec SearchCondition))

(defn authenticate [u p]
  (doto (. RemoteMethodServer getDefault)
    (.setUserName u)
    (.setPassword p)))

(defn sc-name [name]
  (SearchCondition. EPMDocument (EPMDocument/NAME) "LIKE" name false))

(defn make-query-spec [class]
  (QuerySpec. class))

(defn build-query-spec [name]
  (let [qs (make-query-spec EPMDocument)]
    (.appendWhere qs (sc-name name))
    qs))

(defn search [name]
  (enumeration-seq
    (.find PersistenceHelper/manager
      (build-query-spec name))))

;; Authenticate first
(authenticate "orgadmin" "orgadmin")

;; Do a search for `k05*.asm`
(def result
  (search "k05%.asm"))

;; and print out all the resulting objects.
(println result)

The code is also on github.

Things To Note

• The first few lines (1..4) import Classes from the named packages to the current namespace.

• The (doto instance expr) special form saves quite some typing. (line 7)

• It took a while until I figured out how to convert the enumeration from the QueryResult to a Clojure sequence. It’s the (enumeration-seq expr) special form. This is quite cool, as this probably means that the results from the search would be processed lazily, too. (line 23)

• I had quite some problems getting the (let [...] expr) special form right. For some reason I had one pair of parens too much and it kept evaluating a nil result from Java which caused a dreaded Null Pointer Exception.

• I started to put the (authenticate ...) and the imports in a user.clj, such that the REPL has these aitomatically loaded.

Things to explore:

• Use a custom name space. Currently, all is in the user name space.

• Use leiningen to manage dependencies.

• Better VIM integration