- Are there advantages to building workflows using
only XAML? - Are there disadvantages in building workflows using
XAML? - Is XAML only used for quick UI
prototyping?
XAML will be used for production work, not just for prototyping.
Specifically, localizing your application or ensuring that it is
accessible—common for most applications today—will be a lot more work if you
build your own user interface from code instead of using XAML - Will XAML replace other
programming languages like C# and VB?
No. XAML complements procedural languages, much the same way HTML
complements ECMAScript. You can very quickly declare how you want your user
interface to look with XAML, then use a language like C# to define the business
logic behind that user interface - Can XAML be used to develop both
Web and client-server applications?
XAML is used as part of Windows Presentation Foundation to write smart
client applications that take advantage of the power of the class="kLink" href="http://oopsconcepts.com/interviewquestions/#"
onclick="adlinkMouseClick(event,this,16);" oncontextmenu="return false;"
onmouseout="adlinkMouseOut(event,this,16);"
onmouseover="adlinkMouseOver(event,this,16);"
style="POSITION: static; TEXT-DECORATION: underline! important" target="_new">
style="FONT-WEIGHT: 400; FONT-SIZE: 12px; COLOR: green! important; FONT-FAMILY: Arial, Helvetica, Georgia, Sans-Serif; POSITION: static">
style="FONT-WEIGHT: 400; FONT-SIZE: 12px; COLOR: green! important; BORDER-BOTTOM: green 1px solid; FONT-FAMILY: Arial, Helvetica, Georgia, Sans-Serif; POSITION: relative; BACKGROUND-COLOR: transparent">
PC and benefit from all of the power of the CLR. For Windows
Presentation Foundation applications, the logic runs on the client, unlike
ASP.NET, which processes on the server. ASP.NET continues to be the answer to
producing powerful Web applications that take advantage of the benefits of the
CLR on the server - Why do we need XAML as a new way to create applications in .NET
Framework 3.0 (formerly WinFX)?
The new application in Windows Vista separates out declarative
code (XAML) from procedural code (C#, VB.NET, J#, etc.). One major reason for
using XAML is to bridge the gap between developing an application for Microsoft
Windows and developing an application for the Web.XAML does not give you new
functionality; it is just a declarative way to instantiate and initialize
Microsoft .NET objects. XAML does, however, provide you with a way to solve
problems such as:- When you write procedural code (C#, etc.) to create a number of controls, and
compare that to the equivalent XAML, the XAML is more compact, less redundant,
and less error-prone. Writing a designer for XAML will be a lot easier than
writing a forms designer for C# or VB.NET, since the designer won’t have to do
all that code parsing to figure out where to insert or change the setting of a
property. - In the real world, many customers find requests coming in at the very last
minute asking for changes to the user interface—a button needs to be moved or
removed or the company logo needs to appear on every window. It is especially at
the end of the development process, when you think your code is “frozen” and
tested, that you’d rather not have to dive into the source code and start
changing things. Who knows what subtle interaction you might break? With XAML,
most—if not all—of the presentation layer is in its own file, thus providing a
high degree of certainty that making a user interface change in the XAML will
not break business logic code. - XAML enables professional graphic designers or user interface specialists to add
beauty, style and grace to an application without modifying source files
directly. Partitioning the user interface and the logic that drives it means
each of us can get our job done without getting in each other’s way or having to
understand the myriad details of one another’s tools. - XAML is considerably smaller than the equivalent C# code. Since there is less
code, there are fewer opportunities for errors
- When you write procedural code (C#, etc.) to create a number of controls, and
- What is XAML?
“XAML, Extensible Application Markup Language, is Microsoft’s XML-based
language for creating a rich graphical user interface….XAML was introduced in
2003 as the language behind Windows Presentation Foundation, then known as
Avalon.” - Why do we need XAML?
Well, OK, in the real world, there’s been a move towards declarative
programming for a while. XAML is in some ways a logical successor to SGML-based
markup languages like HTML and XML. Although of course XAML is an XML dialect it
provides a way to bind presentational data (the declarative list of UI elements)
with some or all of the code used with them. Now why, you might ask, would
Microsoft be so bothered about that? Simply put, Microsoft needs to find new
ways to exploit the processing power of the client as well as the server, if it
is to continue selling operating systems for the next few decades. If true
thin-client computing ever really got started, it would eviscerate the OS
market. That’s what Google is aiming for, and it’s exactly the thing that
Microsoft fears.XAML allows you to export processing to the client machine in a
way that mere script doesn’t. In effect, you can stream the interface of an
application, plus a portion (or even all) of its logic, over the wire using a
protocol that’s open on most firewalls. You can stream XAML into the browser and
get something roughly equivalent to ActiveX controls or Java applets (which
exports .NET to the browser as Silverlight has done, something Microsoft has
been planning for a while). Silverlight is the first fruit of this particular
plan.However, don’t expect XAML-over-HTTP to stay within the browser for long.
It’s a perfect way to provide desktop apps without installers,
software-as-a-service, all the stuff Microsoft was supposed to be planning years
back when people were still talking about Windows.NET - you didn’t think they
just gave up on all that stuff, did you?Add to this the bare-metal hypervisor
stuff they are developing - ‘Viridian’ for Windows Server 2008 will be a hobbled
implementation of this, but there’s more coming, and it will likely be the core
architecture of whatever ‘Vienna’ turns out to be - and you can see a
developing of (supposedly) safe, sandboxed, virtualised applications streamed
from the net over fast connections, always up to date, running partially on the
client and partially on the server, potentially replacing today’s stateless
browser-based of internet application.I doubt the reality will live up to
the dream - it never does with Microsoft, any more than it does with anyone else
- but that’s the reason they want you to buy into XAML in a nutshell. - What is XAML?
Transaction Authority Markup Language (XAML) is a vendor-neutral standard that
enables the coordination and processing of online transactions in the rapidly
emerging world of XML web services - the revolutionary new of
Internet-based computing that is now being adopted by all major systems and
software vendors. XAML is intended to be a completely open standard for
web-based business transactions.The standard defines a set of XML message
formats and interaction s that web services can use in order to provide
business-level transactions that span multiple parties across the Internet.
Why is XAML important for the delivery of e-commerce solutions?
As plug-and-play e-commerce emerges, businesses are mixing and matching web
services from multiple partners to create sophisticated business web services.
Because these “business webs” are comprised of aggregated calls to loosely
coupled web services distributed across the web, and provided by multiple
businesses, coordination among these web services is imperative, in order to
carry out business-level transactions. There needs to be the notion of a
transaction at the web service level, as well as a means by which software
systems can coordinate the processing of calls to multiple web services to
provide higher-level business transactions.XAML will provide the standard mechanism to enable XML web services to
participate in business transactions spanning multiple parties across the Web.
Web services provide unprecedented business interoperability by enabling
businesses to share processes and competencies on the web, creating a new era of
business connectivity and dynamic, “plug-and-play” e-commerce.What kind of
applications will XAML enable?As plug-and-play e-commerce emerges, businesses
are mixing and matching web services from multiple partners to create
sophisticated e-business applications. Because these “business webs” consist of
loosely coupled web services distributed across the web from multiple
businesses, coordination among these web services is imperative, in order to
carry out business-level transactions. There needs to be the notion of a
transaction at the web service level, as well as a means by which software
systems can coordinate the processing of calls to multiple web services to
provide higher-level business transactions.Who is supporting XAML?
Bowstreet, Hewlett-Packard, IBM, Oracle and Sun are leading the XAML initiative
to ensure distributed e-business transactions across the Internet. However, XAML
is not owned by any one vendor. Instead, the standards proposal will be
submitted to an appropriate open standards body to ensure that it remains an
open industry standard in which any company and organization can participate.Are
the initiative?
Once the specification reaches a stage when it can be reasonably submitted to a
standards body, such as W3C, OASIS, or IETF, the XAML Group will submit the XAML
specification. Any interested company is encouraged to participate in the
evolution of XAML via the standards organization selected. When will
to the public?
The target date for submission to a standards body is Jan 15, 2001. When
is initial spec to be completed?
The XAML Group has targeted Jan. 15, 2001 for the initial draft of the
specification to be completed.
How does
XAML relate to other Web Service standards? title="otherstandards">
In order to understand how XAML
relates to many of the existing standards, it is first necessary to understand
what function each of these standards performs.When a web service is built,
described, discovered and used, there are many elements that will be required.
The combination of these many different elements is called a web services
architecture. Some categories of these elements are: registries, business
process ing, negotiation, service description and web service transport
protocols.In order to use a web service, the existence of
the service must be discovered. This discovery usually takes place in a “phone
book” of web services known as a registry. Registries, such as UDDI and the
ebXML registry/repository, contain human readable information that can be
browsed and searched to find companies and their services.Once a desired service is located, the terms of
use can be reviewed and/or negotiated. The e-speak framework provides an
elaborate negotiation mechanism. ebXML addresses the same issue through TPAML
(Trading Partner Agreement Markup Language.)Now that you know which service you need, you
still have to know some additional things before you can use the web service;
where is it located, what type of input it expects, what type of output it
produces, which web service protocols it uses, etc. Service description
languages, such as WSDL, provide a standard mechanism to outline all these
details about a web service. Typically, for publicly available web services,
their service descriptions are also made publicly available. The URI of the
service description can be registered with a web service in a registry.Once you know those details, you can start
formulating a message to send to the service. However, some web services will
require special packaging wrapped around the message, letting the web service
know what to do with the message.In this situation, an underlying web service
transport protocol may need to be used, which can provide:
1. an envelope which defines what is in a message
and what program should deal with it2. specific information about how to
exchange instances of application-defined data-types in a serialized format (You
can think of this as how the programs agree on the format of a text-based XML
file to send across the internet which contains information about a relational
database or other complicated data structure within an application)3. a
definition of a convention that can be used to represent remote procedure calls
and responses.
XML-based web service transport protocols include:
SOAP, XP (W3C XML Protocol) and ebXML Transport. Most of these web service
transport protocols make use of existing protocols, such as: HTTP, SMTP, TCP,
etc., to carry web service requests and responses across the internet.Another
layer in the web services architecture is business process ing. These
languages define the business level descriptions of what needs to be
accomplished. For example, they can describe a business scenario such as, “if a
purchase order is received by my purchasing web service, the steps that need to
be completed are: check inventory; if the inventory is available, ship product;
if product ships, let accounting know, etc.” Business process ing languages
determine what needs to be completed and the necessary order of completion.
However, they do not control nor monitor the underlying transactions themselves,
where XAML is used to initiate, monitor, commit, cancel, retry, or initiate a
compensating transaction.Consider this web services architecture example: A
distributor of groceries needs to process an order from ACME grocery store.
Included in the order is an order for 100lbs of fresh tomatoes. The grocery
distributor needs to process this order. In order to fulfill this order the web
services architecture will be used in a variety of ways.The first requirement (even before the distributor
gets the order) is to discover that Johnny’s Tomato Farm and Jimmy’s
Refrigerated Transport provide the necessary business services. Both services
are discovered via a registry; in this case, the distributor searched several
different registries.The second action is to make sure the
distributor’s business web understands how to talk with each of these web
services. This is done by downloading a service description for each of the two
services. The registry entry indicated that Jimmy’s Refrigerated Transport is
described as an e-speak service; whereas, Johnny’s Tomato Farm services are
based solely on SOAP. An XML description is retrieved for the e-speak service
and a WSDL document is retrieved for the SOAP service. Links to the service
description documents were found in the registry entries.An additional action must also happen before the
order is placed. The business process of a purchase order must be
executed. 1)check to make sure that the person ordering is authorized to order;
2)check to make sure the ordering company has paid their last invoice; and
3)proceed to order the merchandise by ensuring that both services get managed
using XAML. This entire business process is defined by an ebXML business process
. Some additional s may need to be set up…. If the item is perishable,
then verify the transport availability, etc.Now, the grocery distributor is ready for action
and can accept a tomato order from ACME grocery store.The order from ACME grocery store is taken via the
distributor’s business web, and according to the business process , the
person is authorized and the finance department gives the approval. The
transaction is begun on a business level. Because Tomatoes are marked as
perishable, the “perishable food” is initiated.This determines the business logic which
states that transport must be arranged before tomatoes can be officially
ordered. This logic is then used by the software that coordinates the calling of
the relevant web services. The calling system prepares a message directed to a
web service at Johnny’s Tomato Farm using SOAP, along with XAML to specify
initiation of the transaction. In like manner, the system requests a web service
at Jimmy’s Refrigerated Transport to supply the truck and driver, again using
XAML to stage the request. Once both web services have responded confirming
availability, the calling system interacts with the web services using XAML to
facilitate the completion of the business process.
How does XAML relate to registries (UDDI)?
UDDI defines a registry for companies and their services. In a typical
scenario using UDDI, a user/program would browse through categories (like in a
yellow pages) for a particular service. Once the desired XML service is found,
the ’service description’ for that service can be used to retrieve the details
of calling that service (see service description languages section.) The
‘service description’ (WSDL, etc), defines the semantics of calling a specific
service.As with any other
type of service, XAML services will be able to be registered and located within
UDDI registries. UDDI can register XAML services.
How does XAML relate to service description
languages (WSDL, XMI)?
Services description languages define the details that are needed to
use a web service. Typically that includes: schema for the input, schema for the
output, URI of the service, type of transport used (SOAP, XP, HTTP GET, …) The
XAML group will consider providing binding information to service description
languages.
How
does XAML relate to business process ing languages (ebXML business process,
BPML)? size="2">
BPML covers dimensions of business process ing that are specific
to processes internal to the enterprise, including business rules, security
roles, distributed transactions, and exception handling. XAML is targeted at
coordinating business transactions that span web services crossing corporate
boundaries.
How does XAML relate to
XML-based web service transport protocols
ebXML Transport)?
XAML is designed for the coordination of transactional web services,
not XML transportation and packaging issues. XAML will work with standard
XML-based service transport protocols, including W3C XML Protocol (XP), SOAP and
ebXML transport protocol.
How does XAML relate to ebXML?
ebXML is an OASIS/UN initiative to define all the layers in the web
services stack. That includes categories such as registries, business process
ing, service descriptions, and transport/packaging/messaging. Please refer
to the onclick="javascript:urchinTracker ('/outgoing/xml.coverpages.org/xamlFAQ20001025.html#otherstandards');">
above explanation for details on how XAML relates to each of these
categories.
How does XAML relate to e-speak?
E-speak is an open software platform designed for supporting the
description, registration, and discovery of e-services, the ability to compose
multiple e-services into higher-level e-services, the ability to negotiate among
e-services, and the ability to manage e-service interactions. XAML will enhance
the e-speak platform for the coordination and processing of online business
transactions involving e-services. XAML provides e-speak with a standard set of
XML message formats and interaction s for e-services to use to provide
business level transactions that span across companies over the Internet.
BizTalk/.NET?
BizTalk/.Net is a Microsoft initiative to define all the layers in the
web services stack. That includes four categories, registries(UDDI), business
ing languages (X-Lang), service descriptions (WSDL), and
transport/packaging/messaging(SOAP). Please refer to the
onclick="javascript:urchinTracker ('/outgoing/xml.coverpages.org/xamlFAQ20001025.html#otherstandards');">
above explanation for details on how XAML relates to each of these
categories.What standards body will XAML be submitted to?
At this time, the XAML group has not determined which standards body is the most
appropriate for XAML. However, as the specification evolves, the group will vote
on an appropriate organization and submit a draft of the specification.
existing transaction monitors?
XAML will enable web services to expose transactional semantics of the resources
providing the services. Given that TP monitors commonly provide some of the
management and coordination functions of these resources ‘behind the firewall”
today, one of the goals of XAML is to enable TP monitors to participate and
support the transactional semantics offered by web services. This includes
passing of transaction ID’s through web service messages, and supporting the
XAML web service operations of commit and cancel.
At the level above individual web
services, there is a new layer of software providing business-level
transactions. This software makes calls to multiple web services, often spanning
business boundaries. Given that XAML enables individual web services to support
transactional semantics, there is also an opportunity for XAML to specify
standard means for coordinating business-level transactions across collections
of web services. To this
end, one of the goals of XAML is to define message interfaces and interaction
s that help software systems providing the business-level transactions to
coordinate the interactions among web services. There is an opportunity to
define XML interfaces and interaction s for a new breed of web services
that would help software systems at the business transaction level. These
services would provide brokering capabilities for managing the interactions
among web services, for both web services supporting XAML, as well as web
services that do not support XAML. This new breed of web services requires XML
interfaces and interaction s that defines how software systems at the
business transaction level would interact, to request assistance in shepharding
a set of web services towards completion.
transaction protocols?
Classical online transaction management (OLTP) is the process of making
simultaneous changes in several places “atomically” - that is, all the changes
related to a transaction are made or none of the changes are made.For example, within a single
database connection, the DBMS provides some means of demarcating the beginning
and end of a transaction. This demarcation ensures that changes to the database
are made atomically.Sometimes, changes must be made
atomically across multiple databases. For example, an insurance company might
have to change both its claims information and its audit information at the same
time, even though the audit information is in a separate database from the
claims information. This multiple-database change would ensure that, during a
later audit, the company would know which agent took the first report of the
loss.In this case, the existing XA
(Transaction Authority) protocol is useful. XA provides a standard mechanism for
coordinating changes to multiple databases (called resource managers or RMs) as
an atomic unit of work. Basically, the XA protocol asks each RM to vote on
whether a commit will be successful. Once an RM has voted “yes,” it must be able
to commit the open unit of work without failure. The commit occurs only if all
RMs vote “yes.” This process of obtaining a vote, and then performing a commit,
is called a “two-phase commit.”Resource managers are most
frequently databases, but they can also be message-oriented middleware. XA
allows completely heterogeneous collections of RMs within a single transaction;
for example a transaction can commit across DB/2 and Oracle at the same time.
All major database vendors support XA.What is the relationship
between XAML and JTS/JTA?
J2EE includes support for distributed transactions through two specifications,
Java Transaction API (JTA) and Java Transaction Service (JTS). JTA is a high
level, implementation independent, protocol independent API that allows
applications to access transactions. JTS specifies the implementation of a
Transaction Manager which supports JTA and implements the Java mapping of the
OMG Object Transaction Service (OTS) 1.1 specification using the IIOP protocol.
The JTA API allows you to demarcate transactions in a manner that is independent
of the transaction manager service or JTS.While JTA provides an API for
demarcating transactions in Java-based application logic, XAML provides an
agreed upon protocol or a coordinated process of interaction among
transactionally-aware web services over a defined transport.
web service internally implementing JTA could expose these transactional
capabilities using XAML.
What is XAML?
(Extensible Application Markup Language; pronounced “zammel”)
XAML is a declarative XML-based language that defines objects and their
properties in XML. XAML syntax focuses upon defining the UI (user interface) for
the Windows Presentation Foundation (WPF) and is therefore separate from the
application code behind it.Although XAML is presently for use on the Windows platform, the WPF/E (Windows
Presentation Foundation/Everywhere) initiative will eventually bring XAML to
other platforms and devices.XAML syntax describes objects, properties and their relationships to one
another. Generic XAML syntax defines the relationship between objects and
children. Properties can be set as attributes or by using ‘period notation’ to
specify the object as a property of its parent.-
Why Use XAML?
- XAML allows the programmer to separate the user interface (UI) definition from
the underlying business logic. - XAML, since it is parsed, offers the possibility that a single UI definition can
be used on different platforms - XAML allows the user to edit the presentation layer (not necessarily directly,
but with a simple tool) without requiring the usual development tools or
programming knowledge
How Is XAML Used?
XAML is used for
both web-based and client-based applications. Within those two segments, there
are three camps regarding the usage of XAML:- Declaratively programming 2D and 3D vector graphics (VG)
- Declaratively programming traditional (meaning no VG) UI’s and their controls
(or widgets) - As a general declarative programming language for UI and non-UI constructs
- XAML allows the programmer to separate the user interface (UI) definition from
XAML Interview Questions
June 16th, 2008admin