The MREF Class Loader: your own code and pages, without rebuilding anything

Part 1What a Class Loader is

A Class Loader is a record in MREF that holds files the application server should load in addition to its own. There are two kinds of file:

• Java: a .jar with compiled classes. MREF can call them as a small web service, or as a custom step in a workflow.
• Web: a .zip with HTML, JavaScript, images. MREF serves them as pages, to signed-in users only.

The name comes from Java: a class loader is the part of Java that finds and loads code. Each Class Loader record gets its own, so your jar does not mix with MREF's jars or with another extension's.

Part 2The Class Loader list

Open Tools › System Setup › System › Class Loader. You need an administrator's access.

Most of the list is IBM's own. It is worth reading, because it shows what Class Loaders are used for:

Part 3Inside one record: MREF3D

MREF3D holds two resource files: MREF3D (the Web zip with the page) and MREF3D.jar (the Java class). One Class Loader can hold both kinds, and that is the normal design: the page and the code it calls travel together.

Part 4Where the files live

This is the part that surprises people. The uploaded file is stored in the database, as a blob. The copy on the application server's disk is only a cache: MREF unpacks it from the database the first time the Class Loader is used.

/home/wiotp/userfiles/ClassLoader/
├── EsriJS/
│   ├── Java/   EsriJS.jar, TRIRIGAIntegration.jar
│   └── Web/    EsriJS_arcgis.js, language files, …
├── MREF3D/
│   ├── Java/   MREF3D.jar
│   └── Web/    index.html, app.js, config.json, sample.json, enrich.json
└── TjeneConnectV3/

That is the real folder on our application server pod. Notice two things. The list has 17 Class Loaders, but only three folders exist: the ones somebody has used since the pod started. And the split is always the same: Java/ for jars, Web/ for the unpacked zip.

Part 5The two URLs

Every Class Loader answers on two addresses, both under /html/en/default/rest/:

Both are served only to a signed-in user. Open either one without a session and MREF sends you to the login page. That is why a page delivered this way can call MREF's own data services with the viewer's session, and each person sees only what their security groups allow.

Part 6The web part: Portfolio 3D

The Web zip contains an ordinary web page: index.html, app.js and a few data files. It draws every building that has a latitude and longitude on an Esri 3D globe.

The data is not copied into the page. The page asks MREF for it, with the same data sources the built-in Locate Map application uses: one for buildings with their coordinates, one for rooms with their floor and capacity. If that request is refused, the page falls back to a snapshot file and says so in amber, so nobody mistakes old data for live data.

Pick a building and the page flies to it. The building is drawn as a stack of floors, coloured by the number of rooms or the capacity of each floor. The panel on the right lists the floors (6 floors, 894 rooms, capacity 1,508) and then four sections: leases, capital projects, maintenance, energy and costs. Those four come from the Java part.

A live dashboard on the map

This is the point of the whole exercise. The map is not a picture of the portfolio; it is a live dashboard built on top of a Class Loader. Everything in the right-hand panel is read from MREF at the moment you click the building, with your own session, and the last line of the panel says when.

To put the page on a home page: Tools › Application Builder › Portal Builder, add a Portal Section of type External URL pointing to /html/en/default/rest/MREF3D/resource/index.html, then add that section to a portal. It is the same kind of section as the built-in GIS map sections.

Part 7The Java part: live data for one building

The page needs figures that no ready-made data source gives in one call: this building's leases, projects, work tasks, energy per year and latest costs. So the jar contains one class that reads them and returns JSON.

package com.tririga.custom;                 // required package

public class MREF3D implements IConnect {   // class name = Class Loader name

    public void execute(TririgaWS tws, HttpServletRequest req, HttpServletResponse res) {
        String b = req.getParameter("building");
        if (b == null || !b.matches("\\d{1,19}")) { res.setStatus(400); return; }   // validate input
        // read-only SELECTs on MREF's own data source, the id bound as a parameter
        // … write JSON to res
    }
}

Three rules make it work:

• The class implements IConnect, MREF's interface for "a class that answers a web request".
• It lives in the package com.tririga.custom and has the same name as the Class Loader. That is how /rest/MREF3D finds it.
• It is compiled against the server's own libraries: MREF's ibm-tririga.jar and the Jakarta Servlet API, for the server's Java version (Java 21 on our system).

Called as /html/en/default/rest/MREF3D?building=10336477, it answers:

{ "building": 10336477,
  "leases":   [ 95 leases:  id, name, status, type, annual rent, expiry ],
  "projects": [ 75 capital projects: status, budget, committed, dates ],
  "energy":   [ {"year":2012,"use":1902824,"cost":86845},
                {"year":2013,"use":1333385,"cost":76302},
                {"year":2014,"use":1060894,"cost":57000} ],
  "costs":    { "period":"2014-10-01", "operating":271388, "maintenance":83956,
                "utilities":26929, "energy":12187, "rent":340819 },
  "maintenance": { "counts":[ Planned 871, Completed 391, Active 125, Closed 9 ], … },
  "asOf": "2026-10-03T04:44:46Z" }

Part 8Six traps

Part 9The built-in 3D: the BIM model viewer

MREF also has a 3D feature of its own, and it is a different thing. A building record has a 3D Model tab that shows the building's real geometry: the walls, rooms and equipment from the architect's BIM model (Building Information Model, usually made in Autodesk Revit).

The BIM viewer needs three things, and a new admin usually misses the first:

1. An Autodesk key. The viewer is Autodesk's, and the model is translated and stored in Autodesk's cloud. The key (a client ID and secret from an Autodesk Platform Services application) goes in Tools › System Setup › BIM Connector.
2. A model linked to the building. In BIM Model Management you upload the Revit file and link it to the building record. The 3D Model tab simply lists the active model links of that building.
3. Rooms that match. A room in the model is tied to an MREF space by the Revit unique ID stored on the space record. With that link, clicking a room in 3D opens its space record, and the reverse.

BIM Model Management has four tabs that follow the order of the work: Buckets (the storage folder in Autodesk's cloud, created once), Model Files (upload a Revit file; Autodesk translates it for the viewer), Buildings (link a model to an MREF building) and Viewer (check the result).

Check yourself

Glossary

Class Loader

An MREF record holding extra Java and Web files that the server loads while running.

Resource file

One uploaded file in a Class Loader: a jar (Java) or a zip (Web).

IConnect

The MREF interface a class implements to answer a web request at /rest/<Name>.

Parent First / Parent Last

Whether Java looks in MREF's libraries or in your jar first.

Development Mode

Reload the classes on every call; for development only.

Jakarta

The current name of Java's enterprise APIs; packages start with jakarta. instead of javax.

Portal section

A block on an MREF home page; one of type External URL can show a Class Loader page.

BIM

Building Information Model: the architect's 3D model with data on every room and element.

Autodesk Platform Services

Autodesk's cloud (formerly Forge) that stores and displays BIM models in the browser.

BIM Connector

The MREF setup record that holds the Autodesk key used by the 3D Model tab.

Want a custom page or a 3D view on your own MREF? Send me a message and I'll show you how we built this one.

Screens: IBM Maximo Real Estate and Facilities on IBM Maximo Application Suite, with IBM's GreenPoint demo data. MREF3D / Portfolio 3D is our own extension, not an IBM product. All names, amounts and dates are demo values.