Microsoft Azure

When I first heard about Microsoft Azure, I thought it was yet another feeble attempt by Microsoft to get in on the hype with a subpar product just to get the foot in the door. I have to admit, though, that I was pleasantly surprised. Shockingly, Azure is a robust, well designed cloud platform that may yet prove to be better than some of its competitors.

In a nutshell, Azure encompasses three products.

• Windows Azure
• Compute: Virtualized compute based on Windows Server
• Storage: Durable, scalable, & available storage
• Management: Automated, management of the service
• SQL Azure
• Database: Relational processing for structured/unstructured data
• .Net Services
• Service Bus: General purpose application bus
• Access Control: Rules-driven, claims-based access control

Essentially, Azure provides the complete cloud computing stack that allows developers to write their own applications on top of it. The self administration interface is simple and intuitive. Depending on the services you are using, it allows you to allocate your server or database capacity, hook in the service bus, and configure your application in minutes.

The Windows Azure platform introduces the Web and Worker roles. This is the implementation of a similar pattern used in WCF that decouples the network transport from the component logic. The Web role allows the applications to accept incoming requests via a variety of protocols supported by IIS. The Worker role cannot accept any direct requests from the Internet but instead can receive messages from an internal Azure queue hosted by SQL Azure. Under the covers, Web and Worker roles run in their own instances of Microsoft VM engine. All the queues and communication protocols can be configured via the control panel.

SQL Azure is no less impressive. It allows you to store data directly in the cloud in three different forms:

• Blobs
• Tables
• Relational

All of these operations are exposed through RESTful services and are really easy to use. For relational data, complete databases can be hosted in the cloud and applications can access them directly whether they themselves are hosted in the cloud or a private datacenter.

The .Net Services platform provides a couple of services – access control and message routing. Access control serves the identity validation, transformation, and federation purposes. This is all based on the rules defined through the control panel. The service bus part of the platform does what you would expect any ESB to do – service endpoint registration and access, message transformation and routing, and improved security.

Even though Azure is still a relatively immature platform, it holds a lot of promise. Microsoft has finally hit the mark. Some risks still need to be addressed, however. The typical cloud computing concerns remain – security, privacy, longevity, etc. Additionally, a platform like Azure may cause some issues for IT departments that need to adhere to regulations like Sarbanes Oxley, SAS 70, and others. Division of responsibilities, following IT governance processes, quality control, and other sticky situations may keep CIOs and other IT managers up at night. These things will eventually work themselves out through maturing the Azure platform or enhancing the IT processes. Despite the drawbacks, I believe Azure is a viable and solid platform for “cloudizing” your applications.

SOA Funding Models

One of the primary reasons SOA efforts fail in many companies is simply due to inadequate or inappropriate funding models. Costs are typically at the core of every problem and SOA programs are not exempt. We hear horror stories all the time – the initial investment to establish an SOA environment was too high, so the effort was cancelled; there are many services created in the company but they are hardly reused; etc. Establishing a funding model that is right for your company is the key to moving the SOA program forward.

Any SOA initiative is comprised of two parts – infrastructure and services. Both need to have a separate funding model established in order to successfully support SOA program’s goals.

SOA Infrastructure Funding

Infrastructure funding requires a pretty straight forward approach. When discussing SOA infrastructure, I am referring to shared platforms that are used by a number of services across the organization. Some companies host services on the same platforms whose functionality is being exposed. However, even if this is the case, some shared infrastructure components like ESBs, service management technology, Registry/Repository, etc. must exist to support SOA program’s needs. Thus, it is safe to assume that some form of shared SOA infrastructure exists. There are two possible ways to provide effective funding to build it out.

1. Fund all the SOA infrastructure centrally
2. Identify appropriate projects to acquire / extend new / existing SOA infrastructure

Central funding is probably the easiest and most effective approach. It allows the organizations to establish an independent roadmap for introducing and upgrading SOA infrastructure. It also makes the SOA program operate more efficiently as the cost, scaling, and availability issues will no longer be relevant to individual projects. If central funding option is selected, several approaches for recouping the initial and ongoing investment can be utilized.

• Do not recoup the investment
• Place an entry fee to use any SOA infrastructure component
• Charge a small fee for each usage instance

Since all the SOA infrastructure is provided centrally, not recouping the initial investment is a real option. If the organization’s fiscal model does not call for IT recouping all its costs from the business groups using their products, this option works well. If this is not the case, however, you have a choice between placing a predefined entry fee that each application / project must pay to use the specific SOA infrastructure platform and charging end users based on the total usage.

The per-use-fee scenario is a little tricky as each SOA infrastructure component needs to define what a transactional unit is and how much to charge for it. Transactional units can be different for each SOA platform. For example, an ESB transactional unit can be a service call, Registry/Repository – an individual user and/or a UDDI request, etc. In this case, total usage amount based on predefined transactional units would be calculated, multiplied by the unit cost, and charged to the business units. The most effective way to determine a unit cost is to divide the total investment made in the platform by the total transactional units being consumed. The obvious effect is that unit costs would decrease with increased usage. Here are all the formulae discussed above.

Usage charges per platform:
Unit = Different per Platform
Unit Cost = Total Platform Investment / Total Amount of Units Consumed
Line of Business Usage = Units Used by Line of Business * Unit Cost

Some companies have chosen to grow their SOA infrastructure gradually, without a central program or funding. A typical approach in this scenario has been to attach SOA spending to the most appropriate projects. Thus, the projects would purchase new SOA infrastructure platforms or upgrade existing ones to suit their needs. There are several problems with this approach.

1. Typically, the projects purchasing the infrastructure don’t want to share it with other potential consumers unless there is significant pressure from above. The platforms don’t end up being reused or, if so, only minimally. The projects do not have any incentive to sharing their investments with anyone else, especially since they are seen as critical to projects’ success.
2. Projects often get cancelled due to over-inflated budgets. SOA infrastructure is expensive and cost conscious enterprises do not want to invest into what looks like excessive infrastructure for project’s needs.
3. Demand to extend a platform based on project’s needs typically comes without enough lead time to accommodate project’s timelines. Thus, projects face a tough decision – to extend their delivery date or use alternative infrastructure.

Funding the SOA infrastructure centrally is more effective in delivering service-oriented solutions faster, moving the enterprise more efficiently towards a higher level of SOA maturity, and addressing the project needs. Project-based funding will most likely spell doom to the SOA program as a whole.

Service Funding

As discussed earlier, funding for the SOA infrastructure should come from a central source. Where the money comes to build individual services, however, presents a bigger challenge. Since projects are the primary drivers behind demand for services, special consideration should be given to project needs and budgets. However, service design and implementation can incorporate additional requirements that fall outside of the project scope. Another typical project-related problem stems from the shared nature of services. It is unfair to burden a project with the full cost of a service that will be utilized by a number of other consumers.

There are three possible ways to address the service funding concerns.

1. Make the first project to build a service provide the complete funding
2. Establish a central funding source that will cover all service design and construction expenses
3. Provide supplementary funding to projects building services

If option1 is selected, several strategies for recouping the initial investment can be used.

• Do not recoup the investment
• Place a surcharge on each instance of service leverage
• Charge a small fee for each service call

As mentioned above, it is unfair for the project to carry the complete costs of the service build-out, especially if it includes additional requirements. Thus, unless the project implements one of the options to recoup its initial investment, funding option #1 is not going to be viable. Not recovering the funds is not a realistic option either as it does not incent the projects to build truly reusable services. The other cost recovery strategies may work but require detailed metrics to be captured on the service leverage and/or transactional volume.

Establishing a central funding source for all projects to use when building reusable services is probably the ideal approach. Few companies, however, would be willing to write what in essence would be a blank check for the projects to use in their service delivery efforts. The opportunity for abuse and misappropriations would be too tempting. Unless strong governance and control mechanisms are in place, this funding method will most likely end up costing the company more money and provide unrealistically small return on investment.

Providing supplementary funding to projects building services is probably the most realistic approach. A central fund needs to be established to cover the efforts falling outside of the project scope. Since shared services would typically incorporate other projects’ and enterprise requirements, the actual cost ends up being higher than what projects budgeted for their needs. Thus, the easiest way to distribute supplementary funding is to allow the projects to pay for functionality already included in their budgets and cover all the additional costs through the central fund.

Whatever the funding approach is used, it needs to be carefully administered. A party not involved in day-to-day project work is best suited to play the administrative role. There could be a couple different groups managing the infrastructure and service funding and chargeback mechanisms. Overall, however, this should fall under the SOA Governance umbrella and managed centrally as part of the SOA Program.

Service Orchestration Guidelines

Many SOA articles, white papers, and vendor documents talk about “service orchestration”. But understanding of the underlying concepts and orchestration best practices remain elusive.

A quick Google search will produce a number of articles and links that discuss service orchestration and related topics. Most of them will talk about BPM engines, ESBs, and BPEL. This, unfortunately, pollutes the true definition of service orchestration and gives it a much more technology centric view.

In my opinion, Service Orchestration is an automated way to combine several services together to achieve new functionality. The end result is a new composite service that provides a distinct business capability and can be invoked independently. It must have all the appropriate attributes as discussed in my previous article.

Orchestration is a technology independent concept. It can be achieved via a descriptive language such as BPEL, built-in tools within a specific platform (ESBs typically provide their own orchestration mechanisms), or programmatically. Depending on your needs, situation, or technology available, the best way to perform service orchestration may be different. Here are a few guidelines to help you create service orchestrations faster and make them more flexible, maintainable, and scalable.

• Use the platform with built-in orchestration capabilities as your first choice
• Avoid implementing service orchestrations programmatically whenever possible
• Choose a platform or mechanism that can easily perform flow logic, result aggregation, message transformation, and business rule application
• Ensure the composite service fits the definition of a service, i.e. has all the attributes of a service

The rationale behind the above guidelines is very simple. You want to choose a platform that already provides most of the capabilities you will need when creating new service orchestrations. You will typically need to call several services, aggregate their results in some way or chain the calls together through some kind of logic, transform the end result to match the exposed contract(s), and return it. The less work you have to do and the more you can rely on the platform’s capabilities, the more efficient your orchestration will be. If you can complete your orchestration work through a visual interface and never see the code, you are on the right path. This way, you will spend less time maintaining the orchestration, it will be easier to make changes, and you don’t have to build all the necessary mechanisms from scratch.

Many would argue that a programming language will give you the most flexibility when implementing an orchestration. While this is true, the overhead is pretty large and efficiency is low. First of all, no programming language seamlessly integrates all the mechanism you need to create an orchestration, especially in a visual way. Secondly, every time an orchestration needs to change in some way, no matter how small, new code needs to be written, deployed, and tested. While the same steps need to be performed on any orchestration platform, the level of effort will be a lot smaller on full featured orchestration platforms.

When creating service orchestrations, it is important to maintain proper relationships between composite and atomic services. The diagram below shows which services should be allowed to interact with each other.

The following list details the rules and guidelines for establishing relationships between composite and atomic services.

1. Atomic business services should not call each other. Use orchestration to combine several business services together.
   The goal of service orchestration is to combine several services together through a series of logical steps and expose new capability to the consumers. Orchestration platforms, as discussed above, provide a lot of functionality to make this work easy and efficient. If individual services are allowed to call each other, they would not be taking advantage of the orchestration platform’s capabilities. Furthermore, when business services call each other, it establishes a tight coupling between them, which makes them less reusable and harder to maintain. Atomic business services should provide specific, well defined business capabilities and be reusable in their own right. Reliance on other services to complete work indicates plurality of purpose and lack of specificity.
   
2. Business services can call Utility services.
   While coupling services together should be avoided as much as possible, sometimes generic, low level functionality that needs to be invoked from a business service is exposed via utility services. It would be an overkill and sometimes even impossible to use an orchestration platform in order to allow business services to take advantage of such functionality as logging, retrieving or storing configuration information, and authorization.
   
3. Utility services cannot call Business services.
   Utility services should not be tied to any business processes or capabilities. Thus, a utility service calling a business service would violate this rule.
   
4. Business services cannot call Composite services.
   The logic behind this guideline is the same as in disallowing business services call each other. A composite service is also a business service. Thus, a business service calling a composite service should not be allowed.
   
5. Composite services can call other Composite services.
   Other composite services are allowed to participate in orchestrations. They should be treated as regular atomic services in this case.

Note that, even though atomic business services and composite services are, in essence, business services, they are different and guidelines provided above are not contradictory in their treatment. There are two levels at which they should be compared -- logical and physical. From a logical perspective, atomic business services and composite services are the same. They expose some kind of unique business capability and adhere to the service definition guidelines. From a physical perspective, however, they are different. Atomic business services, as opposed to composite services, rely solely on internal business logic and direct interaction with backend data sources to perform their work. Thus, by definition, atomic business services should not call other business services as part of their implementation. By the same token, since composite services already rely on other business services to complete their work, they should not differentiate between calling atomic business services or other composite services.

Service orchestration is a complex topic and might take a series of articles to discuss completely. However, the rules outlined above should establish a good foundation for creating and managing composite services.

Services Explained

Since the SOA term was coined, many discussions raged on what a service was from a business and technical perspectives. In this article, I offer my views on the topic.

There are several categories of services. Many leading SOA vendors and thinkers typically break them down into Business and Utility types. A Business service represents a business capability that is needed to complete a step within a larger business process. Examples may include retrieving customer information, making payments, or checking order status. Utility services represent a technical capability that is business process agnostic. Examples are e-mail, logging, or authentication services.

Services can be combined together to create composite services. This is called orchestration. An example of this can be a Money Transfer service that needs to debit one account and deposit money into another one. Composite services can also be categorized as Business and Utility. Best practices and general orchestration guidelines as related to orchestrations, atomic services, and their relationships will be discussed separately.

Regardless of the type, a service is comprised of three components.

• Interface
• This defines how services are exposed and can be accessed by its consumers.
• Interfaces are not limited to Web Services and can be represented by any remote messaging protocol.
• Contract
• This defines what services expect during the interaction with the consumer. Message structures, relevant policies, and related security mechanisms are all part of a contract.
• Contract defines a “legal” agreement on how the service and its consumers should interact.
• Implementation
  
  • This is the actual service code.

A service may have multiple interfaces. Different consumers may have the need to access the service via different protocols. For example, a Java consumer would like to access a service via a Web Service protocol while a Mainframe application can only use MQ Series. Even though a service may itself expose multiple interfaces, it is more effective to let the ESB platform handle this. For more details about the rationale behind this recommendation, see “To ESB or Not to ESB?" post.

A service may also have multiple contracts. I have recommended in the past that for a service to be maximally reusable, it needs to implement the Service Façade pattern (see “SOA Façade Pattern” post and “Service Façade” pattern). This pattern recommends that multiple different interfaces and contracts for the same service be created. The Concurrent Contracts pattern also addresses this issue.

It is important to understand that while the interface, contract, and implementation describe a service as a whole, they are not closely tied together. An interface is not dependent on the contract details and should not be tied to the specific messaging structure. The opposite is also true – the contract should not be tied to any specific communication protocols. Additionally, the implementation should be flexible enough to accommodate the potential for multiple interfaces and contracts. Ideally, however, I would recommend that a service expose only a single contract and interface and the ESB would take care of exposing additional endpoints and facades as necessary.

SOA Ecosystem

In the previous post, I’ve discussed the role of the ESB in the SOA ecosystem. However, I failed to adequately describe what an SOA ecosystem was and what were all the inter-relationships that must exist in order to make it truly effective.


If you refer to the diagram above, you will notice several major components that make up the SOA Ecosystem.

1. ESB
2. Registry/Repository (RegRep)
3. Security
4. Service Management
5. Shared Service Environments
6. Service Consumers
   

The SOA Ecosystem also encompasses all the related elements such as the application and service developers and testers as well as all the tools being used to accomplish these activities.

To truly comprehend how the SOA ecosystem operates, a clear understanding must be developed of what each component does and what its role is. Let’s start from the service consumer side.

• Service Consumers
  
  • Application Developers build applications that consume services. They use IDEs and other development tools to construct service requests and parse responses. Developers interact with the Registry/Repository to find the right services, obtain service metadata, and understand usage patterns.
  • Application Testers perform quality assurance tasks on the final product.
  • Application Servers that execute the application code interact directly with the SOA platform hosting the services.
• SOA Infrastructure
• Service Management Platform acts as an entry point into the SOA infrastructure. It retrieves policy information about the service being executed and applies it appropriately to the request. The policy is used to understand service security and authority, associated SLAs, constraints, contracts, etc. The Service Management Platform is often utilized to keep track of the service consumption and run-time metrics, which are then fed into the Registry/Repository.
• The role of the Enterprise Service Bus has already been discussed.
• Registry/Repository acts as a central repository for services and their metadata. Its uses and integrations are discussed at each related point.
• Security / Authentication Platform is a part of the larger IT infrastructure and is typically represented by either LDAP or Active Directory technology.
• Shared Service Environments are used to host reusable services. While different organizations choose to approach service hosting differently, if a common service hosting platform can be established, many issues related to service scalability, performance, reuse, security, implementation, standardization, etc. can be easily resolved. A centrally managed platform can be easily upgraded to accommodate additional – foreseen or unforeseen – volume. Standard capabilities can be provided to perform security, authentication, logging, monitoring, instrumentation, deployment, and many other tasks.
• Service Creation
• Service Architects and Developers create reusable services using the appropriate design and development tools. They also interact with the Registry/Repository to discover existing services and register new services and related metadata. The created services should ideally be deployed into a Shared Service Environment.
• Service Testers perform quality assurance tasks on the new or modified services. They use special SOA testing tools to create test cases and automate their execution. These tools interface with the Registry/Repository to retrieve metadata about the services and update related information once testing is complete.
  

Many vendors have slightly different view of how their products integrate and interact with the SOA ecosystem, what components exist, and where they are located. One can also include other elements into the SOA ecosystem such as the EA Repository, CMDB, IT Governance Tools, Monitoring Tools, etc. However, the general dynamics remain the same. The key point is that the SOA infrastructure interacts with the rest of the IT platforms and people in a certain way. In order for SOA to be truly successful, these interactions must become natural, automated, and symbiotic.

To ESB or Not to ESB?

That is the question. Many SOA thought leaders have addressed this topic. Most recently, David Linthicum wondered if ESBs were evil. He also talked about ESBs hurting SOA in his blog. Eric Roch has chimed in on the debate by providing some general guidelines for how to use the ESBs. Joe McKendrick has summarized the recent debate in his blog.

There seems to be a lot of pent up emotions in the industry when it comes to the ESBs. A lot of people tend to view ESBs as over-engineered, complicated, and unnecessary. Maybe, it is a backlash from the vendor hype or consistent experiences with a failed ESB implementation. Maybe, it is a reaction to the industry’s push towards choosing the tools first and fitting the solution into them later rather than vice versa. Maybe, it is a response to the architects calling the ESB implementation Enterprise SOA. I don’t know. What I do know is that ESBs have its place and when properly used are very useful.

SOA in not just about exposing services via a ubiquitous protocol and letting people use them. A successful SOA must have the following elements in place:

• Governance and Processes
• SOA Governance
• SOA Methodology
• SOA Reference Architecture (and possible Reference Implementations)
• SOA Maturity Model
• Service testing and versioning approaches
• SOA design patterns
• Technology
  
  • ESB
  • Service Management platform
  • SOA Governance platform
  • Registry / Repository (often is part of the SOA Governance platform)
  • SOA testing tools

The diagram below depicts the preferred SOA ecosystem and relationships between all of its different components and actors.



Note that the ESB plays a central role in the SOA ecosystem. It needs to be tightly integrated with the Registry/Repository tool that will store policy information and service metadata, service management platform that will ensure compliance to the predefined policies, and platforms exposing the physical service endpoints. ESBs are very useful when utilized to perform the following tasks:

• SLA and policy management
• Security reconciliation
• Protocol reconciliation
• Message transformation
• Orchestration (possibly, in conjunction with a BPM tool)
• Integration
• Logging and instrumentation
• Metrics collection

ESBs can provide all these capabilities in a central location and in a consistent fashion, so that every service does not have to implement them individually. Every service has to perform each of these tasks in some way, shape, or form. Without a central tool, implementations, tools, and approaches will vary. At the end of the day, you will end up with a hodge-podge of different things, which will be hard and costly to maintain.

When services are created, it is impossible to know who and how will consume them. In fact, it should be irrelevant. Services should not worry about all of the potential consumers, protocols, and contracts. It is the job of the ESB to reconcile all of them. Services should not have to include all of this complexity in their designs and implementations. They should only make sure that the business logic is properly implemented and a standard interface is provided. The ESB will take care of the rest.

Obviously, without proper planning and architectural oversight, ESBs can fail. Using an ESB to support only a handful of services is an overkill. Blindly choosing a product without performing adequate analysis always leads to problems. However, putting ESBs in the right place in the SOA ecosystem and utilizing them for the right purposes will only simplify the development, increase efficiency, clearly distribute the responsibilities between architectural components, and improve standardization. ESBs are not evil when used correctly.

SOA and EDA - One and the Same

Event-Driven Architecture (EDA) has received a lot of coverage lately. Gartner’s analysts spent a lot of time last year talking about it and promoting their ideas on how it relates to the Enterprise Architecture. A lot of companies, lead primarily by the financial institutions, have taken the plunge into the EDA. Alerts offered by virtually every bank are a good example of this. However, I do not feel that the relationship between EDA and SOA has been fully explored yet.

EDA is based on the concepts of events, publishers, and subscribers. At the most basic level, the idea behind EDA is that publishers publish events and subscribers consume them. Of course, some logic and rules must be applied to properly route the events. Through this mechanism, systems become connected in a loosely coupled fashion. This makes the integrations a lot easier and eliminates the need for each publisher and subscriber to know the details of how to communicate with each other.

Sounds familiar? Absolutely! Change the terms events, publishers, and subscribers to services, providers, and consumers respectively and the paragraph above reads like an explanation of SOA. Why is this, you would ask? Because EDA is nothing more than an asynchronous version of SOA. The major difference between the two is that services are typically implemented as real time calls while events are published and consumed asynchronously. All the other concepts are virtually the same.

While the architectural approaches and design patterns for EDA are slightly different from SOA, the fundamental concepts are still the same. A central event handling infrastructure that knows how to receive, route, and transform the messages is required. It should be viewed as practically the same thing as the Enterprise Service Bus (ESB). In fact, generically, I would call it the Enterprise Eventing Bus (EEB). As events are published, they need to be translated into a common representation, so that a consistent set of rules and operations can be applied to them. A canonical model is the best solution to achieve this goal. Additionally, the same façade pattern should be used as described in the SOA Façade Pattern post to abstract the publishers from knowing and being tied directly to the Enterprise Canonical Model. Note that the logical EDA architecture presented below is very similar to the one introduced in the SOA Façade Pattern.

Events, just like services, should be registered and be discoverable via a central Registry mechanism. Subscribers looking to consume specific events should be able to discover them at design time and receive them from EEB at the run-time. Design of the events, their publication and consumption should also follow the same standards and patterns as service design. All of the related documentation should be stored in the same centralized repository. Governance mechanisms applied to events should also be very similar to those applied to services. EDA does not require establishing a completely new governance model but can effectively leverage existing SOA governance practices.

The bottom line is that EDA and SOA are virtually the same architectural approaches. If you think about EDA as an asynchronous version of SOA, everything else will fall in place.