The vSphere MOB (Managed Object Browser) is not a well known tool and unless you are a developer, you probably do not know of its existence. The simplest way to describe the vSphere MOB is that it is a debugging tool to graphical visualize all entities within the vSphere API through a web browser. It is often used to better understand the vSphere API/inventory and aide in developing your own vSphere application or script. For a detailed deep dive of the vSphere inventory, check out Steve Jin's post here.

The vSphere MOB can be reached by pointing your web browser to either an ESX(i) or vCenter host followed by the path "/mob". You will be prompted for credentials as you normally would prior to gaining access to the MOB.

The vSphere MOB may not always be the easiest to navigate. Understanding the vSphere inventory structure is definitely helpful, otherwise it can be very confusing to users. With the release of vSphere 4.1, there are two major changes in the MOB that can help make the navigation easier for developers.

Previous to vSphere 4.1, the MOB would display managed entities using their Managed Object IDs (MoRef ID) as a way to uniquely identify these objects. This made it very difficult for developers to identify the specific object you are viewing without having to dig further.

In vSphere 4.1, the MOB provides both the MoRef ID and the translated the names of the managed entities.

The vSphere MOB not only displays information about the managed entities but also provides a way to interact with the system. It does this by listing the available API methods for each managed entity at the bottom of the page and can be executed by providing the correct input parameters. The issue arises when trying to execute methods which requires complex input that require more than a simple string or integer value. The format of the input is XML-based and it can be challenging to generate the correct format, especially without any examples.

In the new version of the MOB, you are now presented with an XML template of the required parameters which can then be filled out to execute the method.

The following example will demonstrate the change of an ESXi advanced configuration value for configuring a syslog server:

Once you have filled in the required parameters, you will need to click on the "Invoke Method" to execute the specific method.

Here we verify the advanced configuration key "Syslog.Remote.Hostname" has been changed and is set to our new syslog server.

I think these two changes will make it easier for developers to navigate the vSphere MOB and assist with understanding the vSphere API and it's managed entities.