Design pattern overview – integration services
Design pattern is a standard solution for common and recurring problems. Design patterns are an effective way to avoid the expensive process of reinventing, rediscovering and revalidating agnostic software artifacts.
Following are some of the key integration patterns that can be followed as a part of integration engagements
Canonical schema pattern
The Canonical schema pattern helps to limit and structure the mapping code required. Canonical means define one and only or the official format for each enterprise business object which contains fields from all the different businesses available in the enterprise. This pattern is applicable in EAI (Enterprise Application Integration) or SOA (Service Oriented Architecture) scenarios
Figure 1: Canonical schema pattern
Content enrichment pattern
Content enrichment pattern enriches the content of received messages for e.g. If the message originator does not have all the required data items available within it, this pattern is used to collect additional information by accessing an external data source. The detailed step required to implement this pattern includes the following steps:
Figure 2: Content enrichment pattern
Content-based router pattern
Content-based routing routes the message based on the content of the message, rather than by an explicitly specified destination. The Content-based router pattern checks the content of the received message and then uses these details to get the routing information for the message. Based on the routing information, a different channel is available to send the data.
There can be a number of criteria such as existence of fields, specific field values, etc. for routing the message. To implement the Content-based router pattern, values must be available at the run time to decide the destination of the message. In this pattern, usage of business rules and dynamic send port configuration plays a key role.
Figure 3: Content-based router pattern
Correlation identifier pattern
In this pattern, each message has a unique identifier attached with the request message. The unique identifier is either generated after the message is received (for e.g. Message ID, GUID (Globally Unique ID)) or should be a part of the request message (for e.g. Business key like Order ID or any primary key through which the message can be identified). Once the message is received by the destination, it fetches the unique identifier and copies that ID to the response message. And finally, the source system can match the ID with the request and response.
Figure 4: Correlation identifier pattern
Request-reply pattern
This pattern is based on the service provider and consumer. As the name indicates, it is asynchronous messaging between the source and target. The request message should be sent through unidirectional channels. To complete the request and response flow, two asynchronous point-to-point channels should be maintained. The message format is different for request and reply.
Figure 5: Request-reply pattern
Error handling pattern
Error handling pattern is used to automate the message failure case. It should be developed and used as a common reusable error handling component. This provides the flexibility to send a message to the designated location in case of failures. Failed messages can be routed to the subscribing port for reporting or processing. This can also be used for alert. This pattern is mainly used in any one of the below cases:
Suspend with retry pattern
The suspend with retry pattern enables the orchestration to suspend a message when there is an error. The suspension occurs within a loop so that the orchestration suspends, asks for intervention, and then retries the operation a fixed number of times.
Splitter pattern
The splitter pattern splits the received message into multiple messages. Each of the individual messages after split will be processed separately.
Figure 6: Splitter pattern
Sequential and parallel convoy:
A sequential convoy is a set of related messages that have a predefined order. In a sequential convoy, all the types of messages are received in an ordered sequence. The first receive shape in the orchestration initializes the correlation set and the other receive shapes in the orchestration follow the correlation set.
Steps to implement via BizTalk:
Sequential convoys can be implemented by using the "sequential correlated receives" messaging design pattern in BizTalk Server.
Create the orchestration with the first receive shape activate property to true and other as false. In the first receive shape, initialize the correlation set so when the first message is received, this starts a new orchestration instance and initializes a correlation set.
Parallel convoy is useful when the same type of messages is supposed to be received from multiple locations and sources. The sequence of messages to be received is also not known. However, the processing of messages starts only when all the required messages will be received by the orchestration.
Figure 7: Sequential and parallel convoy
Scatter and gather
This pattern is a combination of the splitter pattern and the aggregator pattern. So it can be implemented by using the aggregator pattern to assemble the results from using the splitter pattern and put them under a parallel actions shape. The scatter and gather pattern is a method for broadcasting and processing messages in parallel. The "scatter" portion distributes a series of messages all at the same time, and then an aggregator "gathers" the messages back into the main response before continuing
Saikat Kundu
Practice Manager, MAS AED - Microsoft Presales, Wipro Limited.
Saikat is a TOGAF certified architect and Microsoft Certified Professional (MCP), with 15+ years’ experience in analysis, design, development, testing, support and maintenance of enterprise applications in Microsoft cloud and native technologies for global clients. He currently plays the role of Practice Manager in the Microsoft presales team for the O365/Azure/SharePoint/BizTalk/.NET cluster.
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