the content of the autodiscover server response | part 11#36

of 27 | The content of the Autodiscover server response | Part 11#36

Written by Eyal Doron | o365info.com | Copyright © 2012-2015

The content of the Autodiscover server

response | Part 11#36

n the current article, we will review the subject of the Autodiscover response

content.

The term – “Autodiscover response” relates to the Autodiscover information that

the Exchange CAS server provides to his Autodiscover client.

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In this article, we will relate to the Exchange server Autodiscover response content

from the perspective of the three Outlook providers –EXPR, EXCH and ExHTTP.

Article Series - Exchange and Autodiscover infrastructure | Table of

content

For most of us, the content of the Autodiscover response is a mystery and, most of

the time we are not able to understand the complete meaning of this mystery.

The purpose of the current article is to remove some of the fog that relates to the

content of the Autodiscover Exchange CAS server response so, we will be able to

get more information about the interesting process of Autodiscover.






In addition, to have the ability to solve the advanced problems that relate to the

communication channel and the Autodiscover process that is implemented

between the Autodiscover client and the Exchange CAS server.

Autodiscover response

Q1: Question – what is the meaning of Autodiscover response?

A1: The Autodiscover response is the “answer” that the Exchange CAS server

provides to his Autodiscover clients.

A metaphor that we can use that will help us to understand the relationships that

exist between Exchange server, and his Autodiscover client is a metaphor of a

person that feeds his Children.

The Autodiscover client needs a well (Autodiscover information), and they address

Exchange server asking him to feed them (providing the Autodiscover response).






Q2: How does the client (Outlook) know what are the required parameters that he

needs to use for communicating with the Exchange server?

A2: The Exchange server provides all the required information to the Outlook client

as part of Autodiscover response. The “Autodiscover answer”, include the required

information that relates to the different communication parameters.

The main advantage of the Autodiscover method is that there is no need for using a

complex manual setting for configuring Outlook client to use the required

parameters.






Instead, Outlook uses the Autodiscover protocol for locating the required Exchange

server, and the Exchange server knows how to “Pack and ship” the information

using the Autodiscover response to the Autodiscover client.

The Outlook configuration setting is sent to Outlook Automatically by Exchange and

Outlook client know how to use this information for an automatic creation of an

Outlook mail profile.

Q3: Who are the Exchange Autodiscover clients?

A3: The most prominent Autodiscover client that fully depends on the Exchange

Autodiscover services is the Outlook mail client.

Exchange Autodiscover information is relevant to Exchange mobile client

(ActiveSync client) and also for the Exchange web client (OWA).






Q4: What are the building block or the major parts of the Autodiscover response?

A4: The Autodiscover response includes the following parts:

1. Information about the available Exchange web service

2. Information that is needed for Outlook mail client for creating a new mail profile

3. Information about the communication parameters the Exchange “dictate” to the

Outlook client. For example – the communication protocol, the authentication

protocol, etc.

Q5: Can you provide a detailed explanation for each of the parameters that are

included in the Exchange Autodiscover response?

A5:

The answer to this question is not so simple, and even to me, some of the content

look as a “mysterious words”.

There are two main reasons for the phenomenon of this “mystery”






1. Dynamic environment

The Exchange infrastructure is a very dynamic environment, each of the Exchange

software updates adds an additional type of services or updates to the existing

Exchange services.

This Exchange updates, are “registered” in the Autodiscover file and as long that the

“client side” such as Outlook knows how to relate to this update it’s OK.

2. Lack of documentation or a public information

When I sat down to write this article, I have searched for public articles that will

include a detailed description about each of the data fields that appear in the

Exchange Autodiscover response.

The result – there are very few articles about the subject of the Autodiscover

response content and, regarding the Autodiscover “key” that I’m not familiar with, I

could not find additional or meaningful information.

So what is my point?

My point is that despite the “mysterious parts” in the Autodiscover response file,

there are many other parts that we can understand and use in a troubleshooting

scenario.

Note – many times in the Autodiscover article series, I use the term “Autodiscover

file”.

If we want to be more accurate, actually there is no such thing as an “Autodiscover

file”.The Exchange server “answer” described as “Autodiscover response” and this

“response” include the content which I describe as “Autodiscover file”.

Technically, it doesn’t matter much as long as it’s easier for us to look at the

Exchange server response as a “file”.






The file format of the Autodiscover file

The information that delivered by the Exchange server to his mail client is based on

an XML format.

The XML format is implemented by using XML tags and, the “data” that is included

between the XML tags.

Each of and “XML sentence” began with an opening XML tag and end with a

closing XML tag (the close tag is defined by the slash forward character “/”).

The data or, the information, resides between this XML tag.

The basic assumption is that the “client side”, the element that the request for the

information knows what is the meaning of the XML tag and how to use the

information that resides between this XML tag.

When the Outlook client gets the Autodiscover information that is provided by the

Exchange server, the client knows or to “relate” to each of the XML tags.






In the following diagram, we can see an example for a “piece of information” that

was taken from a standard Autodiscover response.

In our example, the XML tag – <EwsUrl> define the URL address of the element (the

Exchange server) that provides EWS services. The Exchange server hostname who

provides the EWS services is – mail.o365info.com and, the URL address of the

Exchange web services are –

https://mail.o365info.com/EWS/Exchange.asmx

The “client” such as Outlook, need to know or “understand” what the Exchange EWS

services is and know how to access the specified URL when he needs the Exchange

EWS services.

Types of Autodiscover requests

Autodiscover client addresses the Autodiscover Endpoint (Exchange server) asking

for Autodiscover information.

In an Exchange environment, the “request” for Autodiscover information by the

Autodiscover client can be implemented by using three types of format or

standard:

1. EWS Managed API

2. SOAP Autodiscover

3. POX Autodiscover






The more advanced or preferred Exchange interface is the SOAP Autodiscover and

the EWS Managed API.

The “decision”, which interface to use, depends on the Exchange client that

addresses the Exchange CAS server (Autodiscover Endpoint).

Exchange server can answer or provide the required information for each of this

different type of client request.

The term “Exchange client” can relate to the mail client such as Outlook, mobile

devices, other Exchange server or any “Exchange-aware application”.

An exchange mail client such as Outlook, use the SOAP Autodiscover interface or

the POX Autodiscover interface for submitting a request for the Autodiscover

information.

When mail client address Exchange CAS server asking for Autodiscover

information, using the POX Autodiscover interface, the client request is for a file

named – xml

When mail client address Exchange CAS server asking for Autodiscover

information, using the SOAP Autodiscover interface, the client request is for file

named – svc






Note – in this article series when describing the flow in which Autodiscover client

request for Autodiscover information, we will use the autodiscover.xml naming

convention for describing the Autodiscover client request for Autodiscover

information.

In reality, the Autodiscover client request could also refer to the file named

– autodiscover.svc

Additional reading

Autodiscover for Exchange

How to: Generate a list of Autodiscover endpoints

EWS Managed API, EWS, and web services in Exchange

Exchange Outlook Providers

Exchange server needs to provide his client a detailed information about the

Exchange infrastructure. The information that is needed for creating a new Outlook

mail profile, the information that is needed for communicating with the Exchange

server and information about the existing Exchange web services.

To make it even more complicated, the “set of details” that need to be provided to

the internal Outlook client is markedly different than the details that need to be

provided to external Outlook clients.




https://msdn.microsoft.com/en-us/library/office/jj900169(v=exchg.150).aspx

https://msdn.microsoft.com/en-us/library/office/dn467397(v=exchg.150).aspx

https://msdn.microsoft.com/en-us/library/office/dd877012(v=exchg.150).aspx



An Exchange server, know how to “pack and ship” the required information for

Outlook client via the Autodiscover response.

The information is divided into sections.

Some of the sections include relevant information for internal Outlook clients.

Some of the sections include relevant information for external Outlook

clients.

The method in which the Exchange server divides the information into sections for

the different type of Outlook client, meaning external versus internal Outlook

clients, described as – Outlook providers.






OUTLOOK PROVIDERS AND EXCHANGE SERVER VERSION

Exchange 2007\2010 server version supports two types of Outlook providers

The Autodiscover response section (Outlook Provider) that includes relevant

information for internal Outlook clients described as – EXCH

The Autodiscover response section (Outlook Provider) that includes relevant

information for external Outlook clients described as – EXPR






Exchange 2013 server version supports the “former” type of Outlook providers,

meaning EXCH and, EXPR and in addition, a new type of Outlook provider named

– ExHTTP.

Two interesting things about the Exchange 2013 server ExHTTP Outlook provider

1. Identical “ExHTTP section” for internal + external Outlook clients

The Exchange 2013 Autodiscover response, include two sections named ExHTTP for

external + internal Outlook client versus Exchange 2007/2010 that use the different

naming convention for Outlook providers (EXCH for internal Outlook client

and EXPR for external Outlook client)

In case that you are wondering, how the Outlook client “understand” if the

information is related to the internal Outlook client or the for the external Outlook

client, the answer is that the first “ExHTTP section” is for internal Outlook clients and

the second “ExHTTP section” is for external Outlook clients.






2. The content of the “ExHTTP section”

Most of the “ExHTTP section” content, is inherited from the content that exists in

the EXCH section and, from the content that exists in the EXPR.

Attached a quote from Microsoft article –

In Exchange 2007/2010, the way Outlook Anywhere was implemented is that you

had one namespace you could configure. In Exchange 2013, you have both an

internal host name and an external host name. Think of it as having two sets of

Outlook Anywhere settings, one for when you are connected to the corporate

domain, and another for when you are not.

You will see this returned to the Outlook client in the Autodiscover response via

what looks like a new provider, ExHTTP.

However, ExHTTP isn’t an actual provider, it is a calculated set of values from

the EXCH (internal Outlook Anywhere) and EXPR (External Outlook Anywhere)

settings. To correctly use these settings, the Outlook client must be patched to the

appropriate levels (see the Exchange 2013 System Requirements for more

information). Outlook will process the ExHTTP in order – internal first and external

second.






[Source if information – Client Connectivity in an Exchange 2013 Coexistence

Environment]

In the following diagram, we can see the logic of the Exchange Outlook providers.

Exchange 2013 server provides the “old Outlook providers” and the “new Outlook

providers”.

The ExHTTP Outlook provider is used for external + internal Outlook client at the

same time. The “secret” is that the first section of ExHTTP is aiming to internal

Outlook clients and the second section of ExHTTP, is aiming to external Outlook

clients

In case that you want to view the Outlook provider whom a specific Exchange

server provide, you can use the following PowerShell command

Get-OutlookProvider | Select Identity




http://blogs.technet.com/b/exchange/archive/2014/03/12/client-connectivity-in-an-exchange-2013-coexistence-environment.aspx

http://blogs.technet.com/b/exchange/archive/2014/03/12/client-connectivity-in-an-exchange-2013-coexistence-environment.aspx



In the following diagram, we can see that the Exchange 2013 support the “former”

Outlook providers in addition include a new type of Outlook provider named

– ExHTTP

Exchange Autodiscover response XML structure and

content

The Exchange Autodiscover response is built by using a specific structure.

An example to a standard structure of an Autodiscover response (the “XML file”)

that is provided by the Exchange 2013 server is presented in the following diagram.






VIEWING THE CONTENT OF THE EXCHANGE AUTODISCOVER RESPONSE

FILE

To be able to understand better the content of the Autodiscover response, we will

use an example of Exchange 2013 Autodiscover response that located in

environments that have the following characters:

The Exchange 2013 is a Public facing Exchange server, meaning, the Exchange

server provides services to be internal + external mail clients.






The namespace infrastructure is based on a “separation” between the internal

namespace and the external\public namespace.

The internal namespace of the Exchange server is – o365info.local

The external namespace of the Exchange server is – o365info.com

In the following section, we will review some of the content that is included in the

Exchange Autodiscover response.

1. EXPR section – information for external Outlook clients

The XML information is based on “block of information”.

The section of the EXPR (that is relevant to external Outlook clients) has a beginning

and an end (number 1).

The EXPR section is built from a collection of XML tags

Each XML tag has also a “starting tag” and “Ending tag” (number 2).






The content that needs to be “read” by the client is positioned between the XML

tags (number3).

The Exchange server provides to the Outlook client about his host name (his

identity). Outlook client will use this name for addressing the Exchange server

(number 4).

Exchange server “inform” Outlook client what protocol he should use as a

communication protocol. In our scenario, the communication protocol is SSL

(number 5).

Most of the Exchange Autodiscover response content includes information about

the different Exchange web services and other Exchange services.

The information about the specific services is “presented” in the XML tag and the

information about the host who provides the specific services + the URL address of

the specific service is included between the opening and the closing XML tag.

For example, The following XML tag appears in the EXPR section






<ASUrl>https://mail.o365info.com/EWS/Exchange.asmx</ASUrl>

Information about the Exchange availability services (Free\Busy time) is

provided by using the XML tag – <ASUrl>

In our specific example, the Exchange host name who provides the Exchange

availability services is – mail.o365info.com

The URL address that Outlook client need to use when he needs to “consume”

Exchange availability services is – https://mail.o365info.com/EWS/Exchange.asmx

Note that the EXPR section is relevant to external Outlook clients. For this reason,

the information about the services that the Exchange server provide will be based

on the “public identity” of the Exchange server. In our scenario, the Exchange server

“present himself” by using the host name – mail.o365info.com

In the following screenshot, we can see we can see an example of different

Exchange services that are offered to Outlook clients.

Note that Exchange provides different services using the same URL address.

For example, Exchange availability services represented by the XML tag

– <ASUrl> and Exchange OOO (out of office) services, are represented by the XML

tag – <OOFUrl> have identical URL address

– https://mail.o365info.com/EWS/Exchange.asmx

The “yellow arrows” point Outlook different Exchange services that are provided by

using the same URL address (number 1).

An example of additional Exchange services could be:

OAB – the OAB stand for – Outlook offline address book. The XML

tag <OABUrl>, inform the Outlook client about the URL address that they need

to use when that need to access Exchange server and download a local copy

of the Outlook offline address book. In our specific scenario, the URL address

is – https://mail.o365info.com/OAB/45831dde-e32e-4a86-9263-

86ce0df67038 (number 2).

ECP – the Exchange web management interface. The Autodiscover response

includes a dedicated XML tag named – <EcpUrl> that “tell” Exchange web client

such as OWA, what is the URL address that should be used when there is a






need to access the Exchange web management. In our scenario, the URL

address is – https://mail.o365info.com/ecp (number 3).

2. EXCH section – information for internal Outlook clients

In the following screenshot, we can see we can see an example of the EXCH section.

This section is relevant to internal Outlook clients.

For this reason, the information about the services that the Exchange server

provide will be based on the “private identity” of the Exchange server.

In our scenario, the Exchange server “present himself” by using the host name –

exo1.o365info.local






3. ExHTTP section – information for internal + external clients

As mentioned, Exchange 2013 server adds to the Autodiscover response file

additional section that includes a new type of Outlook provider, the ExHTTP section.

In the following screenshot, we can see that the Autodiscover response includes

two different sections of ExHTTP

The XML tag name who is used for the two sections is identical.

The first ExHTTP section (number 1) includes information related to internal

Outlook clients.

The second ExHTTP section (number 2) includes information related to external

Outlook clients.






4. WEB section – information for OWA clients

The Exchange Autodiscover response includes a dedicated section for WEB mail

clients (OWA clients).

We can see that the information that is provided to the WEB mail clients also

includes reference to the subject of internal versus external clients.






Some examples for the content of the Autodiscover XML file

In case that you will have the desired to look at the content of a standard Exchange

Autodiscover response, you will be amazed by the amount of the data.

As I have mentioned before, I’m not familiar with all the information and the XML

Tags that appear in the Autodiscover response.

But, there are some “famous” XML Tags in the Autodiscover response that we

should know about because they represent the most important and essentials

Exchange web services.

In the following diagram, we can see an example for these “famous” XML Tags.






By looking at the structure of the URL address we can use a couple of observations:

The access to Exchange EWS folder (Exchange Web Services) is implemented

by requesting a “file named – asmx

The Exchange web services URL is represented by the XML Tag – <EwsUrl>

Different Exchange web services, are “represented” by the same URL address.

For example- The URL address of the automatic reply (represented by the

XML Tag – <OOFUrl> ) and the calendar sharing URL (represented by the XML

Tag –<SharingUrl>) are “leading” or pointing to the same URL address.

Examples of Exchange web services that paper on the Autodiscover

response.

1. Offline address Book – the Exchange services that enable Outlook client to

download a local copy of the Global address list is represented by the XML Tag

– <OABUrl>. The URL address includes the file name that the client should ask for

(in our example https://mail.o365info.com/OAB/45831dde-e32e-4a86-9263-

86ce0df67038)

2. Unified messaging – the URL address for the Exchange unified messaging is

represented by the XML Tag <UMUrl>






3. Exchange ECP – the ECP is the web address of the Exchange control panel. The

ECP is used by web mail client (OWA) for managing and accessing their personal

details.

Additional reading

The Autodiscover Service and Outlook Providers – how does this stuff work?

When, if and how do you modify Outlook Providers?

Autodiscover Response




http://blogs.technet.com/b/exchange/archive/2008/09/26/3406344.aspx

http://blogs.technet.com/b/exchange/archive/2008/09/29/3406352.aspx

https://msdn.microsoft.com/en-us/library/bb204082(v=exchg.80).aspx

the content of the autodiscover server response | part 11#36

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