Non functional requirements like Availibility,Scalability...

Any application being built in today's world has lot of non functional requirements. 2 of the non functional requirements are Availability and Scalability.
Availability is the ability of the sysytem to serve the requests of the users for the measurable amount of time. It is a major factor when the software is deployed in a production environment. Lots of business processes will depend on the availability of the system and if the system is unavailable then it is more often then not loss to the customer using the system. If the application is a e-biz. application then its a direct loss of money while if application is something else then its a loss in productivity and hence indirect loss of money to the customer.
In a SaaS scenario availability will be of even more concern since downtime of the service may translate into the breach of a legal contract between provider and consumer of the service and can result in bigger losses for the provider of the service.
Scalability of a system can be defined as ability of the system to be able to serve the increasing demands of the system while stealing maintaining the acceptable performance levels. Once a system is online and is a success then its but natural that the it would be used by more and more people and hence it is but natural that the system would have to handle the increasing demands.
Now a system can either be Scaled Up or Scaled Out based on the increasing demands. Scaling Ua system would normally mean increasing the hardware (memory/ more processors) of the server to enable it to perform faster. Scaling Out a system would normally mean that we increase the number of servers in the landscape and try to meet the performance standard with more servers.

I believe These 2 non functional requirements will be affecting the design application .
How is something i will try to figure out and may be post it in a different post.

Clustering is a solution to meet these non functional requirements. Basically clustering is nothing but to present a group of physical servers to the client as 1 virtual resource. The requests coming from the clients to this virtual resource can be redirected to the physical servers based on various algorithms.
A logical view of such an arrangement would look something like this..

So the above picture basically depicts that we have a cluster of server 1 and server 2 which is handling requests from client based on some kind of request routing done by the virtual resource.

There are various ways of configuring a cluster based on what kind of requirements we have. I'll look into them and post on a different post....

~Abhishek

Clustering !!!!

Clustering has always been a term to me rather then a topic. A few days back while having a discussion about application availability, scalability and performance i suggested clustering as a solution.
However i myself was and am not sure of what topic could this term possibly unearth for me.
So after avoiding to read on this topic for around 2 weeks now finally i decided to blog it as an action item.
I'll be reading about clustering soon and would come up with a post or 2 with the label Clustering (And added labels as required for the topics the term unearths for me)

~Abhishek

Implementing logic in the proxy and consuming the service in .NET

First the good news :)
I managed to create the service and was able to consume it from .NET.
Here were the open questions from the last post....
1) How to write some logic in the server proxy
2) Where and how to find the wsdl with binding information so that i can consume it from .NET

In order to write the logic into proxy i went to the package in which i generated the proxy. In that package i found that an interface has been generated for the message interface we generated in ESR and a class to implement the interface. I found the method instance method of the class and went ahead editing the method implementation. My first unassisted ABAP code. Here's how it looked like....

OUTPUT-GET_EMPLOYEE_OUTPUT-ID = INPUT-GET_EMPLOYEE_INPUT.
OUTPUT-GET_EMPLOYEE_OUTPUT-NAME-FIRST_NAME = 'Abhishek'.
OUTPUT-GET_EMPLOYEE_OUTPUT-NAME-LAST_NAME = 'Kumar'.

Once done i went to the transaction SOAMANAGER. This is the new transaction which replaces the transactions WSADMIN and WSCONFIG. This opened a webdynpro UI with a tab Business Administration on which there's a link Web Service Administration. There i can search for the design time component i want to configure. (EmployeeService) in my case. Once selecting the service i can go to Configurations tab where i select to Create a Service. I can choose a name for the service and binding. Whatever i choose here appears in the final wsdl as service and binding. Once done I can choose a type of authentication. I chose http authentication. and saved the configuration.

On the same page i found the link to the wsdl with all the binding and port information. On having a look at the wsdl i confirmed that binding and service tags are available.
Copy the link to the wsdl and try setting the reference to this wsdl in Visual Studio. Once done i am able to call the service easily from .NET.

Now the second question which was how to add more then one operation to the Message Interface. This is a limitation in 700 release of BASIS. And unfortunately the sandbox system has a 700 release of BASIS. According to some documentation i found i can add more then 1 operations in the message interface. So i parked it for the time being.....

~Abhishek

PS :- This was my hello world to the world of ABAP. i.e. a first program in ABAP. This post is the last in the series of blogs i started on May 23rd 2008 :)

Generating a Proxy

Here's what i did next. I just added a message interface called EmployeeService in the Message interfaces of my . I marked it as inbound synchronous method in the option. I couldn't find much documentation about what the various options mean however i assume that inbound means inbound message coming from client to the server and synchronous means that server would process them and give the results back to client then and there itself.
Now i selected the input and output messages and there you go . I got a nice wsdl which looks like the following....

<?xml version="1.0" encoding="ISO-8859-1"?>

<wsdl:definitions xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" xmlns:p1="http://sap.office.tst" name="EmployeeService" targetNamespace="http://sap.office.tst">
    <wsdl:types>
        <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://sap.office.tst" targetNamespace="http://sap.office.tst">
            <xsd:element name="GetEmployeeInput" type="EmployeeId" />
            <xsd:element name="GetEmployeeOutput" type="Employee" />
            <xsd:simpleType name="EmployeeId">
                <xsd:annotation>
                    <xsd:appinfo source="http://sap.com/xi/TextID">
                    a64268c22be811dda00f000bcd9b93dd
                    </xsd:appinfo>
                </xsd:annotation>
                <xsd:restriction base="xsd:string" />
            </xsd:simpleType>
            <xsd:complexType name="Employee">
                <xsd:annotation>
                    <xsd:appinfo source="http://sap.com/xi/TextID">
                    a644d9c02be811dd90e2000bcd9b93dd
                    </xsd:appinfo>
                </xsd:annotation>
                <xsd:sequence>
                    <xsd:element name="Id" type="xsd:string">
                        <xsd:annotation>
                            <xsd:appinfo source="http://sap.com/xi/TextID">
                            4ca5845028aa11ddb1c2001321f4509b
                            </xsd:appinfo>
                        </xsd:annotation>
                    </xsd:element>
                    <xsd:element name="Name" type="Name">
                        <xsd:annotation>
                            <xsd:appinfo source="http://sap.com/xi/TextID">
                            4ca5845128aa11ddb4a1001321f4509b
                            </xsd:appinfo>
                        </xsd:annotation>
                    </xsd:element>
                </xsd:sequence>
            </xsd:complexType>
            <xsd:complexType name="Name">
                <xsd:annotation>
                    <xsd:appinfo source="http://sap.com/xi/TextID">
                    a64994b02be811ddc2e4000bcd9b93dd
                    </xsd:appinfo>
                </xsd:annotation>
                <xsd:sequence>
                    <xsd:element name="FirstName" type="xsd:string">
                        <xsd:annotation>
                            <xsd:appinfo source="http://sap.com/xi/TextID">
                            93b077b028aa11ddcc0b001321f4509b
                            </xsd:appinfo>
                        </xsd:annotation>
                    </xsd:element>
                    <xsd:element name="LastName" type="xsd:string">
                        <xsd:annotation>
                            <xsd:appinfo source="http://sap.com/xi/TextID">
                            93b077b128aa11ddb07c001321f4509b
                            </xsd:appinfo>
                        </xsd:annotation>
                    </xsd:element>
                </xsd:sequence>
            </xsd:complexType>
        </xsd:schema>
    </wsdl:types>
    <wsdl:message name="GetEmployeeInput">
        <wsdl:documentation>
        Input to GetEmployee Operation
        </wsdl:documentation>
        <wsdl:part name="GetEmployeeInput" element="p1:GetEmployeeInput" />
    </wsdl:message>
    <wsdl:message name="GetEmployeeOutput">
        <wsdl:part name="GetEmployeeOutput" element="p1:GetEmployeeOutput" />
    </wsdl:message>
    <wsdl:portType name="EmployeeService">
        <wsdl:operation name="EmployeeService">
            <wsdl:input message="p1:GetEmployeeInput" />
            <wsdl:output message="p1:GetEmployeeOutput" />
        </wsdl:operation>
    </wsdl:portType>
    <ifr:properties xmlns:ifr="urn:com-sap:ifr:v2:wsdl">
        <ifr:category>
        ifmmessif
        </ifr:category>
        <ifr:methods>
            <ifr:method name="EmployeeService">
                <ifr:isSynchron>
                true
                </ifr:isSynchron>
                <ifr:isInbound>
                true
                </ifr:isInbound>
                <ifr:interfaceCategory>
                inbound
                </ifr:interfaceCategory>
            </ifr:method>
        </ifr:methods>
        <ifr:messages>
            <ifr:message name="GetEmployeeInput">
                <ifr:messType>
                ifmmessage
                </ifr:messType>
                <ifr:technicalNamespace>
                http://sap.office.tst
                </ifr:technicalNamespace>
            </ifr:message>
            <ifr:message name="GetEmployeeOutput">
                <ifr:messType>
                ifmmessage
                </ifr:messType>
                <ifr:technicalNamespace>
                http://sap.office.tst
                </ifr:technicalNamespace>
            </ifr:message>
        </ifr:messages>
    </ifr:properties>
</wsdl:definitions>

As soon as i was done with this i though of generating a .NET proxy for this wsdl. (Me being a .NET developer i couldn't control my instincts and stay away from Visual Studio too long :) )

Anyways i tried to generate a proxy and failed. Basically nothing is generated. On looking closely at the wsdl i found that wsdl:service and wsdl:binding tags are missing. Which is understandable. If i was designing the ESR i wouldn't want the information about binding and implementation address in my repository. I would probably keep it somewhere else like UDDI. This is an open question that i need to figure out now. Where doesn SAP keep this information. I'll touch this back once i am sure that implementation works.

So leaving the visual studio i came back to my ABAP system and started sproxy to generate a implementation proxy for my wsdl. After struggling a lot with package concept of ABAP i was suggested to make the proxy as a local object. I still can't figure out why it can't be a server object.... Everyone i contacted gave me different reasons however i chose to believe that i do not have appropriate permissions to create a server side object. (Sad and interesting, since this is a sandbox i thought i have all the permissions)

So i have managed to generate a proxy for this wsdl in ABAP and now comes the first place where i would code. All i want to do is to give back the employee with some hardcoded name and passed id from the method. Once i am able to do this i would actually go ahead and find the answer to my first question i.e. where to find the binding and service info for this interface.

Another open question which looms large is to add another method to this interface. I choose to address this at the end.

~Abhishek

Show a document on the post

One of my friends wanted to post a pdf document on the blog. On doing a quick google i found a nice tool to post documents on the blog.
Check out http://www.scribd.com/ for finding how to upload and show documents on your blog.....

~Abhishek

Posting xml on the blog

Here's a simple javascript web application application that will format source code text into html for inserting into your blog.

http://formatmysourcecode.blogspot.com/

~Abhishek

Defining the Interface using Integration builder

In the previous steps I am done with setting the prereqs to start defining an interface in the ESR. I started with defining the interface now. Here are the steps
1) Login to the PI system
2) Double click on User Menu -> Exchange Infrastructure ->SXMB_IFR - Start Integration Builder. Alternatively execute the transaction SXMB_IFR.
3) This should open an internet explorer window with links to various tools. Click on Integration Repository
4) Step 3 would download and install a Java application (jnlp file) to your system
5) Provide credentials to login to the integration builder
6) Once the integration builder starts go to Tools -> Transfer from System Landscape Directory -> Import Software Component Versions
7) Select the software component in which we want to develop our interface and import it
8) Once we do this select the Software Component Version in the left naviagtion menu. Right click and add a namespace in which we would be doing the development
9) Expand the interface objects -> Data Types and right click on Data Types to add Data Types
10) Add the Data Types Employee, EmployeeId, Name

Here's how various structures look like after editing them using Integration Builder ...

a) Name

<?xml version="1.0" encoding="ISO-8859-1"?>

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://sap.office.tst" targetNamespace="http://sap.office.tst">
<xsd:complexType name="Name">
  <xsd:annotation>
      <xsd:appinfo source="http://sap.com/xi/TextID">
      1a2def0028c111dd8c9c000bcd9b93dd
      </xsd:appinfo>
  </xsd:annotation>
  <xsd:sequence>
      <xsd:element name="FirstName" type="xsd:string">
          <xsd:annotation>
              <xsd:appinfo source="http://sap.com/xi/TextID">
              93b077b028aa11ddcc0b001321f4509b
              </xsd:appinfo>
          </xsd:annotation>
      </xsd:element>
      <xsd:element name="LastName" type="xsd:string">
          <xsd:annotation>
              <xsd:appinfo source="http://sap.com/xi/TextID">
              93b077b128aa11ddb07c001321f4509b
              </xsd:appinfo>
          </xsd:annotation>
      </xsd:element>
  </xsd:sequence>
</xsd:complexType>
</xsd:schema>

b) EmployeeId

<?xml version="1.0" encoding="ISO-8859-1"?>

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://sap.office.tst" targetNamespace="http://sap.office.tst">
<xsd:simpleType name="EmployeeId">
   <xsd:annotation>
       <xsd:appinfo source="http://sap.com/xi/TextID">
       b58a93e028c111ddcfe2000bcd9b93dd
       </xsd:appinfo>
   </xsd:annotation>
   <xsd:restriction base="xsd:string" />
</xsd:simpleType>
</xsd:schema>

c) Name

<?xml version="1.0" encoding="ISO-8859-1"?>

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://sap.office.tst" targetNamespace="http://sap.office.tst">
<xsd:complexType name="Name">
    <xsd:annotation>
        <xsd:appinfo source="http://sap.com/xi/TextID">
        1a2def0028c111dd8c9c000bcd9b93dd
        </xsd:appinfo>
    </xsd:annotation>
    <xsd:sequence>
        <xsd:element name="FirstName" type="xsd:string">
            <xsd:annotation>
                <xsd:appinfo source="http://sap.com/xi/TextID">
                93b077b028aa11ddcc0b001321f4509b
                </xsd:appinfo>
            </xsd:annotation>
        </xsd:element>
        <xsd:element name="LastName" type="xsd:string">
            <xsd:annotation>
                <xsd:appinfo source="http://sap.com/xi/TextID">
                93b077b128aa11ddb07c001321f4509b
                </xsd:appinfo>
            </xsd:annotation>
        </xsd:element>
    </xsd:sequence>
</xsd:complexType>
</xsd:schema>

Next we go ahead and define 2 Message Types as input and output message of the operation we want to define in our wsdl . ( I am unable to find how to have more then 2 messages in my interface for wsdl and hence i am adding only 2 Message Types as off now. To Add a message type in the Navigation Tree we can right click on Message Type and add a new one

Here are 2 schemas of 2 message types i added

a) GetEmployeeInput

<?xml version="1.0" encoding="ISO-8859-1"?>

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://sap.office.tst" targetNamespace="http://sap.office.tst">
 <xsd:element name="GetEmployeeInput" type="EmployeeId" />
 <xsd:simpleType name="EmployeeId">
     <xsd:annotation>
         <xsd:appinfo source="http://sap.com/xi/TextID">
         02f3c70028c211ddad54000bcd9b93dd
         </xsd:appinfo>
     </xsd:annotation>
     <xsd:restriction base="xsd:string" />
 </xsd:simpleType>
</xsd:schema>

b) GetEmployeeOutput

<?xml version="1.0" encoding="ISO-8859-1"?>

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://sap.office.tst" targetNamespace="http://sap.office.tst">
  <xsd:element name="GetEmployeeOutput" type="Employee" />
  <xsd:complexType name="Employee">
      <xsd:annotation>
          <xsd:appinfo source="http://sap.com/xi/TextID">
          886faed028c211dd8216000bcd9b93dd
          </xsd:appinfo>
      </xsd:annotation>
      <xsd:sequence>
          <xsd:element name="Id" type="xsd:string">
              <xsd:annotation>
                  <xsd:appinfo source="http://sap.com/xi/TextID">
                  4ca5845028aa11ddb1c2001321f4509b
                  </xsd:appinfo>
              </xsd:annotation>
          </xsd:element>
          <xsd:element name="Name" type="Name">
              <xsd:annotation>
                  <xsd:appinfo source="http://sap.com/xi/TextID">
                  4ca5845128aa11ddb4a1001321f4509b
                  </xsd:appinfo>
              </xsd:annotation>
          </xsd:element>
      </xsd:sequence>
  </xsd:complexType>
  <xsd:complexType name="Name">
      <xsd:annotation>
          <xsd:appinfo source="http://sap.com/xi/TextID">
          88721fd228c211ddb301000bcd9b93dd
          </xsd:appinfo>
      </xsd:annotation>
      <xsd:sequence>
          <xsd:element name="FirstName" type="xsd:string">
              <xsd:annotation>
                  <xsd:appinfo source="http://sap.com/xi/TextID">
                  93b077b028aa11ddcc0b001321f4509b
                  </xsd:appinfo>
              </xsd:annotation>
          </xsd:element>
          <xsd:element name="LastName" type="xsd:string">
              <xsd:annotation>
                  <xsd:appinfo source="http://sap.com/xi/TextID">
                  93b077b128aa11ddb07c001321f4509b
                  </xsd:appinfo>
              </xsd:annotation>
          </xsd:element>
      </xsd:sequence>
  </xsd:complexType>
</xsd:schema>

Once done with adding these 2 MessageTypes i have added a MessageInterface to my little POC using the Add New MessageInterface wizard which we again get by right clicking the MessageInterfaces node on the navigation tree in my SCV
Here's where my confusions have started as there are various options on what type of Message Interfaces do i want. So i am stopping this blog post here and would write the next steps in my next post.....

~Abhishek

PS: Its relatively simple to write a service in .NET since we follow inside out approach of defining a wsdl i.e. we define our classes first and wsdl is generated out of the box by the Visual Studio. This approach is time consuming however this way i have more control over how my wsdl, schemas etc. should look like so i like this more then .NET :) . Its taking lot of time since it is my first time i am doing this however i am sure with time it would become easier for me to use outside in approach of defining a web service.....