Bloomberg API: How to check wether connection works? - vba

Question

I am implementing a tool which relies on Bloombergs blpapilib2, which is the Bloomberg API COM Lib 3.5.
Before giving my user access to any refresh-data functionality, I want to make sure that the connection works. My approach so far:
Check wether the library is available and linked. Basically a loop through references does the job.
Open a connection with session.Start() . I was hoping to get an error here, but it won't give me one. Thus, step 3.
Request some data and verify it (make sure its not empty)
Surporisingly, I cannot reliably reproduce getting an empty result. I expected my session relies on a user being looged into the terminal. It seems I was wrong; even if I log out, my request will be handled and return correct data.
I can imagine two scenarios:
some background caching in the bbcom-Server
an alternative authentication method is used
I have two questions:
Q1. What is the best way to make sure a user will be able to download data?
Q2. How can I verify whether a connection has been established successfully and a user is authenticated?
Thanks.

Answer 1

To "cut" the connection, you need to log out and log in on a different machine. If you simply log out the feed is still available using the API.
This is how I test the connection - I think it works fairly well. I have a BloombergWrapper class that handles all the low level stuff of communicating with the API and it has the following functions:
Private pSession As blpapicomLib2.Session
Private pService As blpapicomLib2.Service
Private Sub Class_Initialize()
Dim locStatusBar As Variant
Dim locBbResult As Variant
On Error GoTo error_handler
If Application.StatusBar = False Then locStatusBar = False Else locStatusBar = Application.StatusBar
Application.StatusBar = "Connecting to Bloomberg..."
Set pSession = New blpapicomLib2.session
pSession.Start
pSession.OpenService ("//blp/refdata")
Set pService = pSession.getService("//blp/refdata")
Application.StatusBar = locStatusBar
Exit Sub
error_handler:
If InStr(Err.Description, "timeout") Then
Call MsgBox("A Bloomberg timeout has occured. Make sure you are logged on your terminal.", vbCritical + vbOKOnly, "Bloomberg error...")
End If
If locStatusBar <> "" Then Application.StatusBar = locStatusBar
End Sub
Private Sub Class_Terminate()
pSession.Stop
Set pSession = Nothing
End Sub