admin2012 buchan web_services-v101

Who am I?

•  Bill Buchan, CEO of hadsl - one of the vendors on the showfloor s  Come visit the booth - we don’t bite

•  Dual PCLP in v3, v4, v5, v6, v7, v8, and v8.5 •  Enterprise-level consultant on Domino since 1995

What we’ll cover

•  Introduction •  Web Services Overview •  Using Domino to provide Soap Based Web Services •  Using Notes to consume Web Services •  Using xPages to provide REST based Web services •  Consuming web services from C# •  Wrap up

Introduction

•  I am Bill Buchan. I am: s  A blogger - http://www.billbuchan.com s  A principal of HADSL - http://www.hadsl.com s  A Notes veteran of some 14 years

•  You are s  Lotus Domino developers s  Interested in starting or enhancing Web Services in your

environment s  Familiar with LotusScript, and perhaps xPages/Java


What we’ll cover

A quick overview

•  SOAP Stands for s  Simple Object Activation Protocol

•  SOAP Based Web services are: s  A standard application to application protocol for exchanging structured data

�  Usually (but not always) using the http protocol �  Usually (but not always) using XML �  Usually we provide meta-information on what our service will do, using a

language called WSDL (Web Service Description Language) – formatted in XML.

•  Web services are Language independent, Platform independent, Data format representation independent

•  But hopefully you all knew this already...

Web Services Architecture

•  The players: s  The Web Service server

�  Can answer questions on what it can do �  Can accept requests from Web Service clients �  Can respond to requests from Web service clients

s  The Web Service client (or consumer)‏ �  Knows where the web service server is located �  Knows the services that it requires �  Knows how to prepare a Web Services Query �  Knows how to interpret the returned data

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Web Services Protocol

§  A typical web service session looks like:  Client to Web Service Server

§  “Tell me the answer to this question”  Web Service Server

§  “Here it is” §  Conclusion:

 The clients drive the conversation  The Server cannot initiate a conversation with the client.

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Web Services Protocol (in more detail)‏

§  The Web Services Protocol:   The client decides it needs to ask the server for some information

It constructs the relevant XML based web services query (either dynamically or in a static fashion depending on the complexity of the application)‏

  It then connects to the Web Service Server §  Pushing the web request up as an HTTP 'Post' request §  It waits for a response

  The Web service server then 'Posts' back an XML payload representing the answer

  The client then unpacks and interprets the data.

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This sounds hard...

•  Not really. s  Its a combination of web protocol and XML construction and

unpacking s  Most of the hard work is done for you by the various Web

Service servers and Consumers s  Its fairly easy to debug using the correct tools

What about REST?

•  REST stands for: �  REpresentational State Transfer

•  REST Means s  The query is passed as the URL s  The results can be in XML or REST s  NO WSDL

•  REST is s  Far more lightweight s  Easier to parse in JavaScript

•  Choose the best approach…

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REST versus Web Services?

•  Is REST a Web Service ? Well, not really •  Which is best?

s  Web services are good for delivering very structured, complex information in nested XSL

s  REST is very convenient to parse, and is better for lightweight frameworks such as JavaScript

•  Pick your architecture based on your consumer needs, and your authentication requirements

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Authentication

•  Some web services or REST services can supply information without authentication s  But we live in the real world

•  Authentication is proving you are allowed to see this data •  Can be achieved by:

s  Passing a Session Identifier in a cookie s  Passing a username/password pair to an application s  Authenticating using Kerberos/NTLM in an Active Directory

world •  A simple rule of thumb

s  Lightweight consumers tend to use cookies s  Heavyweight data lifting services tend to use authentication

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Authentication Gotchas

•  Some frameworks – such as JavaScript or Flex – can re-use the cookie provided on their launch page s  Very convenient for us. Just have the consumer launch the Rich

Internet Application from that page •  Some more complex applications require KERBEROS

authentication s  A C# Windows based service, for instance, might run under

specific service credentials, which can then be Single-Sign-On authenticated to Domino �  See SPNEGNO and/or IIS Websphere Plugin

•  Otherwise s  You will have to hold encrypted username/password keys.

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A sample application

•  Fairly simple Domino Contact Database s  A single ‘Contact’ form with some information s  Not meant to be a ‘real-world’ example - Its here to demonstrate

the techniques •  All example code is in the database

s  Simple to figure out and ‘research’ s  Probably is not best practice!

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Example Database:

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Example Database: Contacts.nsf

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How do we test a web service?

•  I recommend SoapUI s  Its free! •  http://www.soapui.org

•  It allows you to interrogate a web service s  And build test case with real data

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SoapUI: Example Screenshot


What we’ll cover

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Domino Web Service Server

•  By far the simplest is to use a LotusScript Web Service s  The majority of the work is done for you!

•  Servlets should be avoided unless s  You are running on Domino v6.5.x or older s  You absolutely require persistence

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LotusScript Web Services

•  Introduced in Lotus Domino 7 •  Robust •  Code the web service using LotusScript •  Fairly high performance but

s  Remember: Lack of persistence between calls, so �  Be aware of what your code is doing! �  Use ‘Agent Profiling’ to see timings…

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Profiling a Web Service

•  LotusScript web services are very similar to LotusScript agents s  So you can profile them. s  Enable Profiling on the Web

Services Properties tab s  View the last run profile:

�  Right click on the Web Service �  View Profile Results

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A Sample Profile

•  This shows how long the agent took to run, and how long the agent spent inside the Notes Object Interface s  In our case, 761ms total, and 0ms within NOI s  One call to CurrentDatabase, and one call to Title.

s  Obviously, this wasn’t a very interesting web service call…

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Designing a Web Service

•  Spend time thinking about how your consumer will use this web service. s  More time thinking, less time coding s  You do NOT want to change this web service interface often

�  Instead - roll out a new web service s  Think through client use cases s  Remember - you can use LotusScript to perform complex

business rules, and provide summary data to your consumer �  Don’t assume the consumer has lots of CPU or memory

§  BlackBerry smartphones / Windows Mobile ? •  Put complex code in script libraries, and call them

�  It means you can put a normal agent ‘test harness’ around it and debug it

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Contacts.nsf

•  In our case we wish to: s  Be able to list all users by Name, by Department s  Be able to get details on a particular user s  Be able to search for users

•  Do we s  Pass all fields back as web service items? s  Pass back an array of fields?

•  In this case, we pass back Web Service Items s  Assume data mapping knowledge and responsibility.

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Web Service Design

•  We design our web service interface within a ‘Class’ in LotusScript. s  At this point, you probably wished that you studied the

Object Orientated LotusScript sessions I used to give… •  Our web service will expose all ‘public’ methods and

properties s  We do not have to put all the code in one ‘class’ s  Beware of extending existing classes - you might expose

more than you want! �  Beware over-exposure…

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Web Service Design

•  LotusScript does NOT allow functions to return Arrays. s  This is a language limitation, not a Web Service Limitation s  It can return simple types - but not variants (web services

does not support them) s  Instances of other classes…

�  Which can contain other classes •  We need to use arrays to return results

s  For instance, we need to return an array of Zero or more entries to list our users. How do we do that?

•  We can define a class and return an instance of that class…

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Returning complex types

•  We can define a class called ‘ReturnArray’ which has a single array as a public member. s  The constructor initialises the

array so that it has one blank entry. •  We can then populate this array

with one or more entries. •  Nd7 supports arrays with one

element or more - nd8 supports ‘empty’ arrays.

Class returnArray

Public S() As String Sub new

Redim S(0)

S(0) = ""

End Sub

End Class

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Complex types…

•  We shall return our Person contact record using a class. s  We DON’T have a constructor s  All elements are Public - so it’ll

be exposed to the Web Service as data.

s  Our property names will be used by the web service as field names

s  Since LotusScript is case insensitive, the web service field names will be UPPERCASE.

Class Person

Public FirstName As String Public MiddleInitials As String Public LastName As String Public FullName As String

Public Telephone As String Public Cellphone As String Public eMail As String Public HomePhone As String Public Department as String Public Notes As String

End Class

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Lets make it better

•  We need to add: s  Logging. We need to know when it works, and importantly,

when it does not s  Error Handling. We need to pass errors back to the consumer s  Security. We might want to harden this service somewhat

•  We committed the following sins: s  We put all the code in the web service itself, making it hard to

test. Best to consider embedding most of the code in script libraries

s  We’ve tightly bound the data structures in our data to our web service �  If we add more fields to our contact record - we shall have

to change the web service. And therefore, all our clients will have to be checked and/or recompiled.

�  If the data set is likely to change, construct a more flexible data-mapping schema

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ND7 and ND8 differences

•  Web services built or compiled in Notes 8 Designer WONT run on ND7 anymore! So be careful about what web services you host on which servers, and which version of designer you use. s  Just bear this version difference in the same manner as all

other version differences.

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ND7 and ND8 differences

•  In ND7, the class used for the web service has to reside in the web service design element. In ND8, this can be in a script library. s  This means that for complex services, you can place all the

business code in a script library, allowing simple construction of a test harness.

•  ND8 now supports code in Java Libraries •  ND8 supports more error handling SOAP elements •  ND8 supports ‘empty’ arrays - nd7 does not


What we’ll cover

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Consuming a web service

•  Why consume web services? s  To gain access to information in other systems s  To prevent the synchronisation and replication of external data sources to

Notes s  Real time, up to date data lookup

•  Where? s  We could use a scheduled Java agent in Domino to interrogate external

services - no UI means you have to monitor and check s  We could use client-driven code on the client workstation - be aware of network

issues between the clients and the remote service

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Overview

•  Security s  Remote web services may require

�  Username/password login, Encrypted username/password pairs in data, SSL.

•  Things change s  You may have to change your web service consumer to

accommodate this s  The remote web service may move s  When designing, don’t hard-code…

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Consuming Web Services

•  Summary: s  Notes 8 - Its very simple - It works in LotusScript and in Java s  It does a lot of work for you

•  How do I construct a Web Service Consumer in LotusScript? s  Create a new, empty script library s  Click on the Import WSDL button s  It creates a Class definition s  You can then “use” the script library and class.

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•  On the nd8 basic client: create a new LotusScript Script Library:

•  Click on the WSDL button…


•  On nd8 standard designer, go to Code, Web services consumer

Consuming Web services

•  Click on ‘New Web service consumer’ and fill in the dialog:

Consuming web services

•  And then use the web service consumer library that has been created:

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•  It needs a WSDL file. What's that? s  You can open the WSDL

definition for your web service in your browser

s  Use View Source, and save that as a WSDL file.

s  Select it… •  Designer will then construct

helper classes and a main class which we can then call

•  That’s it!

Sub Initialize Dim C As New Contacts Dim V As Variant Set V = C.listUsers() Forall thisUser In V.S Print "Found User: " + thisUser End Forall End Sub

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Gotchas

•  The entire LotusScript library is taken up with the computed Web service definition. Best not to make changes. s  Next time its refreshed, you will lose those changes!

•  If you change the web service, you must remember to update the Web Services consumer. s  It does not take long - so don’t forget it. s  And when you change the web service consumer script

library, you must recompile all the LotusScript that relies on it. �  ‘Tools, Recompile LotusScript’ is your friend

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Gotchas

•  It requires the Notes 8 client to run on: s  We as Application Developers deploy solutions on users’

target notes clients s  Notes 8 may not yet be adopted in your environment

�  So catch up! s  This may help drive the upgrade process

•  What if you need Web Service consumption now, and are not yet on Notes 8? s  You can use MS COM objects s  You can hand-code Java-based agents which perform Web

Service calls s  But really. Upgrade

Summary

•  Web Services s  Are pretty straightforward s  An important part of your armoury s  Help break down barriers between Domino and other systems s  Help prevent data duplication in your environment

•  By now, you know enough to make a real difference

•  Keep learning.


What we’ll cover

How difficult is it to provide REST from xPages?

•  Its pretty simple •  It relies on the Extension Library

s  (Its pretty straightforward, but we’ll not cover it here) •  What does REST look like?

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So REST can be JSON or XML

•  JSON is JavaScript Object Notation s  It can be directly parsed in JavaScript (and many other

languages) s  You can pass collections of objects (which may contain other

objects) •  Considerations:

s  It can get large. You might want to keep it light: �  So don’t try and pass back thousands of records. Let the

consumer ‘page’ through a reasonable set of results s  Everything is a String or a Number

�  So decide quickly how to pass back currency, dates, etc. •  See http://json.org for more information

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Lets add a JSON based REST service:

•  Add a new xPage. I called mine RestService.xsp

•  Drag in a REST object from the Data Access Controls area:

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JSON REST Service:

•  Give it a name: I called mine ‘all’ •  Set ViewName to the name of

your view. In this case, ‘Contacts.FirstName’

•  Set service to ‘xe:viewJsonService’ •  Set ‘pathInfo’ to the URL you

wish to use. I set mine to ‘all’ •  Set contentType. I set mine to ‘text/plain’, but ‘application/

JSON’ is better •  I set ‘compact’ to ‘false’ so we could read it. Set it to ‘true’ •  Now set your columns…

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JSON REST Service

•  I set my columns to:

•  But of course you could set more or less columns, and compute variables on the fly

•  Lastly, I set SystemColumns to the computed value of ‘false’ to skip the system computed columns

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JSON Summary

•  You don’t have to use xPages for all the site – you can use xPages for the JSON part

•  The REST based xPages JSON provider is pretty basic, but very fast s  Matt White (of ideaJam and xPages101 fame) has measured this

API versus traditional web service pages, and found it to be at least 10x faster

s  It might be worth the effort to implement for that sort of performance gain

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What we’ll cover

Consuming Web Services from C#

•  C# is part of Microsoft’s Visual Studio suite of langages s  Similar to Java in terms of being Object Orientated s  It’s a very useful tool in our corporate landscape

•  So lets construct a C# Web Services client for this application: s  It’ll be simple – a console based application s  It’ll just pull data via web services s  It’ll ignore authentication, error handling, etc.

•  But it will demonstrate the technique

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C# Starter

•  Create a new project in VS2010 s  A console application s  C# Based

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Adding the Service Reference

•  Right click on your project (on the right, in the Solution Explorer pane) and select ‘Add Service Reference’

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Pass the WSDL for the service

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•  Enter the WSDL URL, and give a name to the web service, then click ‘Advanced’

Add a Web Reference

•  Now click on ‘Web Reference’

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•  Finally, enter the URL again, and update the reference

Now add a splash of code…

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EndpointAddress endpoint = new EndpointAddress(new Uri(DominoHostName));

BasicHttpBinding httpBinding = new BasicHttpBinding(); httpBinding.Security.Mode =

BasicHttpSecurityMode.TransportCredentialOnly; httpBinding.Security.Transport.ClientCredentialType =

HttpClientCredentialType.Basic; ws = new sr1.ContactsService(); ws.Credentials = new NetworkCredential(DominoUserName, DominoPassword); Console.WriteLine("Program name is: " + ws.GETAPPLICATIONNAME());

C# Conclusion

•  It’s a highly scalable, secure environment •  This is a trivial example –it can handle millions of records, and

very complex structures •  The LINQ structures within C# make data comparison and

reporting very simple •  Step through it with the debugger and all will be revealed.

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What we’ll cover


Resources

•  SOAPUI – http://www.soapUI.org •  The xPages Extension Library – http://www.openNtf.org •  xPages101 series of xPages tutorials – http://www.xpages101.net •  All my previous presentations are on http://www.hadsl.com

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7 Key Points to Take Home

•  Web services are a platform and application agnostic way of passing information around

•  Both Web Services and REST are lightweight protocols and should be used for smaller packets of information

•  Use SoapUI to help debug SOAP based web services •  Authentication needs to be architected •  Lotus Domino servers can easily serve web services using classic

LotusScript and Java •  xPages can provide information via REST •  xPages REST is 10x faster than LotusScript based SOAP web

services

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Your Turn!

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How to contact me: Bill Buchan

[email protected]

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