IDS Forum

Re: JDBC URL question

Posted By: Laird Nelson
Date: Thursday, 16 June 2011, at 2:44 p.m.

In Response To: Re: JDBC URL question (Art Kagel)

On Thu, Jun 16, 2011 at 2:12 PM, Art Kagel <art.kagel@gmail.com> wrote:

> OK Laird, here's a basic Informix education.

Great!

Most of this you can get
> piecemeal from different parts of the Informix Administrator's Guide and
> Administrator's Reference manuals and I would recommend that as a source
> for
> more detail.

Happy to do so; it's just hard to know where to start (it's the "piecemeal"
part). I also now have in my hands a Redbook that compares Informix to SQL
Server--which I don't particularly care about, but it has the happy side
effect of giving an overview of the architecture.

> An Informix database engine or server is known as an instance for
> simplicity
> and to reduce confusion as to what is meant by "server". An Informix
> instance can manage multiple databases whose names are also part of your
> JDBC URL string. A host or machine can have multiple instances running on
> it each of which is identified internally by a SERVERNUM integer which
> clients do not need to know about and a DBSERVERNAME which links the
> instance to a particular communications method or protocol (share memory,
> named stream pipe, TCP/IP using Informix's native "SQLI" protocol, or
> TCP/IP
> using IBM's DRDA protocol), IP address (or addresses), and service or port
> number.

OK, that makes sense. Question: if I'm connecting to a TCP port 1001,
haven't I already pretty much established the communications protocol (TCP +
SQLI) and port number (1001)? In this case, why do I need to specify a name
that serves to group this information? Can't it just be inferred from the
fact that someone answered the phone on 1001 and understood my request in
SQLI format?

> Java either uses the underlying ODBC mechanisms or the URL string you
> allude to for the same thing.
>

I guess my point is: can't all that information be inferred WITHOUT the
INFORMIXSERVER variable, if I'm connecting with the JDBC driver to a
particular host on a particular port speaking a particular communications
protocol? (Clearly it cannot, or you wouldn't have this INFORMIXSERVER
variable as a requirement, but I don't see how.)

> jdbc:informix-sqli://devfoo.jenzabar.com:1001/ngp:INFORMIXSERVER=devnotfoo
>
> software protocol: Native Informix SQLI
>

Yep.

> hardware protocol: TCP/IP (default)
>

Yep.

> host:
> devfoo.jenzabar.com<
> http://devfoo.jenzabar.com:1001/ngp:INFORMIXSERVER=devnotfoo>
>

OK, yep.

> port for initial connection request: 1001
>

Yep.

> database name: ngp
>

Yep.

> servername/alias: devnotfoo
>

OK, this is where I pause. :-) I'm already connected to *something* on
host devfoo, port 1001, speaking SQLI--you refer to this as the "initial
connection", suggesting that perhaps other connections (by me? by...?) will
be made soon--so what extra value does devnotfoo add here? What does it
convey? Surely it doesn't just convey TCP/SQLI/port1001, because I've
already got that. If instead it conveys that I should be looking up this
configuration from the sqlhosts file, or otherwise dereferencing it into the
various settings it stands in for, what happens if those settings (which
include things like communications protocol) specify a different port, or a
shared memory configuration? I'm already hooked up via TCP to port 1001, so
what good would any alternate information here do me?

(A quick side note to say how much I appreciate the community's help here.
I'm really REALLY grateful.)

Best,
Laird

--0015174be8a8cb17da04a5d8a6ca

Messages In This Thread

• JDBC URL question
  Laird Nelson -- Thursday, 16 June 2011, at 12:22 p.m.
  • Re: JDBC URL question
    Alexandre Marini -- Thursday, 16 June 2011, at 12:36 p.m.
  • Re: JDBC URL question
    Art Kagel -- Thursday, 16 June 2011, at 2:12 p.m.
    • Re: JDBC URL question
      Laird Nelson -- Thursday, 16 June 2011, at 2:44 p.m.
      • Re: JDBC URL question
        Art Kagel -- Thursday, 16 June 2011, at 3:17 p.m.

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